Chapter 19. Hip

At the completion of this chapter, the reader will be able to:

1. Describe the anatomy of the joint, ligaments, muscles, and blood and nerve supply that comprise the hip joint complex.

2. Describe the biomechanics of the hip joint, including the open- and close-packed positions, normal and abnormal joint barriers, force couples, and the static and dynamic stabilizers of the joint.

3. Describe the purpose and components of the examination of the hip joint.

4. Perform a comprehensive examination of the hip joint, including palpation of the articular and soft tissue structures, specific passive mobility, passive articular mobility tests, and stability stress tests.

5. Evaluate the total examination data to establish a diagnosis.

6. Describe the relationship between muscle imbalance and functional performance of the hip.

7. Summarize the various causes of hip dysfunction.

8. Develop self-reliant intervention strategies based on clinical findings and established goals.

9. Develop a working hypothesis.

10. Describe and demonstrate intervention strategies and techniques based on clinical findings and established goals.

11. Evaluate the intervention effectiveness in order to progress or modify an intervention.

12. Plan an effective home program and instruct the patient in same.

The hip articulation is a ball-and-socket joint formed between the head of the femur and the acetabulum of the pelvic bone (Fig. 19-1). Structurally, the hip is suited for stability first, then mobility.1 The primary function of the hip is to support the weight of the head, arms, and trunk during the static erect posture and during dynamic activities such as ambulation, running, and stair climbing.2 In addition, the hip joint provides a pathway for the transmission of forces between the pelvis and the lower extremities. The hip joint is a marvel of physics, transmitting truly impressive loads, both tensile and compressive. For example, during walking, the hip supports 1.3–5.8 times the body weight, and 4.5–8 times the body weight while running.3 Finally, the hip joint functions to provide a wide range of lower limb movement.

The hip joint is well designed to provide such an important service, provided that it is permitted to grow and develop normally.

Normal hip joint growth and development occur because of a genetically determined balance of growth of the acetabulum and the presence of a strategically located spherical femoral head.4–8

• Absence of a normal femoral head during growth, such as in developmental dysplasia of the hip (DDH), causes the acetabulum to have a flat shape.
• A deformed head stimulates the formation of a correspondingly deformed acetabulum if the deformation occurs at a young enough age.4

Bony Anatomy

The os coxa (hip bone) initially begins life as three individual bones: the ilium, the ischium, and the pubis.

Ilium

The ilium (see Fig. 19-1) is the largest of these three bones. It is composed of a large fan-like wing (ala) and an inferiorly positioned body. The body of the ilium forms the superior two-fifths of the acetabulum.

• The wing of the ilium spans superiorly from the posterior superior iliac spine (PSIS) to the anterior superior iliac spine (ASIS). The wing serves as the insertion for the gluteus minimus, medius, and maximus.
• The anterior surface of the ilium forms a fossa and serves as the proximal attachment of the iliacus muscle.

Ischium

The ischium (see Fig. 19-1) is composed of a body, which contributes to the acetabulum, and a ramus. The ischium forms the posterior two-fifths of the acetabulum. Together, the ischium and the ramus form the ischial tuberosity. The ischial tuberosity is an important landmark for palpation, as it serves as the attachment for several muscles (Table 19-1) and the sacrotuberous ligament. The ischial spine, located on the body of the ischium, serves as the attachment for the sacrospinous ligament.

Pubis

The pubis (see Fig. 19-1) is the smallest of the three bones and consists of a body and inferior and superior rami. The pubis forms the anterior fifth of the acetabulum.

Acetabulum

The ilium, ischium, and pubis fuse together within the acetabulum and form a deep-seated depression in the lateral pelvis, which allows for the proximal transmission of weight from the axial skeleton to the lower extremity.9 The surface of the acetabulum faces laterally, inferiorly, and anteriorly (see Fig. 19-1). The superior and posterior margins of the acetabulum are reinforced with a compact cortical bone, which extends the peripheral brim of the fossa, enhancing the stability of the joint during weight-bearing from both flexed and extended positions.9 While the majority of acetabular development is determined by the age of eight,10–12 the depth of the acetabulum increases additionally at puberty, because of the development of three secondary centers of ossification.4,5,13 Around the periphery of the acetabulum is a thickened collar of fibrocartilage known as the acetabular rim, or labrum (see “The Acetabular Labrum” section), that further deepens the concavity and grasps the head of the femur.9 The transverse acetabular ligament is a fibrous tissue link spanning the inferior acetabular notch that connects the anteroinferior and posteroinferior horns of the semilunar surface of the acetabulum. The posterior aspect of the ligament attaches to the bone beneath the lunate surface, and the anterior aspect attaches to the labrum.14 The transverse acetabular ligament contains no cartilage cells.15 The function of this ligament in the hip is currently unknown.

The articular surface of the acetabulum is limited to an inverted horseshoe-shaped area covering the anterior, superior, and posterior margins.9 This relatively small contact area, may contribute to the prevalence of hip degenerative joint disease in humans.16 The articular surface is covered by a thickened layer of hyaline cartilage, which thins near the center of the joint, and is absent over the acetabular notch (see Fig. 19-1), the area occupied by the ligamentum teres and obturator artery. The diameter of the acetabulum is slightly less than that of the femoral head and results in an incongruous fit of the joint surfaces. This incongruity unloads the joint during partial weight-bearing (PWB), by allowing the femoral head to sublux laterally out of the cup, while in full weight-bearing, the femoral head is forced into the acetabulum.9 In addition, elastic deformation of the acetabulum increases joint congruency of the two-joint surfaces in weight-bearing.17 Finally, a strong vacuum contributes to the joint coaptation.1 The position of maximum articular congruence corresponds to a quadriped position: 90 degrees flexed, slightly abducted, and externally rotated.

Femur

The femur is the strongest and the longest bone in the body. The proximal end of the femur consists of a head, a neck, and a greater and lesser trochanter (see Fig. 19-1). Approximately two-thirds of the femoral head is covered with a smooth layer of cartilage except for a depression, the fovea capitis, which serves as the attachment of the ligamentum teres.

The femoral head is composed of a trabecular bone core encased in a thin cortical bone shell. Both the trabecular framework of the head and its pliable hyaline cartilage covering contribute toward the shaping of the femoral head within the acetabulum during full weight-bearing.9 The trabecular bone in the femoral neck and head is specially designed to withstand high loads because of the incorporation of both primary and secondary compressive and tensile patterns. However, within this trabecular system, there is a point of weakness called the Ward triangle, which is a common site of osteoporotic fracture.18

The neck of the femur is located between the shaft of the femur and its head. On the anterior surface of the femoral neck is the rough intertrochanteric line. The femoral neck serves to extend the weight-bearing forces lateral and inferior to the joint fulcrum. The intertrochanteric crest marks the posterior junction between the neck and the shaft of the femur. The greater trochanter serves as the insertion site for several muscles that act on the hip joint (Table 19-2). The lesser trochanter, located on the posteromedial junction of the neck and the shaft of the femur, is created from the pull of the iliopsoas muscle.

The head of the femur is angled anteriorly, superiorly, and medially. The femoral neck is externally rotated with respect to the shaft. The angle that the femoral neck makes with the acetabulum is called the angle of anteversion/declination (see “Biomechanics” section).

Joint Capsule

The joint capsule of the hip (Fig. 19-2), a substantial fibrous sleeve, attaches proximally to the pelvis just lateral to the acetabular labrum and extends laterally over the femoral head and neck to attach to the intertrochanteric line anteriorly. Posteriorly, the capsule attaches to the lateral one-third of the femoral neck allowing for the attachment of the obturator externus tendon in the posterior intertrochanteric fossa.9 Both the articular cartilage and the joint capsule are thicker anterosuperiorly, where maximal stress and weight-bearing occurs, and thinnest posteroinferiorly. The joint capsule has three thickened regions that constitute the capsular ligaments. These anterior capsular thickenings include the iliofemoral ligament and the pubofemoral ligament.

• The iliofemoral ligament (Y ligament of Bigelow) (Fig. 19-2) consists of two parts: an inferior (medial) portion and a superior (lateral) portion. The iliofemoral ligament is the strongest ligament in the body. The ligament is oriented superior laterally and blends with the iliopsoas muscle. By limiting the range of hip extension, this ligament, with the assistance of the pubofemoral ligament, allows maintenance of the upright posture and reduces the need for contraction of the hip extensors in a balanced stance. Hip adduction tightens the superior portion of the iliofemoral ligament.
• The pubofemoral ligament (Fig. 19-2) blends with the inferior band of the iliofemoral, and with the pectineus muscle. The orientation of the pubofemoral ligament is more inferior-medial. Its fibers tighten in extension and abduction and reinforce the joint capsule along the medial surface.

The posterior thickening of the capsule accounts for the ischiofemoral ligament (Fig. 19-2), which winds posteriorly around the femur and attaches anteriorly, strengthening the capsule. This ligament, which tightens with internal rotation of the hip, is more commonly injured than the other hip ligaments.

All these capsular thickenings/ligaments are taut in hip extension, especially the inferior portion of the iliofemoral ligament. Conversely, all the ligaments are relaxed in hip flexion. In external rotation of the hip, the superior portion of the iliofemoral ligament and the pubofemoral ligament are both taut. Because of their inherent strength, the hip ligaments are only usually compromised with severe macrotrauma involving a fracture/dislocation of the hip.

The ligamentum teres, or capitis femoris ligament (Fig. 19-3), is a structure seen only in the hip joint.9 This ligament spans the hip joint running from the acetabular notch to the fovis capitis of the femur, attaching the femoral head to the inferior acetabular rim. The ligament is entirely enclosed by synovial membrane, which forms a sheath around the ligament. Within this sheath, vessels and nerves pass to the femoral head, providing an important source of arterial blood from a tiny posterior branch of the internal iliac artery. This arterial supply is a significant source of blood to the femoral head in infants and children19 but becomes less significant in adulthood, because of collateral circulation from the circumflex arteries (see “Vascular Supply” section) surrounding the femoral neck, although chronic interruption the blood supply of the femoral head has been associated with avascular necrosis and degenerative arthritis.20

The ligamentum teres tightens during adduction, flexion, and external rotation and, although it provides very little to stability, it can contribute to symptoms when injured.

The Acetabular Labrum

The acetabular labrum (Fig. 19-3) is a ring consisting of fibrocartilage and dense connective tissue21 that encases the femoral head and is attached to the acetabular margin. The acetabular labrum of the hip, to a large extent, is analogous to the meniscus of the knee (see Chap. 20) and the labrum of the glenohumeral joint (see Chap. 16) in that it enhances joint stability, decreases the forces transmitted to the articular cartilage,22,23 and provides proprioceptive feedback.22,23 The majority of the acetabular labrum is thought to be avascular. However, cadaver studies have shown blood vessels entering primarily the peripheral part of the labrum, with penetration only into the outer one-third of the substance of the labrum.21 Nerve-endings and sensory end organs in the superficial layers of the labrum participate in nociceptive and proprioceptive mechanisms.17,24 The osseous acetabulum in the hip provides substantial static stability to the hip joint.24 Deepening of the socket that is provided by the labrum would, therefore, appear to be less important at the hip. Some research does indicate, however, that the labrum may enhance stability by providing negative intra-articular pressure in the hip joint.25 Another study, by Konrath et al.,17 examined the role of the acetabular labrum in load transmission in a biomechanical study. The distribution of contact area and pressure between the acetabulum and the femoral head was measured in cadaver hips before and after removal of the acetabular labrum. No appreciable changes with regard to contact area, load, and mean pressure were noted after removal of the labrum.17

Another proposed function of the labrum is to improve the mobility of the hip by providing an elastic alternative to the bony rim.17 The labrum, which varies greatly in form and thickness, has a triangular cross section: an internal articular surface, an external surface contacting the joint capsule, and a basal surface attached to the acetabular bone and transverse ligaments.15 Most of the labrum is composed of thick, type I collagen fiber bundles principally arranged parallel to the acetabular rim, with some fibers scattered throughout this layer running obliquely to the predominant fiber orientation.26 The normal microvasculature of the acetabular labrum consists of a group of small vessels located in the substance of the labrum traveling circumferentially around the labrum at its attachment site on the outer surface of the bony acetabular extension.27 In addition, the labrum is surrounded by highly vascularized synovium that is present in the capsular recess.27

Muscles

The hip joint is surrounded by a wide variety of muscles that accelerate, decelerate, and stabilize the hip joint. Indeed 21 muscles cross the hip, providing both tri-planar movement and stability between the femur and the acetabulum.28 Consequently, abnormal performance of the muscles of the hip may alter the distribution of forces across the joint articular surfaces, potentially causing, or at least predisposing, degenerative changes in the articular cartilage, bone, and surrounding connective tissues.28 The origin, insertion, and innervation of these muscles are outlined in Table 19-3. Since the hip joint is able to move through a wide range of motion (ROM), a muscle's line of pull may be altered with changing hip position, which makes describing a muscle's action difficult. For example, the orientation of the gluteus medius allows it to work as an internal rotator in hip flexion yet as a weak external rotator in hip extension.29 Similarly, the tensor fascia latae (TFL) is a hip abductor and flexor, depending upon the hip position, while being a weak internal rotator in all positions.30 The hip muscles and their respective actions are outlined in Table 19-3 and Table 19-4.

Iliopsoas

The iliopsoas muscle, formed by the iliacus and psoas major muscles (see Fig. 19-4), is the most powerful hip flexor, while also functioning as a weak adductor and external rotator of the hip. The iliopsoas attaches to the hip joint capsule, thereby giving it some support. Since the muscle spans both the axial and appendicular components of the skeleton, it also functions as a trunk flexor, and affords an important element to the vertical stability of the lumbar spine, especially when the hip is in full extension and passive tension is greatest in the muscle.28,31 Theoretically, a sufficiently strong and isolated bilateral contraction of any hip flexor muscle will either rotate the femur toward the pelvis, the pelvis (and possibly the trunk) toward the femur, or both actions simultaneously.28

Gluteus Maximus

The gluteus maximus (Fig. 19-5) is the largest and most important hip extensor. It is also an important external rotator of the hip. The larger, superficial portion of this muscle inserts at the proximal part of the ITB, while the deep portion inserts into the gluteal tuberosity of the femur. The inferior gluteal nerve, which innervates the muscle, is located on the deep portion.

The gluteus maximus is normally active only when the hip is in flexion, as during stair climbing or cycling, or when extension of the hip is resisted.32

Gluteus Medius

The gluteus medius (Fig. 19-5) is critical for balancing the pelvis in the frontal plane during one leg stance,33 which accounts for approximately 60% of the gait cycle (see Chap. 6).34 During one leg stance, approximately 3 times the body weight is transmitted to the hip joint with two-thirds of that being generated by the hip-abductor mechanism.34 In addition to its role as a stabilizer, the gluteus medius also functions as a decelerator of hip adduction.

Because of its shape, the gluteus medius is known as the deltoid of the hip. The muscle can be divided into two functional parts: an anterior portion and a posterior portion. The anterior portion works to flex, abduct, and internally rotate the hip. The posterior portion extends and externally rotates the hip. On the deep surface of this muscle is located the superior gluteal nerve and the superior and inferior gluteal vessels.

Gluteus Minimus

The gluteus minimus (Fig. 19-6), the major internal rotator of the femur, is a relatively thin muscle situated between the gluteus medius muscle and the external surface of the ilium. It receives support from the TFL, semitendinosus, semimembranosus, and gluteus medius.32 The gluteus minimus also abducts the thigh, as well as helping the gluteus medius with pelvic support.

Piriformis

The piriformis (Fig. 19-6) is an external rotator of the hip at less than 60 degrees of hip flexion. At 90 degrees of hip flexion, the piriformis reverses its muscle action, becoming an internal rotator and abductor of the hip.35 Because of its close association with the sciatic nerve, the piriformis can be a common source of buttock and leg pain.36–39

Rectus Femoris

The rectus femoris muscle (Fig. 19-7), one of the four quadriceps muscles (see Chap. 20), is a two-joint muscle that arises from two tendons: one, the anterior or straight, from the anterior inferior iliac spine (AIIS); the other, the posterior or reflected, from a groove above the brim of the acetabulum. The rectus femoris combines movements of flexion at the hip and extension at the knee. It functions more effectively as a hip flexor when the knee is flexed, as when a person kicks a ball.32

Obturator Internus

The obturator internus (Fig. 19-6) is normally an external rotator of the hip and an internal rotator of the ilium but becomes an abductor of the hip at 90 degrees of hip flexion.40

Obturator Externus

The obturator externus (Fig. 19-6), named for its location external to the pelvis, is an adductor and external rotator of the hip.15

Gemelli

The superior and inferior gemelli muscles (Fig. 19-6) are considered extensions of the obturator internus tendon. The superior gemellus is the smaller of the two. Both the gemelli function as minor external rotators of the hip.15

Quadratus Femoris

The quadratus femoris muscle (Fig. 19-6), another external rotator of the hip, is a flat, quadrilateral muscle, located between the inferior gemellus and the superior aspect of the adductor magnus. The quadratus femoris and the inferior gemellus share the same innervation (L4–L5).15 The obturator internus and superior gemellus also share the same innervation (L5–S1).15

Pectineus

The pectineus (see Fig. 19-7) is an adductor, flexor, and internal rotator of the hip. Like the iliopsoas, the pectineus attaches to and supports the joint capsule of the hip.

Tensor Fascia Latae

The TFL (see Fig. 19-5) envelops the muscles of the thigh. The TFL counteracts the backward pull of the gluteus maximus on the iliotibial band (ITB). The TFL also flexes, abducts, and externally rotates the hip. The trochanteric bursa is found deep to this muscle, as it passes over the greater trochanter (see later).43 The attachment of the TFL via the ITB to the anterolateral tibia provides a flexion moment in knee flexion and an extension moment in knee extension.2

Sartorius

The sartorius muscle (see Fig. 19-7) is the longest muscle in the body. The sartorius is responsible for flexion, abduction, and external rotation of the hip, and some degree of knee flexion.44

Hamstrings

The hamstrings muscle group consists of the biceps femoris, the semimembranosus, and the semitendinosus.

Biceps Femoris

The biceps femoris (see Fig. 19-8) arises by way of a long and short head. Only the long head acts on the hip. The long head is active during conditions that require lower amounts of force, such as decelerating the limb at the end of the swing phase and during forceful hip extension.45 The biceps femoris extends the hip, flexes the knee, and externally rotates the tibia. The biceps femoris (53%) is the most commonly strained muscle of the hamstring complex. The anatomy of the biceps femoris may help to explain its higher rate of injury. Firstly, it has a long and a short head, both with separate nerve supplies. This dual innervation may lead to asynchronous stimulation of the two heads. Mistimed contraction of the different parts of the muscle group may mean a reduced capacity to generate effective tension to control the imposed loads of the muscle. There may also be anatomical variations in the attachments of biceps femoris, which may predispose certain people to injury. Burkett suggested that an extensive femoral attachment of the short head of the biceps femoris with an overlying strength deficit pre-disposes to hamstring strain. The long head of the biceps femoris originates from the lower part of the sacrotuberous ligament; therefore, it could be argued that the biceps femoris has a triarticular function and is, therefore, more predisposed to injury than the other hamstring muscles. The insertion of the biceps femoris into the head of the fibula may also be a predisposing factor to injury. A previous knee or ankle injury resulting in alteration in the movement of the superior tibiofibular joint may affect the biomechanics of the biceps femoris, although this notion is speculative. However, incomplete knee excursion caused by meniscal damage may lead to excessive loading of the biceps femoris.46 The biceps femoris acts as an external rotator of the semiflexed knee and the extended hip. Given the rotational demands of many sports, this function may also predispose the biceps femoris to injury.

Semimembranosus

The semimembranosus (see Fig. 19-8) gains its name from its membranous origin at the ischial tuberosity.

Semitendinosus

The semitendinosus (see Fig. 19-8) arises from the ischial tuberosity and inserts as part of the pes anserinus on the superior and medial aspect of the tibia, and deep fascia of the leg.

All three muscles of the hamstring complex (except for the short head of the biceps) work with the posterior adductor magnus and the gluteus maximus to extend the hip. The hamstrings also flex the knee and weakly adduct the hip. The long head of the biceps femoris helps with external rotation of the thigh and leg; the more medial semimembranosus and semitendinosus muscles assist with internal rotation of the thigh and leg. When the hamstrings contract, their forces are exerted at both the hip and knee joints simultaneously; functionally, however, they can actively mobilize only one of the two joints at any one time. Compared to walking and jogging, running is a stressful activity for the hamstrings and increases the high demands on their tendon attachments, especially during eccentric contractions. During running, the hamstrings have three main functions:

1. They decelerate knee extension at the end of the forward swing phase of the gait cycle. Through an eccentric contraction, the hamstrings decelerate the forward momentum (i.e., leg swing) at approximately 30 degrees short of full knee extension. This action helps provide dynamic stabilization to the weight-bearing knee.

2. At foot strike, the hamstrings elongate to facilitate hip extension through an eccentric contraction, thus further stabilizing the leg for weight-bearing.

3. The hamstrings assist the gastrocnemius in paradoxically extending the knee during the takeoff phase of the running cycle.

Hip Adductors

The adductors of the hip (Fig. 19-9) are found on the medial aspect of the joint.

Adductor Magnus

The adductor magnus is the most powerful adductor, and it is active to varying degrees in all hip motions except abduction. The posterior portion of the adductor magnus is sometimes considered functionally as a hamstring because of its anatomic alignment. Because of its size, the adductor magnus is less likely to be injured than the other hip adductors.47

Adductor Longus

The adductor longus is the most prominent muscle of the adductors during resisted adduction, and forms the medial border of the femoral triangle. The adductor longus also assists with external rotation, in extension, and internal rotation in other positions. The adductor longus is the most commonly strained adductor muscle.48

Gracilis

The gracilis (see Fig. 19-9), the longest of the hip adductors, is also the most superficial and medial of the hip adductor muscles. The gracilis functions to adduct and flex the thigh and flex and internally rotate the leg.

The other adductors of the hip include the adductor brevis, obturator externus, and the pectineus muscles. The main action of this muscle group is to adduct the thigh in the open kinetic chain and stabilize the lower extremity to perturbation in the closed kinetic chain. Each individual muscle can also provide assistance in femoral flexion and rotation.49

Bursa

There are more than a dozen bursae in this region.50 The more clinically significant ones are described below.

Iliopsoas Bursa

Many names have been used to describe the iliopsoas bursa (IPB), including the iliopsoas, iliopectineal, iliac, iliofemoral, and subpsoas bursa.51 The IPB is the largest and most constant bursa about the hip, present in 98% of normal adult individuals, usually bilaterally.52 The IPB is situated deep to the iliopsoas tendon and serves to cushion the tendon from the structures on the anterior aspect of the hip joint capsule. Its dimensions may be up to 7 cm in length and 4 cm in width.52 Anatomic boundaries of the bursa include the iliopsoas muscle anteriorly, the pectineal eminence and the hip joint capsule posteriorly, the iliofemoral ligament laterally, and the acetabular labrum medially.53

In 15% of patients, the IPB communicates with the hip joint via a 1-mm-to-3-cm point of relative capsular thinning between the iliofemoral and pubofemoral ligaments.18,51 While this connection may occur on a congenital basis,51 this number rises to 30–40% in patients with hip joint pathology.54

As with other bursae, the IPB can become inflamed and distended. Inflammation and distension of this bursa are most commonly associated with rheumatoid arthritis, but it is also seen in association with athletic activity, overuse and impingement syndromes, osteoarthrosis, pigmented villonodular synovitis, synovial chondromatosis, infection, pseudogout, metastatic bone disease, and, in rare cases, after THA (see “Interventions” section).55

Trochanteric Bursa

Three bursae are consistently present at the greater trochanter, two major bursae and one minor bursa. The two clinically significant trochanteric bursae are the subgluteus medius bursa, and the more superficial subgluteus maximus bursa:

• Subgluteus medius bursa: located at the superoposterior tip of the greater trochanter and functions to prevent friction between the gluteus medius muscle and the greater trochanter and also between the gluteus medius and gluteus minimus muscles.
• Subgluteus maximus bursa: located between the greater trochanter and the fibers of the gluteus maximus and tensor fascia lata muscles as they blend into the ITB

Ischiogluteal Bursa

The ischiogluteal bursa is located between the ischium and the gluteus maximus muscle. It can be painfully squeezed between the ischial tuberosity and the hard surface of a chair during sitting, producing an ischial bursitis. This condition is often referred to as weaver's bottom.

Femoral Triangle

For topographic reasons, it is important to have an understanding of the anatomy of the femoral triangle. The femoral triangle is defined superiorly by the inguinal ligament, medially by the adductor longus, and laterally by the sartorius (Fig. 19-10). The floor of the triangle is formed by portions of the iliopsoas on the lateral side and by the pectineus on the medial side (Fig. 19-10). A number of neurovascular structures pass through this triangle. These include (from medial to lateral) the femoral vein, artery, and nerve (Fig. 19-10). Thus, the clinician should use caution when palpating in this area or applying soft tissue techniques.

Neurology

The posterior gluteal region receives cutaneous innervation by way of the subcostal nerve; the iliohypogastric nerve; the posterior (dorsal) rami of L1, L2, and L3; and the posterior (dorsal) primary rami (cluneal nerves) of S1, S2, and S3 (Figs. 19-11, and 19-12A).56

The anterior region of the hip has its cutaneous supply divided around the inguinal ligament. The area superior to the ligament is supplied by the iliohypogastric nerve. The area inferior to the ligament is supplied by the subcostal nerve, the femoral branch of the genitofemoral nerve, and the ilioinguinal nerve (see Chap. 3).56

The nerves of the muscles that cross the hip joint (femoral, obturator, superior gluteal, and the nerve to the quadratus femoris) also supply the joint capsule and the joint. Therefore, pain referred from the hip joint may be felt anywhere in the thigh, leg, or foot.

Vascular Supply

The internal iliac artery becomes the femoral artery (Figs. 19-12B and 19-13), as it passes underneath the inguinal ligament. The femoral artery forms two branches. The anterior portion of the femoral neck and the anterior portion of the capsule of the hip joint are supplied by the lateral femoral circumflex artery. The medial femoral circumflex artery (MFCA) perforates and supplies the posterior hip joint capsule and the synovium.56 The deep branch of the MFCA gives rise to two to four superior retinacular vessels and, occasionally, to inferior retinacular vessels.57,58

Most of the femoral head, comprising its upper one-half or upper two-thirds, is supplied by the obturator artery and a terminal branch of the MFCA (Fig 19-3).20 The inferior epiphyseal artery, a branch of the lateral circumflex artery, contributes to the vascularization of the lower area of the femoral head. The supply to the femoral head from the ligamentum teres artery is extremely variable.59 The blood supply to the weight-bearing portion of the head of the femur is derived from the MFCA.60

Two other branches are formed from the internal iliac artery: the inferior and superior gluteal arteries. These arteries supply the superior portion of the capsule and the gluteus maximus muscle.

The hip joint, classified as an unmodified ovoid joint, has three degrees of freedom, which permits motion in three planes: sagittal (flexion and extension around a transverse axis), frontal (abduction and adduction around an anteroposterior axis), and transverse (internal and external rotation around a vertical axis) (Fig. 19-14). All three of these axes pass through the center of the femoral head.

Active range of motion (AROM) of the hip is variable. Hip flexion averages 110–120 degrees, extension 10–15 degrees, abduction 30–50 degrees, and adduction 25–30 degrees. Hip external rotation averages 40–60 degrees and internal rotation averages 30–40 degrees (Table 19-5). Motions about the hip joint can occur independently; however, the extremes of motion require motion at the pelvis.61

The structure and design of the hip allows for both mobility and stability. The stability is particularly important for weight-bearing and ambulation. In the human body, the center of gravity is located at the second sacral vertebral level, several segments above and medial to the femoral head. Control of the body mass from such a distant fulcrum requires the generation of significant counterbalance forces as well as the ability of the joint to sustain both high compression and tensile strains.62

Quantitative and qualitative analysis of the generation of compressive forces at the hip and the muscular mechanisms during weight-bearing have been thoroughly documented.63–70 During walking, the hip extensors have a vital, stabilizing role at the onset of each stride. As body weight is dropped onto the forward limb, the extensor muscles contract sharply to preserve upright stance by resisting the forward fall of the pelvis and the trunk.71 The hip's flexed position, before attaining the passive stability provided by full extension in midstance, creates the demand (see Chap. 6). In a standing position, weakness of the hip extensors causes the pelvis to fall forward.71

The relationship between the proximal femur, the greater trochanter, and the overall femoral neck width is affected by muscle pull and the forces transmitted across the hip joint. In addition, normal joint nutrition, circulation, and muscle tone during development play an important role.4,72–74

In the anatomic position, the orientation of the femoral head causes the contact force between the femur and the acetabulum to be high in the anterosuperior region of the joint.75 Since the anterior aspect of the femoral head is somewhat exposed in this position, the joint has more flexibility in flexion than extension.76

The femoral neck is subjected to shearing and torsional strains because of its oblique orientation to the shaft of the femur.9 Downward forces act to displace the femoral head inferiorly and to bend the femoral neck downward. To counter these forces, the femoral neck has developed a unique system of obliquely oriented trabeculae that traverse the head and the neck.9 The angle between the femoral shaft and the neck is called the collum/inclination angle (Fig. 19-15). This angle is approximately 125–130 degrees (Fig. 19-15)35 but can vary with body types. In a tall person, the collum angle is larger. The opposite is true with a shorter individual. The collum angle has an important influence on the hips. An increase in the collum angle causes the femoral head to be directed more superiorly in the acetabulum and is known as coxa valga (Fig. 19-15). Coxa valga has the following effects at the hip joint:

• It alters the orientation of the joint reaction force (JRF) from the normal vertical direction to one that is almost parallel to the femoral shaft.77,78 This lateral shift of the JRF reduces the available weight-bearing surface, resulting in an increase in stress applied across joint surfaces not specialized to sustain such loads.
• The moment arm of the hip abductors is shortened, placing these muscles in a position of mechanical disadvantage.78 This causes the abductors to contract more vigorously to stabilize the pelvis, producing an increase in the JRF.76
• It increases the overall length of the lower extremity, impacting other components in the kinetic chain. For example, coxa valga decreases the normal physiologic angle at the knee, which places an increased mechanical stress on the medial aspect of the knee joint and more tensile stress on the lateral aspect of the joint.

If the collum angle is reduced, resulting in a more horizontal orientation of the femoral neck, it is known as coxa vara (Fig. 19-15). This position increases the downward shear forces on the femoral head and the tensile stretching forces through the superior trabecular bone along the lateral portion of the neck.9 In coxa vara, the joint compression forces are significantly reduced as the greater trochanter is displaced lateral and superior, which increases the effective angle of pull and the lever arm of the hip abductors.79 While the reduced compressive forces generated across the joint surfaces serve to decrease the incidence of articular cartilage damage, the increase in shearing and torsional forces at the femoral head/neck junction significantly increases the incidence of damage to the epiphyseal plate.9

Femoral alignment in the transverse plane also influences the mechanics of the hip joint. The torsion angle of the femur describes the relative rotation that exists between the shaft and the neck of the femur. Normally, as viewed from above, the femoral neck projects on average 5–15 degrees anterior to a mediolateral axis to the femoral condyles. An anterior orientation of the femoral neck to the transverse axis of the femoral condyles, is known as anteversion (Fig. 19-16), or a reverse orientation known as retroversion.76,80,81 The normal range for femoral alignment in the transverse plane in adults is 5 degrees of anteversion (Fig. 19-16).81,82 Typically, an infant is born with about 30 degrees of femoral anteversion.83,84 This angle usually decreases to 15 degrees by 6 years of age because of bone growth and increased muscle activity. Subjects with excessive anteversion usually have more hip internal rotation ROM than external rotation, and gravitate to the typical “frog-sitting” posture as a position of comfort. There is also associated in-toeing while weight-bearing.76

Excessive anteversion directs the femoral head toward the anterior aspect of the acetabulum when the femoral condyles are aligned in their normal orientation. Some studies have supported the hypothesis that a persistent increase in femoral anteversion predisposes to osteoarthritis (OA) of the hip,79,85–88 and knee,89–91 although other studies have refuted this.92–94

The most stable position of the hip is the normal standing position: hip extension, slight abduction, and slight internal rotation.15,70,95 The commonly cited open-packed (resting) positions of the hip are between 10 and 30 degrees of flexion, 10–30 degrees of abduction, and 0–5 degrees of external rotation.

When body weight is evenly distributed across both legs during upright standing, the forces acting on the hip joint are equivalent to half the partial weight made up of the trunk, head, and upper extremities.96 Were this partial body weight to represent 60% of total body mass, then each hip would be compressed by a force equal to 30% of the total body weight. In a single-limb support, however, shifts in the center of gravity away from the supporting limb dramatically change the equilibrium forces necessary to maintain balance and create a state of disequilibrium. This state of disequilibrium requires the generation of compensatory forces by the hip musculature, in order to maintain balance. The hip joint is the fulcrum for all of the forces. Depending on the length of the moment arm created by the abductor muscles, the added force of the hip abductors acting on the hip joint can increase the pressures translated across the joint to levels exceeding three times body weight.96

During ambulation, these compressive joint forces are further multiplied by ground reaction forces and inertial forces related to acceleration and deceleration of the lower limb. Because of muscle tension, compression on the hip is approximately the same as body weight during the swing phase.97 However, during the support phase, peak joint forces can range from 300 to 400% of body weight at normal walking speed, to 550% of body weight during fast walking and jogging, and as high as 870% of body weight during stumbling.32,98 Stair climbing and descending increase the loads on the hip by approximately 10% and 20%, respectively.32,99 When pain accompanies degeneration of the hip joint articulation, the body compensates by attempting to reduce the forces generated across the articular surfaces. Since the contribution of body mass cannot be changed, the patient attempts to reduce joint pressures by shifting the upper trunk over the supporting limb during the stance phase. While this maneuver decreases the joint compression forces, the energy expended by laterally bending the trunk during stance significantly increases the energy cost of gait. For a patient with a painful hip, the use of a cane or crutch in the hand contralateral to the involved hip can be used to substantially reduce the excessive trunk motion and to decrease pressure on the hip joint.2

Bending forward at the waist requires a coordinated sequence of movements between the lumbar spine, pelvis, and hips. As the head and the upper trunk initiate flexion, the pelvis shifts posteriorly to maintain the center of gravity over the base of support. The trunk continues to forward bend, being eccentrically controlled by the extensor muscles of the spine, until approximately 45 degrees at which point the posterior ligaments of the spine become taut, and the facets of the zygapophyseal joints approximate. Once all of the vertebral segments are at the end of the range and stabilized by the posterior ligaments and facets, the pelvis begins to rotate forward (anterior pelvic tilt), being controlled eccentrically by the gluteus maximus and hamstring muscles. The pelvis continues to rotate forward until the full length of the muscles is reached. The return to the upright position begins with the hip extensor muscles rotating the pelvis posteriorly through reverse muscle action, then the back extensor muscles extending the spine from the lumbar region upward.

The hip extensor muscles, as a group, produce the greatest torque across the hip of any of the muscle groups.103 This extensor torque is often used to rapidly accelerate the body upward and forward from a position of hip flexion, such as when pushing off into a sprint, arising from a deep squat, or climbing a very steep hill.28 Furthermore, with the hip markedly flexed, many of the adductor muscles produce an extensor torque, thereby assisting the primary hip extensors.104 With the trunk held relatively stationary, contraction of the hip extensors and abdominal muscles (with the exception of the transversus abdominis) functions as a force couple to posteriorly tilt the pelvis (Fig. 19-17).28 Assuming the trunk remains upright during this action, the lumbar spine must flex slightly, thereby reducing its natural lordotic posture. 28

The functional potential of the entire external rotator muscle group at the hip is most fully recognized while performing pelvic and trunk rotation activities while bearing weight over one limb. With the right femur held relatively fixed, contraction of the external rotators would rotate the pelvis and the attached trunk to the left. This action of planting the limb and cutting to the opposite side is a natural way to abruptly change direction while running.28 The gluteus maximus appears uniquely designed to perform this action as, with the right limb securely planted, a strong contraction of the gluteus maximus would, in theory, generate a very effective extension and external rotation torque about the right hip, helping to provide the necessary thrust to the combined-cutting and propulsion action.28

In sharp contrast to the external rotators, no muscle with any potential to internally rotate the hip lies even close to the horizontal plane in the anatomic position, making it difficult to assign any muscle as a primary internal rotator of the hip.28,105 Since the overall orientation of the internal rotator muscles is positioned closer to the vertical and horizontal position, these muscles possess a far greater biomechanical potential to generate torque in the sagittal and frontal planes than in the horizontal plane.28

The adductors of the hip are found on the medial aspect of the joint. The primary function of this muscle group is to create an adduction torque bringing the lower extremity toward the midline.106 This adduction torque can also bring the pubis symphysis region of the pelvis closer to the femur.106 From the anatomic position, the adductors are also considered hip flexor muscles.

The most frequent demands placed on the hip abductors occur while walking during the single-limb support phase of walking.28 The external (gravitational) abduction torque about the hip dramatically increases within the frontal plane as soon as the contralateral limb leaves the ground.107 The hip abductors respond by generating an abduction torque about the stance hip that stabilizes the pelvis relative to the femur.107 In addition, the hip abductors can hike the hip when working concentrically, and can lower the pelvis when working eccentrically.

According to Cyriax,108,109 the capsular pattern of the hip is a marked limitation of flexion, abduction, and internal rotation. Kaltenborn95 considers the capsular pattern of the hip to be extension more limited than flexion, internal rotation more limited than external rotation, and abduction more limited than adduction. Klassbo and colleagues110 performed a theory-testing, observational, cross-sectional, and descriptive study involving 168 patients (mean age 61.7 years, range 36–90 years), of whom 50 had no hip OA, 77 had unilateral hip OA, and 41 had bilateral OA, based on radiological reports. The purpose of the study was to arrange and describe passive range of motion (PROM) patterns and to count the number of hips presenting with Cyriax's or Kaltenborn's capsular patterns. One examiner tested PROM bilaterally, using a goniometer and a standardized protocol. PROM limitations were calculated by comparing norms from the symptom-free hips (n = 100) in the study, from Kaltenborn, and, in patients with unilateral hip OA (n = 77), from the non-OA hip. The limitations were arranged by size in PROM patterns. The patterns and the numbers of hips with patterns corresponding to Cyriax's and Kaltenborn's capsular patterns were counted. Between 68 and 138 PROM patterns were identified by the use of different PROM norms for defining limitations. The results from this study showed that few OA hips showed Cyriax's capsular pattern and none demonstrated Kaltenborn's capsular pattern. In addition, it was concluded that it is impossible to anticipate radiological evidence of hip OA from the multitude of PROM patterns. A more useful determination can be made by assessing hip ROM in all planes and, if three planes of motion or more are restricted, OA is likely present.111

Although injuries of the hip are not as common as injuries to the knee or shoulder, they can create diagnostic and therapeutic challenges, and diseases of the hip can be very disabling. The common pathologies and the interventions for the hip joint are detailed after the examination. Table 19-7 outlines the clinical findings, differential diagnosis, and intervention strategies of some hip conditions, and Table 19-8 describes some of the physical findings for some of the more common causes of hip and thigh pain. An understanding of the pathology and the clinical findings is obviously necessary. Identifying the primary source of the pain is essential if one hopes to provide long-lasting relief of the symptoms. Acute presentations usually have a clear and identifiable cause, whereas in chronic conditions the true etiology may not be as obvious. For example, a protracted hip joint disorder can result in compensations that can develop secondary dysfunctions, which in turn may lead to symptoms such as trochanteric bursitis or chronic gluteal discomfort. As mention of the various pathologies occurs with reference to the examination and vice versa, the reader is encouraged to switch between the two.

History

The importance of history taking cannot be overemphasized as the potential causes of hip pain are numerous (Table 19-9). The history should determine the onset of the symptoms, the mechanism of injury, if any, and the patient's chief complaint. A medical screening questionnaire for the pelvis, hip, and thigh is provided in Table 19-10. It is important for the clinician to determine:

Patient Age

The patient's age may help in the diagnosis. OA of the hip is diagnosed most often in patients over 60 years of age, although it can occur earlier.

Pain Location

The location of the pain can provide the clinician with some useful information (Table 19-12). Complaints of hip or groin pain, morning stiffness, stiffness after sitting, and hip pain with weight-bearing are suggestive of joint involvement, such as OA. It is important to identify patients with symptomatic OA correctly and to exclude conditions that may be mistaken for or coexist with OA.113,114 Periarticular pain that is not reproduced by passive motion and direct joint palpation suggests an alternate etiology such as bursitis, tendinitis, or periostitis. Groin pain can result from local and referred sources. One of the more common causes of groin pain in the older patient is OA of the hip. However, OA of the hip may also cause pain behind the greater trochanter, anterior thigh, and knee because of the various nerves that cross the hip.115

Lateral and posterior hip (buttock) and thigh pain may be referred from the lumbar spine.

Distribution of Symptoms

The distribution of painful joints is helpful to distinguish OA from other types of arthritis because MCP, wrist, elbow, ankle, and shoulder arthritis are unlikely locations for OA except after trauma.

Symptom Fluctuations

The time of day that appears to change the pain for better or worse can provide some clues. Hip joint pathology is usually associated with stiffness of the hip in the morning on arising. Such pathologies include

• OA of the hip joint;
• rheumatoid arthritis of the hip joint; prolonged morning stiffness (greater than 1 hour) should raise suspicion for this type of inflammatory arthritis;
• avascular necrosis of the femoral head.

Motion Restrictions

The first two motions that are diminished in hip OA are usually hip internal rotation and hip flexion, although as previously discussed, this can vary significantly.116 A significant decrease or loss of motor function will always necessitate imaging studies to rule out an avulsion fracture, and/or nerve injury (see Chap. 7).

Mechanism of Injury

Patients who present with acute macrotrauma (e.g., falls and motor vehicle accidents) and who report having difficulty moving the hip or bearing weight require radiographs to rule out a fracture and/or dislocation. Falls on the outside of the hip are a common cause of trochanteric bursitis or contusion of the iliac crest (hip pointer). Such an injury may also involve the abdominal and/or gluteal muscles at their attachment sites. When the abdominal muscles are involved, patients may complain of pain with deep inspiration or have difficulty with trunk rotation.117 Macrotraumatic forces applied along the femur such as those that occur with dashboard injuries and falls on the knee can result in damage to the articular cartilage, an acetabular labrum tear, a pelvic fracture, or a hip subluxation. An immediate loss of movement following direct trauma to this area usually indicates the presence of a hip or pelvic fracture, or a dislocation. Posterior contusions to the gluteus maximus and sciatic nerve can occur from a direct blow to the buttock.117 In such cases, the patient may complain of pain in the buttocks and of pain, numbness, and/or tingling radiating down the course of the sciatic nerve. Both the athlete and nutritionally compromised individual are at risk of pelvic rami or femoral neck stress fractures. Anterior blows to the thigh can produce quadriceps contusions. These contusions can also result in myositis ossificans. The femoral nerve is fairly well protected and not usually injured. Acute muscle strains in the hip and thigh region, especially of the hamstrings, are usually seen in the athletic individual, most often occurring following a short sprint, jump kick, fall, or collision.117 Quadriceps strains, usually involving the rectus femoris, occur in sprinters and kickers. The most frequently strained adductors are the longus and magnus, while hamstring injuries usually involve the biceps femoris.118–120

If the patient is unable to recall a specific mechanism, the clinician should suspect a systemic (see “Systems Review” section and Chap. 5) or biomechanical cause. The hip is a region that is prone to overuse injuries. Walking or running can aggravate trochanteric bursitis, ITB friction syndrome, hamstring and adductor strains, or a femoral neck stress fracture. Pain with bursitis is frequently referred along the course of the muscle it underlies and nearby neurologic structures.117 Obturator internus bursitis can refer pain to the back and buttock or along the course of the sciatic nerve. Subtrochanteric bursitis commonly refers pain to the LB, lateral thigh, knee, and hip.117 Iliopectineal bursitis can refer pain along the course of the femoral nerve and anterior thigh. Ischiogluteal bursitis can refer pain along the posterior femoral cutaneous or sciatic nerve.117

Behavior of Symptoms

Reports of twinges of pain with weight-bearing activities may indicate the presence of a loose body within the joint. Noises in and around the joint can result from many causes so are not particularly diagnostic. One of the more common causes for clicking is a “snapping” hip, especially if the snapping consistently occurs at approximately 45 degrees of hip flexion. This type of snapping hip is thought to be because of the iliopsoas tendon riding over the greater trochanter or anterior acetabulum. The other types of snapping hip are described in the “Interventions” section. If pain is associated with the clicking, it requires further investigation.

Aggravating or Relieving Factors

Information must be gathered with regard to the activities or positions that appear to aggravate or lessen the symptoms. For example, prolonged sitting on a hard surface may aggravate the ischial bursa, whereas buttock pain with prolonged sitting on a soft surface is more likely to be the result of a lumbar disk lesion. Rising from a seated position can be especially painful and the patient may experience an accompanying catching or sharp stabbing sensation. Entering and exiting an automobile is often difficult, because the hip is in a flexed position along with twisting maneuvers. As the hip is a weight-bearing joint and weight-bearing tends to aggravate articular pathologies, it is very important to gather information concerning the role of weight-bearing in painful activities, particularly whether the patient has pain at rest as well as during weight-bearing, or whether specific weight-bearing activities (e.g., stair climbing and walking) are the cause of increased pain.

Questions about work environment, athletic participation, and other daily and recreational activities help the clinician identify risk factors for cumulative trauma that might not be apparent to the patient.117 Activities and positions that aggravate and alleviate symptoms should be identified (Table 19-11).

The hip and pelvic areas are also common sites for pain referral (Table 19-12). The differential diagnosis of hip pain is described in Chapter 5. To help determine the symptom distribution, a pain diagram should be completed by the patient (see Chap. 4). Following its completion, the patient should be encouraged to describe the type of symptoms experienced for each of the areas highlighted on the diagram, as well as the motions or positions that increase or decrease the symptoms. Since the lumbar spine can refer symptoms to the hip region, the clinician should always rule out involvement of the lumbar spine before a hip problem is suspected. The most common source of referred pain from the LB includes both neurogenic (nerve root compression) and spondylogenic (facet or sacroiliac joint) causes. Brown and colleagues124 identified a limp, groin pain, and limited hip internal rotation as signs that significantly predicted a hip problem rather than a lumbar problem.

Finally, the clinician should determine the impact that the patients' condition has on their activities of daily living (ADL).

Systems Review

Referred pain to the hip is common and should be considered in the absence of acute trauma or when symptoms do not clearly originate from the hip. Pain may be referred to the hip region from a number of neuromusculoskeletal sources (see Chap. 5). In addition to those already mentioned, these can include

• pubic symphysis dysfunction;
• sacroiliac joint dysfunction;
• lumbar and low thoracic disk-degenerative disease;
• lumbar stenosis with neurogenic claudication;
• peripheral nerve entrapments (lateral cutaneous nerve of the thigh);
• myofascial pain syndrome;
• spondyloarthropathy.

Complaints associated with referred pain include

• thigh pain, knee pain, and leg pain with or without hip pain, which may be indicative of lumbar radiculopathy;
• pain that is decreased with walking up stairs, which may indicate the presence of lumbar spine stenosis.

Referred pain is often related to posture and positioning. Other conditions that can refer symptoms to the pelvis, hip, and thigh region in an adult include cancer, pathological fractures of the femoral neck, and osteonecrosis of the femoral head (avascular necrosis). In the child, pain and loss of range at the hip joint should always alert the clinician to the possibility of transient synovitis, Legg–Calvé–Perthes disease, or a slipped femoral capital epiphysis (Table 19-13).

The Cyriax lower quarter scanning examination can be used to screen for the presence of upper or lower motor neuron lesions or the referral of symptoms from the spine (see Chap. 4). Key muscle testing is used to test for neurologic weakness. (see also “Active, Passive, and Resistive Tests” section).

Trigger points in patients with myofascial pain syndrome can cause both localized and referred symptoms that often closely resemble the referral patterns of a radiculopathy.117

Evidence of intense inflammation on examination suggests infectious or microcrystalline processes such as gout or pseudogout. Weight loss, fatigue, fever, and loss of appetite should be sought out, because these are clues to a systemic illness such as polymyalgia rheumatica, rheumatoid arthritis, lupus, or sepsis.

Examples of viscerogenic referred pain (see Chap. 5) include renal calculi (pain radiates into the groin), ovarian cysts or an ectopic pregnancy (pain radiating into the back or hip, or along the course of the sciatic nerve when there is direct compression), and diverticulitis or inguinal hernias (pain radiating across the abdomen or back or into the groin).117

Referred pain to the buttock can be a form of vasculogenic pain (see Chap. 5) and occurs in patients who have vascular claudication from stenosis of the distal aorta or common iliac vessels.117

If, following the history and systems review, the clinician is concerned with any signs or symptoms of a visceral, vascular, or systemic disorder, the patient should be referred to the appropriate health-care professional.

Tests and Measures

The hip can be one of the more challenging joints to examine. Unlike the knee or ankle, the joint is not readily palpable, and one must rely on a number of provocative tests and maneuvers to identify intra-articular or bony abnormalities.117 Even many of the soft tissue structures are difficult to manually identify but can usually be isolated with proper clinical skills.

Observation

The most important aspect of inspection is stance (standing and sitting) and gait. The patient is observed from the front, back, and sides for general alignment of the hip, pelvis, spine, and lower extremities (see Chap. 6). While standing, a slightly flexed position of the involved hip and the ipsilateral knee is a common finding associated with hip pathology. In the seated position, slouching or listing to the uninvolved side avoids extremes of flexion. An antalgic gait may or may not be present depending on the severity of the symptoms.

The clinician observes the hip region, noting any scars, anatomical abnormalities, muscle atrophy, bruising, swelling, etc.

• A localized soft tissue mass or swelling may indicate a bursitis, an acute muscle contusion or tear with a hematoma, an avulsion fracture, myositis ossificans, a tumor, infection, or deep vein thrombosis.117
• Asymmetric muscle atrophy is usually an indication of a radiculopathy or peripheral neuropathy, but can also be seen with a tendon rupture.
• An ecchymosis may be seen with contusions, muscle tear, fracture, and patients with a bleeding diathesis.117
• Vesicular skin lesions that have a dermatomal distribution may be found in cases of herpes zoster. Café au lait spots greater than 3 cm and greater than six in number are characteristic of neurofibromatosis.
• Skin rashes may be because of secondary psoariatic arthritis, drug reactions, or one of the collagen vascular diseases.
• Obvious joint or bony deformity should raise suspicion of a fracture or dislocation.

Both pain and musculotendinous dysfunction can produce movement and postural dysfunctions at the hip joint.125 According to Kendall,126 the ideal alignment of the pelvis is indicated when the ASIS is on the same vertical plane as the symphysis pubis. The degree of pelvic tilt, which is measured as the angle between the horizontal plane and a line connecting the ASIS with the PSIS, varies from 5 to 12 degrees in normal individuals.127 Both a low ASIS in women and a structurally flat back in men can cause structural variations in pelvic alignment, which can be misinterpreted as acquired postural impairments.125 According to Sahrmann, all of the following are necessary to indicate the presence of a postural impairment of the hip125:

• An increase or decrease in the depth of the normal lumbar curve.
• A marked deviation from the horizontal line between the ASIS and PSIS.
• An increase or decrease in the hip joint angle in the anterior–posterior plane, with neutral knee joint alignment.

The following should be examined125:

• The glutei should be symmetrical and well rounded, not hanging loosely. The pelvic crossed syndrome (see Chap. 6) demonstrates weakness and inhibition of the glutei muscles.128 This syndrome can be easily identified by having the patient perform a partial bridge with single leg support. This maneuver results in cramping of the hamstrings within a few seconds if the pelvic crossed syndrome is present. Atrophy of one buttock cheek compared with the other side may also indicate a superior or inferior gluteal nerve palsy. A balling-up of the gluteal muscle typically indicates a grade III tear of the gluteal muscles. Buttock swelling occurs with the “sign of the buttock.”108

• Swelling over the greater trochanter could indicate trochanteric bursitis.
• Adaptive shortening of the short hip adductors is indicated by a distinct bulk in the muscles of the upper third of the thigh.128
• The bulk of the TFL should not be distinct. A visible groove passing down the lateral aspect of the thigh may indicate that the TFL is overused, and both it and the ITB are adaptively shortened.128

The architecture and position of the hip joint and lower extremity is observed.

• In acute arthritis and gross osteoarthrosis, the hip joint is usually held in flexion and external rotation. This may be compensated for by an anterior tilt of the pelvis, together with an increased lordosis of the lumbar spine.
• Excessive external rotation of the leg, accompanied with toeing-out, occurs in extreme femoral neck retroversion, or a slipped femoral epiphysis.
• Increased hip flexion in standing can result from weakness or excessive lengthening of the external oblique or rectus abdominis muscles. Increased hip flexion may also be because of a hip flexion contracture.
• Increased hip extension in relaxed standing is indicative of a swayback posture. This is characterized by a posterior pelvic tilt and hyperextension of the knees, and results in a stretch on the anterior joint capsule of the hip and stress on the iliopsoas muscle and tendon.
• Lateral asymmetry in relaxed standing is characterized by a high iliac crest on one side. The difference in height between the two crests must be greater than one-half inch to have clinical significance. Lateral asymmetry may indicate a positive Trendelenburg sign (see “Special Tests” section), which indicates hip-abductor weakness.

Observation of the lower components of the kinetic chain includes

• the degree of genu varum/valgus (see Chap. 20);
• the degree of tibial torsion (see Chap. 20);
• the amount of calcaneal inversion/eversion (see Chap. 21).

Gait

Analysis of both the stance and swing phases of gait is essential (see Chap. 6). Determinants of the stance-phase of gait involve interaction between the pelvis and hip and distal limb joints (knee and ankle)129,130 The clinician should note whether70

• the patient is using an assistive device. If they are, is it fitted at the correct height and do they use it correctly?
• there is a lack of hip motion, particularly extension. A lack of hip extension can have an impact on gait (see Chap. 6).
• there is a lateral horizontal shift of the pelvis and trunk over the stance leg during the swing phase. This may indicate a positive Trendelenburg sign (see “Special Tests”section). Activation of the abductor mechanism on weight-bearing is necessary to stabilize the hip and pelvis and prevent excessive lateral tilting of the pelvis to the contralateral side during the swing phase.
• the ankle alignment is neutral. Increased ankle pronation increases the degree of hip internal rotation which can place greater stress on hip rotators. This can be especially traumatic to those hip rotators that cross bony prominences, increasing the risk of bursitis; conversely, supination causes greater external rotation.

Strong activation of the hip extensors (with the abductors) is necessary at initial contact into early stance, from 30 degrees initial flexion to approximately 10 degrees of extension at terminal stance.129 If the hip flexors are short or stiff in relation to the abdominal muscles, there may be an exaggeration in the anterior pelvic tilt and increased lumbar extension during this phase.125

Joint Loading Tests

Pain on weight-bearing is a common complaint in some patients with hip joint pathology, including rheumatoid arthritis and OA.70 Depending on the capability of the patient, the following weight-bearing tests may produce pain:

• High step. The patient places one foot on a chair and then leans onto it (Fig. 19-18). This maneuver flexes the raised hip and extends the other. The test is repeated on the other side. This test gives the clinician an indication as to the range of flexion and extension at the hip.
• Unilateral standing. The patient stands on one leg (Fig. 19-19). An inability to maintain the pelvis in a horizontal position during unilateral standing is called a positive Trendelenburg (see “Special Tests” section).

Palpation

The palpatory exam is done to identify both anatomic abnormalities and potential sources of symptoms other than from the hip joint itself. Given the location of the hip joint, palpation is usually unrevealing as far as any specific areas of discomfort related to an intra-articular source of hip symptoms. A palpable mass following acute trauma that is not well defined usually indicates a muscle tear, a muscle spasm, or hematoma.117 A mass that developed 2–3 weeks after the initial injury and is warm and erythematous may be the first indication of myositis ossificans. A bursitis usually presents with some localized swelling, warmth, and erythema, and no history of acute trauma. Trigger points are usually identified as discrete nodules or bands within muscle tissue. There is no associated swelling and no warmth or erythema. Postural or bony malalignment can increase the risk of both acute traumatic and overuse injuries. The anatomic relationships of the joints of the lower extremity should be compared, looking for valgus and varus deformities, pes cavus or planus, spine mobility, hip anteversion, pelvic asymmetry, and leg length discrepancies (see Chap. 29).117

Hoppenfeld131 advocates an approach to palpation that is organized by region. Under this system, the palpation of bony structures occurs separately from the palpation of the soft tissues. While this may be helpful to the clinician, time constraints often dictate that the two are examined concurrently.

Anterior Aspect of Hip and Groin

Anterior–Superior Iliac Spine. The anterior iliac spine serves as the origin for the sartorius muscle and the TFL. Both can be located by flexing and abducting the patient's hip, which produces a groove that resembles an inverted V close to the ASIS. The lateral side of the inverted V is formed by the TFL, while the medial side is formed by the tendon of the sartorius.

Anterior–Inferior Iliac Spine. The anterior–inferior iliac spine can be palpated in the space formed by the sartorius and the TFL, during passive flexion of the hip in the space known as the lateral femoral triangle. The lateral cutaneous nerve of the thigh passes through this triangle. Compression of this nerve produces a condition called meralgia paresthetica (see Chap. 5). The AIIS serves as the origin for the rectus femoris tendon.

Pubic Tubercle. The pubic tubercle is located by finding the groin crease and then traveling in an inferomedial direction, or by following the tendon of the adductor longus proximally. In males, the spermatic cord runs directly over the tubercle and can be tender to palpation in normal individuals. Inguinal hernias are usually found superior and medial to the tubercle, while femoral hernias are located lateral to the tubercle.

Adductor Magnus. The adductor magnus is palpable in a small triangle in the distal thigh, posterior to the gracilis muscle and anterior to the semimembranosus.

Rectus Femoris. The rectus femoris has its origin at the AIIS, which is located just distal to the ASIS, between the TFL and sartorius.

Iliopsoas Bursa. At the iliopectineal eminence, the iliopsoas muscle makes an angle of about 30 degrees in a posterolateral direction. To palpate this bursa, the patient is positioned in supine, with the hip being positioned in approximately 40 degrees of flexion and external rotation, and resting on a pillow. At the proximal end of the femur, the clinician palpates the adductor tubercle and then moves to the ASIS. From there, the clinician proceeds to the inguinal ligament, under the fold of the external oblique, and into the femoral triangle. The psoas bursa is located under the floor of the triangle, close to the pubic ramus.

Femoral Triangle. The femoral artery lies superficial and medial to the iliopsoas muscle and is easily located by palpation of the pulse. The femoral nerve is the most lateral structure in the femoral triangle. To examine the femoral triangle, the patient is positioned in supine and, if it is possible for the patient to do this, the heel of the leg is placed upon the opposite knee. This places the patient in a position of flexion–abduction and external rotation.

Inguinal Ligament. The inguinal ligament is located in the fold of the groin, running from the ASIS to the pubic tubercle. It can be located by using transverse palpation.

Adductor Longus. Together with the gracilis, the adductor longus forms the medial border of the femoral triangle. The gracilis is located medial and posterior to the adductor longus. The adductor longus is best viewed during resisted adduction, when it forms a cord-like structure just distal to the pubic tubercle, before crossing under the sartorius. It is often tender in dancers, cheerleaders, and others who perform strenuous activities requiring abduction at the hip.

Lateral Aspect of the Hip

The patient is positioned in side lying.

Iliac Crest. The iliac crest is easy to locate. The cluneal nerves are superficial structures and can be located just superior to the crest.

Greater Trochanter. The superior border of the greater trochanter represents the transverse axis of hip, and when the leg is abducted, an obvious depression appears above the greater trochanter. The gluteus medius inserts into the upper portion of the trochanter and can be palpated on the lateral aspect.132

Palpation of the greater trochanter is also used to assess the angle of anteversion and retroversion using the Craig test (see “Special Tests” section).

Lesser Trochanter. The lesser trochanter, covered as it is with the iliopsoas and adductor magnus, is very difficult to palpate directly, but it can be located on the posterior aspect if the hip is placed in extension and internal rotation, and the palpation is performed deeply lateral to the ischial tuberosity.

Piriformis Attachment. The origin of the piriformis can be found on the medial aspect of the superior point of the greater trochanter. Moving inferiorly from this point and the quadratus femoris located on the quadrate tubercle, the following tendon insertions can be palpated: superior gemellus, obturator internus, and inferior gemellus.

Psoas. The insertion for the psoas is located on the inferior aspect of the greater trochanter and can be found by placing the patient's hip in maximum internal rotation. Once the superior aspect of the greater trochanter is located, the clinician moves in a posterior/medial/inferior direction to locate the inferior aspect of the greater trochanter.

Subtrochanteric Bursa. The subtrochanteric bursa cannot be palpated directly. However, it can be tested by positioning the patient's leg in hyperadduction. At this point, the patient is asked to abduct the hip isometrically against the clinician's resistance. The contraction of the hip abductors compresses the bursa and may cause pain if the bursa is inflamed.

Posterior Aspect of the Hip

The patient is positioned in side lying or prone.

Quadratus Lumborum. Palpation of the quadratus lumborum is best accomplished with the patient in side lying, with the arm abducted overhead to open the space between the iliac crest and the 12th rib.

Ischial Tuberosity. A number of structures have their attachments on the ischial tuberosity. These include the ischial bursa, the semimembranosus tendon, the sacrotuberous ligament, the biceps femoris and semitendinosus tendons, and the tendons of the quadratus femoris, adductor magnus, and inferior gemellus. The ischial tuberosity is best palpated in the side lying position with the hip flexed to 90 degrees (see Chap. 29). This position moves the gluteus maximus upward, permitting direct palpation at the tuberosity. The ischial bursa is located on the inferior and medial aspect of the ischial tuberosity. A diagnosis of ischial bursitis is usually based on a history of pain with sitting on a hard surface and finding tenderness with palpation of the ischial tuberosity.

Sciatic Nerve. One of the most important structures to palpate in this area is the sciatic nerve. It can be located for palpation at a point halfway between the greater trochanter and ischial tuberosity. Tenderness of this nerve can be produced by a piriformis muscle spasm or by direct trauma.

Active, Passive, and Resistive Tests

The clinical procedures for performing ROM measurements vary, and disagreement exists about the accuracy of visual estimates compared to goniometer measurements. A study by Holm and colleagues133 comprising 25 patients (6 M, 19 F; mean age 68.5 years, range 46–76 years) with osteoarthrosis of the hip, verified both clinically and radiologically, examined the reliability of goniometric measurements and visual estimates of hip ROM. Hip ROM measurements (abduction, adduction, extension, flexion, and internal /external rotation) were recorded by four different teams on the same day and were repeated 1 week later. Teams 1, 2, and 3 consisted of physiotherapists using standardized goniometric measurements. Team 4 involved an experienced orthopaedic surgeon making the assessments from visual estimates only. With the exception of abduction (p = 0.03), there were no significant differences between the measurements recorded on the first and second occasions for the same teams. The coefficient of variance was 5.5% for flexion (lowest) and 26.1% for extension (highest). Reproducibility was best for flexion. There was also high reliability when all the arcs of motion were summed up (abduction + adduction + extension + flexion + internal/external rotation). With the exception of internal rotation, there were highly significant differences between the teams when two people performed the measurements compared to the values measured by a single individual. Concordance, expressed as the standardized agreement index, between visual estimates made by one individual (the orthopaedic surgeon) and goniometric measurements made by two experienced physiotherapists, was 0.77–0.83, which indicates good agreement.

Bierma-Zeinstra and colleagues134 performed a study to compare the reliability of measurements of hip motions obtained with two instruments, an electronic inclinometer and a two-arm goniometer, and to investigate whether the two instruments, and different body positions, produce the same measurement data. Maximal active and passive hip movements were measured simultaneously with both instruments, in nine subjects during 10 consecutive measurements at short intervals. The results from the study demonstrated the following134:

• The intraobserver variability was lower with the inclinometer in measurements of passive hip rotations.
• The two instruments showed equal intraobserver variability for hip movements in general.
• The inclinometer showed lower interobserver variability in the measurements of active internal rotation.
• More rotational movement was measured with the two-arm goniometer and more extension and flexion with the inclinometer. Also, more rotational movement was found in the prone position compared to the sitting and supine positions.

The study concluded that the inclinometer is more reliable in measurements of hip rotation; for hip movements, in general, the two-arm goniometer is just as accurate when used by only one observer; and the two instruments, and some positions, are not interchangeable during consecutive measurements.134

During the examination of the ROM, the clinician should note which portions of the ROM are pain free and which portion causes the patient to feel pain. An assessment of the lumbopelvic rhythm can alert the clinician to the primary area of a particular limitation. During normal forward bending, the patient should be able to touch their toes without bending the knees and with a flattening of the lordosis (Fig. 19-20). However, if the hamstrings are adaptively shortened, toe touching, cannot be accomplished even with a flattening of the lordosis. If the tightness is located in the LB, as the patient bends forward, no flattening of the lordosis occurs, and the patient is unable to touch the toes even with good hamstring flexibility.

The capsular pattern of the hip appears variable and is an unreliable method for determining the presence of OA when used alone,110 Twinges of pain with active motions may indicate the presence of a loose body within the joint. At the end of available AROM, passive overpressure is applied to determine the end-feel. The normal ranges and end-feels for the various hip motions are outlined in Table 19-5. Abnormal end-feels common in the hip include a firm capsular end-feel before expected end range; empty end-feel from severe pain, as in the sign of the buttock; and bony block in cases of advanced OA.18 Horizontal abduction and adduction of the femur occur when the hip is in 90 degrees of flexion. Since these actions require the simultaneous, coordinated actions of several muscles, they can be used to assess the overall strength of the hip muscles.

Resisted testing of the muscles that cross the hip joint (Table 19-4) is performed to provide the clinician with information about the integrity of the neuromuscular unit, and to highlight the presence of muscle strains (see “Systems Review” section).131

If the history indicates that repetitive motions or sustained positions cause the symptoms, the clinician should have the patient reproduce these motions or positions.135

In addition to reports of pain and overall ROM, the clinician also notes information about weakness, joint end-feel, palpation of the moving joint, and muscle tightness.

Flexion. The six muscles primarily responsible for hip flexion are the iliacus, psoas major, pectineus, rectus femoris, sartorius, and TFL (Table 19-4). The primary hip flexor is the iliopsoas muscle.

Hip flexion motion can be tested in sitting or supine, first with the knee flexed (Fig. 19-21) and then with the knee extended. With the hip flexed, the ROM should be approximately 110–120 degrees. More hip flexion should be available with the knee flexed.

Resisted tests are then performed.

• To test the strength of the iliopsoas, the patient is seated with the thigh raised off the bed and resistance is applied by the clinician.
• The action of the sartorius muscle, which flexes, abducts, and externally rotates the hip, is tested by asking the patient to bring the plantar aspect of the foot toward the opposite knee. The clinician applies resistance at the medial malleolus and at the lateral aspect of the thigh to resist flexion, abduction, and external rotation.

A painless weakness of hip flexion is rarely a good sign. Although it may indicate a disk protrusion at the L1 or L2 level, these protrusions are not common. A more likely scenario is compression of the nerves by a neurofibroma or a metastatic invasion. Pain with the active motion or resisted tests should prompt the clinician to examine the contractile tissues individually. Passive stretching can also produce pain in a contractile structure.

Extension

The primary hip extensor is the gluteus maximus (Table 19-4). The hamstrings also serve as hip extensors. Hip extension also involves assistance from the adductor magnus, gluteus medius and minimus, and indirect assistance from the abdominals and the erector spinae.136

The patient is positioned in prone or over the end of a table. As the clinician monitors motion at the pelvis to ensure the lumbar spine does not extend, the patient is asked to lift the thigh toward the ceiling (Fig. 19-22). With a normal recruitment pattern, the order of firing should be gluteus maximus, opposite erector spinae, and then the ipsilateral erector spinae and hamstrings.128 Poor recruitment patterns are demonstrated as follows:

1. An initial activation of the hamstrings and erector spinae with a delayed contraction of the gluteus maximus. The biceps femoris has a tendency to become shortened and overactive, resulting in delayed activation of the gluteus maximus.137

2. The erector spinae initiate the movement with a delayed activity of the gluteus maximus. This would lead to little, if any, extension of the hip joint, as the leg lift would be achieved by an anterior pelvic tilt and a hyperextension of the lumbar spine. This is a very poor movement pattern.

The normal ROM for hip extension is approximately 10–15 degrees. Reduced hip extension with the knee flexed can be the result of a number of reasons, including

• adaptive shortening of the iliopsoas, characterized by an increased lumbar lordosis, an externally rotated lower extremity, and a noticeable groove in the ITB in standing138;
• a hip flexion contracture.

As before, the pelvis is monitored, and the patient is asked to raise the thigh off the table. The strength of the gluteus maximus is tested with the knee flexed (Fig. 19-23). The role of the hamstrings at the hip can be tested with the knee extended. By observing the patient's shoulder during this test, the recruitment pattern can be analyzed. The opposite shoulder should be seen to rise off the bed. With the abnormal pattern, the same shoulder rises off the bed. Patients who use this abnormal recruitment pattern will often have well-developed thoracic musculature on the posterior aspect and, as a result, develop problems at the thoracolumbar junction.128

Resistance is then applied by the clinician. A strong and painful finding with resisted hip extension may indicate a grade I muscle strain of the gluteus maximus or hamstrings. It may also indicate a gluteal bursitis or a lumbosacral strain. The strength of the medial and lateral hamstrings is also tested using resisted knee flexion, with the patient positioned in prone (see Chap. 20).

Abduction/Adduction

Hip adduction (Fig. 19-24) and abduction (Fig. 19-25) ROM can be tested in supine or sidelying making sure that both ASIS are level, and the legs are perpendicular to a line joining the ASIS.

Abduction. The clinician monitors the ipsilateral ASIS, and the patient is asked to abduct the leg. The abduction motion is stopped when the ASIS is felt to move. The prime movers for this movement are the gluteus medius/minimus and the TFL. The quadratus lumborum functions as the stabilizer of the pelvis. The strength of the gluteus medius and minimus can be tested against gravity in the sidelying position. The patient is asked to perform hip abduction of the uppermost leg without any flexion or external rotation occurring (Fig. 19-25). The clinician applies resistance to the distal thigh.

The correct sequence of firing for hip abduction in side lying should be gluteus medius, followed by the quadratus lumborum and TFL after approximately 15 degrees of hip abduction. Altered patterning demonstrates the following:

1. External rotation of the leg during the upward movement, indicating an initiation and dominance of the movement by the TFL, accompanied by a weakness of the gluteus medius/minimus. The TFL has a tendency to become shortened and overactive.137

2. Full external rotation of the leg occurs during the leg lift, indicating a substitution of hip flexion and iliopsoas activity for the true abduction movement. If the piriformis is shortened and overactive, the external rotation of the leg is reinforced.137

3. A lateral pelvic tilt at the initiation of movement, indicating that the quadratus lumborum, which has a tendency to become shortened and overactive, is both stabilizing the pelvis and initiating the movement.137 This is indicative of a very poor movement pattern.

Adduction. Hip adduction is tested with the patient supine and with the uninvolved leg adducted over the other leg or held in flexion (Fig. 19-24). As before, the ASIS is monitored for motion, indicating the end of range for adduction. The primary hip adductor is the adductor longus. Adaptive shortening of the hip adductors can theoretically result in inhibition of the gluteus medius, a decrease in frontal stability, ITB tendinitis, and anterior knee pain. Pain can be referred from the hip adductors into the anterolateral hip, groin, medial thigh, the anterior knee, and medial tibia. Pain in these regions with passive abduction, or adduction, may indicate a strain of one of the adductors. The cause of the pain can be differentiated between the two-joint gracilis and the other hip adductors (longus, brevis, and pectineus) in the following manner. The patient is positioned in supine, with the tested leg over the edge of the table, monitored by the clinician. The clinician places the involved hip into the fully abducted position and the knee is flexed (Fig. 19-26). If no pain is reproduced with this maneuver, the patient is asked to extend the knee (Fig. 19-27), thereby bringing in the gracilis and implicating it if the pain is now reproduced. This can be confirmed with resisted hip adduction and knee flexion. If the other adductors are implicated, this can be confirmed with resisted adduction (longus and brevis) or resisted hip adduction and hip flexion (pectineus).

The strength of the hip-adductor muscle group can also be tested in side lying, by flexing the uninvolved leg over the tested leg or by supporting the upper leg and then applying resistance. This position also stretches the hip abductors and can be a source of pain in the case of an ITB syndrome.

A strong and painful finding with resisted adduction is usually the result of an adductor longus lesion, whereas a painless weakness with resisted abduction is often found in a palsy of the fifth lumbar root because of a disk herniation of the same level.

Internal and External Rotation

Although a number of muscles contribute to external rotation of the femur (see Table 19-4), six muscles function solely as external rotators.32 These are the piriformis, gemellus superior, gemellus inferior, obturator internus, obturator externus, and quadratus femoris. Normal ROM for hip external rotation is approximately 40–60 degrees. Excessive external rotation of the hip may indicate hip retroversion.

The major internal rotator of the femur is the gluteus minimus, assisted by the gluteus medius, TFL, semitendinosus, and semimembranosus. The internal rotators of the femur are estimated to be only approximately one-third the strength of the external rotators.96 Normal ROM for hip internal rotation is approximately 30–40 degrees. Excessive internal rotation of the hip may indicate hip anteversion.

If an asymmetry exists between the two positions such that more ROM is available in the prone position compared with supine, a muscle restriction is likely present.139 When the asymmetry of internal rotation ROM is much greater than the external rotation range in both the hip flexed and hip extended positions, structural anteversion may be present.139 If retroversion is present, the range of external rotation is greater than the range of internal rotation in both the flexed and extended positions of the hip.139

To assess the ROM of the hip rotators, the patient is positioned in supine, with the leg in 90 degrees of hip flexion and 90 degrees of knee flexion. Hip IR (Fig. 19-28) and ER (Fig. 19-29) is then assessed. Alternatively, the patient can be positioned in prone, with the knee flexed to 90 degrees and the hip in neutral. Once the ROM measurements have been established, the strength of the internal rotators and external rotators is then assessed.

Functional Assessment

In addition to gait analysis, the function of the hip can be assessed through observation during functional activities such as sit to stand, or through use of a self-report measure, which allow a patient to rate his or her capacity to perform ADL. Table 19-14 outlines a functional assessment tool for the hip.

The Harris Hip Rating Scale (Table 19-15) is the most commonly used functional outcome assessment for the hip and can be used to assess patient status following the onset of traumatic arthritis, and a variety of hip disorders.

Examination of Movement Patterns

Some of the movement patterns were assessed in the “Active, Passive, and Resistive Tests” section. One further test is described here.

Trunk Curl Up

This test assesses the patient's ability to sit up from a supine position and the relationship between the abdominal and iliopsoas muscles. The patient is positioned in supine with the hips and knees flexed, both feet flat on the bed.

The patient is then asked to perform a sit-up while actively plantar flexing their ankles, thus removing the effect of the iliopsoas.136 The patient progressively flexes the spine, starting at the cervical region, until the lumbar region is flexed. As soon as the iliopsoas becomes involved in the motion, the patient's feet will lift from the bed. Normally, the patient should be able to curl up so that the thoracic and lumbar spines are clear of the bed before the feet lift. A patient in excellent condition can complete a full sit-up without the feet lifting from the bed.

Passive Accessory Movements

Because of the extreme congruency of the joint partners at the hip joint, this is a difficult area to assess with any degree of accuracy, especially as the glides that occur are very slight. Unless otherwise indicated, the patient is positioned supine with the hip in its resting position. The clinician can wrap a belt around the patient's pelvis and the treatment table to help stabilize the pelvis.

Distraction

A joint distraction can be used to assess for pain and any hypomobility at the hip joint. The patient's thigh is grasped by the clinician as proximal as possible, and a distraction force is applied along the line of the femoral neck (see Fig. 19-30).

Leg Traction

The clinician grasps the patient's ankle and applies a longitudinal force along the length of the leg (Fig. 19-31).

Posterior Glide

The clinician stands on the medial side of the patient's thigh. A belt can be placed around the clinician's shoulder and under the patient's thigh, to help hold the weight of the lower extremity. The clinician places one hand on the distal thigh of the patient and the other hand on the anterior surface of the patient's proximal thigh (Fig. 19-32). Keeping the elbows extended and flexing the knees, the clinician applies a force through the patient's hip in a posterior direction (Fig. 19-32).

Anterior Glide

The patient is positioned prone, with the trunk resting on the table, their thigh over the edge, and the opposite foot supported (Fig. 19-33). The clinician stands on the lateral side of the patient's thigh. A belt can be placed around the clinician's shoulder and under the patients thigh to help hold the weight of the lower extremity. Using one hand, the clinician grasps the patient's lower leg. The other hand of the clinician is placed posteriorly on the proximal thigh of the patient, just below the buttock (Fig. 19-33). Keeping the elbows extended and flexing the knees, the clinician applies a force through the proximal hand in an anterior direction.

Inferior Glide

The patient is positioned with the hip and knee each flexed to 90 degrees and the lower leg placed against the clinician's shoulder. The clinician grasps the anterior aspect of the proximal femur as far proximally as possible with one hand. An inferior glide is imparted using the hands, while simultaneously rocking the patient's thigh into flexion (Fig. 19-34).

Neurological Tests

For sensation testing, the clinician should be aware of the dermatomal pattern as well as the areas supplied by the peripheral nerves (inferior femoral cutaneous nerve, lateral cutaneous nerve of the thigh, and posterior femoral cutaneous nerve).

Paresthesia or anesthesia is not commonly found in the buttock, hip, or groin region because of the degree of dermatome overlap. However, paresthesia in the “saddle” region should be considered indicative of a sign of cauda equina compression.

Special Tests

Special tests are merely confirmatory tests and should not be used alone to form a diagnosis. The results from these tests are used in conjunction with the other clinical findings to help guide the clinician. To assure accuracy with these tests, both sides should be tested for comparison.

Quadrant (Scour) Test

The quadrant or scour test is a dynamic test of the inner and outer quadrants of the hip joint surface.140

The patient is positioned in supine, close to the edge of the bed, with their hip flexed and foot resting on the bed. The clinician places one hand over the top of the patient's knee. The patient's hip is placed in 90 degrees of flexion, with the knee being allowed to flex comfortably. From this point, the clinician adducts the hip to the point at which the patient's pelvis begins to lift off the bed, to assess the inner quadrant (Fig. 19-35). At the end range of flexion and adduction, a compression force is applied through the knee along the longitudinal axis of the femur. From this point, the clinician moves the hip into a position of flexion and abduction to examine the outer quadrant. Throughout the entire movement, the femur is held midway between internal and external rotation, and the movement at the hip joint should follow the smooth arc of a circle. An abnormal finding is resistance, apprehension, or pain felt anywhere during the arc. The pain can result from compression of, or stress to, a number of structures including140

• the articular surfaces of the hip joint;
• the labrum;
• the hip joint capsule;
• the insertion of the TFL and the sartorius;
• the iliopsoas muscle;
• the IPB and neurovascular bundle;
• the insertion of the pectineus;
• the insertion of the adductor longus;
• the femoral neck.

The resistance may be caused by capsular tightness, an adhesion, a myofascial restriction, or a loss of joint congruity. Given all of the possible diagnoses, extreme care must be taken when interpreting the results from this test. Of the various studies that have looked at the Scour test, most have had poor study designs. Given the wide range of possible diagnoses with a positive finding, and the variety of patients this test is used with, bias is likely to result.

FABER or Patrick's Test

The FABER (flexion, abduction, external rotation) test (Fig. 19-36) is a screening test for hip, lumbar, or sacroiliac joint dysfunction, or an iliopsoas spasm (see Chap. 29).

SI Provocation Tests

A number of tests can be used to examine the sacroiliac joint (see Chap. 29).

In addition to the provocative tests, the passive motions of the hip can be examined with the innominate stabilized. The hip motions and their respective innominate motions in parenthesis are outlined in Table 19-6.

Craig Test

The Craig test is used to assess femoral anteversion/retroversion. The patient is positioned in prone with the knee flexed to 90 degrees. The clinician rotates the hip through the full ranges of hip internal and external rotation, while palpating the greater trochanter and determining the point in the range at which the greater trochanter is the most prominent laterally. If at this point the angle is greater than 8–15 degrees in the direction of internal rotation, when measured from the vertical and long axis of the tibia, the femur is considered to be in anteversion.80,87,139,141

One study141 showed this test to be accurate to within 4 degrees of intraoperative measurements, for the assessment of femoral anteversion/retroversion, and was more accurate than radiographic measurement techniques.

Flexion–Adduction Test

This test is used as a screening test for early hip dysplasia.142 The patient is positioned in supine, and the hip is passively flexed to 90 degrees and in neutral rotation while maintaining the contact of the patient's pelvis to the bed. From this position, the clinician monitors the pelvis and the hip is passively adducted (Fig. 19-37). The resultant end-feel, restriction, discomfort, or pain is noted and compared with the normal side. A positive test for an early sign of hip dysplasia is the inability to adduct the flexed hip past midline toward the opposite hip. Although Woods and Macnicol142 found the sensitivity to be 100% with this test, the test was performed on adolescents and demonstrated many design flaws.

Supine Plank Test

This test is used to detect hamstring weakness or injury. The patient is positioned in supine, resting on his or her arms and heels. The patient is asked to elevate the pelvis while maintaining their body weight on the arms and heels (Fig. 19-38). The patient is then asked to alternately lift one leg at a time. The test is positive for weakness if pelvic collapse or rotation occurs, or for injury if pain occurs at the ischial origin or in the hamstring musculature.

Trendelenburg Sign

The Trendelenburg sign indicates weakness of the gluteus medius muscle during unilateral weight-bearing. This position produces a strong contraction of the gluteus medius, which is powerfully assisted by the gluteus minimus and TFL, in order to keep the pelvis horizontal. For example, when the body weight is supported by the left foot (Fig. 19-19), the left hip abductors contract both isometrically and eccentrically to prevent the right side of the pelvis from being pulled downward by gravity.

The clinician crouches or kneels behind the patient so that the eyes are level with the patient's pelvis, and ensures that the patient does not lean to one side during the testing. The patient is asked to stand on one limb for approximately 30 seconds, and the clinician notes whether the pelvis remains level. If the hip remains level, the test is considered negative. A positive Trendelenburg sign is indicated if during unilateral weight-bearing the pelvis drops toward the the side of the unsupported limb (Fig. 19-19). A number of dysfunctions can produce the Trendelenburg sign. These include superior gluteal nerve palsy, lumbar disk herniation, weakness or tear of the gluteus medius, and advanced degeneration of the hip. Thus, if used in isolation, this test has little diagnostic value.

Pelvic Drop Test.92

The patient is asked to place one foot on a 20-cm (8-inch) stool or step and to stand up straight. The patient then lowers the non–weight-bearing leg to the floor (Fig. 19-39). On lowering the leg, there should be no arm abduction, anterior or pelvic motion, trunk flexion, or any hip adduction or internal rotation occuring at the weight-bearing hip. These compensations are indications of weak external rotators or an unstable hip.

Piriformis Compression of the Sciatic Nerve.117

Piriformis compression of the sciatic nerve can be reproduced by maximally stretching the piriformis muscle. The patient lies supine with both legs flat on the exam table. The clinician raises one leg, and positions it in maximum flexion of the hip and knee. The hip is then internally rotated and fully adducted (Fig. 19-40). Pain radiating down the leg constitutes a positive test for piriformis syndrome.

Stinchfield's Test

Stinchfield's test is designed to help determine the source of a patient's back, buttock, groin, and/or leg pain. The patient is positioned in supine and asked to lift their leg, without bending the knee, to about 30 degrees. If this maneuver does not reproduce any pain, the clinician applies pressure downward on the patient's raised leg, in an attempt to extend the flexed hip, while the patient resists the force (Fig. 19-41). Pain produced either with or without resistance is assessed for location. If the pain is felt in the groin or anterior thigh, it is considered to arise from the hip; if from the buttock or lumbar spine, the sacroiliac joint or lumbar spine is the likely source. Stinchfield's test should not be confused with the straight-leg raise test used to detect neuromeningeal problems (see Chap. 11). Stinchfield's test is not dependent on the range obtained but rather on the location of symptoms. The only manner in which the two diagnoses could be confused is if a lumbar lesion was producing a restriction of the SLR at or below 30 degrees, but other signs and symptoms would help differentiate between the two. Unfortunately, Stinchfield's test has not been subjected to criteria validity research, so no sensitivity or specificity numbers are available.

Auscultatory Patellar-Pubic Percussion Test.143–145

The ausculatory patellar-pubic percussion test is used when there is a suspicion of occult hip fracture. The patient is positioned in supine, and the clinician places the head of a stethoscope over the pubic symphysis. With the lower extremities extended and positioned symmetrically, the clinician taps (percusses) each patella with a finger or reflex hammer and compares the generated sound (Fig. 19-42). The percussion note should have symmetrical quality and intensity of sound. Any bony disruption along the conduction path (femur) will result in a diminished or muffled sound intensity of a duller quality. Reliability and validity of the technique has been demonstrated.143 Tiru and colleagues146 noted a positive predictive value of 0.98, sensitivity of 0.96, and specificity of 0.76. Although the study design was not without fault, the test does appear to have diagnostic value as a screening tool and as a diagnostic tool. Thus, a positive patellar-pubic percussion test should prompt a referral for diagnostic imaging.143

Muscle Length Tests

Restrictions in motion limit functional capacity, decrease muscle strength (by adversely affecting the muscle length–tension relationship), and can have an adverse effect on muscle and joint biomechanics.

Thomas Test and Modified Thomas Test. The original Thomas test was designed to test the flexibility of the iliopsoas complex but has since been modified and expanded to assess a number of other soft tissue structures. Neither the original test nor the suggested variations have ever been substantiated for reliability, sensitivity, or specificity.

The original test involves positioning the patient in supine, with one knee being held to the chest at the point where the lumbar spine is felt to flex (Fig. 19-43). The clinician assesses whether the thigh of the extended leg maintains full contact with the surface of the bed. If the thigh is raised off the surface of the table, the test is positive. A positive test indicates a decrease in flexibility in the rectus femoris or iliopsoas muscles or both. One of the limitations of this test is that it merely determines the amount of hip extension possible at any given degree of pelvic flexion.147 Another problem is that there are better methods of measuring the flexibility of the iliopsoas complex. For example, positioning the patient in prone, stabilizing the pelvis, and then extending the thigh. The precise point at which the pelvis begins to rise marks the end of the hip motion and the beginning of pelvic and spine motion.

A modified version of this test is commonly used to help eliminate the effect of the lumbar curve. For the modified version, the patient is positioned in sitting at the end of the bed. From this position, the patient is asked to lie back, while bringing both knees against the chest. Once in this position, the patient is asked to perform a posterior pelvic tilt. While the contralateral hip is held in maximum hip flexion by the patient's hands, the tested limb is lowered over the end of the bed toward the floor (Fig. 19-44). If normal, the thigh should be parallel with the bed, in neutral rotation, and neither abducted nor adducted, with the lower leg being perpendicular to the thigh and in neutral rotation. There should be 100–110 degrees of knee flexion present with the thigh in line with the table.

If the thigh is raised compared to the table, a decrease in the flexibility of the iliopsoas muscle complex should be suspected. If the rectus femoris is adaptively shortened, the amount of knee extension should increase with the application of overpressure into hip extension.136 If the decrease in flexibility lies with the iliopsoas, attempts to correct the hip position should result in an increase in the external rotation of the thigh.136

The application of overpressure into knee flexion can also be used. If the increase in knee flexion produces an increase in hip flexion (the thigh rises higher off the bed), the rectus femoris is implicated, whereas if the overpressure produces no change in the degree of hip flexion, the iliopsoas is implicated.

This test can also be used to assess the flexibility of the TFL, if the hip of the tested leg is maximally adducted while monitoring the ipsilateral ASIS for motion. There should be 20 degrees of hip adduction available.

Two things must be remembered when interpreting the results of this test:

• The criteria are arbitrary and have been shown to vary between genders and limb dominance and to depend on the types and the levels of activity undertaken by the individual.148
• The apparent tightness might simply be normal tissue tension, producing a deviation of the leg because of an increased flexibility of the antagonists.

As always, the cause of the asymmetry must be found (or at least looked for) and addressed.

Ely's Test. This is a test designed to assess the flexibility of the rectus femoris. The patient is positioned in prone and the knee is passively flexed by the clinician (Fig. 19-45). If the rectus is tight, the hip flexes on the same side and the pelvis is observed to anteriorly rotate early in the range of knee flexion. The other side is tested for comparison. No diagnostic accuracy studies have been performed to determine the sensitivity and specificity of this test.

Ober Test. The Ober test is used extensively to evaluate the flexibility of the ITB and TFL (see Thomas test).149 The patient is placed in the side lying position, and with the hip extended and abducted and the knee flexed to 90 degrees, the proximal part of the tested leg is released and allowed to drop passively (Fig. 19-46). The test is considered positive when the leg fails to lower. However, there have been some doubts expressed as to the reliability of the Ober test as a measure for ITB tightness and to date, no diagnostic accuracy studies have been performed to determine the sensitivity and specificity of this test.150

Modified Ober Test. The modified Ober test is performed in the same fashion as the Ober test except that the knee of the tested leg is extended (Fig. 19-47).151 A study by Reese and Bandy151 was performed to determine the intrarater reliability of the Ober test and the modified Ober test for the assessment of IT band flexibility using an inclinometer to measure the hip adduction angle and to determine if a difference existed between the measurements of IT band flexibility between the Ober and the modified Ober test. Sixty-one subjects, with a mean age of 24.2 (SD = 4.3) years, were measured during two measurement sessions over 2 consecutive days.151 During each measurement session, subjects were positioned on their left side and, with an inclinometer at the lateral epicondyle of the femur, hip adduction was measured during the Ober test (knee at 90 degrees of flexion) and the modified Ober test (knee extended).151 If the limb was horizontal, it was considered to be at 0 degrees, if below horizontal (adducted), it was recorded as a positive number, and if above horizontal (abducted), it was recorded as a negative number. The ICC values calculated for the intrarater reliability of the repeated measurement were 0.90 for the Ober test and 0.91 for the modified Ober test.151 Results of the dependent t test indicated a significantly greater ROM of the hip in adduction using the modified Ober test as compared to the Ober test.151 The study concluded that the use of an inclinometer to measure hip adduction using both the Ober test and the modified Ober test appears to be a reliable method for the measurement of IT band flexibility, and the technique is quite easy to use.151 However, given that the modified Ober test allows significantly greater hip adduction ROM than the Ober test, the two examination procedures should not be used interchangeably as a measurement of IT band flexibility.151

Straight-Leg Raise Test for Hamstring Length. The patient is positioned in supine with the legs staright and together resting on the table. The clinician stands on the side of the leg to be tested and grasps the patient's ankle with one hand, while visually monitoring, or palpating the patient's opposite ASIS. With the patient's knee extended, the clinician lifts the patient's leg, flexing it at the hip until motion is detected at the opposite ASIS (Fig. 19-48). The angle of hip flexion from the table is measured. The clinician returns the leg to the table and repeats the maneuver from the other side of the table with the other leg. The hamstrings are considered shortened if a straight leg cannot be raised to an angle of 80 degrees from the horizontal, while maintaining the other leg straight.128 Any limitation of flexion is interpreted as being caused by adaptively shortened hamstring muscles.

This straight-leg raise test may also be used as a screen for adverse neural tension, particularly of the sciatic nerve (see Chap. 11), and to differentiate between a hamstring lesion and a sciatic nerve lesion by adding ankle dorsiflexion (Fig. 19-49)—adding dorsiflexion places tension through the sciatic nerve but does not alter hamstring length.

90–90 Straight-Leg Raise. Hamstring length can also be assessed with the patient positioned in supine and the tested leg flexed at the hip and knee to 90 degrees. From this position, the patient is asked to extend the knee of the involved side without extending the hip (Fig. 19-50). A measurement of knee motion is taken at the first resistance barrier.

Piriformis. The FAIR (flexion, adduction, and internal rotation) test is designed to detect compression of the sciatic nerve by the piriformis. The patient is positioned in side lying or supine with the involved extremity by the clinician. Holding the patient's knee, the clinician brings the involved extremity into a position of hip flexion, adduction, and internal rotation (Fig. 19-51). If pain is elicited at a point corresponding to the intersection of the sciatic nerve and the piriformis during this test, the result is considered positive.152,153 The FAIR test has been demonstrated to have a sensitivity of 0.88, a specificity of 0.83, a + LR of 5.2, and a –LR of 0.14.152,154

Leg Length Discrepancy

The tests used to detect the presence of a leg length discrepancy are described in Chapter 29.

Fulcrum Test

The fulcrum test155 is used to test for the presence of a stress fracture of the femoral shaft. The patient is positioned in sitting, with their knees bent over the edge of the bed and feet dangling. The clinician positions his or her arm under the thigh to be tested and moves it proximal to distal, as gentle pressure is applied on the thigh with the clinician's hand (Fig. 19-52). A positive test is when the patient reports sharp pain or expresses apprehension when the fulcrum arm is placed under the fracture site. The fulcrum test has not been subjected to criteria validity research, so no sensitivity or specificity numbers are available.

Diagnostic Imaging

The standard radiographic views of the hip include anteroposterior views and axial or frog leg views (see Chap. 7).

The hip joint and surrounding tissues are prone to a number of common conditions, including joint dysfunction, soft tissue injuries, impingement syndromes, and muscle imbalances of strength and flexibility. Also, because of the high potential of symptom referral from other regions to this area, any intervention for the hip joint must take the entire lower kinetic chain (lumbar spine, pelvis, and lower extremities) into consideration.

The techniques to increase joint mobility and soft tissue extensibility are described in the “Therapeutic Techniques” section.

Acute Phase

During the acute phase, the principles of PRICEMEM (protection, rest, ice, compression, elevation, manual therapy, early motion, and medication) are applied as appropriate. Elevation of the hip joint is usually not applicable or possible. The goals of the acute phase include

• protection of the injury site;
• restoration of pain-free ROM in the entire kinetic chain;
• improvement of patient comfort by decreasing pain and inflammation;
• retardation of muscle atrophy;
• minimization of the detrimental effects of immobilization and activity restriction156–161;
• maintenance of general fitness;
• independence with home exercise program.

The promotion and progression of healing ususally involves a decrease in weight-bearing with rest and/or modification of activities, or through use of an assistive device. Assistive devices are often used to offset the load through the hip joint and to promote a symmetric gait pattern.70,162 The use of a walker for maximum functional ambulation and safety may be required for some patients, particularly those with poor balance.70

The use of shoes with specially made cushion heels may further aid in diminishing the pain associated with weight-bearing.

According to patient tolerance, the clinician should also attempt to remove any other stresses to the hip joint such as joint restrictions in the lumbar spine or sacroiliac joint, and any muscle imbalances.

The approach during this phase may depend on the specific tissue involved:

• Contractile tissue lesions are treated with rest, gentle friction massage, submaximal isometric exercises (glut sets, quad sets, ham sets), pain-free range-of-motion exercises (heel slides, supine hip abduction/adduction), and with appropriate modalities. Whenever possible, active exercises are performed within a functional context.
• Articular lesions are best treated by placing the joint in the open-packed position (flexion, abduction, and external rotation) and with grade I and II joint mobilizations.

A progressive stretching program is initiated for those muscles that are prone to adaptive shortening (the hip flexors, short hip adductors, sartorius, piriformis, rectus femoris, hamstrings, TFL, and ITB), and those that are prone to be weak or inhibited (glutei muscles and the lumbar erector spina. Initially, the stretches can be performed using the milder techniques of postisometric relaxation techniques and myofascial release before progressing to other techniques (see “Techniques” section) as symptoms subside. The stretch positions used are those that are used for testing muscle length. Self-stretching is taught to the patient at the earliest opportunity.

Balance and coordination retraining activities are usually performed in some form of weight-bearing (sitting then standing), provided that there are no contraindications (pain or instability) to weight-bearing.70 Simultaneous contraction of hip extensors and abductors in weight-bearing is the normal co-activation pattern used in early stance-phase of gait.70,129 Once the patient is able to weight bear, these exercises are initially performed with double limb support (Fig. 19-53) and then progressed to single leg support as the patient progresses (Fig. 19-54). Once the static weight-bearing exercises can be performed, sit–stand transfers and gait activities are introduced. Functional exercises such as sit–stand–sit require simultaneous activation of hip muscles coordinated with other trunk and limb patterns normally used to accomplish the activity.70 Gait-training procedures163,164 during this phase involve the use of manual contacts at the pelvis to guide and stretch, and to apply joint approximation or resistance to help promote the development of appropriate patterns of neuromuscular control.

The essential components of normal swing-phase gait129,164 to develop are

• posterior rotation of the pelvis during swing-phase flexion of the hip;
• a pelvic dip (drop) of no more than approximately 5 degrees on the side of swing limb;
• flexion of the hip to a maximum of 30 degrees (activation of hip flexors) with simultaneous knee flexion and dorsiflexion.

While standing, active hip flexion with adduction, combined with knee flexion, and dorsiflexion simulates the normal swing phase of gait, and promotes balance control in weight-bearing on the contralateral stance leg.70 A multi-hip machine can be introduced as the hip muscles become stronger.

Cardiovascular fitness can be maintained during this phase using an upper body ergometer. If tolerated, a stationary bicycle can be used.

Functional Phase

Once there is no pain, and when the ROM is equal to that of the uninvolved limb, the patient progresses to the functional stage. The patient should also be able to perform normal walking and daily activities without pain. The goals of the functional phase include

• restoring normal joint kinematics;
• improving muscle strength to within normal limits;
• improving neuromuscular control;
• restoring normal muscle force couple relationships.
• Return to normal function or athletic performance as appropriate

The following exercises are recommended during this phase:

• Quadruped exercises incorporating rocking forward and backward. These exercises help to stretch the joint capsule and apply joint compression.
• Lunging (Fig. 19-55), squatting (Fig. 19-56), and hip circumduction (Fig. 19-57). These exercises increase functional ROM and strength while simultaneously stretching the capsule.
• Open-chain exercises using cuff weights or tubing may be used to develop strength and endurance of all of the hip musculature (Fig. 19-58). The exercises are initially performed using concentric contractions and then advanced to eccentric contractions using a variety of speeds and resistance.
• Bridging. Bridging utilizes body weight as a resistance force to the hip extensors and abductors.70 A variety of bridging exercises exist, from the traditional, where the patient lies supine with the hips and knees flexed and the feet resting on the table and then raises the trunk until it is parallel with the thighs, (Fig. 19-59), to the more difficult unilateral bridging exercises (Fig. 19-60). Manually applied resistance can be superimposed on the pelvis or thighs to generate maximal muscular tension in the contracting muscles.
• Strengthening of the gluteus medius muscle is often an important component of the hip rehabilitation program. The gluteus medius can be strengthened in side lying, with the upper leg in slight hip extension and external rotation (Fig. 19-61), the pelvic rise and drop exercise (Fig. 19-62), which also strengthens the quadratus lumborum, stool rotations (Fig. 19-63) and the clam shell exercise progression (Figs. 19-64, 19-65, 19-66, and 19-67).
• Strengthening of the hamstrings, including supine bent knee bridge walk-outs (Fig. 19-68 and Fig. 19-69), the supine single-leg chair bridge (Fig. 19-70 and Fig. 19-71), unilateral good mornings with rotations (Fig. 19-72 and Fig. 19-73), lunges with torso rotations (Fig. 19-74), hamstring lowers (Fig. 19-75), and grapevine stepping (Fig. 19-76). The grapevine stepping exercise, using the right leg as an example, is performed by asking the patient to stand with the feet together. The patient is then asked to take one step to the right, and then using the left leg to step behind and slightly to the right of the right foot, thereby crossing the left leg behind the right leg. The left foot should be pointed toward the right heel, but not directly behind it (Fig 19-76). The patient is then asked to take a step to the right with the right foot, and then to move the left foot so that the feet are together again. The routine is then repeated. The exercise is then performed moving to the left.
• The stationary bicycle can be used to increase lower extremity strength, endurance, and range during repetitive reciprocal movements of the lower extremities.70 Electromyographic (EMG) analysis of lower limb muscles during pedaling has shown that the highest peak of activity for the gluteus maximus and biceps femoris muscles (as hip extensors) occurs during the pedal downstroke.165 Stationary bicycling has also been found to be as effective for increasing ROM at the hip joint as static stretching.166 The stationary bicycle is a convenient mode of exercise for home use; however, the use of vigorous protocols should be carefully monitored for cardiac effects, especially in light of the fact that both blood pressure and heart rates have been found to increase markedly during this type of exercise.70,167
• Pool walking, swimming, and kicking may also be incorporated if available.

Neuromuscular reeducation exercises for the hip are prescribed to emphasize specific movement patterns and sequencing of muscle contractions. These exercises demand a high level of control and coordination.168–171 Ambulation activities can be used initially, progressing to more difficult unilateral extremity exercises.

Task-oriented exercise programs (work hardening) should be instituted for the patient who intends to resume a type of employment that requires a predetermined level of work performance. A more aggressive protocol needs to be adopted for the returning athlete. These exercise programs attempt to incorporate activities that simulate the actual circumstances and patterns of contraction used in the sport.70,172 Examples of two such protocols are outlined in Tables 19-16 and 19-17.

Practice Pattern 4A: Primary Prevention/Risk Factor Reduction for Skeletal Demineralization

Idiopathic Transient Osteoporosis of the Hip

Osteoporosis is the most prevalent bone disease among the aging population, and osteoporotic hip fractures account for substantial morbidity, mortality, and health-care costs.173 Two types of osteoporosis are distinguished on the basis of age of presentation174 and differing rates of loss of cortical or trabecular bone.175 Type I is characterized by vertebral fractures in postmenopausal women at about the age of 65 years; type II may occur in both sexes at about 75 years of age and produces mainly osteoporotic hip fractures.175

Men with osteoporosis of the hip are likely to have an underlying metabolic abnormality contributing to bone loss. The most common etiologies in men are hypogonadism, alcohol and corticosteroid use, anticonvulsant use, malabsorption syndromes, hyperthyroidism, and neoplasias.176 Many factors have been cited for women, including decreased bone mass with an accelerated loss after menopause, parity, smoking, alcohol consumption, various medications, and diet. Although the reasons are unclear, in male patients either hip may be involved, whereas in women, the left hip is involved much more frequently.177

Hip pain begins spontaneously, without an antecedent history of trauma. The condition is aggravated by weight-bearing. The symptoms may become severe enough to result in a limp. The clinical findings are self-limiting and resolve in 2–6 months without permanent sequelae.177 Biopsy of the synovium reveals normal findings or slight (mild, minimal, or equivocal) chronic inflammation.178

Radiographic findings are characteristic and become apparent within weeks or months of the onset of clinical findings. Osteoporosis is not usually found in the acetabulum but may be seen in the femoral neck. Progressive and marked osteoporosis of the femoral head is identified on plain radiographs.178 The joint space is normal and the femoral subchondral bone is usually intact.

The differential diagnosis includes avascular necrosis, OA, septic arthritis, and rheumatoid arthritis.178 The intervention for osteoporosis is discussed in Chapter 5.

Practice Pattern 4D: Impaired Joint Mobility, Motor Function, Muscle Performance, and ROM Associated with Connective Tissue Dysfunction

Osteoarthritis

OA involves a focal loss of articular cartilage with variable reaction of the subchondral bone. The prevalence of hip OA ranges from 7 to 25% in adults aged 55 years and older in the white European population.179 Studies of the natural history of hip OA clearly demonstrate heterogeneity of disease progression, and the lack of a universal agreement as to the definition of progression of hip OA. Most define progression by radiological features such as loss of joint space, osteophytes, and sclerosis.180,181 However, the demonstration of a correlation between radiographic features and clinical symptoms is not easy in OA: factors differentiating symptomatic OA from asymptomatic disease are unknown.182 The two clinical sequelae of OA are joint pain and functional impairment.

Hip OA usually begins insidiously, although in a few cases it may start abruptly. The development of OA at any joint site depends on a generalized predisposition to the condition and abnormalities of biomechanical loading, which act at specific joints.183 Individual risk factors, which may be associated with a generalized vulnerability to the disorder, include family history, obesity, and hypermobility of the joint.182 Those that reflect local biomechanical insults include minor trauma to an already diseased joint, abnormalities of joint shape, and physical activity.182

The pain of hip OA can vary greatly in both its site and its nature, sometimes making early diagnosis difficult.184 The pain may be felt in the buttock, groin, thigh, or knee and varies in character from a dull ache to sharp and stabbing. The C sign (Fig. 19-77) may be encountered when asking the patient describe the location of the pain—the patient will cup the hand above the greater trochanter with the thumb posterior and the fingers gripping deep into the anterior groin when describing deep interior hip pain.185 The discomfort associated with hip OA is generally related to activity and the bouts of pain can last for several hours.184 Stiffness of the hip is usual, particularly after inactivity, and can be the presenting feature. As the disease progresses, the patient experiences difficulty in climbing stairs with the involved leg and may have difficulty in donning socks or stockings.186 In advanced cases of the disease, the patient may complain of severe pain that is present at night or during rest, and there is a marked decline in the participation of recreational activities.

Early physical signs include restriction of internal rotation and abduction or flexion of the affected hip, with pain at the end of the range.184 Birrell et a1.111 notes that as the number of restricted planes of hip motion increases, the specificity, or ruling in of the diagnosis of hip OA, increases. As specificity increases, sensitivity, or the ruling out of a diagnosis of hip OA, decreases in those patients with mild-to-moderate and severe OA of the hip.111,116 This trade-off, where sensitivity decreases while specificity increases, is common with sensitivity and specificity.116 The diagnostic value of decreased ROM in the hip is best when present in two or three planes of motion (positive likelihood ratio of 2.5–5), as compared to just one plane of motion (positive likelihood ratio of 1.9).111,116

A diagnosis of hip OA can usually be confirmed by radiography; joint space width of 2.5 mm or less indicates substantial loss of cartilage in the hip joint, and osteophytes, subchondral bone sclerosis, or cysts are usually present.184 As mentioned, though, radiographs can be misleading because of the relative insensitivity of the their findings with clinical signs and symptoms. Two separate studies by Bierma-Zeinstra et al.187 and Altman et al.188 examined the relationship between patients with clinical signs and symptoms of hip OA and radiographic findings. The clinical diagnosis of early hip OA according to Bierma-Zeinstra et al.187 includes such variables as decreased external rotation, no pain aggravation with sitting, and over 60 years of age. The criteria from the Altman et al. study included hip internal rotation less than 15 degrees and an age of over 50 years. Diagnostic measurement properties, like sensitivity, specificity, and likelihood ratios, are probabilistic statistics; consequently, false-positive and false-negative results will always be potentially possible.116

The narrowing of the joint space associated with OA could potentially slacken the supporting ligaments, rendering them less effective and producing changes in proprioceptive input. Indeed, OA of the hip has been associated with deficits in a patient's proprioception and balance.189,190 The joint space narrowing may also result in a relative decrease in the length of the muscles that cross the hip joint, which could feasibly result in a mechanical disadvantage of the muscles that act on the hip joint. In addition, OA of the hip can have many manifestations in neighboring joints, particularly the lumbar spine and the foot. This is likely because the joint stiffness associated with the disease diminishes the amount of rotation available at the hip, forcing the lumbar spine and foot to compensate for this loss.

Systematic reviews have concluded that exercise reduces the pain and disability associated with hip OA. Weigl et al.191 demonstrated that strengthening exercises, flexibility, relaxation, and endurance training decreased pain and improved physical function in patients with OA.116 van Baar and colleagues192 showed that exercise improved function and reduced pain in patients with hip OA, but later found that the beneficial effect of exercise declined over time.116,193 Research on the use of manual physical therapy in the treatment of hip OA is limited. Hoeksma and colleagues,194 in a randomized clinical trial comparing the effectiveness of two different therapy programs in a group of patients with hip OA, demonstrated the superiority of manual physical therapy plus exercise over exercise alone for improving pain and ROM. MacDonald and colleagues,195 in a case series describing the outcomes of individual patients with hip OA treated with manual physical therapy and exercise reported that all patients exhibited reductions in pain and increases in PROM, as well as a clinically meaningful improvement in function. The inherent limitations of the case series, however, do not allow for the identification of a cause-and-effect relationship. Further research, including randomized clinical trials, is necessary to uncover the exact effect of manual physical therapy and exercise in the treatment of hip OA.195

Based on the above research, the intervention goals for hip OA include relieving symptoms, minimizing disability, and reducing the risk of disease progression.184 Intervention in the earlier stages includes:

• Patient education and empowerment through advice about what patients can do for themselves. Patients are often frightened that use of the hip will “wear out” an already damaged joint and feel they need “permission” to use it.184 Evidence suggests that the involved joint will benefit from regular loading to help maintain its integrity.
• Modalities for muscle relaxation, pain relief, and anti-inflammation.
• Modification of ADL and self-care. Patients need to learn an appropriate balance and intersperse periods of activity with rest, as prolonged or heavy activity involving the diseased hip may cause further damage.196
• It is important to maintain a full range of hip movement, if possible. In addition to specific exercises for hip ROM, recreations such as swimming or cycling may help. Contact sports and activities such as jogging, which can cause repetitive high impact loading of the hip, are probably best avoided.196
• Diet and weight. There is no evidence for the involvement of any dietary factor in the etiopathogenesis of hip OA.184 However, it is possible that obesity may accelerate progression or cause more pain. A reduction in weight can significantly improve a patient's symptoms, increase mobility, and improve health status.197
• Many people with arthritis of the spine or legs are more comfortable wearing trainers or other shoes with good shock-absorbing properties than they are in regular footwear. Sorbithane and other shock-absorbing insoles, which are available in sports and shoe shops, may be helpful.184
• A simple walking stick can make a big difference, reducing loading on a hip by 20–30%, but attention must be given to its length, characteristics, and use. In most cases, it will be most beneficial if it is held on the uninvolved side of the body and that it comes to the top of the pelvis and has a good ferrule and comfortable handle.184