The amount of swelling present may provide the clinician with valuable information regarding the internal damage that may have resulted. Diffuse swelling indicates fluid in the joint or synovial swelling, or both. An effusion can be detected by noticing the loss of the peripatellar groove and by palpation of the fluid. A perceptible bulge on the medial aspect suggests a small effusion; this sign may not be present with larger effusions. The swelling is examined with the patient positioned in supine, in the following manner274:
- Patellar ballottement (maximal effusion). Ballottement of the patella is a useful technique for detecting an effusion. Using one hand, the clinician grasps the patient's thigh at the anterior aspect about 10 cm above the patella, placing the fingers medial and the thumb lateral. The patient's knee is extended. With the other hand, the clinician grasps the patient's lower leg about 5 cm distal to the patella, placing the fingers medial and the thumb lateral. The proximal hand exerts compression against the anterior, lateral, and medial aspects of the thigh and, while maintaining this pressure, slides distally. The distal hand exerts compression in a similar way and slides proximally (Fig. 20-8). Using the index finger of the distal hand, the clinician now taps the patella against the femur. In the normal knee joint with minimal free fluid, the patella moves directly into the femoral condyle and there is no tapping sensation underneath the clinician's fingertips. However, in the knee with excess fluid, the patella is “floating”; thus, ballottement causes the patella to tap directly against the femoral condyle. This sensation is transmitted to the clinician's fingertips. A positive test is indicative of a significant synovial effusion or hemarthrosis in the knee joint. However, sometimes, this test can produce false-positive results. When this is the case, the uninvolved side usually tests positive as well.
Patellar ballottement test.
If there is no swelling but there is evidence of bruising or bleeding into the tibial area, disruption of the joint capsule may be present, or a SCFE, if the patient is an adolescent. Popliteal swelling, which can compress the tibial or common fibular (peroneal) nerves, or both, can produce complaints of paresthesia and anesthesia.
The formal observation of the patient is divided into three sections: standing and walking, seated, and lying examinations.
The patient is asked to stand with the feet slightly apart and aligned straight ahead. This position can be used to assess overall limb alignment as well as to identify possible foot abnormalities. A careful physical examination of the hip, knee, and ankle is performed, observing for both static restraints, and, to a great degree, dynamic restraints.127 Following this position, the patient is asked to stand with the feet shoulder-width apart. The entire trunk and lower extremities are observed. Areas of atrophy should be noted and correlated with other findings. Common areas include the medial aspect of the quadriceps following trauma, nerve injury, or knee surgery.
Degree of Femoral Retroversion or Anteversion
Femoral retroversion–anteversion is indicated by whether the feet are rotated outward or inward, respectively, in the relaxed standing position. The position of the patella is examined to see whether it looks inward (the so-called squinting patella), which could indicate femoral anteversion. Femoral anteversion results in internal rotation of the femoral sulcus, and an increase in the Q-angle. Femoral anteversion has been associated with abnormal patellofemoral mechanics.147,275 Even if the patella looks straight in the presence of femoral anteversion, it may be held there by tight lateral structures.266
Compensations for leg-length discrepancies include excessive foot pronation, toeing-out (forefoot abduction), and a flexed knee gait or stance.276,277
Degree of Genu Varum/Genu Valgum
Genu varus (“bow legs”) can be the result of bowing of the tibia or varus at the knee joint. An increased varus moment can contribute to early degeneration of the knee and, when exaggerated, is most often an indication of advanced degenerative joint disease (DJD).278 On the basis of the relationship between the proximal and distal aspects of the femur, a change in the orientation between the shaft and the neck will change the orientation of the tibiofemoral joint, thereby altering the weight-bearing forces through the knee joint. For example, an increase in the normal angle of inclination at the hip (coxa valga) will redirect the femoral shaft more laterally than normal, resulting in a decrease in the normal physiologic valgus angle of the knee (genu varus). This results in a shifting of the mechanical axis to the medial compartment of the knee, increasing the compression forces medially.66
Genu valgus (“knock knees”) can result from a change of angulation of the femur caused by femoral anteversion, tibial torsion, or excessive foot pronation. A valgus knee increases the Q-angle by displacing the tibial tuberosity laterally and can be associated with patellofemoral pain.279
To observe genu varum and genu valgum, the patient is positioned in standing so that the patellae face anteriorly and the medial aspect of the knees and the medial malleoli of both lower extremities are as close together as possible. A distance of 9–10 cm (3.5–4 inches) between the malleoli of the ankles with the knees touching is considered excessive and indicates genu valgum, whereas a distance of 4 cm (1.6 inches) measured between the knees when the ankles are together, indicates genu varum.280–282
A flexed knee in the relaxed standing position is often indicative of arthritic changes of the knee.
Degree of Genu Recurvatum or Hyperextension
Knee recurvatum may be an expression of a generalized ligamentous laxity or may be associated with patella alta.205 Hyperextension of knee produces stress on the posterior capsule, slackening of the ACL, and alterations in the compressive forces acting on the anterior articulating surface of the tibia.278 The anterior compressive forces can cause the inferior pole of the patella to be driven posteriorly into the fat pad, producing an irritation.
A properly measured Q-angle can contribute significantly to the evaluation of patellofemoral malalignment. However, relying solely on the Q-angle measurement to determine patellofemoral alignment is an oversimplification. As with other clinical signs, an abnormal value does not necessarily identify the source of pain. The Q-angle itself is not pathologic and is increased in only a small percentage of patients with patellar pain.283
The Q-angle should be assessed dynamically and statically. It is important that this angle be measured in a consistent fashion. The preferred position for this test is the one-legged standing position without shoes. Hyperpronation of the feet can be masked unless the foot and ankle are placed in a subtalar neutral position284 (see Chap. 21). A measurement is then taken using an imaginary line drawn from the ASIS to the center of the patella, and a second line from the tibial tuberosity to the center of the patella (Fig. 20-6). The weight-bearing position can be simulated in a supine patient by dorsiflexing the ankles, extending the knees, and pointing the toes to the ceiling. With the knee flexed to 90 degrees, the tibial tubercle should lie less than 20 mm lateral to the midline of the femur at the upper edge of the femoral condyles; a distance of more than 20 mm indicates an abnormally lateral tubercle.11 Both tight hamstrings and a decrease in ankle dorsiflexion can result in an increase in the dynamic Q angle.188
Degree of Tibial Torsion285
External tibial torsion increases the Q-angle, whereas internal torsion decreases it.147 The vast majority of the studies focusing on anterior knee pain have examined the coronal relationships at the knee (Q-angle, patellar tilt, patellar subluxation). Few studies have addressed the rotational relationships, specifically the rotational orientation of the tibia to the femur.286 This rotational relationship of the tibia to the femur in the transverse plane is referred to as knee version. Knee version often is recognized as a factor in the context of the osteoarthritic knee.287–289 The significance of this rotational characteristic of the knee with anterior pain is that the patella is tethered to the tibia by the infrapatellar tendon and retinaculum, and if the tibia is rotated externally with respect to the femur, the patella will be pulled laterally by virtue of this attachment.286 If the patella is not free to translate laterally, because of its soft tissue attachments and its conformity with the patellar groove, increased pressure may be placed on the lateral facet. This pressure may produce a condition called a lateral patellar compression syndrome.286,290
If the tibia-to-floor angle is 10 degrees or greater, the extremity requires an excessive amount of subtalar joint pronation to produce a plantigrade foot.205
Patella Tendon‐to-Patella Height Ratio
This measurement is best performed radiographically. The patella tendon length should be equal, or slightly longer than the height of the patella.291 If a ratio of greater than 15–20% exists, patella alta should be suspected. If the ratio is less than 15–20%, patella baja should be suspected.
An often-neglected feature, which directly impacts the patellofemoral joint, is that of foot alignment. The normal weight-bearing foot exhibits a mild amount of pronation. If the foot pronates excessively, a compensatory internal rotation of the tibia may occur. This produces an increased amount of rotatory stress and dynamic abduction movement at the knee that has to be absorbed through the peripatellar soft tissues at the knee joint.205,226,275,292 These stresses can force the patella to displace laterally.293,294 In addition, a change in the position of the talus can affect the functional leg length. Subtalar supination may cause the leg to lengthen, whereas subtalar pronation shortens the leg.
Abnormal foot mechanics are manifested during ambulation, and abnormal gait patterns may suggest an underlying condition (see Chap. 6). The gait assessment relative to the knee allows the clinician to identify deviations of the foot, ankle, knee, or hip joint, such as excessive subtalar and midtarsal joint pronation, limited ankle dorsiflexion, tibial or femoral torsion abnormalities, and excessive varus or valgus at the knee, all of which could place the knee structures at risk for further microtrauma.167
During normal gait, the knee should be observed to flex to approximately 15 degrees at initial contact before extending to the neutral position at terminal stance.278 An increase in 5 degrees of pronation at midstance, a period where the foot should be in supination, holds more potential for producing pain than if the 5 degrees occurs during the contact phase.229
Since the joint reaction forces are reported to increase with the magnitude of quadriceps contraction and the knee-flexion angle,295 patients with patellofemoral pain often adopt compensatory gait strategies to reduce the muscular demands at the knee. Evidence in support of this premise was reported by Dillon et al.,296 who found that subjects with patellofemoral pain limited the amount of stance phase knee flexion during level and ramp walking.
An injury to the ACL produces distinct changes in lower extremity biomechanics during gait.297 Although healthy individuals demonstrate an extensor torque at the knee for 10–45% of the stance phase,298–300 gait analysis of individuals with recent ACL deficiency shows functional adaptations in a high proportion of patients, with an extensor torque that lasts for nearly the entire stance phase.298 Other analysis has also shown a decrease in the flexion moment of the knee in the range of 0–40 degrees of flexion in patients who have a chronic tear of the ACL.301,302
When the normal limb moves into the midstance phase, gravity and inertia generate a moment that tends to flex the knee. Since the quadriceps muscles balance this moment, a decrease in the flexion moment suggests a decrease in the quadriceps muscle moment.303 Such a decrease has been noted in both limbs of patients who had only one knee with a torn ACL.302
Andriacchi303 termed this finding the quadriceps-avoidance gait, although not all patients who have a torn ACL have such a gait, and its prevalence appears to be partly related to the time since the injury.304 In activities that involve knee-flexion angles of less than 30 degrees (i.e., those involving normal gait), the quadriceps-avoidance gait is most effective in preventing anterior tibial translation.303,305,306 In activities that involve knee-flexion angles of 40 degrees or more (e.g., jumping or sharp changes in running direction), increased contraction of the hamstrings is effective in preventing anterior tibial translation.154,306–308
Gait adaptations in individuals with ACL injury who have reconstruction surgery are less clear for two reasons297:
Very few comprehensive gait analyses have been conducted on this population.
The large variations in surgical and rehabilitation procedures and patient characteristics, and in patient compliance with rehabilitation, limit the generalization of these potential results.
Gait can also be affected by genu recurvatum, because during the loading response in gait, an individual with genu recurvatum transfers body weight directly from the femur to the tibia without the usual muscle energy absorption and cushioning of a flexed knee provided. This may lead to pain in the medial tibiofemoral joint (compression) and posterolateral ligamentous structures (tensile). In individuals with quadriceps weakness, compensation may occur by hyperextending the knee to provide greater knee stability.
Although formally assessed as part of the active range of motion (AROM) with passive overpressure tests (see later), active knee extension may also be used during the observation phase of the examination. The patient should fully extend the knee from a flexed position. Normally, the patella follows a straight line, or a slight and smooth, gradual, lateral concave “C” curve as the knee extends. The presence of a “J sign,” in which the patella slips off laterally as the knee approaches extension, or apprehension with motion involving lateral or medial stress, is necessary to confirm patellar instability.11
The patella may be compressed with the palm of the hand through the full ROM, as ulcerated lesions can be tender with this provocative test.11 However, care should be taken with this maneuver, because it can provoke pain in otherwise asymptomatic patients.
Distal patellar lesions are often tender with this test in the early degrees of knee flexion, whereas proximal lesions are tender at approximately 90 degrees.11 This information can help guide the clinician with the intervention. Crepitus at the knee is a nonspecific finding and can be associated with both cartilaginous and synovial lesions.11 Although often a concern to patients because they believe it to be indicative of arthritis, crepitus is often a result of tight, deep, lateral retinacular structures and can be improved with retinacular stretching techniques.266
In addition to observing the patella during active knee extension, the clinician should also note any evidence of a quadriceps lag manifested by an inability to fully extend the knee. This lag can result from muscle atrophy, pain, effusion, reflex inhibition, or a loss of mechanical advantage. Quadriceps reflex inhibition has been well documented throughout the literature and is thought to result from pain or effusion, or both, although the exact etiology has yet to be determined.262,309–314
Some of the proposed causes for this reflex inhibition include
- the result of capsular stretching;313
- the result of increased intra-articular pressure.310
In the presence of various pain syndromes, such as CRPS,309 additional muscle inhibition can occur. In most patients, limitations of motion resolve as the pain and effusion dissipate. However, this quadriceps inhibition may allow scar tissue to form while the knee is held in a flexed position. Atrophy of the quadriceps muscle and flexion contracture usually results, and activities of daily living become more difficult to perform. Joint immobilization can complicate all of these factors. Disuse may induce abnormal cross-links between collagen fibers at abnormal locations,315,316 decreasing their extensibility317 and promoting intra-articular and extra-articular scarring.
Malalignment can be observed on certain the supine, resting patients, whereas in other subjects a dynamic evaluation (walking, jumping, squatting, etc.) is required to detect an abnormal alignment. The lateral pull test can be performed to assess patellar tracking.318 The patient lies supine with the knee extended and the clinician asks the patient to perform an isometric quadriceps contraction. The clinician observes patellar tracking during the contraction. The test is considered positive if the patella tracks more laterally than superiorly, and negative if superior displacement is equal to lateral displacement.318 However, since the lateral pull test has been found to have only fair intrarater, and poor interrater reliability, care must be taken in placing too much emphasis on this test when making clinical decisions.
With the patient supine and then prone, the hip is flexed and rotated as the clinician checks for a source of referred pain.196
Since patellar malalignment can be associated with adaptive shortening, the following structures (in decreasing order of frequency) are assessed187,196:
- Lateral retinaculum (see “Special Tests” section). A tight lateral retinaculum may pull the patella laterally.
- Hamstrings (see “Special Tests” section). When an individual with tight hamstrings runs, there is a decrease in stride length and a potential for the quadriceps to fatigue in an effort to overcome the passive resistance of the hamstrings.319 Tightness of the hamstrings also produces an increase in knee flexion at heel strike. Since the knee cannot straighten, an increased dorsiflexion is required to position the body over the planted foot.266 If the range of full dorsiflexion has already occurred at the talocrural joint, further range is achieved by subtalar pronation. This has the effect of increasing the valgus vector force and the dynamic Q-angle.266,320
- Iliotibial band (see “Special Tests” section). The ITB is maximally taut at 20–30 degrees of flexion. Adaptive shortening of this band can cause a lateral tracking and tilting of the patella, and often a stretching of the medial retinaculum.229
- Tensor fascia latae and rectus femoris (see Chap. 19). Adaptive shortening of these structures can increase the amount of compression of the patella on the femur.229
- Hip rotators. The hip rotators can accentuate anteversion or retroversion (see Chap. 19).229
- Achilles–Soleus Length. A decrease in talocrural joint dorsiflexion ROM may result in a compensatory subtalar pronation during ambulation and weight-bearing.321 Soft tissue tightness is particularly prevalent during the adolescent growth spurt, in which the long bones are growing faster than the surrounding soft tissues.322
ROM testing for the tibiofemoral joint should include assessment of knee flexion and extension, tibial internal and external rotation. Normal knee motion (Table 20-7) has been described as 0 degrees of extension to 140 degrees of flexion, although hyperextension is frequently present to varying degrees.323 In general, however, the best way to ascertain normal motion is to examine the contralateral knee, provided that it has no abnormal conditions.
Table 20-7 Normal Ranges and End-Feels at the Knee ||Download (.pdf)
Table 20-7 Normal Ranges and End-Feels at the Knee
Range of Motion (degrees)
Tissue approximation or tissue stretch
External rotation of tibia on femur
Internal rotation of tibia on femur
The ROM testing can often be diagnostic and provides the clinician with some clues as to the cause of the problem. Examining the uninvolved knee first allays a patient's fears and helps to determine what the normal ROM is. In addition, observation of the uninvolved knee can afford the clinician information about the patellofemoral joint and the tracking of the patella.324
Full active range of knee motion requires the following:
- Congruent articular surfaces
- Adequate muscle function
- An articular capsule with suitable capacity and flexibility
- Effective space in the medial and lateral articular recesses, intercondylar notch, and suprapatellar pouch
- Sufficient meniscal motion325
A number of studies have demonstrated that goniometric measurements of knee ROM performed in a clinical setting can be highly reliable.326–330 Rothstein et al. showed that intratester and intratester reliability for flexion of the knee was high (r = 0.91–0.99 and r = 0.88–0.97, respectively).326 Watkins et al. showed that the intertester reliability for measurements of knee ROM obtained by visual estimation was 0.83 for flexion and 0.82 for extension.330
The amount of knee flexion should be assessed to see if the motion is restricted by tight structures. If no restriction is suspected, tests are required for generalized ligament laxity and for abnormally loose patellar retinacula (see later discussion).
The primary flexors of the knee are the three hamstring muscles, assisted by the gracilis, sartorius, popliteus, and gastrocnemius muscles, and the TFL (in 45–145 degrees of flexion; see Table 20-2). The patient lies in the supine position. Using one hand, the clinician grasps the anterior aspect of the patient's lower leg, just proximal to the malleoli, while the other hand grasps the anterior aspect of the patient's thigh, just above the patella. The patient's hip is flexed to about 90 degrees and stabilized with one hand, while the clinician flexes the knee with the other hand (Fig. 20-9). At the end of the ROM, the clinician exerts slight overpressure. The normal end-feel is usually one of soft tissue approximation. A flexion limitation other than soft tissue approximation is usually the result of an articular lesion, such as arthritis or arthrosis (capsular pattern), a lesion of one of the menisci, or a loose body.274
Rotation of the tibia relative to the femur is possible when the knee is flexed and non–weight-bearing, with rotational capability greatest at approximately 90 degrees of flexion.97
The primary extensors of the knee are the quadriceps muscles, consisting of the rectus femoris, VL, vastus medialis, and vastus intermedius (see Table 20-2). Also assisting with knee extension in the 0–30-degree flexion range is the ITB and TFL.
The patient extends the knee (see Fig. 20-10), and the clinician applies overpressure by stabilizing the thigh and pulling the ankle up to the ceiling, while allowing the conjunct external rotation of the tibia. Under normal conditions, the end-feel is usually hard.
A limitation of active knee motion can have a number of causes. The patient may have a neurologic deficit from a lumbar intervertebral disk (IVD) herniation, with loss of knee motion as the primary symptom. Any acute injury causing pain may limit active knee motion as a result of muscle inhibition.310
Passive movements, as elsewhere, can determine the amount of available motion, the presence or absence of a capsular pattern, and the end-feel. At the tibiofemoral joint, the end-feel of flexion should be tissue approximation, whereas the end-feel of extension and medial and lateral rotation of the tibia on the femur is tissue stretch. Passive hyperextension of the knee with overpressure is performed to assess (from the end-feel) whether the knee extension is limited as a result of an articular disorder. Such articular disorders include arthritis or arthrosis, a lesion of one of the menisci, or a loose-body involvement. Hayes et al.331 found the intrarater reliability of end-feel and pain/resistance judgments at the knee to be generally good, especially after accounting for subject change and unbalanced distributions. Interrater reliability, however, was generally not acceptable, even after accounting for these factors.331 In a separate study, Hayes et al.332 explored the construct validity and test–retest reliability of the passive motion component of the Cyriax soft tissue diagnosis system and compared the hypothesized and actual patterns of restriction, end-feel, and pain/resistance sequence (P/RS) of 79 subjects with OA of the knee and examined associations among these indicators of dysfunction and related constructs of joint motion, pain intensity, and chronicity. The results of the study are discussed next.
Consistent with the hypotheses based on Cyriax's assertions about patients with OA, most subjects had capsular end-feels for extension; subjects with tissue approximation end-feels for flexion had more flexion ROM than did subjects with capsular end-feels, and the P/RS was significantly correlated with pain intensity (ρ = 0.35, extension; ρ = 0.30, flexion).332
Contrary to the hypotheses based on Cyriax's assertions, most subjects had noncapsular patterns, tissue approximation end-feels for flexion, and what Cyriax called pain synchronous with resistance for both motions.332
Pain intensity did not differ depending on end-feel. The P/RS was not correlated with chronicity (ρ = 0.03, extension; ρ = 0.01, flexion).332
Reliability, as analyzed by ICCs (ICC[3,1]) and Cohen's κ coefficients, was acceptable (≥0.80) or nearly acceptable for ROM (ICC = 0.71–0.86, extension; ICC = 0.95–0.99, flexion) but not for end-feel (κ = 0.17, extension; κ = 0.48, flexion) and P/RS (κ = 0.36, extension; κ = 0.34, flexion).332
The study concluded that the use of a quantitative definition of the capsular pattern, end-feels, and P/RS as indicators of knee OA should be reexamined and the validity of the P/RS as representing chronicity and the reliability of end-feel and the P/RS are questionable.332
Others have found that a ratio of loss of extension to loss of flexion during passive range of motion (PROM) of between 0.03 and 0.50 was more likely than a noncapsular pattern in patients with an inflamed knee or osteoarthrosis (likelihood ratio = 3.2).333
According to the osteopathic theories of somatic dysfunction,334 the following guidelines are used:
- If the restriction to movement is opposite to the direction that the bone seems to have traveled (e.g., the tibia has a reduced joint glide), a mobilization or a manipulation is the intervention of choice.
- If the restriction to movement is in the same direction that the bone seems to have moved and the opposite movement seems to be excessive (a change has occurred in the overall starting position), a muscle imbalance should be suspected, and a muscle energy technique used.
- If the patient demonstrates normal range but pain with movement, the joint cannot be at fault.
- If a muscle is very hypertonic, a spinal dysfunction may be present (unless trauma is involved), producing a hypermobility.
Even minor losses of knee motion may have adverse effects. It is common to lose both flexion and extension; however, loss of extension is usually more debilitating.335 A loss of extension of more than 5 degrees may cause patellofemoral pain and a limp during walking,336 whereas restricted flexion does not severely affect gait as long as the knee can be flexed to at least 60 degrees. 337 Diminished running speed is associated with loss of flexion of 10 degrees or more,338 whereas an extension deficit of more than 10 degrees is poorly tolerated by active people.339 A loss of more than 20 degrees of extension may cause a significant functional limb-length discrepancy.338
Probably the most important part of the patellofemoral examination is the observation of the dynamics of patellar tracking in weight-bearing and non–weight-bearing.
A unilateral squat (Waldron test) can be used to assess patellofemoral function.340 The patient stands on the involved leg, and the clinician sits or squats next to the patient. Using the entire surface of the palm, the clinician exerts slight pressure in an anteroposterior direction against the patient's patella (Fig. 20-11). From this position, the patient is asked to bend the knee slowly, if possible, to about 90 degrees, while the clinician palpates for crepitus and locking of the patella and assesses the course of movement of the patella. Crepitus or locking can indicate the presence of patellofemoral chondropathy or patellofemoral arthrosis. However, Nijs et al.341 reported unimpressive positive and negative likelihood ratios for this test.
In patellar malalignment or pathologies of the corresponding femoral joint surface, movement of the patella can be disturbed. The patella is observed while the patient initiates flexion of the knee to see if it engages smoothly at the proximal end of the trochlea or more distally than normal. Lateralization of the patella can occur during flexion, particularly when the Q-angle is excessive.
The passive mobility tests for the patella are outlined in “Patellar Stability Tests” section.
Ankle motions are tested because, as has been discussed, a number of structures share a common relationship with the foot, ankle, and knee joint complex (see Chap. 21) and can therefore have an impact on knee function. For example, adaptive shortening of the gastrocnemius, particularly in the presence of adaptively shortened hamstring muscles, may produce increased knee flexion at initial contact and during the stance phase of gait.215
Several muscles cross both the hip and the knee. These include the rectus femoris, gracilis, sartorius, and hamstrings muscles. Adaptive shortening of any of these structures may cause alterations in postural mechanics and gait. The hip rotators can also influence other aspects of the lower kinetic chain. Sahrmann advocates the testing of length–strength relationship of the hip external rotators because of their CKC function of decelerating lower extremity internal rotation.167,342
Passive Accessory Motion Testing
The passive accessory motion tests, or joint glides, are performed at the end of the patient's available range to determine if the joint itself is responsible for the loss of motion.
The patient lies in the prone position. The clinician is beside the patient. Using one hand to stabilize the thigh, the clinician uses the other hand to grip the distal tibia from the medial and lateral sides. The clinician then applies a force perpendicular to the tibial joint surface (Fig. 20-12).
Posterior Glide of the Tibia on the Femur
The patient lies in the supine position with the thigh supported by a towel. Standing to the side of the patient, the clinician applies a posterior glide through the tibia (Fig. 20-13).
Posterior glide of the tibia on the femur.
Anterior Glide of the Tibia on the Femur
The patient lies in the supine position with the knee flexed and the foot placed on the table. The clinician stands to the side of the patient. Using both hands, the clinician applies an anterior glide of the tibia (Fig. 20-14).
Anterior glide of the tibia on the femur.
Proximal Tibiofibular Joint
The proximal tibiofibular joint can be assessed with the patient in the supine position and the knee flexed to approximately 90 degrees. The clinician stabilizes the tibia using one hand and uses the other hand to grasp the fibular head and to assess the anterolateral and posteromedial glides (Fig. 20-15).
Mobility testing of the proximal tibiofibular joint.
Passive Tibial External Rotation
The patient lies in the supine position. Using one hand, the clinician grasps the patient's foot and brings the ankle into maximal plantar flexion. The other hand is positioned to monitor the joint space.274 The patient's knee is flexed to 90 degrees and the hip to approximately 45 degrees. The distal hand performs an external rotation of the tibia while maintaining the ankle in maximum plantar flexion (see Fig. 20-16). At the end of the ROM, the clinician exerts slight overpressure. Under normal conditions, the end-feel is firm. The clinician notes whether the pain is provoked or whether there is a hypermobility or hypomobility274:
- Pain with passive external rotation of the tibia can be the result of a lesion of the medial meniscotibial ligament, medial meniscus, MCL, or the posteromedial capsuloligamentous complex.
- Hypermobility with this maneuver can be the result of a lesion of the posteromedial capsuloligamentous complex, often in combination with lesions of the MCL and the ACL. Hypermobility may also be seen in ballet dancers.
- Hypomobility of passive tibial external rotation is seen only in severe articular disorders with significant capsular limitations of motion.
Passive external rotation of tibia.
Passive Tibial Internal Rotation
The patient lies in the supine position. Using one hand, the clinician grasps the patient's foot and brings the ankle into maximal plantar flexion. The other hand is positioned to monitor the joint space. The patient's knee is flexed to 90 degrees and the hip to about 45 degrees. The distal hand performs an internal rotation of the tibia while maintaining the ankle in maximum plantar flexion (see Fig. 20-17). At the end of the ROM, the clinician exerts slight overpressure. Under normal conditions, the end-feel is firm. The clinician notes whether pain is provoked or whether there is hypermobility or hypomobility274:
- Pain can be the result of a lesion of the lateral meniscotibial ligament, lateral meniscus or posterolateral capsuloligamentous complex.
- Hypermobility can be the result of a lesion of the posterolateral capsuloligamentous complex.
- Hypomobility is seen only in severe articular disorders with significant capsular limitations of motion.
Passive tibial internal rotation.
Patellofemoral Joint Mobility Tests
The patient lies in the supine position with the involved knee supported in slight flexion. The clinician moves the patella superiorly, inferiorly, medially, and laterally (Fig. 20-18). Caution must be used with the lateral glide in case the joint is hypermobile, as this is the most common direction for patella dislocations. To assess the various tilts of the patella, both hands are wrapped around the patella and the thumbs are used to tilt the patella medially and laterally (Fig. 20-19). The findings are compared with the contralateral side.
Patellar mobility testing.
Gross muscle testing is useful in checking for deficits in the lower extremities. Strength testing involves the performance of resisted isometric tests. The joint is placed in its resting position to minimize any joint compression forces.
The strength of the knee flexors (the hamstrings) can be assessed by positioning the patient prone with the knee flexed to approximately 80–90 degrees. By internally rotating the tibia (Fig. 20-20) and resisting knee flexion, the clinician can theoretically assess the integrity of the medial hamstrings (semimembranosus and semitendinosus). The biceps femoris is assessed similarly by externally rotating the tibia and resisting knee flexion (Fig. 20-21).
Goniometric Measurement of Knee Flexion
Manual Muscule Testing: Lateral and Medial Hamstrings
Strength testing the medial hamstrings.
Strength testing the biceps femoris.
Pain may be reproduced, and localized, with multiple angle isometric testing of the quadriceps, as described by McConnell.189 Thus, the strength of the knee extensors (the quadriceps) is tested in 0, 30, 60 (Fig. 20-22), 90, and 120 degrees of knee flexion and held for 1 second with the femur externally rotated, to see if the pain can be reproduced or localized. The reproduction of pain with these tests suggests excessive pain from patellar compression. Any abnormal tibial movement with these tests may suggest ligamentous instability.343 If pain is noted during this testing, McConnell suggests returning the knee to full extension, producing and maintaining a medial glide of the patella, and then returning the knee to the painful position to retest. This action should reduce the pain if it is of a patellofemoral origin.189
Strength testing of knee extensors at 60 degrees.
The final 15 degrees of knee extension require a 60% increase in muscle firing.137 An extension lag (passive knee extension that is greater than active knee extension) indicates a slight loss of quadriceps muscle function.167,266,344
Siegel and Jacob343 suggest testing the quadriceps muscle at 0, 30, 60, and 90 degrees while observing for any abnormal tibial movement. Any abnormal tibial movement would suggest ligament instability or excessive pain from patellar compression.
The heel raise can be used to assess the strength of the gastrocnemius. The strength of the gastrocnemius muscle is tested because of its intimate relationship to the knee and its importance in lower extremity function. The patient is positioned in standing, leaning against a wall, or supported by the clinician with the knees extended. One foot is tested at a time as the patient rises up on the toes for 10–20 repetitions (depending on age and physical ability) while standing.
- The patient everts the foot and raises up on the toes to test the lateral head.
- The patient inverts the foot and raises up on the toes to test the medial head.
The soleus muscle can be tested similarly by having the patient perform a unilateral heel raise while keeping the knee flexed.
Palpation of the soft tissues about the knee is critical and often reveals more important information than any imaging tool. For palpation to be reliable, the clinician must have a sound knowledge of surface anatomy (Figs. 20-23 and 20-24), and the results from the palpation examination should be correlated with other findings. A logical sequence should be employed by the clinician. The skin, retinacula, quadriceps tendon, and patellar tendon are palpated to rule out any soft tissue sources of pain. Differences in temperature between the knees suggest inflammation in the warmer of the two. The following structures should be identified and palpated.
Palpable structures on the anterolateral surface of the knee.
Palpable structures on the anteromedial surface of the knee.
The patient lies in the prone position. The clinician locates the popliteal fossa. The semimembranosus and semitendinosus form the proximal medial border of the fossa. Deep inside this fossa, a Baker's cyst can be palpated if it is present. With the knee in a slightly flexed position, the thin round tendon of the semitendinosus should be easy to palpate. Medial and lateral to this tendon are the deeper parts of the semimembranosus. The popliteal pulse can be located just below the crease of the knee, more to the lateral side than to the medial side, and posterior to the tibial plateau. Medial to the pulse is the tendon of semimembranosus. At this point, if the thumb is pushed deeper, the attachment of the PCL can be located as it arises from the back of the tibia. Even under normal circumstances, this attachment will be tender. A little lateral to this is the attachment of the meniscofemoral ligament. The PCL and meniscofemoral ligament curve inward, to attach on the inner aspect of the medial condyle of the femur.
At the proximal lateral part the fossa, the biceps femoris tendon is found. This tendon is palpable together with the common fibular (peroneal) nerve. The tendon of the gracilis is medial and anterior to the medial part of the semimembranosus. Palpation performed medially and anteriorly to this point leads to the sartorius muscle. The tendons of the sartorius, gracilis, and semitendinosus form the pes anserinus. The sartorius and gracilis muscles can be differentiated as follows: the gracilis contracts during hip adduction, while the sartorius contracts during hip abduction. Palpation more anteriorly leads to the medial femoral condyle and the adductor tubercle. Tenderness at the anterior aspect of the medial femoral condyle, associated with a snapping sensation as the knee is flexed, can indicate a symptomatic plica.345 The adductor tubercle serves as the attachment site for the patellar retinaculum and the medial patellofemoral ligament, and is a hallmark site of tenderness with lateral patellar dislocation.274 The adductor tubercle is also the attachment site of the adductor magnus, and the origin of the MCL. The distal borders of the popliteal fossa are palpated by positioning the patient's knee in slight flexion. The medial head of the gastrocnemius can be palpated deep within and medial to the fossa, while the lateral head can be found deep within and medial to the tendon of the biceps femoris muscle.
The patient lies supine with the hip and thigh positioned in extension. The clinician palpates the medial and lateral edges of the patella. The VMO normally inserts into the upper third or half of the medial patella and is readily palpable. In patients with patella malalignment, the VMO may be dysplastic and virtually invisible inserting proximal to the superior pole of the patella.346 Palpation of the rectus femoris insertion on the superior aspect of the patella is only possible with the patella tipped slightly forward.274 Complaints of pain distal to the patella during extension of the knee may indicate a patella tendon–ligament lesion at the inferior pole. In some individuals, the continuation of the tendon of the VL muscle, the lateral patellar retinaculum, can be palpated at the lateral side of the patella.274
Palpation of the joint space is made easier when the tibia is rotated internally and externally while in the flexed position. The anterior part of the medial meniscus is palpable in the medial joint space with the tibia externally rotated, between the patellar tendon–ligament and the anterior edge of the MCL. Under normal circumstances, the medial meniscus is not palpable beyond 30 degrees of flexion.274 The medial meniscotibial or coronary ligament, which attaches the medial meniscus to the tibia, is palpable anteriorly with the knee positioned at 90 degrees of flexion and the tibia maximally externally rotated, proximal to the tibia (passive external rotation of the knee will provoke the patient's pain, if the ligament is damaged).274
Joint line tenderness usually is associated with a tibiofemoral injury, such as a meniscal or collateral ligament tear, but it can also be associated with patellar pathology, although the reasons are probably multifactorial.205,269,272 Numerous studies have shown that joint line tenderness, when used in isolation, is of little value in specifically diagnosing a meniscus tear.
Other structures to palpate for tenderness on the anterior aspect of the knee include the following:
- Base (inferior pole) of patella. Tenderness at the inferior tip of the patella indicates patellar tendinitis.
- Infrapatellar fat pad (Hoffa's fat pad). This structure is located between the patella ligament (anteriorly) and the anterior joint capsule (posteriorly).
- Lateral retinaculum.
- Apex of patella.
- Accessory retinaculum from the ITB.
- Medial retinaculum.
- Medial and lateral patellar facets. These facets, which are readily palpated using the thumb and index finger, can be tested for tenderness and alignment, as can the overhang of the lateral facet over the patellar groove, by pushing the patella to one side and then the other (glide test), and then curling the fingers around and under the borders of the patella. Palpation of the facets should not elicit pain. The clinician should be able to palpate under one-third of the patella. A tilt of the patella (lateral side down) reflects a tight retinaculum, especially if the tilt cannot be passively corrected by the clinician.346 When the patella is laterally displaced by the clinician and the patient reports sudden and considerable discomfort as the knee approaches extension, this is termed the apprehension sign (see “Special Tests” section).346 The combination of tilt and lateral facet tenderness in the absence of any other positive findings on physical examination suggests clinically significant patella malalignment.346
- Dynamic restraints. The patient is asked to contract the quadriceps. In patients with malalignment, the VMO typically cannot be identified by sight or palpation; it inserts no farther distally than the proximal pole of the patella and it remains soft, even with maximal quadriceps contraction.196 In the normal knee, the VMO should be felt to contract simultaneously with the VL.
The fibular head can be palpated by following the tendon of the biceps femoris distally. It is often more distal and posterior than imagined. On the lateral side, the highest point on the lateral femoral condyle is the lateral epicondyle, which serves as the origin of the LCL. The LCL is best palpated when the hip is maximally externally rotated and the knee is flexed to 90 degrees in the “figure-four” cross-legged stance.274 If the LCL is followed down to the fibular head, it will be felt to blend with the biceps femoris. On the posterolateral aspect of the condyle is the attachment for the lateral head of the gastrocnemius. Anterior to this, there is a small circular groove, which is where the tendon of the popliteus originates from the lateral condyle. Tenderness in this location, just behind the LCL, either anterior or posterior to it, would suggest damage to the popliteus muscle.274 On the anterolateral aspect of the knee is Gerdy's tubercle, the largest bony prominence medial to the apex of the fibular head, which serves as the attachment site for the ITB.
The lateral joint space is palpated starting at a point just lateral to the patellar tendon–ligament. The anterior part of the lateral meniscus is best palpated with the knee in an extended position.
The highest point of the medial aspect of the femur is the medial epicondyle, which serves as the origin for the MCL. Superior to this point is the adductor tubercle, and superior to that is the supracondylar ridge, which is the attachment for the VMO. Very localized tenderness at the medial aspect of the knee, away from the joint line, may indicate a neuroma.344
The stress tests are used to determine the integrity of the joint, ligaments, and the menisci. A complete history and physical examination can diagnose approximately 90% of ligamentous injuries. The goal of the stress tests is to identify the degree of separation and the quality or end-feel of the separation when a stress is applied in a specific direction. Intact ligaments have an abrupt and firm end-feel, whereas sprained ligaments have a soft or indistinct end-feel depending on the degree of injury. A comparison should always be made with the uninvolved knee before a determination is made. It is important to remember that both pain and swelling can hamper the sensitivity of these tests.347
Serious functional instability of the knee appears to occur unpredictably. The reasons for such discrepancies are unknown, but they may be a result of36
- varying definitions of instability;
- varying degrees of damage to the ACL;348,349
- different combinations of injuries;71
- different mechanisms of compensation for the loss of the ACL;
- differences in rehabilitation;
- the diverse physical demands and expectations of different populations.
The patient lies in the supine position, with the involved knee extended. The clinician applies a strong valgus force, with a counterforce applied at the lateral femoral condyle (Fig. 20-25). Normally, there is little or no valgus movement in the knee, and, if present, it should be less than the amount of varus motion. Under normal conditions, the end-feel is firm. With degeneration of the medial or lateral compartments, varus and valgus motions may be increased, while the end-feels will be normal.
With the knee tested in full extension, any demonstrable instability is usually very significant. Pain with this maneuver is caused by an increase in tension of the medial collateral structures or the connection of these structures with the medial meniscus. If pain or an excessive amount of motion is detected compared with the other extremity, a hypermobility or instability should be suspected. The following structures may be implicated:
- Superficial and deep fibers of the MCL
- Posterior oblique ligament
- Posteromedial capsule
- Medial capsular ligament
A study by Garvin et al.350 looked at 23 patients with a surgically proven tear of the MCL, where findings from magnetic resonance imaging (MRI) of the knee were evaluated retrospectively. MRI revealed the tear in all cases, although when the injury was severe, distinguishing high-grade partial tears from complete tears was difficult.350 Physical examination had indicated a tear in 22 (96%) of the cases.350 A high prevalence of associated cruciate and meniscal injuries was seen (in 23 [100%] and 12 [52%] of the cases, respectively). Tears of the LCL occurred in 13 (57%) of the patients and at least one bony infarction in 22 (96%); most of the infarctions were in the lateral compartment. Infarctions of the lateral femoral condyle were frequently geographic (in 14 [70%] of the 20 cases) or impacted (in 5 [25%]).350
To further assess the MCL, posterior oblique ligament, and PCL, the test is then repeated at 20–30 degrees of flexion. Hughston55 concluded that a valgus stress test positive at 30 degrees and negative at 0 degree indicates a tear limited to the medial compartment ligaments (posterior oblique ligament) and posterior medial capsule, whereas a valgus stress test positive at 0 degree indicates a tear of both the PCL and the medial compartment ligaments.
The posterior fibers of the MCL can be isolated, by placing the knee in 90 degrees of flexion with full external rotation of the tibia.274 The femur is prevented from rotating by the clinician's shoulder. The clinician places one hand on the posterior aspect of the foot and the other on the heel, and an external rotation force is applied using the foot as a lever.
These tests can be graded by the following:63
- Grade I: The joint space opening is within 2 mm of the contralateral side.
- Grade II: The joint space opens 3–5 mm more than the contralateral side in 20 degrees of knee flexion and less than 2 mm more than the normal knee in full extension.
- Grade III: The joint space opens 5–10 mm more than that of the normal knee in 20 degrees of flexion and full extension.
More research is needed to evaluate the diagnostic accuracy and reliability of this test.
The patient lies in the supine position, with the involved knee in full extension. The clinician applies a strong varus force, thereby gapping the lateral aspect of the knee (see Fig. 20-26). To be able to assess the amount of varus movement, the clinician should repeat the maneuver several times, applying slight overpressure at the end of the ROM. Under normal conditions, the end-feel is firm, after slight movement. Unlike the valgus stress test, the varus test has been shown to be highly unreliable with many false-negative findings.351
Theoretically, if this test is positive for pain or excessive motion compared with the other extremity, the following structures may be implicated:
- Lateral capsular ligament
- Arcuate-popliteus complex
If the instability is gross, one or both cruciate ligaments as well as, occasionally, the biceps femoris tendon and the ITB may be involved, leading to a rotary instability if not in the short term, certainly over a period of time.159
The test is then repeated at 10–30 degrees of flexion with the tibia in full external rotation to further assess the LCL, posterolateral capsule, and arcuate–popliteus complex.
Grading of these injuries is the same as for MCL injuries and is based on the degree of opening of the lateral joint line.63
More research is needed to evaluate the diagnostic accuracy and reliability of this test.
One-Plane Anterior Instability
Ensuring the integrity of the ACL is crucial for maintaining the normal biomechanical properties of the knee joint, protecting its periarticular structures, and preventing premature OA. Knee joints with ACL deficiencies have rotary instabilities that expose supporting ligaments and menisci adjacent to the ACL to further damage and degenerative joint disease.28 Signs and symptoms of chronic rotary knee instabilities from ACL deficiencies include swelling, pain, a “giving way” of patients' knee joints, arthritis, and possible subsequent meniscal injuries.
Several tests have been advocated for testing the integrity of the ACL. Three of the more commonly used ones are the Lachman test, the anterior drawer test, and the pivot shift (see “Anterolateral Rotary Instability” section).
Torg et al.352 were the first to publish a description of the Lachman test, whereby the knee is held in 30 degrees of flexion while the tibia is anteriorly translated with respect to the femur (Fig. 20-27).
The accuracy and reliability of the Lachman appears to vary. Katz et al. found that in the hands of an experienced clinician, accuracy of this test was 81.8% sensitive and 96.8% specific,353 increasing to 100% if the patient was anesthetized.354,355 In contrast, Cooperman et al.356 reported that the predictive value of a positive test was 47% for all examiners, whereas the predictive value of a negative test was 70%, results that would indicate that Lachman test judgments have limited reliability and may be more useful for predicting that a patient does not have an ACL injury than for predicting that the ACL is injured.357
These discrepancies likely occur as there are a number of factors that can influence the results. These include
- an inability of the patient to relax;
- the degree of knee flexion;
- the size of the clinician's hand;
- the stabilization (and thus relaxation) of the patient's thigh.
According to Weiss et al., 358 these factors can be minimized by the use of the modified Lachman test. In this modification, the patient lies in the supine position, with the feet resting firmly on the end of the table and the knees flexed 10–15 degrees. The clinician stabilizes the distal end of patient's femur using the thigh rather than the hand, as in the Lachman test, and then attempts to displace patient's tibia anteriorly. If the tibia moves forward, and the concavity of the patellar tendon–ligament becomes convex, the test is considered positive.
The grading of knee instability is as follows55,359,360:
- 1 + (mild): 5 mm or less
- 2 + (moderate): 5–10 mm
- 3 + (serious): more than 10 mm
With this test, false-negatives can occur. False-negatives may be caused by a significant hemarthrosis, protective hamstring spasm, or tear of the posterior horn of the medial meniscus.352
The patient lies in the supine position with a bolster under the distal femur so that the knee is flexed to 30–40 degrees. The patient is asked to actively extend the involved knee and then to relax back to the starting position. A positive test for a torn ACL is indicated by an anterior glide of the proximal tibia during the knee extension. The one study361 that examined this test did not report reliability or diagnostic accuracy.
The aforementioned Lachman test is a modification of the anterior drawer test.274 The patient lies in the supine position with the clinician standing to the side of the patient's involved knee. The clinician grasps the lower leg of the patient just distal to the joint space of the knee and the patient's knee is flexed to 90 degrees so that the foot is flat and the lower leg is not rotated. The clinician fixates the patient's leg by sitting on the foot. The clinician can place the thumbs either in the joint space or just distal to it to assess mobility. The clinician tests the tension in the musculature. It is important that all muscles around the knee be relaxed to allow any translatory movement to occur. With both hands, the clinician now abruptly pulls the lower leg forward (Fig. 20-28). This test is positive for an ACL tear when an abnormal anterior movement of the tibia occurs compared with the other extremity. Overall, there is wide variation in the reported sensitivities of the anterior drawer test. The anterior drawer test in 80 degrees of flexion without rotation has been found to be 40.9% sensitive and 96.8% specific.353 This test appears to be a specific test helpful at ruling in a torn ACL when the test is positive.352,362,363 False-negatives may occur with this test for the same reasons as those in the Lachman test. Given the low sensitivity of this test, the clinician should not rule out an acute ACL injury solely on the basis of a negative anterior drawer.
The anterior drawer test.
There are a number of variations to the anterior drawer test, all of which involve positioning the patient supine274:
- Anterior drawer test and maximal external rotation.274 The initial positions of the patient and clinician are the same as in the anterior drawer test in 80 degrees of flexion without rotation, except that the lower leg is positioned in maximum external rotation. For the performance, refer to the preceding description. The ACL and the medial and posteromedial capsuloligamentous structures are tested in this position. If this test is positive, there is likely to be an anteromedial rotatory instability. The specific medial and posteromedial structures that are affected can be further differentiated by the abduction (valgus) stress tests previously described. No diagnostic accuracy studies have been performed to determine the sensitivity and specificity of this test.
- Anterior drawer test and maximal internal rotation.274 The initial positions of the patient and clinician are the same as in the anterior drawer test in 80 degrees of flexion without rotation, except that the lower leg is now maximally internally rotated. Performance of the test is the same as described earlier for that test. When in maximal internal rotation, the PCL can completely restrict anterior translation of the tibia. Thus, for this test to demonstrate excessive anterior translation, the PCL, ACL, and lateral or posterolateral capsuloligamentous structures have to be affected. No diagnostic accuracy studies have been performed to determine the sensitivity and specificity of this test.
Comparison of the Lachman and Anterior Drawer Tests
The Lachman test has two advantages over the anterior drawer test in 90 degrees of knee flexion. First, all parts of the ACL are more or less equally taut. Second, in acute lesions it is often impossible to position the knee in 90 degrees of flexion because of a hemarthrosis. In a study of patients with an ACL rupture, the Lachman test was positive in 80% of nonanesthetized patients and 100% of anesthetized patients. In comparison, the anterior drawer sign was positive in 9% of nonanesthetized patients and 52% of anesthetized patients.364
Jonsson et al.365 compared both the Lachman and anterior drawer tests in 45 patients with an acute ACL injury and 62 patients with a chronic knee injury. Patients were tested while nonanesthetized and anesthetized, and the diagnosis was verified by arthroscopy. The Lachman test results for the acute injury group was 87% (conscious) and 100% (anesthetized). The anterior drawer test results were 33% and 98%, respectively. The chronic injury group scored a positive Lachman test in 97% (conscious) and 99% (anesthetized). The anterior drawer test was positive in 92% and 100%, respectively.
According to Larson,366 the Lachman test proved to be the most sensitive test for an ACL rupture. However, this article lacked statistical data to verify this assertion. Another study355 that compared the two tests reported a sensitivity of 99% for the Lachman test and a sensitivity of 70% for the anterior drawer sign.
One-Plane Posterior Instability
The PCL is very strong and is rarely completely torn. It is typically injured in a dashboard injury or in knee flexion activities (falling on the patella). Several tests have been advocated to test the integrity of the PCL.274
Posterior Sag (Godfrey) Sign
The patient lies in the supine position with the knees flexed to approximately 90 degrees and the legs supported under the lower calf/heel by the clinician's arm. The clinician assesses the contour of the tibial tuberosities (Fig. 20-29). If there is a rupture (partial) of the PCL, the tibial tuberosity on the involved side will be less visible than that on the noninvolved side.367 This discrepancy is caused by an abnormal posterior translation, resulting from a rupture of the PCL. In cases of doubt, the patient can be asked to contract the hamstrings slightly by pushing the heels into the clinician's arm. This maneuver usually results in an increase in the posterior translation of the tibia and is often performed as a quick test of the integrity of the PCL. This test may have some value as a screening test when negative due to its high sensitivity.368,369
The patient lies in the supine position, with the involved knee flexed to 90 degrees. The clinician attempts a posterior displacement of the tibia on the femur (Fig. 20-30). In a blinded, randomized, and controlled study involving 39 patients to assess the clinical examination skills of orthopaedic surgeons with fellowship training in sports medicine, Rubinstein et al.370 reported that the accuracy for detecting a PCL tear was 96%, with a 90% sensitivity and a 99% specificity. The examination accuracy was higher for grades II and III posterior laxity than for grade I laxity.370 Eighty-one percent of the time, the examiners agreed on the grade of the PCL tear for any given patient.370
Functional Posterior Drawer Test.371
The patient lies in the prone position with the foot in neutral rotation and the knee flexed to 80–90 degrees. The patient is asked to isometrically contract the hamstrings while the clinician stabilizes the foot (Fig. 20-31). A positive result for a PCL tear is a posterior subluxation of the lateral tibial plateau.
Functional posterior drawer test.
The patient lies in the supine position and the relaxed limb is supported with the knee flexed to 90 degrees in the drawer-test position. The patient is asked to execute a gentle quadriceps contraction to shift the tibia without extending the knee. If the PCL is ruptured, the tibia sags into posterior subluxation (∼2 mm or more), and the patellar ligament is then directed anteriorly. Studies have shown significantly different sensitivities for this test. Rubinstein et al.370 reported a sensitivity of 54% and a specificity of 97% whereas Daniel372 reported a sensitivity of 98%.
Rotary or complex instabilities occur when the abnormal or pathologic movement is present in two or more planes. The ligamentous laxities present at the knee joint in these situations allow motion to take place around the sagittal, coronal, and horizontal axes.
This type of instability is relatively rare, because it requires complete posterior cruciate laxity. It occurs when the lateral tibial plateau subluxes posteriorly on the femur, with the axis shifting posteriorly and medially to the medial joint area. With a hyperextension test, this posterior displacement is obvious and has been labeled as the external rotation recurvatum sign.
Modified Posterolateral Drawer (Loomer's) Test.55,360
The patient lies in the supine position with the hip and knee flexed to 90 degrees, and the lower leg in external rotation (Fig. 20-32).373 If the tibia rotates posteriorly during the test, the test is positive for posterolateral instability, indicating that the following structures may have been injured:
- Arcuate–popliteus complex
- Posterolateral capsule
Modified posterolateral drawer.
The one-plane medial and lateral stability tests, described earlier, can be used to further differentiate which lateral and posterolateral structures are affected.
This test is used to assess abnormal external tibial rotation to help differentiate between an isolated posterolateral corner injury and combined ACL/PCL injuries. The patient lies in the supine position with the knee flexed to 30 degrees over the edge of the table.374 The clinician applies an external rotation force to the patient foot by placing the fingers and thumb alongside the talocalcaneal bone contours (Fig. 20-33). The foot–thigh angle is measured and compared with the uninjured knee. The test is then performed with 90 degrees of knee flexion and the foot–thigh angle is remeasured. When comparing the two angles, a difference of 10 degrees or more is significant. As the knee is flexed to 90 degrees, a reduction in increased rotation may occur although the amount of motion remains greater than the uninjured side if the PCL is still intact. This increased rotation occurs because the PCL is a secondary stabilizer to external rotation and gains mechanical advantage when the knee is flexed.375
Posteromedial Displacement with Valgus Stress Test
The patient lies in the supine position, with the involved leg slightly flexed.373 The clinician pushes the lower leg posteriorly into hyperextension while applying a valgus stress (Fig. 20-34). If the tibia sags posteriorly during the test, the test is positive for posteromedial instability, indicating that the following structures may have been injured:
- Posterior oblique ligament
- Posteromedial capsule
Posteromedial displacement with valgus stress test.
The one-plane medial and lateral stability tests, described earlier, can be used to further differentiate which medial and posteromedial structures are affected.
Anterolateral Rotary Instability
The pathology for this condition almost certainly involves the ACL and, clinically, the instability allows the medial tibial condyle to sublux posteriorly, because the axis of motion has moved to the lateral joint compartment.159
The diagnosis of anterolateral instability is based on the demonstration of a forward subluxation of the lateral tibial plateau as the knee approaches extension and the spontaneous reduction of the subluxation during flexion, in the lateral pivot-shift test.159 This form of instability usually occurs when the individual is either decelerating or changing direction, and the sudden shift of the lateral compartment is experienced as a “giving way” phenomenon, often associated with pain.159
This test was first described by Galway et al.376 in 1972 and has been described since by a number of authors.377–380
The pivot shift is the anterior subluxation of the lateral tibial plateau that occurs when the lower leg is stabilized in (almost) full extension, whereby further flexion produces a palpable spring-like reduction.381 The pivot shift is the most widely recognized dynamic instability of the knee, and it has been shown to correlate with reduced sports activity,382 degeneration of the cartilage,383,384 reinjury, meniscal damage,385 joint arthritis,385 and a history of instability symptoms.357,386
Since the majority of patients with an ACL rupture complain of a “giving way” sensation, the pivot-shift test is regarded in current literature as capable of identifying rotational instability.377,378,380
The patient lies in the supine position with the clinician standing to the side of the patient's involved knee. There are two main types of clinical tests to determine the presence of the pivot shift: the reduction test and the subluxation test.
- Reduction test. The clinician stabilizes the patient's lower leg and flexes the knee to 90 degrees with one hand while using the palm of the other hand to medially rotate the tibia, effectively subluxing the lateral tibial plateau (Fig. 20-35).386 A sudden reduction of the anteriorly subluxed lateral tibial plateau is seen as the pivot shift.376
- Subluxation test. This test is effectively the reverse of the reduction test.55 The test begins with patient's knees flexed. The clinician internally rotates the patient's tibias with one hand and applies a valgus stress to the knee joint with the other hand (Fig. 20-36). The clinician slowly extends the knee, maintaining rotation of the tibia. As the patient's knee reaches full extension, the tibial plateau will be felt to relocate. However, only 35–75% of patients whose knees pivot while the patient is under anesthesia will experience such a pivot when awake.355,387–389
Although the specificity of the pivot shift test is very high, namely 98% (95% CI, 25–38), there is little agreement in the literature with regard to the sensitivity of the test, which varies between 0% and 98%.355,364,390 However, in a meta-analysis that looked at 28 studies to assess the accuracy of clinical tests for diagnosing ACL ruptures, Benjaminse et al.391 found the pivot shift test to be very specific both in acute as well as in chronic conditions, and recommended that both the Lachman and pivot-shift tests be performed in all cases of suspected ACL injury.
It is worth noting that the pivot-shift test can be positive with an isolated ACL injury355,392 or a tear or stretching of the lateral capsule,379,393 although an injury to the MCL reduces the likelihood of a pivot shift even with ACL injury.355,394
The McMurray test was originally developed to diagnose posterior horn lesions of the medial meniscus. The patient lies in the supine position, and the clinician, standing on the same side as the involved knee, maximally flexes the hip and knee. This is accomplished by grasping the patient's foot in such a way that the thumb is lateral, the index and middle fingers are medial, and the ring and little fingers hold the medial edge of the foot (Fig. 20-37). The thumb of one hand is placed against the lateral aspect of the patient's knee (see Fig. 20-37). To test the medial meniscus, the clinician rotates the tibia into external rotation, then slowly extends the knee. To test the lateral meniscus, the clinician flexes the knee again but now internally rotates the patient's tibia and then slowly extends the knee. A positive test traditionally is indicated by an audible or palpable thud or click. In a study by Dervin et al.396 to determine clinicians' accuracy and reliability for the clinical diagnosis of unstable meniscus tears in patients with symptomatic OA of the knee, a positive McMurray test was the only positive predictor of an unstable meniscal tear.396
Numerous variations exist for the McMurray test, including the addition of varus/valgus stresses. An examination of the variation seemed to indicate that the McMurray test has some value as a specific test where a positive test would rule in the disease.
The patient is placed in the prone position, with the knee flexed to 90 degrees. The patient's thigh is stabilized by the clinician's knee. The clinician grasps the patient's foot with one hand, distracts the tibia, and rotates the tibia internally and externally, noting whether or not pain is reproduced. A positive test is indicated by worse pain with rotation and is indicative of a rotation sprain of soft tissue. The clinician then applies internal and external rotation with compression to the lower leg, noting any pain and the quality of motion (Fig. 20-38). A positive test for a meniscus tear is indicated by more pain in compression than distraction. It would appear from a number of studies that the Apley test can be used as a specific test to rule in a meniscus tear when positive.
Steinmann's test can be used to diagnose meniscal lesions. The patient is placed in the supine position, while the clinician stands to the side. Using one hand, the clinician grasps the patient's lower leg just proximal to the malleolus. The other hand grasps the lateral side of the patient's lower leg as proximal to the knee as possible while also palpating the medial joint space with the fingers (Fig. 20-39). The knee is extended, and the joint line between the patellar tendon and the MCL is palpated. After the painful site is located with the fingers, pressure against this site is maintained while the knee is flexed. After several degrees of motion, the pain disappears, and the painful site can sometimes again be palpated more posteriorly in the joint space. If the most painful site is found in the joint space at the level of the MCL, the test is less reliable, because both the medial meniscus and the ligament move posteriorly during flexion.
Anderson Mediolateral Grind Test
The Anderson mediolateral grind test398 can be used to detect meniscal lesions. The patient is placed in the supine position, and the clinician grasps the involved leg between the trunk and arm. The clinician places the index finger and thumb of the other hand over the anterior knee joint line. With the patient's knee flexed at 45 degrees, a valgus stress is applied as the knee is simultaneously slightly flexed (Fig. 20-40), followed by a varus component while the knee is extended, producing a circular motion of the knee. The maneuver is repeated, increasing the valgus and varus stresses with each rotation.
Anderson mediolateral grind test.
In one study398 that examined 100 knees with the Anderson mediolateral grind test, as well as arthroscopy, the test was found to have a sensitivity of 70% and a specificity of 67%. However further research needs to be performed to corroborate the statistics reported in this study.
The patient is placed in the supine position and the clinician extends the involved knee to end range (Fig. 20-41). A positive test for meniscus tear is indicated by a block preventing full extension, or pain at end-range extension. A number of studies seem to indicate that neither pain at full extension nor an extension block seem to indicate a torn meniscus.399–401
This test was developed to detect popliteomeniscal fascicle tears, which create instability of the lateral meniscus. The patient lies in the supine position and is asked to place the foot of the involved knee by the contralateral knee, forming a figure 4 (Fig. 20-42). The clinician pushes the involved knee toward the bed. A positive test is indicated by pain over the lateral joint line at the popliteal hiatus. In a very small study402 involving only six patients the test demonstrated a sensitivity of 100%. Further research is necessary before diagnostic conclusions can be made from this test.
The patient is placed in the supine position or sits and places the foot of the involved knee on the medial aspect of the contralateral knee, forming a figure 4. The clinician pushes the involved knee toward the floor (Fig. 20-43). A positive test for a posterior horn lesion of the medial meniscus is indicated by reproduction of the patient's pain over the medial joint line. In a study by Jerosch and Riemer403 this test was found to have a sensitivity of 54% and a specificity of 44%, demonstrating a diagnostic value similar to that of a coin toss.