Chapter 5

### Objectives

After completion of this chapter, the physical therapist should be able to do the following:

• Describe the interaction of posture and proprioception.

• Articulate the role of posture in functional movement.

• Relate alterations in posture to musculoskeletal pathology.

• Identify key components of a postural assessment.

### Introduction and Background

Postural assessment is a mainstay in any evaluation of a patient or client with musculoskeletal pain. The late physical therapist Florence Kendall was a pioneer and clinical guru in postural assessment. Her classic textbook, Muscle Testing and Function, serves as the reference for many students and practicing therapists who assess posture. By her definition, posture is the composite alignment of all the joints in the body at any given movement in time.25 Furthermore, Kendall25 defined ideal posture as skeletal alignment with minimal stress and strain, conducive to maximal efficiency.

Taking a structural and biomechanical approach, Kendall focused on using a plumb line to identify asymmetries in posture through observations of skeletal alignment. She suggested that a plumb line enabled a therapist to see the postural deviations that occur with respect to the forces of gravity. This static view of the musculoskeletal system is very helpful in observing the relationship between anterior–posterior and medial–lateral force imbalances. For example, a forward head posture indicated by position of the head in front of the frontal plane bisecting the body would create extra work for the posterior spine and muscles to support the head.

Although Kendall's structural approach to postural assessment provides a biomechanical assessment of the musculoskeletal system, the late Vladimir Janda, MD, saw postural assessment as a functional impression of the status of the sensorimotor system. According to Janda, the sensorimotor system is 1 functional unit comprised of the afferent sensory system and the efferent motor system; 2 systems that cannot be considered to function independent of each other.34 He noted that changes in muscle tension are the first response of the system to nociception. By combining static biomechanical assessment popularized by Kendall with his observation of muscle function, Janda was able to form an early observational description of the possible cause of the patient's musculoskeletal pain from a neurological perspective.34

Clinical Pearl

Postural assessment is often a first impression of the status of the sensorimotor system, and should subsequently lead the diagnostic pathway with regard to musculoskeletal dysfunction.

### The Role of Proprioception in Posture

Proprioception is vital to maintaining postural alignment, both statically and dynamically. The afferent information from joint mechanoreceptors and muscular receptors provides valuable information needed to maintain postural reflexes and to facilitate normal posture and movement patterns. Dr. Janda proposed 3 key areas of proprioception in the body that provide strong influences on posture: the sole of the foot, sacroiliac joint, and cervical spine. The position of the foot influences posture,14 while cutaneous and ...

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