The term posture is used to describe the position of the body at a given point in time. Ideal posture is characterized by specific landmarks being aligned with the force of gravity, minimizing energy expenditure and maximizing function.1 Proper posture requires the least amount of muscular effort, resulting in reduced stress on the joints and surrounding structures. Faulty posture produces an increased amount of muscular activity and places increased stress on the joints and surrounding soft tissues, resulting in impairments.2 Conversely, impairments can result in faulty posture. Clinically, it is difficult to determine if the faulty posture is the result of muscle imbalances, caused by overuse of certain muscles during the activities of daily living (ADLs), or if these imbalances are the result of faulty posture. Poor posture in and of itself usually does not prompt people to seek medical attention.
Postural assessment is used to identify postural deviations that may be contributing to the patient's pain or abnormal movement patterns. The postural examination begins with the patient in a standing or sitting position but can progress to include the dynamic postures of walking and running (see Chapter 7).3 Static positions assessed in a health-care facility may not replicate the postures that the patient normally assumes during athletic, school, home, or work activities.
This chapter describes the relationship between common postural deviations and the resulting clinical examination findings. The cause-and-effect relationship between faulty posture, common compensatory motions, and associated musculoskeletal dysfunctions is also discussed.
Before understanding how deviations in one region of the body affect another region, a review of basic anatomical and biomechanical concepts is needed. The musculoskeletal system is designed to function in a mechanically and physiologically efficient manner to use the least possible amount of energy. The change in position of one joint results in a predictable change in position of the other interrelated joints.4 When a postural deviation or skeletal malalignment occurs, other joints in the kinetic chain undergo compensatory motions or postures to allow the body to continue to function as efficiently as possible. For example, a forward shoulder posture can result from tightness of the pectoralis minor. This, in turn, changes the functional positions of the scapula and may predispose the patient to chronic shoulder pain.5
The musculoskeletal system is a series of kinetic chains in which different joints are directly or indirectly linked to each other (Fig. 6-1). In a kinetic chain, movement occurring at one joint causes motion at an adjacent joint, creating a "chain reaction" of movements up or down the associated kinetic chain. Kinetic chains are classified as open chain (non–weight-bearing) or closed chain (weight-bearing). Because the definitions of open and closed kinetic chain motions become blurred, the terms "weight-bearing" and "non–weight-bearing" are often used instead. The lower extremity-pelvis-lumbar ...