**1. Introduction**

Recognition of inherent physiological asymmetry has not yet been applied to the understanding, assessment, or treatment of scoliosis or other spinal and postural disorders. Even without an accurate baseline model of human form and function, interventions to correct dysfunction can be successful; however, while a local dysfunction may be rectified, the underlying biomechanical imbalance will persist as will the musculoskeletal strategies developed to compensate for the imbalance.

The Postural Restoration Institute® (PRI) methodology is a theoretical framework, which describes a model of universal human anatomical and physiological asymmetry. This unique model provides a new baseline for understanding common postures, movement patterns, and respiratory mechanics, which generate from our asymmetrical bias. It also explains the factors that support human right-side dominance. While human asymmetry can be understood as a positive factor that facilitates movement, overuse or misuse of the dominant muscle pattern will promote progressive imbalance within the body and will likely result in dysfunction. The treatment goal for dysfunction resulting from musculoskeletal imbalance needs to be restoration of the baseline in which there is relative balance between the dominant and nondominant muscle patterns [1–4].

Scoliosis is an example of a tri-planar, biomechanical dysfunction. In its most common form (90% of the cases), right thoracic convexity and left lumbar convexity [5–7], it exemplifies the extreme progression of normal human asymmetry according to the PRI model, which will be described in this chapter. Other postural disorders such as kyphosis and lordosis, exhibiting primary sagittal plane dysfunction, also belong to the spectrum of disorders developing from unbalanced human asymmetry. These conditions result in musculoskeletal stress, subsequent structural damage, loss of efficiency in movement and in respiratory function, as well as in a diminished quality of life.

This chapter introduces the fundamental concepts of PRI's theoretical framework and its baseline model. It will then describe how PRI's clinical tests can more accurately evaluate a patient's status by taking into account the inherent human asymmetry. These tests guide exercise prescription and treatment progression. Some examples of exercises used in the treatment of scoliosis have been selected to demonstrate activity progression from supported target muscle isolation, to complex, unsupported, multiple muscle integration, all with a major emphasis on respiration. Three case studies are presented here to illustrate this process. Many similarities exist between PRI rehabilitation concepts and exercises and the well-known Schroth methodology [8, 9].
