Pathomechanics of stance. Clinical concepts for analysis.

This paper presents some basic biomechanical considerations that can form a basis for analysis of stance deviations. The floor reaction forces and their effects on the lower extremity are reviewed as a basis for understanding the pathomechanics of stance. Pathomechanics includes the unwanted motions that tend to be created by the floor reaction forces in the absence of critical muscle activity. Compensatory postures that a patient may assume to prevent these unwanted motions and compensatory postures that a patient may assume at one joint because of abnormal positioning at another joint are discussed. Finally, the influence of joint posture from one phase of gait to another is explained.