Contralateral compensation with knee impairment

Knee motion of four healthy teenagers was unilaterally impaired by means of cast braces. Computerized analysis from video recording of walking was used to study the compensatory effects and to compare them with six patients. Restricted knee flexion caused little change in stance-phase knee motion on the restricted side. The unimpaired knee displayed exaggerated stance phase flexion and phase shifts, which in turn produced pelvic vaulting. The forces on the braces were high. Impairments to extension produced bilateral crouch without loss of flexion extension patterns within the limits of the impairment. Fatigue was more prominent than with blocks to flexion. Circumduction was found to be overrated as a compensation for stiff-leggedness. Lateral shift to the well side, combined with freezing of the well-side stance adduction, was a frequently used effective clearance mechanism. Phasic changes in motion of many body parts may combine to produce low-level pelvic displacement, especially when clinical weakness is present. Shortened stride length is the most sensitive indicator of this phenomenon. Graphs of individual joint motion do not easily convey the important phasic relationships that are fundamental to that motion and to the interpretation of its effects. Stick figures were better for analysis of this aspect of motion analysis, even though they are more subjective.