Quantitative gait analysis after total knee arthroplasty for monarticular degenerative arthritis.

By quantitative gait analysis, we characterized the functional results of total knee arthroplasty in a group of twelve elderly patients with isolated degenerative arthritis of one knee. All patients had had a standard replacement arthroplasty performed at least two years before the study. In the gait analysis we used high-speed movie cameras synchronized with force platforms and electromyograms to provide kinetic and kinematic data. The data were compared with those obtained from an age-matched control group. In the patients most of the measurements of gait had been restored to normal levels. These measurements included: velocity; stride length; arcs of motion of the hip, knee, and ankle bilaterally; phasic muscle activity; and the amount of mechanical work performed. There were three patterns of external torque across the implants and in the control knee which were comparable in magnitude but varied in relative frequency between the two groups. As compared with the controls, the patients spent approximately 30 per cent more time in double-limb stance and had prolonged cycle times. These findings may have been the result of muscle weakness, neural impairment, or habit, but the cause could not be determined by this study.