Proprioceptive function in knees with and without total knee arthroplasty

The goal of this study was to evaluate the differences in angle reproduction capability after nonconstrained posterior cruciate ligament retaining total knee arthroplasty after a follow-up time of 63.9 months compared with the healthy contralateral leg and a control group. In 28 total knee arthroplasty patients (mean age, 65.7 yr) and 25 control subjects (mean age, 55.7 yr), 16 measurements were made between 0 degrees and 90 degrees in 30 degrees steps. The leg was positioned by the examiner and then relaxed; afterward, the subject was asked to reproduce the original position. Each measurement was made with the patient or control being blindfolded and not blindfolded to assess the influence of visual control. We found significant differences in total knee arthroplasty patients in contrast to healthy subjects. Without visual control, the mean deviation of the total knee arthroplasty group starting with a 0 degrees angle was 7.7 +/- 5.9 degrees and 4.6 +/- 4.7 degrees for the healthy subjects. With visual control, the mean deviation in the patient group was 11 +/- 7.5 degrees, and in the control group, it was 7.2 +/- 5.0 degrees. Total knee arthroplasty patients did not show significant differences between the operated on and the contralateral knee. Also, in the total knee arthroplasty group, significant differences could not be found comparing reproduction with and without visual control and comparing both starting positions. In the control group, significant differences could be found comparing visual and nonvisual control in the 60 degrees angle. The comparison between the 30 and 60 degrees repositioning from both 0 degrees and 90 degrees starting positions showed a significant difference in the 60 degrees angle. In summary, reduced proprioceptive capabilities are present after knee arthroplasty in both the operated on and the contralateral leg in our study group. Postoperative complaints can perhaps be explained by a loss of proprioceptive capabilities, especially at the 60 degrees angle. The operative technique should involve special care of ligaments and muscles to preserve stability and receptors as well. Rehabilitation should pay more attention to the remaining receptors.