RELEASE OF THE POSTERIOR KNEE JOINT CAPSULE AND RANGE OF KNEE MOTION- A PROSPECTIVE STUDY.

Abstract

In terms of function, range of movement is an important measure of outcome.

The purpose of this study was to determine whether or not stripping the capsule of the distal femur at the time of primary total knee arthroplasty had a significant effect on the range of knee movement achieved at the end of the operation. An improvement of 5 degrees or more was considered significant.

One hundred and twenty-five patients (47 males; 78 females) presenting for primary total knee arthroplasty were recruited. All operations were performed by the senior author using the LCS rotating platform system without patellar resurfacing.

Preoperatively, the tip of the greater trochanter, the lateral femoral epicondyle and the anterior border of the lateral malleolus were marked. Using a digital camera, images of the limb proposed for surgery were taken with the knee in extension, forced extension, flexion and forced flexion. Camera set up was standardised for all photographs.

Using a random numbers program, patients were randomised either to have release of the posterior knee joint capsule or not. The surgeon was informed at the time of the operation.

At the end of the procedure the digital images were repeated. Total arc of knee movement preoperatively ranged from 41° to 161° (average, 115°). Postoperatively, this varied from 95° to 157° (average, 124°).

Average arc of knee movement was 125° for the no release group and 123° for the released group. Of the 78 patients where the increase in total arc of knee motion was significant, 41 had been released and 37 had not. No statistically significant difference was noted.

In conclusion, we report that releasing the posterior capsule of the knee joint routinely during primary total knee arthroplasty conveys no significant advantage in terms of the range of knee motion achieved immediately following surgery. Consequently, it is unlikely to increase the long-term range of movement.