The effect of tourniquets on patellofemoral joint congruity during total knee arthroplasty.

Abstract

Incongruity of the patellofemoral joint after total knee arthroplasty (TKA) causes anterior knee pain. Intraoperative congruity tests are necessary to avoid unnecessary lateral retinacular release, and the usage of tourniquets may influence these results. The purpose of this study was to examine the effect of tourniquets on patellofemoral joint congruity during TKA. Two hundreds and seventeen knees were examined after TKA. Skyline radiographs at 60° and 90° flexion were taken immediately after wound closure before and after tourniquet deflation to compare changes in patellar tilt angle. In the patellar tilt angle at 60° flexion, lateral tilt was observed in 18 knees. Tourniquet deflation changed the patellar tilt angle by a mean -0.7°±1.2° (p=0.030). Medial tilt was observed in 10 knees. Tourniquet deflation changed the patellar tilt angle by 0.9°±0.7° (p=0.004). Tourniquet deflation improved the degree of lateral and medial patellar tilt. In the patellar tilt angle at 90° flexion, lateral tilt was observed in 118 knees. Tourniquet deflation changed the patellar tilt angle by a mean -1.1°±1.2° (p<0.001). Medial tilt was observed in 71 knees. Tourniquet deflation changed the patellar tilt angle by 0.5°±1.0° (p<0.001). Tourniquet deflation improved the degree of lateral and medial patellar tilt. Tourniquet deflation improved patellofemoral congruity in a statistically significant way, but only to a small extent, indicating low clinical significance. Therefore, intraoperative congruity tests performed with tourniquets in place are reliable.