EFFECTS OF PATELLAR TENDON ADHESION TO THE ANTERIOR TIBIA ON KNEE MECHANICS

The effects of patellar tendon adhesion on the knee extensor mechanism and on the kinematics and contact areas for both the patellofemoral a nd tibiofemoral joints were determined for five cadaveric knees in an open kinetic chain testing configuration. Patellar tendon adhesion dec reased the distance from the inferior patellar pole to the tibial tube rosity, effectively creating patella infera. When compared with the co ntrols, knees with adhesion had medial and distal translation of the p atella, as well as increased patellar flexion. Although the patellar a rticular contact location shifted distally, the overall contact area d id not change significantly. For the tibia, adhesion resulted in signi ficant medial, proximal, and anterior translation, and internal rotati on. Adhesion also resulted in a posterior shift of the tibial contact location. For the extensor mechanism, adhesion decreased the knee exte nsion force created by the quadriceps muscle on the tibia, indicating a decrease in the effective moment arm of the extensor mechanism. Furt hermore, as a result of patellar tendon adhesion, the angle formed by the quadriceps and patellar tendons decreased, suggesting an increase in patellofemoral joint reaction force with adhesion. The increased pa tellofemoral joint reaction force and the altered contact location may be related to anterior knee pain after knee trauma and knee surgery. Therefore, patients should be observed for subtle patella infera, whic h may indicate patellar tendon adhesion.