Anterior cruciate ligament reconstruction alters the patellar alignment.

Although there are many articles dealing with anterior cruciate ligament (ACL) reconstruction, there are none dealing with the possibility of changes of the patellofemoral alignment after these procedures. Forty-six patients were evaluated preoperatively and 1 year postoperatively, after undergoing intra-articular ACL reconstruction, for changes of the patellofemoral alignment. Patella-tilt and congruence angles were measured on tangential view radiographs that were taken in the supine position. Analysis of covariance was performed and revealed a significant change of the congruence angle 1 year postoperatively. The patella-tilt did not change. One year postoperatively, the patella shifted on average 5 degrees medially after ACL grafting. It can be deduced that anterior knee pain after ACL reconstruction could be caused by distinct changes in the patellofemoral alignment.