Patellar tendon length after anterior cruciate ligament reconstruction.

We studied changes in patellar tendon length after reconstruction of the anterior cruciate ligament using either the medial third of the patellar tendon as a graft (n = 40) or a Leeds-Keio artificial ligament (n = 40). Both types of ligament replacement had been supplemented with a MacIntosh extra-articular lateral substitution. The mean change in length in the tendon graft group was 6% (SD 5.39); in the Leeds-Keio group it was 2.4% (SD 4.93). The change in length was significant in both groups, but shortening was more frequent and more severe in the tendon graft group. There was shortening of 10% or more in 25% of knees after patellar tendon graft and 7.5% after use of a Leeds-Keio prosthesis.