ACL RECONSTRUCTION BY PATELLAR TENDON - A COMPARISON OF LENGTH BY MAGNETIC-RESONANCE-IMAGING

In 50 knees the length of the anterior cruciate ligament (ACL), the pa tellar tendon, and the distance between the tibial tuberosity and the femoral origin of the ACL were evaluated by means of three-dimensional magnetic resonance imaging (MRT), which permits subsequent reconstruc tion of any sectional view. The measurements showed that the patellar tendon was always markedly longer than the ACL (mean 14.4 mm), but alw ays shorter than the distance between the tibial tuberosity and the fe moral insertion of the ACL (mean 19.2 mm). The mean lengths of the ACL and the patellar tendon were 38.2 mm and 52.6 mm, respectively. The m ean distance between the femoral ACL origin and the tibial insertion o f the patellar tendon was 71.8 mm. These results demonstrate that a di stally based patellar tendon autograft alone (with the patellar bone b lock but without extension into the periosteum of the patella or the q uadriceps tendon) cannot be placed anatomically correctly to the isome tric femoral insertion of the ACL. When the patellar tendon is used fo r ACL reconstruction, it must be implanted as a free autograft. Nevert heless, considerable variations of length must be taken into account.