Tibiofemoral and Patellofemoral Kinematics After Reconstruction of an Isolated Posterior Cruciate Ligament Injury

Abstract

Background The actual in vivo tibiofemoral and patellofemoral kinematics of the posterior cruciate ligament (PCL)-reconstructed knee joint are unknown. Hypothesis Current single-bundle PCL reconstruction is unable to correct the abnormal tibiofemoral and patellofemoral kinematics caused by rupture of the ligament. Study Design Controlled laboratory study/case series; Level of evidence, 4. Methods Seven patients with an isolated PCL injury in 1 knee and the contralateral side intact were included in the study. Magnetic resonance and dual fluoroscopic imaging techniques were used to compare the tibiofemoral and patellofemoral kinematics between the intact contralateral (control group), PCL-deficient, and PCL-reconstructed knee during physiologic loading with a single-legged lunge. Data were collected preoperatively and 2 years after single-bundle reconstruction. Results The PCL reconstruction reduced the abnormal posterior tibial translation in PCL-deficient knees to levels not significantly different from those of the intact knee. Posterior cruciate ligament deficiency resulted in an increased lateral tibial translation between 75° and 120° of flexion, and reconstruction was unable to restore these values to normal. No differences were detected among the groups in varus-valgus and internal-external rotation. The PCL reconstruction reduced the increased patellar flexion of PCL-deficient knees between 90° and 120° of knee flexion and the lateral shift at 120°. The abnormal patellar rotation and tilt seen in PCL deficiency at flexion angles of 75° and greater persisted after reconstruction. Conclusion Single-bundle PCL reconstruction was successful in restoring normal anteroposterior translation of the tibia, as well as the patellar flexion and shift. However, single-bundle PCL reconstruction was unable to achieve the same success in mediolateral translation of the tibia or in the patellar rotation and tilt. Clinical Relevance The persistent abnormal mediolateral translation of the tibia, as well as decreased patellar rotation and tilt, provide a possible explanation for the development of cartilage degeneration after reconstruction of an isolated PCL injury.