Search

Background: Although anatomical double-bundle anterior cruciate ligament reconstruction can successfully restore normal knee biomechanics for knees with typical varus-valgus alignment, the efficacy of the same reconstruction method for knees after a valgus high tibial osteotomy is unclear. Hypothesis: Anatomical double-bundle anterior cruciate ligament reconstruction for valgus knees after a high tibial osteotomy cannot restore normal knee kinematics and can result in abnormally high in situ forces in the ligament graft. Study Design: Controlled laboratory study. Methods: Ten cadaveric knees were subjected to valgus high tibial osteotomy followed by an anatomical double-bundle anterior cruciate ligament reconstruction. The valgus knees were tested using a robotic/universal force-moment sensor system before and after the ligament reconstruction. The knee kinematics in response to anterior tibial load and combined rotatory loads, as well as the corresponding in situ forces of the anterior cruciate ligament bundles and grafts, were compared between the ligament-intact and ligament-reconstructed valgus knees. Results: After reconstruction, the anterior tibial translation and internal tibial rotation for the valgus knee decreased approximately 2 mm and 2°, respectively, at low flexion angles compared with those of the anterior cruciate ligament-intact knee (P < .05). The in situ forces in the posterolateral graft became 56% to 200% higher than those in the posterolateral bundle of the intact anterior cruciate ligament (P < .05). Conclusion: Performing an anatomical double-bundle anterior cruciate ligament reconstruction on knees after valgus high tibial osteotomy may overconstrain the knee and result in high forces in the posterolateral graft, which could predispose it to failure. Clinical Relevance: Modifications of anterior cruciate ligament reconstruction procedures to reduce posterolateral graft force may be needed for valgus knees after a high tibial osteotomy. [ABSTRACT FROM AUTHOR]

Background: In double-bundle anterior cruciate ligament reconstruction, overloading either 1 of the 2 grafts should be avoided to decrease the risk of graft failure. Hypothesis: Overloading of the posterolateral graft may occur when it is fixed at 30° of knee flexion because the posterolateral bundle is elongated as the knee approaches extension. Study Design: Controlled laboratory study. Methods: Ten human cadaveric knees were tested at (1) intact, (2) anterior cruciate ligament-deficient, (3) double-bundle anterior cruciate ligament reconstruction with the anteromedial and posterolateral grafts fixed at 60° of flexion and full extension, respectively (fixation 60/FE), and (4) double-bundle anterior cruciate ligament reconstruction with both grafts fixed at 30° of flexion simultaneously (fixation 30/30). Two external loading conditions simulating clinical examinations were used: (1) 134-N anterior tibial load and (2) combined rotatory loads of 10 N·m valgus and 5 N·m internal tibial torques. Data on knee kinematics and in situ forces in the 2 bundles of the intact anterior cruciate ligament and the respective grafts were obtained. Results: In response to 134-N anterior tibial load, knee kinematics and in situ force in the grafts were similar to the intact knee for both fixation protocols. The force in the anteromedial graft for fixation 60/FEwas 34% higher, whereas the posterolateral graft for fixation 30/30 was 46% higher, compared with the intact anteromedial and posterolateral bundles, respectively. In response to combined rotatory loads, the posterolateral graft for fixation 30/30 carried 67% higher load than did the intact posterolateral bundle. Conclusion: Fixation 30/30 overloaded the posterolateral graft, whereas fixation 60/FE overloaded the anteromedial graft. Clinical Relevance: In double-bundle anterior cruciate ligament reconstruction, even though overall forces in the graft are the same as intact anterior cruciate ligament, the force distributions may not be the same as the intact bundles, and overloading of 1 of the 2 grafts may occur. [ABSTRACT FROM AUTHOR]