Influence of the Anteromedial and Posterolateral Bundles of the Anterior Cruciate Ligament on External and Internal Tibiofemoral Rotation

Abstract

Background The influence of the anteromedial and posterolateral bundles of the anterior cruciate ligament on tibiofemoral rotation might be of great value to detect anterior cruciate ligament injuries and investigate the postoperative restoration of rotational stability. Hypothesis The anterior cruciate ligament and especially the posterolateral bundle will have a significant influence on isolated tibiofemoral rotation. Study Design Controlled laboratory study. Methods Tibiofemoral rotation was measured in 20 human cadaveric knees using a noninvasive external measurement device (Rotameter) and a knee navigation system. The measurements of the knees with the intact anterior cruciate ligament were compared with the measurements after isolated resection of the posterolateral bundle and after a complete resection of the anterior cruciate ligament at an applied torque of 5,10, and 15 N·m. Statistical analysis was made using analysis of variance and the post hoc Scheffé test. The Pearson coefficient was used to compare both measurement techniques. Results In comparison with knees with an intact anterior cruciate ligament, the knees after isolated resection of the posterolateral bundle showed significant increase of tibiofemoral rotation at almost all applied torques (P < .05). Total resection of the anterior cruciate ligament also produced significant increases compared with the intact anterior cruciate ligament at torques of 5, 10, and 15 N·m as measured by the Rotameter (P < .05). Total resection of the anterior cruciate ligament yielded increases in rotation compared with posterolateral bundle resection alone, but these differences were not significant. The results of the knee navigation system confirmed the measured results of the Rotameter. Comparison of the 2 measurement methods revealed a high correlation at all applied torques, with Pearson correlation coefficients ranging from .85 to .95. Conclusion The anterior cruciate ligament and especially the posterolateral bundle of the anterior cruciate ligament have a significant effect on isolated tibiofemoral rotation. Therefore, the developed noninvasive device might be of great importance to investigate the status and the postoperative reconstruction of the anterior cruciate ligament in the clinical setting. Clinical Relevance Noninvasive measurement of tibiofemoral rotation might be useful to detect anterior cruciate ligament tears and to evaluate the restoration of rotational stability after anterior cruciate ligament surgery.