The effect of lateral meniscectomy on motion of the knee

With the use of a five-degrees-of-freedom testing apparatus, we studied changes in the motion of the knees of cadavera after isolated resection of the lateral meniscus, with section of the anterior cruciate ligament and resection of the medial meniscus. Primary anterior and posterior translations were not affected by lateral meniscectomy. When lateral meniscectomy was done in addition to resection of the anterior cruciate ligament, anterior translation did not increase compared with that measured after isolated section of the anterior cruciate ligament. However, when the means of the paired differences in anterior translation were compared, a significant increase was found. This differed from the results after excision of the medial meniscus and section of the anterior cruciate ligament; in that situation, medial meniscectomy resulted in significantly more anterior translation. Clinical relevance: Anatomically, the capsular components that attach the lateral meniscus to the tibia do not affix the lateral meniscus as firmly as they affix the medial meniscus. Our biomechanical results confirm this observation and indicate that, in contrast to the medial meniscus, the lateral meniscus does not act as an efficient posterior wedge to resist anterior translation of the tibia on the femur. Therefore, in knees that lack an anterior cruciate ligament, the lateral meniscus is subjected to different forces than those that occur on the medial side. This may account for the different patterns of injury of the lateral and the medial meniscus in knees that lack an anterior cruciate ligament.