We used an in vitro knee-testing apparatus to measure anterior-posterior displacement of the tibia on the femur and the accompanying tibial rotation in response to an applied anterior-posterior force. Testing was performed on nine intact knees, on five knees after medial meniscectomy, on three knees after isolated section of the anterior cruciate ligament, and on eight knees after both excision of the medial meniscus and section of the anterior cruciate ligament. The induced anterior-posterior displacement and the coupled rotation were unaffected by meniscectomy. Isolated section of the anterior cruciate ligament allowed a significant (p < 0.05) increase in anterior displacement but had no effect on posterior displacement. The coupled internal rotation associated with anterior displacement was lost after section of the anterior cruciate ligament. Excision of the medial meniscus and section of the anterior cruciate ligament allowed significantly (p < 0.05) greater increases in anterior displacement than those already increased by isolated section of the anterior cruciate ligament. Clinical Relevance: Mechanical tests are an excellent means of quantitating clinical impressions. The results of this study indicate that in knees in which the anterior cruciate ligament is intact, medial menisectomy does not influence anterior-posterior displacement in the early post-suical period. In knees that lack a functioning anterior cruciate ligament, the medial meniscus can restrict anterior displacement of the tibia, and its excision may compromise stability of the knee by allowing additional anterior displacement.
ASJC Scopus subject areas
- Orthopedics and Sports Medicine