Influence of a posteromedial meniscocapsular injury on the knee anterior laxity. A cadaveric study.

PURPOSE

The number of anterior cruciate ligament (ACL) injuries has considerably increased in the recent years, especially in young adults and adolescents. Associated meniscal tears increase anterior and rotary laxity. Posterior peripheral meniscocapsular tear of medial meniscus is also called ramp lesion. Prevalence of 9% to 17% in adults and up to 23% in pediatric population has been reported. The aim of this study was to determine anterior laxity of cadaveric ACL-deficient knees with several size of ramp lesions.

METHODS

Fresh cadaveric knees were explored. Major osteoarthritis and/or ACL and meniscal tears on arthroscopy were exclusion criteria. Mean age at death was 86 years old. Dynamic laximetry with GNRB® device was made in several conditions: Knee prior to any procedure, after arthroscopic exploration, after ACL section, and then after increasing sizes of ramp lesions up to 30 mm. Anteroposterior laxity was measured with 2 loading forces successively (134N and 200N).

RESULTS

After ACL section only, tibiofemoral joint anterior laxity was significantly increased. Mean increase was 156% regardless of the loading force. No statistical laxity difference was found between knees with ACL section only and knees with ACL and meniscal section for any size of ramp lesions. Increasing size of ramp lesion was not correlated with increasing of laxity.

CONCLUSION

We could not find a threshold size of ramp lesion which increases knee anterior laxity. We were not able to determine a threshold recommending a ramp lesion repair.