Influence of a posteromedial meniscocpsular injury on the tibiofemoral joint laxity: A cadaveric study

Abstract

Objectives Up to 61% of meniscal tears can be associated with ACL ruptures. These lesions lead to anterior and rotary laxity increase. Posterior peripheral meniscocaspsular tear of medial meniscus is also called ramp lesion. Prevalence of this kind of lesion is 9% to 17% in adults and up to 23% in pediatric popultation. The aim of this study was to determined anterior laxity of cadaveric ACL deficient knees. Hypothesis was to find a correlation between size of ramp lesion and laxity in order to determine a threshold of size for which reparation is mandatory. Methods Twelve fresh cadaveric knees were explored for the study. Two knees was excluded because they presented major lesions of osteoarthritis and ACL and meniscal tears. 10 remaining knees were from 3 males and 2 females. Mean age at time of death was 86 years old. Dynamic laximetry with GNRB device was made in several conditions: Knee without any intervention, full of water knee, after ACL rupture and after ACL rupture and increasing sizes of ramp lesions up to 30 mm. Anteroposterior laxity was measured at each time with 3 kind of loading charge (134 N, 200 N and 250 N). Results After ACL section only, tibiofemoral joint anterior laxity was significatively increased. Mean increasing was 156% whatever is the loading force. No statistical laxity difference was find between knees with ACL tears only and knees with ACL and meniscal tears for each size of ramp lesions. Increasing size of ramp lesion was not correlated to increasing of laxity. We could not be able to determine a threshold for ramp lesion reparation. Conclusion: GNRB® is a valid device of knee laxity measure, escpecially for ACL deficient knee. Despite use of this performing tool, we can’t confirm our hypothesis. Stephen et al in 2015 have shown, with cadaveric study, significant increase of anterior tibial translation and rotary laxity in knees with extended ramp lesions. There is no data about a ramp lesion size threshold with clinical relevance. GNRB gives reliable measures of laxity in ACL deficient knees. We could not find a threshold size of ramp lesion which increase tibial anterior laxity. Cadaveric rotary laxity has to be also studied to find this threshold.