Lateral meniscal root tears associated with anterior cruciate ligament injury: classification and management (SS-70)

Abstract

Objective: The purpose of this study was to define the incidence of posterior horn lateral meniscal root tears, classify the tear patterns, correlate these findings with the preoperative MRIs, and describe a technique for repair. Methods: The operative notes from 298 consecutive ACL reconstructions (1999–2001) were reviewed to identify associated posterior lateral meniscal root tears. These tears were defined as ones that occurred within one centimeter from the posterior bony insertion of the lateral meniscus. This tear pattern was identified in 37 (12.4%) patients. Two surgeons and one musculoskeletal radiologist performed an independent review of the MRIs, operative records, and arthroscopic pictures. Associated injuries and tear patterns were identified. An arthroscopic classification system and a technique for repair was developed. Results: Preoperative MRIs were available for review in 30 of the 37 patients. MRI findings included abnormal gray signal at the root insertion on the T1 images in 26 (87%) patients. T2 signal changes at the root were much less frequent, occurring in only 57% of patients. Lateral and medial compartment edema was present in 83% and 74% of the patients, respectively. MCL injury was present in 48% of the patients, and partial PCL injury was seen in 30%. Medial meniscal tears and additional lateral meniscal tears were identified in 43% and 22% of the patients, correspondingly. An arthroscopic classification system was developed based on three typical tear patterns. Type I injuries were root avulsions. Type II tears were isolated radial split tears within one centimeter from the root insertion, and type III injuries were complex root tears with radial and longitudinal components. The type I and III tears were amenable to arthroscopic repair using a trans-osseous tunnel technique. Conclusions: The association of lateral meniscal tears with ACL injuries is well documented. However, limited data is available on posterior lateral root tears. The mechanism, incidence, natural history, and associated injuries of lateral root tears is unknown. By disrupting the hoop forces, root tears can potentially have a detrimental effect on the lateral compartment biomechanics. This study has helped to define the incidence of concomitant ACL and lateral root tears, associated injuries, and treatment options.