The purpose of this study was twofold: (1) to describe and compare histopathological findings of 3 different therapeutic options for medial meniscus posterior root tear (MMPRT): nonoperative management, partial meniscectomy, and meniscal root repair; and (2) to test the hypothesis that meniscal root tears treated conservatively predispose to a lower risk of osteoarthritic progression compared to partial meniscectomy.
Study Design: Prospective, randomized, and experimental study.
Posteromedial meniscal root tears were carried out in 39 New Zealand White (NZW) rabbits. Animals were randomly assigned into three experimental groups: partial meniscectomy after root tear (PM; n=13), root tear left in situ (CT; n=13), and transtibial root repair (RR; n=13). Contralateral limbs were used as healthy controls. The animals were euthanized at 16 weeks postoperatively; tissue samples of femoral and tibial articular cartilage were collected and processed for macro and microscopic assessment to detect signs of early osteoarthritis (OA). Each sample was histopathologically assessed using the Osteoarthritis Research Society International (OARSI) grading and staging system.
Osteoarthritic changes were the hallmark in all three experimental groups. The root repair group had the lowest scores for cartilage damage (2.5; 2-3) and the meniscectomy group exhibited higher and more severe signs of OA (16; 9-16) compared to the conservative treatment group (5; 4-6). The between-group comparison revealed significant differences as the PM group showed a significantly higher rate of macro and microscopic osteoarthritic changes compared to the RR (p< 0.001) and CT group (< 0.001). The weight-bearing area of the medial femoral condyle was the most severely affected and tidemark disruption was evident in all tissue samples.
Meniscus root repair could not completely arrest the histopathological progression of knee OA but lead to significantly less severe degenerative changes than partial meniscectomy and conservative treatment. Partial meniscectomy leads to the most severe osteoarthritic progression, while stable radial tears left in situ presented lower OA progression compared with partial meniscectomy.