Concomitant Centralization Procedure With Medial Meniscus Posterior Root Repair May Have Zone-Specific Effects on the Medial Femoral Condyle and Enhance Repair Healing Compared With Isolated Root Repair: An In Vivo Experimental Study in Rabbit Knees.

BACKGROUND: Short-term clinical outcomes of meniscal centralization are promising, but questions remain whether it can protect articular cartilage and delay osteoarthritis progression.

PURPOSE: To assess cartilage status and healing potential after isolated medial meniscus posterior root (MMPR) repair (RR) versus MMPR repair augmented with a centralization procedure (RR-CP) in a rabbit stifle model.

METHODS: MMPR tears were surgically induced in 16 New Zealand White rabbits. Eight underwent RR and 8 underwent RR-CP using interlocking knotless anchors; contralateral limbs served as controls. After 4 months, animals were euthanized and articular cartilage was harvested for macro- and microscopic evaluation, including repair tissue assessment for healing potential. Microscopic assessment was performed using the Osteoarthritis Research Society International (OARSI) scoring system. Cartilage thickness and meniscal extrusion (ME) were assessed using high-resolution magnetic resonance imaging (MRI) at 9.4 T. The medial femoral condyle was divided into 3 regions of interest (anterior, central, and posterior), and zone-specific changes were evaluated.

RESULTS: The mean ± standard deviation gross pathology joint degeneration score was significantly higher in the RR group compared with the RR-CP group (12.3 ± 2.2 vs 9.1 ± 2.0; P = .01). The mean OARSI score was significantly lower in the RR-CP group compared with the RR group (3.1 ± 1.6 vs 4.2 ± 1.5; P = .04). Nonhealed root repairs were more frequent in the RR group, and repair healing scores favored the RR-CP group (1.75 ± 0.5 vs 2.5 ± 0.7; P = .041). MRI demonstrated significantly reduced central and posterior cartilage thickness in the RR group compared with the RR-CP and control knees (P ≤ .02), with no difference anteriorly (P = .23). ME did not differ between the RR and RR-CP goups (P = .12). Both experimental groups showed greater chondral damage compared with contralateral controls (P < .001).

CONCLUSION: RR-CP was associated with reduced total joint cartilage damage and improved repair healing compared with isolated RR. MRI showed greater loss of central and posterior cartilage thickness after RR, while no difference in postoperative ME was detected. Both treatment groups demonstrated increased chondral damage compared with control knees.

CLINICAL RELEVANCE: This study provides important biological insights into a clinically relevant question and establishes a foundation for future clinical investigations aimed at defining patient selection criteria and surgical indications for a concomitant meniscal centralization procedure.

STUDY DESIGN: Controlled laboratory study.