High-resolution magnetic resonance imaging can predict osteoarthritic progression after medial meniscus posterior root injury: randomized in vivo experimental study in a rabbit model.

Abstract

IMPORTANCE: The field of meniscal root preservation has undergone significant advancement over the past decades; however, the challenge remains to fully understand whether meniscal root repair can ultimately arrest or delay osteoarthritic changes. OBJECTIVE: To assess longitudinal changes in articular cartilage, subchondral bone, and progression to meniscal extrusion (ME) using high-resolution magnetic resonance imaging (MRI). METHODS: Medial meniscus posterior root tear was surgically induced in 39 New Zealand white rabbits. Animals were randomly assigned into three experimental groups: partial meniscectomy after root tear (PM, n&#xa0;&#x200b;=&#xa0;&#x200b;13); root tear left in situ (CT, n&#xa0;&#x200b;=&#xa0;&#x200b;13); and transtibial root repair (RR, n&#xa0;&#x200b;=&#xa0;&#x200b;13). Contralateral limbs were used as healthy controls. High resolution 4.7 Tesla MRI of the knee joint was performed at baseline, after 2-, and 4-months of post-surgery. Cartilage thickness was calculated in medial and lateral compartments. In addition, the evaluation of ME, subchondral bone edema and healing potential after root repair were assessed too. RESULTS: Progressive cartilage thinning, ME, and subchondral bone edema were evident in all 3 study groups after 4-months of follow-up. The mean cartilage thickness in the PM group was 0.53&#xa0;&#x200b;mm (&#xb1;0.050), 0.57&#xa0;&#x200b;mm (&#xb1;0.05) in the CT group, and 0.60&#xa0;&#x200b;mm (&#xb1;0.08) in the RR group. The PM group exhibited significantly higher cartilage loss when compared to the CT and RR groups (p&#xa0;&#x200b;<&#xa0;&#x200b;0.001). Moreover, progressive ME and subchondral bone edema were associated with a more severe cartilage loss at the final follow-up. CONCLUSION: Meniscal root repair did not halt but rather reduced the progression of osteoarthritis (OA). Degenerative changes worsened at a rapid rate in the PM group compared to the RR and CT groups. Early cartilage swelling, persistent subchondral edema, and progressive ME predicted a more severe progression to knee OA in the CT and RR groups. LEVEL OF EVIDENCE: II.