Impact of tear morphology and meniscal laterality on repair failure in stable knees: Medial repairs show over twofold risk.

Abstract

To evaluate the failure rates of all-inside meniscal repair based on tear morphology in stable knees (i.e., without concomitant anterior cruciate ligament reconstruction [ACLR]) and to assess the influence of failure. This retrospective cohort study included 1008 patients who underwent arthroscopic all-inside meniscal repair between 2015 and 2022 at Capio Artro Clinic, Stockholm, Sweden. Inclusion criteria were isolated medial or lateral meniscal repair with clearly documented tear morphology. Tears were categorised as longitudinal (LT), bucket-handle (BH), undersurface (US), radial (RT), horizontal (HT) or discoid (DT). The primary outcome was repair failure, defined as reoperation with partial or total meniscectomy within three years. Kaplan-Meier survival analysis and Cox proportional hazards regression were used to identify factors associated with failure. The overall failure rate was 29.4% (296/1,008). Medial meniscus repairs demonstrated a significantly higher failure rate compared with lateral repairs (37.0% vs. 18.3%, p < 0.001). Among medial tears, LT had the highest failure rate (39.8%), followed by BH tears (35.5%) and unstable simple US tears (34.3%). In contrast, lateral LT and BH tears showed substantially lower failure rates (16.7% and 19.3%, respectively). Cox regression analysis identified medial meniscus repair as an independent risk factor for failure (hazard ratio 2.33, 95% confidence interval 1.78-3.05, p < 0.001), whereas tear type, age >30 years, and female sex were not independently associated with failure. Medial meniscus repairs in stable knees were associated with more than twice the hazard of failure compared with lateral repairs and the only significant predictor of failure. Tear morphology did not independently affect outcomes, highlighting meniscal laterality as the key factor influencing repair survival. Level III.