Side-to-side repair improves coronal meniscal extrusion in lateral meniscus oblique radial tears concomitant with anterior cruciate ligament reconstruction.

PURPOSE: To determine the proportion of lateral meniscus oblique radial tear repairs during anterior cruciate ligament reconstruction and compare extrusion and clinical outcomes between side-to-side repair of lateral meniscus oblique radial tear and posterior longitudinal tear repair. METHODS: Among 609 primary anterior cruciate ligament reconstructions from 2016 to 2023, 34 patients with intraoperatively confirmed lateral meniscus oblique radial tear underwent side-to-side repair and magnetic resonance imaging at 6 months and 1 year; 27 with posterior longitudinal tears underwent all-inside repair. Coronal and sagittal lateral meniscal extrusion, clinical outcomes, knee stability and Knee Injury and Osteoarthritis Outcome Score subscales were compared. Multivariate regression assessed predictors of preoperative-to-1-year coronal extrusion change; receiver operating characteristic analysis assessed whether preoperative lateral meniscal extrusion distinguished tear types. RESULTS: Lateral meniscus oblique radial tear treated with side-to-side repair accounted for 7.4% of cases. Preoperative coronal lateral meniscal extrusion was greater in the lateral meniscus oblique radial tear group than in the longitudinal tear group (1.71 ± 1.31 vs. 0.32 ± 0.61 mm; p < 0.001). Coronal extrusion improved by approximately 0.6 mm after lateral meniscus oblique radial tear repair and was similar between groups at 1 year; sagittal extrusion increased slightly in both groups. Clinical outcomes were similar at 1 year and final follow-up. Preoperative coronal lateral meniscal extrusion was an independent predictor of coronal extrusion change (β = -0.514, p < 0.001). Preoperative coronal lateral meniscal extrusion >1.0 mm identified lateral meniscus oblique radial tear with acceptable diagnostic performance (area under the curve = 0.787, p < 0.001). CONCLUSIONS: Side-to-side lateral meniscus oblique radial tear repair during anterior cruciate ligament reconstruction reduced coronal extrusion by 1 year to levels comparable to those of longitudinal tear repair, with similar clinical outcomes. These findings support side-to-side repair as a reliable meniscal preservation strategy. LEVEL OF EVIDENCE: Level III.