Inside-Out Repair Technique Results in Less Medial Meniscal Extrusion Than All-Inside Repair Technique for Complete Radial Tears of the Medial Meniscus Posterior Segment: A Cadaveric Study

Background: Evaluation of medial meniscal extrusion (MME) under physiological loads is crucial because of the influence of MME on meniscal function. Reducing the MME is essential for meniscal function. Few studies have compared the extent of MME in cases of complete radial tears of the posterior segment of the medial meniscus (MM) treated using basic meniscal repair techniques: the inside-out and all-inside techniques. Purpose: To compare the extent of MME after the treatment of complete radial tears of the posterior segment using inside-out and all-inside meniscal repair techniques in a cadaveric model. Study Design: Controlled laboratory study. Methods: Six fresh-frozen human cadaveric knees were subjected to a compression load of 250 N using a 6 degrees of freedom robotic system under ultrasound evaluation. The MME was evaluated at 30° and 90° knee flexion in 4 meniscal conditions: (1) intact; (2) complete radial tear in the posterior segment of the MM; (3) inside-out repair technique; and (4) all-inside repair technique using 1 horizontal suture. Conditions 3 and 4 were performed on the same knee in a randomized order. Measurements were obtained at the center of the superficial medial collateral ligament (MCL) (central image) and 1 cm posterior to the superficial MCL (posterior image). Statistical analysis was conducted using a 2-factor repeated-measures analysis of variance with Bonferroni post-hoc correction, with significance level set at P < .05. Results: The amount of MME under compression load after inside-out repair was significantly lower than that after all-inside repair (mean ± SD values for the central image: 30°, 1.93 ± 0.26 mm vs 2.45 ± 0.34 mm; 90°, 2.02 ± 0.29 mm vs 2.53 ± 0.42 mm; for the posterior image: 30°, 1.98 ± 0.30 mm vs 2.43 ± 0.35 mm; 90°, 2.45 ± 0.26 mm vs 3 ± 0.42 mm; P < .001 for all comparisons). Conclusion: Although the inside-out repair technique reduced the amount of MME to a greater extent than the all-inside repair technique using a single horizontal stitch for MM posterior segment tears, neither technique was able to reduce MME to the same level as that of the intact state; furthermore, the change in MME was relatively small. Clinical Relevance: The findings indicate that the inside-out repair technique should be used to repair complete radial tears in the posterior segment of the MM.