Long

Meniscal allograft transplantation (MAT) is a widely performed surgical technique used to reconstruct meniscal deficiencies after meniscectomy. However, the long-term effects of extrusion on clinical and radiologic outcomes are unclear. In long-term follow-up, extrusion after MAT would show poorer outcomes than nonextrusion and would lead to faster progression of arthritic changes. Cohort study; Level of evidence, 3. Forty-five MAT cases (lateral, n = 36; medial meniscal, n = 9) with a minimum 8-year follow-up period were selected. The mean follow-up period was 12.3 years (range, 8.0-19.6 years). Data were collected on patients’ sex, age, surgical side, and mechanical axis deviation. Patients were categorized into 2 groups: extrusion (≥3 mm) and nonextrusion (<3 mm). Categories were based on extrusion length measured via magnetic resonance imaging taken 1 year after surgery. Joint space width (JSW) on the affected and contralateral sides was measured on bilateral weightbearing posterior-anterior radiographs at 45° of flexion at 3 time points (preoperative, 4-6 years postoperative, and >8 years postoperative). Differences of the measured and relative JSW values between the groups and differences at different time points were analyzed. The Lysholm score was used to evaluate clinical function. Mean ± SD extrusion was 3.07 ± 0.82 mm. The extrusion and nonextrusion groups were composed of 19 (42.2%) and 26 (57.8%) patients, respectively. Analysis of JSW showed a difference in relative JSW between the groups at >8 years (P = .017). At the point of transition from 4 to 6 years to >8 years, the differences in absolute JSW values were ？1.25 ± 0.78 mm (extrusion group) and ？0.58 ± 0.66 mm (nonextrusion group; P < .001). Relative JSW values also differed between groups (extrusion group, ？0.22 ± 0.13; nonextrusion group, ？0.04 ± 0.18; P < .001). No differences were observed in the Lysholm scores between the groups at each time point. Long-term follow-up after MAT revealed a greater decrease in JSW in the extrusion group than in the nonextrusion group. However, no significant differences in clinical outcomes were observed