Patient-Related Risk Factors for the Extrusion of Lateral Meniscal Allograft Transplants

Purpose The objective of this study was to identify the patient-related risk factors for lateral meniscal extrusion after lateral meniscal allograft transplantation (MAT) regarding demographic characteristics, alignment, and pre-existing arthrosis. Methods Seventy-one patients who underwent arthroscopic lateral MAT with bone bridge fixation between 2008 and 2011 were assessed. Lateral meniscal subluxation was measured on mid-coronal sections of magnetic resonance images 1 year postoperatively. Subluxation of more than 3 mm was considered to be extrusion. Age, gender, body mass index, time from previous meniscectomy, mechanical axis deviation, Kellgren-Lawrence grade on preoperative radiographs, and intraoperative International Cartilage Repair Society grade were assessed as possible patient-related factors. Results The mean lateral subluxation in the coronal plane was 2.6 ± 1.6 mm. Among our patients, 23 transplants (32.4%) showed extrusion. The intraoperative cartilage status of the femoral condyle and tibial plateau showed significant differences between the nonextruded (≤3 mm) and extruded (>3 mm) groups ( P = .010 and P = .001, respectively). There were no differences in other factors between these 2 groups. Binary logistic regression analysis showed that tibial-side cartilage wear of International Cartilage Repair Society grade 3 or more was a significant risk factor for meniscal extrusion. Conclusions Lateral meniscal extrusion 1 year after lateral MAT is affected by the degree of intraoperative cartilage wear, most notably on the tibial side. Patient demographic characteristics, alignment, and radiographic arthritic changes did not differ between nonextruded and extruded MAT cases. Level of Evidence Level IV, therapeutic case series.