Association between postoperative meniscal extrusion and clinical outcomes of the pullout fixation technique for medial meniscus posterior root tear

OBJECTIVE: To evaluate the correlation between meniscal extrusion in the coronal plane with clinical and radiological outcomes at a minimum of 1 year after transtibial pullout fixation for medial meniscus posterior root tear (MMPRT). METHODS: Data from 30 patients (five males, 25 females) with MMPRT who underwent arthroscopic root fixation by the transtibial pullout technique between 2011 and January 2015 were retrospectively analyzed. The mean patient age was 60.7 ± 8.3years. The median time between injury and surgery was 3.8 months (range, 0.5–15 months). Medial meniscus radial displacement was assessed on magnetic resonance imaging performed preoperatively and at 1 year after fixation. The patients were divided into two groups based on the presence on magnetic resonance imaging of decreased meniscal extrusion (group A) or increased meniscal extrusion (group B) at 1 year postoperatively compared with preoperatively. The two groups were compared regarding factors including age at surgery, sex, body mass index, time between injury and surgery, and the Lysholm score and Kellgren-Lawrence (K-L) grade preoperatively and at 1 year postoperatively. RESULTS: There were seven knees in group A, and 23 in group B. Both groups had a significantly improved Lysholm score postoperatively compared with preoperatively (p < 0.001). Although the postoperative K-L grade was significantly worse than the preoperative K-L grade in group B (p < 0.001), the postoperative K-L grade did not worsen postoperatively in group A. CONCLUSION: The K-L grade did not worsen postoperatively in the group with decreased meniscal extrusion at 1 year after transtibial pullout fixation for MMPRT compared with preoperatively.