High body mass index is a risk factor for unfavorable clinical outcomes after medial meniscus posterior root repair in well-aligned knees

Background: Severe chondral lesions and varus knee alignment are associated with poor outcomes following transtibial pullout repair for medial meniscus posterior root tears and meniscus tear is strongly associated with body mass index. The prognostic factors in well-aligned knees (femorotibial angle < 180°) with mild chondral lesions are unknown. Therefore, we investigated the prognostic factors in these patients. We hypothesized that high body mass index would lead to poor clinical outcomes following pullout repair of medial meniscus posterior root tears. Methods: We retrospectively reviewed the files of 28 patients who had undergone pullout repair of medial meniscus posterior root tears between October 2016 and December 2017. We recorded the baseline characteristics (age, gender, height, weight, and body mass index) and the time between injury and surgery. We recorded the International Knee Documentation Committee scores, Knee injury and Osteoarthritis Outcome Scores, and pain visual analog scale scores. Using magnetic resonance imaging preoperatively and 1 year after surgery, we measured the medial meniscus body width and absolute and relative medial meniscus extrusion. Pearson correlation and multivariate linear regression analyses were used to assess potential associations between these factors and clinical outcomes. Results: Age positively correlated (coefficient = 0.49, P < 0.01) and body mass index negatively correlated with the postoperative International Knee Documentation Committee score (coefficient = −0.64, P < 0.01). In multivariate linear regression analysis, body mass index was a significant factor leading to poor postoperative International Knee Documentation Committee score (R² = 0.29, P < 0.05). Conclusions: Body mass index > 30 kg/m² is a risk factor for unfavorable clinical outcomes following pullout repair of medial meniscus posterior root tears in well-aligned knees. Level of evidence: III, Comparative retrospective study.