Medial Opening Wedge High Tibial Osteotomy Decreases Medial Meniscal Extrusion and Improves Clinical Outcomes and Return to Activity

BACKGROUND: Medial meniscal extrusion (MME) is defined as displacement of the meniscus that extends beyond the tibial margin. Knee varus malalignment increases MME. PURPOSE/HYPOTHESIS: The purpose of this study was to quantify MME before and after medial opening wedge high tibial osteotomy (HTO) and to correlate the reduction of MME with clinical outcomes and return to activity. It was hypothesized that MME would decrease after HTO and that patients with lower MME after surgery would have improved clinical outcomes and return to activity at short-term follow-up. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: This study included 66 patients who underwent HTO to correct the anatomic axis with a minimum follow-up of 2 years. MME was measured using magnetic resonance imaging preoperatively and 6 weeks after surgery (study protocol). Patients were assessed preoperatively and postoperatively with the Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale (VAS) score for pain, and Tegner score. RESULTS: The mean ± SD preoperative and postoperative MME values were 3.9 ± 0.6 mm and 0.9 ± 0.5 mm, respectively. At 2 years after surgery, KOOS, pain VAS, and Tegner scores were higher than those found preoperatively (P < .001). Patients with less than 1.5 mm of MME after surgery had better clinical outcomes and return to activity compared with patients who had MME of 1.5 mm or more (P < .05). CONCLUSION: Medial opening wedge HTO decreased MME after 6 weeks and improved clinical outcomes and return to activity at a minimum 2-year follow-up. Additionally, patients with postoperative MME of less than 1.5 mm had better clinical outcomes and return to activity compared with patients who had postoperative MME of 1.5 mm or more.