Outcomes of Distal Medial Collateral Ligament Release During Opening-Wedge High Tibial Osteotomy

BACKGROUND: During opening-wedge, high-tibial osteotomy (OWHTO), various methods of managing the superficial medial collateral ligament (sMCL) can be performed to obtain a sufficient medial side opening. PURPOSE/HYPOTHESIS: The purpose of this study was to evaluate the outcomes of distal sMCL release during OWHTO. It was hypothesized that distal sMCL release would not cause valgus instability. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: This retrospective study included 77 patients who underwent OWHTO between January 1, 2018, and October 31, 2019, and completed serial radiological assessments including weightbearing line ratio (WBLR), medial proximal tibial angle (MPTA), coronal translation, total tibial plateau inclination (TTPI), valgus medial joint-space width (valgus-MJSW), valgus joint-line convergence angle (valgus-JLCA), varus lateral joint-space width (varus-LJSW), and varus joint-line convergence angle (varus-JLCA) on standing whole-leg and varus-valgus stress radiographs. Subgroup analysis of pre- to postoperative changes in radiologic parameters was performed according to TTPI (group 1: <25th percentile, group 2: 25th-75th percentile, group 3: >75th percentile) and Ahlbäck osteoarthritis classification (group 1: Ahlbäck grade 1, group 2: Ahlbäck grades 2 and 3). RESULTS: The mean time to final follow-up was 34.6 ± 6.4 months. The WBLR and coronal translation did not change significantly over the follow-up period. The valgus-MJSW at 6 months postoperatively was significantly wider than that preoperatively and at 1 year postoperatively (P < .001). The varus-LJSW at 6 months postoperatively was significantly wider compared with preoperatively and 1 year postoperatively (P < .001), and the varus-LJSW at 1 year postoperatively was wider than that found preoperatively. Coronal translation was significantly more reduced for patients in TTPI group 1 versus group 3 (P = .019). There was no significant differences according to the Ahlbäck groups. All clinical outcomes improved at final follow-up compared with preoperative values (P ≤ .002). CONCLUSION: The study findings indicated that sMCL release did not cause valgus instability or valgus overcorrection at 1 year postoperatively, and improved clinical outcomes were seen at the final follow-up compared with preoperative status after OWHTO with sMCL release.