Extra-articular Lateral Hinge Fracture Does Not Affect the Outcomes in Medial Open-Wedge High Tibial Osteotomy Using a Locked Plate System.

PURPOSE: To compare the radiologic and clinical outcomes in patients with and without lateral hinge fractures (LHFs) during medial open-wedge high tibial osteotomy (MOWHTO) using a locked plate system, as well as to assess whether LHFs could affect the midterm outcomes.

METHODS: From May 2008 to November 2015, 164 knees underwent MOWHTO using a locked plate system for the treatment of knee osteoarthritis. LHFs were recognized by radiographs during or after the high tibial osteotomy and were not additionally treated. In all patients, we applied the same rehabilitation protocol that allowed full weight bearing at 6 weeks. Patients were divided into LHF (types I and II) and nonfracture groups. Radiologically, we compared any serial changes in the hip-knee-ankle angle, femorotibial angle, medial proximal tibial angle, and posterior tibial slope angle from the immediate postoperative radiographs to the final radiographs. The union process of the osteotomy site among the groups was also evaluated. Clinically, the postoperative American Knee Society Score and knee range of motion at latest follow-up were compared. Postoperative complications were also evaluated.

RESULTS: The average age at operation was 56.0 years (range, 42-67 years), and the average follow-up period was 62.2 months (range, 24-120 months). LHFs were observed in 37 knees (22.6%) and were divided into the type I (16 knees) and type II (21 knees) groups. All groups showed no significant changes in serial evaluations of the postoperative hip-knee-ankle angle, femorotibial angle, medial proximal tibial angle, and posterior tibial slope angle. The improvements in the American Knee Society Score and knee range of motion were not significantly different among the groups. No patients showed correction loss or union problems.

CONCLUSIONS: Type I and II LHFs in MOWHTO using a medial locked plate system and relatively conservative rehabilitation protocol with full weight-bearing walking commenced at 6 weeks postoperatively showed no radiologic changes or functional deterioration during midterm follow-up.

LEVEL OF EVIDENCE: Level IV, case series.