Implant Removal After Medial Opening Wedge High Tibial Osteotomy Provides Implant-Related Pain Relief and Functional Improvement

Abstract

PurposeTo (1) investigate the incidence of implant-related pain after medial opening wedge high tibial osteotomy (MOWHTO) using locking plate, (2) determine whether implant removal provides pain relief and functional improvement, and (3) evaluate bone healing and loss of correction after implant removal. Materials and MethodsBetween March 2014 and September 2017, MOWHTO was performed without bone graft. The inclusion criteria were patients who underwent implant removal after MOWHTO and were followed up for a minimum of 2 years. Patients were evaluated for implant removal one and two years after surgery. Clinical and functional evaluations were conducted to investigate implant-related pain using the visual analog scale, Lysholm score, and Tegner score. The radiographic indices measured were the gap-filling rate, weight-bearing line (WBL) ratio, hip-knee-ankle angle (HKAA), medial proximal tibial angle (MPTA), and posterior tibial slope angle (PTSA). ResultsA total of 55 patients were enrolled. Fifty-one (92.7%) patients experienced implant-related pain prior to implant removal, with 43 and eight patients reporting mild pain and moderate pain, respectively. At one and two years after implant removal, mild pain was six (10.9%) and five (9.1%) patients, respectively. The remaining patients reported no implant-related pain. Prior to implant removal and one year after implant removal, the Lysholm score improved from 77.0±5.6 to 86.8±5.7 (P<0.001), and the Tegner score improved from 3.3±1.2 to 3.9±1.3 (P<0.001). The mean gap-filling rate was 84.4%±9.6% at implant removal, and it significantly increased to 93.7%±5.4% and 97.4%±2.6% at one and two years after implant removal, respectively (P<0.001) For the WBL ratio, HKAA, MPTA, and PTSA, no statistical differences were found after implant removal. ConclusionThe incidence of implant-related pain after MOWHTO using medial proximal tibial locking plate was high. Implant removal provides pain relief and functional improvement (met minimal clinically important differences). Even after implant removal, bone healing progressed gradually without a loss of correction in all patients.