Mild asymptomatic lateral osteoarthritis does not compromise outcomes after medial opening‐wedge high tibial osteotomy

Abstract Purpose High tibial osteotomy (HTO) is a reliable treatment for medial gonarthrosis in painful varus knees, relieving pain by redistributing load to the lateral compartment. Traditionally, lateral compartment osteoarthritis (OA) has been considered a contraindication. However, the recent ESSKA consensus suggests that mild lateral OA may not be an absolute contraindication, although supporting evidence remains limited. This retrospective study investigates the safety and efficacy of HTO in patients with mild‐to‐moderate asymptomatic lateral OA, hypothesising that HTO provides significant pain relief and functional improvement. Methods A single‐centre retrospective observational study was conducted on 132 patients who underwent HTO between 2017 and 2020 at AZ Herentals, Belgium. Inclusion criteria were completion of a 2‐year postoperative questionnaire and preoperative magnetic resonance imaging (MRI) or single‐photon emission computed tomography (SPECT‐CT) within 1 year before surgery. The ‘Knee Injury and Osteoarthritis Outcome Score–Physical Function Short Form’ and ‘Numeric Pain Rating Scale’ were used. Lateral OA severity was assessed using radiographs, MRI and SPECT‐CT. Outcomes were compared across different grades of lateral OA. Results A total of 132 patients (95 men, 38 women; mean age 56 ± 8.7 years) were included. Patients with mild or moderate lateral OA signs on MRI showed significant improvement in pain and function up to 2 years. This was consistent with SPECT‐CT and radiographic findings. No significant differences were observed between patients with different degrees of lateral OA. Linear regression revealed that larger osteophytes on MRI predicted more pain ( β = 40.2, p = 0.0037) and worse function ( β = 23.2, p = 0.049), while lower SPECT uptake predicted less pain ( β = –16.9, p = 0.031). Conclusion At 2 years post‐HTO, pain and function did not differ significantly between patients with or without mild‐to‐moderate lateral gonarthrosis. Thus, mild asymptomatic lateral gonarthrosis should not be considered a contraindication for HTO. Longer‐term studies are needed to confirm these findings. Level of Evidence Level III, retrospective comparative study.