Anterior Popliteus Transtibial Tuberosity Osteotomy for Moderate-to-Severe Medial Knee Osteoarthritis in a Karst Mountain Population: Factors Associated with Satisfaction and 2-Year Clinical Outcomes

Abstract Patients in Karst mountain regions are exposed to unusually high biomechanical demands because of frequent hill climbing, deep flexion, and long-term weight-bearing labor. This study evaluated the 2-year clinical and radiographic outcomes of anterior popliteus transtibial tuberosity osteotomy (APTTO) for moderate-to-severe medial knee osteoarthritis in this high-demand population and explored factors associated with postoperative satisfaction. We retrospectively reviewed 79 patients with moderate-to-severe medial knee osteoarthritis (Kellgren–Lawrence [K–L] grade III–IV) treated with APTTO with a minimum 2-year follow-up. Clinical outcomes, including the Visual Analog Scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Lysholm score, and range of motion, were assessed together with radiographic parameters, including the hip–knee–ankle (HKA) angle, weight-bearing line (WBL) ratio, and medial proximal tibial angle (MPTA). Overall satisfaction was evaluated using a strict binary classification in which neutral responses were categorized as dissatisfied. Factors associated with satisfaction were analyzed using Firth-penalized logistic regression, and exploratory receiver operating characteristic (ROC) analysis was performed for postoperative MPTA. At the minimum 2-year follow-up, radiographic alignment and clinical outcomes improved significantly. The HKA angle improved from 172.25 ± 3.93 degrees preoperatively to 181.23 ± 3.14 degrees at 2 years, and the WBL ratio improved from 19.53 ± 14.35% to 57.32 ± 12.47%. Overall satisfaction was 79.7%, reaching 84.8% in the K–L grade IV subgroup. In the simplified Firth-penalized logistic regression model, postoperative MPTA remained significantly associated with satisfaction (odds ratio [OR] = 1.364; 95% confidence interval [CI], 1.055–1.763; p = 0.018). Exploratory ROC analysis showed an area under the curve of 0.718 (95% CI, 0.578–0.858; p = 0.007), and the cohort-derived postoperative MPTA threshold was 91.2 degrees. At a minimum 2-year follow-up, APTTO provided favorable clinical and radiographic outcomes and patient-reported satisfaction in this high-demand cohort. Postoperative MPTA was significantly associated with satisfaction, although the cohort-derived threshold of 91.2 degrees should be interpreted only as an exploratory reference rather than a validated correction target. Longer-term follow-up is needed to determine the durability of these short-term results. The level of evidence was III: a retrospective, prognostic study.