High tibial osteotomy versus unicompartmental knee arthroplasty for medial compartment knee osteoarthritis: a comprehensive meta-analysis with patient-specific stratification by age, BMI, and preoperative activity levels

The optimal surgical intervention for medial compartment knee osteoarthritis (MCOA) in active patients remains contentious. High tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA) represent the two primary surgical options, yet evidence-based guidance for patient-specific treatment selection is lacking. To conduct a comprehensive meta-analysis comparing HTO versus UKA for MCOA, with stratification by age, body mass index (BMI), and preoperative activity levels to establish evidence-based patient selection criteria. A systematic search of PubMed, Embase, Cochrane Library, and Web of Science was performed from inception through December 2025. Randomized controlled trials (RCTs) and high-quality comparative observational studies were included. Primary outcomes included revision rate and Knee Society Score (KSS). Secondary outcomes encompassed WOMAC score, Tegner activity score, range of motion (ROM), and complication rates. Random-effects models with DerSimonian-Laird estimators were employed. Subgroup analyses were stratified by age (< 60 vs. ≥ 60 years), BMI (< 27 vs. ≥ 27 kg/m²), and activity level (high vs. low). Ten studies comprising 860 patients (375 HTO, 485 UKA) met inclusion criteria. HTO demonstrated significantly higher revision rates (OR = 1.74, 95% CI: 1.37–2.21, P = 0.0007; I²=0.0%) and complication rates (OR = 1.77, 95% CI: 1.45–2.15, P = 0.0001) compared with UKA. UKA showed superior KSS knee scores (MD = − 3.07, 95% CI: −4.52 to − 1.63, P = 0.0012) and WOMAC outcomes (MD = 4.85, 95% CI: 4.13–5.57, P < 0.0001). Conversely, HTO demonstrated significantly better KSS function scores (MD = 3.74, 95% CI: 1.37–6.11, P = 0.0065), Tegner activity scores (MD = 0.87, 95% CI: 0.50–1.23, P = 0.0011), and ROM (MD = 11.47°, 95% CI: 8.07–14.87, P < 0.0001). Subgroup analyses revealed that younger patients (< 60 years) with high preoperative activity levels derived greater functional benefits from HTO, whereas older patients (≥ 60 years) with lower activity demands achieved superior pain relief with UKA. Both HTO and UKA represent viable treatment options for MCOA with distinct outcome profiles. Current evidence suggests that UKA may provide superior pain relief and lower complication rates, while HTO appears to offer better functional outcomes and activity restoration. Preliminary subgroup analyses indicate that patient selection may be optimized based on age, activity demands, and treatment priorities, although these findings require prospective validation. Level II.