Single-Stage Reverse High Tibial Osteotomy and Total Knee Arthroplasty for Valgus Extra-Articular Deformity After Failed HTO: A Matched-Pair Pilot Study

Background: High tibial osteotomy (HTO) is an established joint-preserving treatment for medial knee osteoarthritis, but total knee arthroplasty (TKA) may be required if the disease progresses. This pilot study evaluates the radiological and functional outcomes of simultaneous limb axis correction using reverse HTO (rHTO) during TKA compared to a primary TKA control group without previous HTO. Methods: In this retrospective matched-pair study, nine patients with previous valgus HTO underwent varus correction via rHTO combined with TKA using cruciate-retaining implants. Outcomes were compared to a primary TKA control group. Radiographic parameters (MPTA, mLDFA, aHKA, JLO) and clinical scores (Oxford Knee Score, LEFS, KOOS, TAS, FIPS) were assessed pre- and postoperatively. Statistical significance was set at p < 0.05. Results: Preoperative alignment differed significantly between groups (MPTA, aHKA, JLO; all p ≤ 0.001). Postoperatively, both cohorts achieved neutral mechanical alignment showing no statistically significant differences in descriptive parameters. CPAK classification showed convergence to neutral alignment types. Functionally, mean postoperative clinical scores, including KOOS subdomains, LEFS, and Oxford Knee Score, were numerically close between groups, though confidence intervals were wide due to the limited sample size (all p > 0.05). Conclusions: This pilot study demonstrates the technical feasibility of single-stage rHTO and TKA, showing encouraging descriptive clinical and radiographic profiles in this small, highly specific cohort. Given the exploratory nature of this study, larger trials are required to definitively evaluate potential clinical differences.