Effect of Medial Closing Wedge Distal Femoral Osteotomy on Tibial Tuberosity-Trochlear Groove Distance in Patients With Genu Valgum According to Diagnosis (Lateral Osteoarthritis or Patellar Dislocation).

BACKGROUND Medial closing wedge distal femoral osteotomy (CWDFO) is used to correct valgus deformities and manage lateral osteoarthritis (OA) and patellar dislocation (PD). However, its effect on the tibial tuberosity-trochlear groove (TT-TG) distance remains debated, with limited studies evaluating contributing factors. PURPOSE To determine whether TT-TG distance changes after CWDFO differ by the underlying diagnosis prompting the procedure and to identify preoperative factors influencing the extent of TT-TG distance changes. STUDY DESIGN Case series; Level of evidence, 4. METHODS This study analyzed 43 knees of 34 patients with valgus deformity who underwent CWDFO, categorized into the lateral OA (n = 14) and PD (n = 29) groups. Radiographic parameters, including the TT-TG distance, were assessed preoperatively and at least 1 year postoperatively. Regression analyses were conducted to identify the factors influencing TT-TG distance changes. A predictive model with 95% confidence intervals determined the thresholds for deviations from the expected values. RESULTS The TT-TG distance significantly decreased from 14.7 ± 5.1 to 11.5 ± 4.7 mm after CWDFO (P < .001). On average, the TT-TG distance decreased by 21.8% after CWDFO. Changes in the TT-TG distance did not significantly differ by diagnosis (lateral OA: -3.0 ± 2.3 mm; PD: -3.3 ± 4.5 mm; P = .771). The preoperative TT-TG distance and osteotomy type significantly influenced TT-TG distance changes. A higher preoperative TT-TG distance was correlated with a greater reduction (odds ratio, -0.375; P = .001), and biplanar osteotomy showed a more pronounced effect than uniplanar osteotomy (odds ratio, -3.083; P = .013). Patients with preoperative TT-TG distances >23.5 mm demonstrated greater variability in TT-TG distance changes in the predictive model. CONCLUSION CWDFO effectively reduced the TT-TG distance regardless of the diagnosis. Preoperative TT-TG distance and osteotomy type were key determinants of this reduction. In cases with preoperative TT-TG distances >23.5 mm, TT-TG distance changes demonstrated greater variability, suggesting that radiographic outcomes may deviate from expected values. These findings highlight the need for careful postoperative assessments and consideration of additional procedures in select cases.