Decision making for concomitant high tibial osteotomy (HTO) in cartilage repair patients based on a nationwide cohort study of 4968 patients

Background High tibial osteotomy (HTO) for varus deformities is a common concomitant treatment in cartilage surgery. Aim of the present study was to analyze factors influencing the decision towards accompanying HTO in patients with cartilage defects of the medial femoral condyle, such as the amount of varus deformity. Methods Data from 4986 patients treated for cartilage defects of the knee from the German Cartilage Registry (KnorpelRegister DGOU) were used for the current analysis. Seven hundred and thirty-six patients fulfilled the inclusion criteria. Their data were analyzed for factors influencing the decision towards performing a concomitant HTO using t test, univariate and multivariate binary logistic regression models. Results The break point at which the majority of patients receive a concomitant HTO is 3 degrees of varus deformity. Several factors apart from the amount of varus deformity (5.61 +/- 2.73 degrees vs. 1.72 +/- 2.38 degrees, p < 0.00) differed significantly between the group of patients with HTO and those without. These included defect size (441.6 +/- 225.3 mm(2) vs. 386.5 +/- 204.2 mm(2), p = 0.001), symptom duration (29.53 +/- 44.58 months vs. 21.85 +/- 34.17 months, p = 0.021), defect grade (62.5% IVa/IVb vs. 57.3% IVa/IVb, p = 0.014), integrity of corresponding joint surface (10.8% grade III-IV vs. 0.2% grade III-IV, p < 0.001), meniscus status (15.5% > 1/3 resected vs. 4.4% > 1/3 resected, p < 0.001) and number of previous surgeries (1.01 +/- 1.06 vs. 0.75 +/- 1.00, p = 0.001). In the stepwise multivariate binary logistic regression test, only the amount of varus deformity, symptom duration and quality of the corresponding joint surface remained significant predictors associated with performing a concomitant HTO. Conclusion Based upon data from a nationwide cohort, additional HTO in context with cartilage repair procedures of the medial femoral condyle is frequently performed even in mild varus deformities less than 5 degrees. Other factors also seem to influence decision for HTO.