Current Practice of Analysis and Treatment of underlying Varus Deformity in Patients with Cartilage Defects of the medial Femoral Condyle: Data of the German Cartilage Registry (KnorpelRegister DGOU)
Authors: Faber Svea , Zellner Johannes , Hochrein Alfred , Spahn Gunter , Niemeyer Philipp 
Published: June 2019

Aims and Objectives: In the context of cartilage repair, identification of the underlying pathologies depends on detailed preoperative evaluation. High tibial osteotomy (HTO) for varus deformities is one of the most common concomitant treatments, though scientific evidence about efficiency of concomitant HTO is still limited. The present study was initiated to describe preoperative analysis of alignment and to analysis outcome comparing patients with combined cartilage repair and HTO with those who received cartilage repair procedures alone. Materials and Methods: The multicenter data (3855 data sets on April 15, 2018) was provided by the attending physician and a self-reported outcome analysis (KOOS). Inclusion criteria: Existence of a leg full length portrait, a single defect at the medial femoral condyle, either no accompanying surgery or a HTO and information on leg axis misalignment. For outcome evaluation patients were divided into three different groups with regard to the extent of varus deformity: MILD (0-4° varus), MODERATE (5-9° varus) and SEVERE (> 10°). Statistical Analysis was performed using SPSS (IBM) Version 23. For detection of significances between different groups one-way ANOVA test was applied. P-values < 0.05 were considered statistical significant. Results: In 55.1% (n=2125) of the patients a full leg weight-bearing radiographs has been performed preoperatively. Out of these 834 (39%) cases with isolated defects of the medial femoral condyle have been identified of which 179 received HTO in combination with the cartilage repair procedure (21.5%), while 411 cases have been treated with isolated cartilage repair (49.3%). From the remaining 385 patients, 256 patients were considered MILD (67,3%), 113 MODERATE (29.5%) and 4.2% (n=16) SEVERE. Incidence of HTO significantly depended on the degree of varus deformity for mild (19% HTO) and moderate (83% HTO) deformity, but there was no significance between the moderate and severe (81% HTO) group. Significant differences of the KOOS score could be shown preoperatively between the mild (mean: 57.3), as well as moderate (mean: 55.95), and the severe group (mean 39.53) and six months postoperatively between the mild (mean: 71.48) and the severe (mean: 52.6) group. Conclusion: The present analysis of a large patients cohort extracted from the German Cartilage Registry (KnorpelRegister DGOU) demonstrates that, against common guidelines, full-leg weigth-bearing radiographs are not conducted on a regular basis in patients assigned for cartilage repair procedures. In those cases with detailed preoperative analysis of alignment, the degree of deformity seems to influence the decision, whether a realignment procedure (HTO) is performed. For the moderate subgroup a trend towards better clinical outcome was found for combined treatment in terms of realignment and cartilage repair in comparison to cartilage repair alone. Since there was no difference in the MILD subgroup, more evidence is needed to proof, whether those patients benefit from a HTO or not.