Femoral derotational osteotomy reduces knee version significantly in contrast to tibial derotational osteotomy.

PURPOSE: The knee version has increasingly been recognised as a potential contributing risk factor to patellofemoral maltracking. However, it remains unclear whether the knee version can be influenced by surgical procedures such as derotational osteotomies. Therefore, the aim of this study was to elevate the effect of derotational osteotomies on knee version. The hypothesis of this study is that derotational osteotomies improve knee version in patients with abnormal knee version and that the magnitude of change of knee version correlates to the extent of the correction. METHODS: The patient cohort consisted of 37 patients, 16 patients were treated with a tibial and 21 patients with a femoral derotational osteotomy. Standardised computer tomography (CT) scan was obtained pre and postoperative and the knee version was measured. The values were compared within the whole study population and divided into a tibial and a femoral group. RESULTS: A significant decrease in knee version by 3.1° on average of the patient population was found between pre and postoperative values (p < 0.0001). In tibial osteotomies, the decrease of knee version was not statistically significant (0p = 0.1116), whereas in femoral osteotomies the decrease was statistically significant (p < 0.0001). No strong correlation was found between the degree of torsional correction and the degree of change in knee version. CONCLUSION: This study shows that pathological increased knee version can be reduced by derotational osteotomy, although only the femoral osteotomy was significantly effective in contrast to tibial osteotomy. Furthermore, there was no correlation between the degree of derotation and the magnitude of change in knee version. LEVEL OF EVIDENCE: Level IV.