Superior functional outcome after femoral derotation osteotomy according to gait analysis in cerebral palsy

- The outcome after femoral derotation osteotomy in cerebral palsy was investigated.
- The deviation of derotation amount from hip rotation in gait analysis was calculated.
- Optimum results if derotation amount averaged internal hip rotation in gait analysis.
- Adverse effects if derotation amount deviated from hip rotation in gait analysis.
- Derotation amount should be defined by gait analysis to obtain an optimum outcome.

The femoral derotation osteotomy (FDO) is seen as the golden standard treatment in children with cerebral palsy and internal rotation gait. Variable outcomes with cases of over- and undercorrection mainly in the less involved patients have been reported. The determination of the amount of derotation is still inconsistent. 138 patients (age: 11 (±3.3) years) with cerebral palsy and internal rotation gait were examined pre- and 1 year postoperatively after distal or proximal FDO, using standardized clinical examination and 3D gait analysis. Three groups were defined retrospectively depending on the amount of derotation in relation to the mean hip rotation in stance (MHR) during gait analysis: Group A (derotation angle > MHR + 10°), Group B (derotation angle = MHR ± 10°), Group C (derotation angle < MHR − 10°), and compared according to their postoperative mean hip rotation. ANOVA with Bonferroni post hoc test was used for statistics (p < 0.05). Group B had the greatest benefit with the highest rate (86%) of good results (postoperative MHR = ±15°). In contrast there were 14% cases of overcorrection and 5% cases of deterioration in Group A with only 81% good results and only 79% good results in Group C. It can be concluded, that it is less likely to have unsatisfactory outcomes if the amount of FDO is defined according to the findings of gait analysis compared with clinical examination.