Methods

A total of 49 derotation osteotomies were performed in 39 patients. There were 32 females and 7 males. Average age was 29 years (range 14 to 59 years). Osteotomies were performed closed with an intramedullary saw (Figure 1). Fixation was performed with a variety of intramedullary nails. Patients requiring a varus or valgus intertrochanteric osteotomy were excluded. Pure rotational corrections only were performed. Twenty-four percent of patients had a retroversion deformity (average −8° retroversion, range +1 to −23°), 76% had excessive anteversion of the femur (average +36° anteversion, range +22° to +53°). Etiology was post-traumatic in 5 (10%), diplegic cerebral palsy in 4 (8%), fibrous dysplasia in 2 (4%), Prader-Willi Syndrome in 1 (2%) and idiopathic in 37 (76%). Previous surgery had been performed in 51% of hips. Fifty-seven percent underwent concomitant surgery with the index femoral derotation osteotomy, including hip arthroscopy in 39% (labral debridement alone or with femoral neck osteochondroplasty), a tibial derotation osteotomy in 12% and periacetabular osteotomy in 6%. Concomitant tibial osteotomies were performed to correct a compensatory excessive external tibial torsion that would be exacerbated in the correction of excessive femoral anteversion. The modified Harris Hip Score was used to assess the results in patients with a minimum of 24 months follow-up.