Clinical and radiological outcome of combined femoral and Chiari osteotomies for subluxed or dislocated hips secondary to neuromuscular conditions: a minimum of 10-year follow-up.

We evaluated the medium-term results of combined Chiari pelvic and femoral osteotomies performed at the Manchester Children's Hospitals between the years 1985 and 1994. The indications for these osteotomies were either hip dislocation or subluxation in children with neuromuscular disease. We clinically and radiologically evaluated 20 hips in 18 patients treated for hip subluxation and dislocation with Chiari osteotomy. The average post-operative clinical follow-up period was 11.32 years (range 10.1-12.9). The mean age at the time of surgery was 7.3 years (range 3.1-13.2 years). Clinically, 9 hips had a 'Good' outcome, 10 were "Fair" and 1 was "Poor" according to Osterkamp criteria. At last follow-up, radiologically the mean Sharp's angle improved from 51° to 44° (p = 0.09), the mean Centre-Edge angle improved from -16° to 18° (p = 0.067), the mean Migration Index improved from 59 to 29 % (p = 0.011), the mean femoral neck-shaft angle from 160° to 117° (p < 0.0001) and the Severin criteria improved from an average grade of 4.5-2.9 (p < 0.0001). Our results compared to previous studies confirm that combined femoral and Chiari osteotomies provide a favourable outcome both clinically and radiologically at least 10 years following surgery. Accepting that the numbers are small, we report no statistical difference in the mean age at the time of operation when comparing the children with an eventual 'good' outcome and those with an eventual 'fair' or 'poor' outcome.