Varus derotation osteotomy for the treatment of hip subluxation and dislocation in GMFCS level III to V patients with unilateral hip involvement. Follow-up at skeletal maturity

Purpose: Hip displacement is common in children with cerebral palsy (CP). The risk of hip displacement is related to gross motor function level as graded with the Gross Motor Function Classification System (GMFCS). Most clinicians agree that surgical treatment is indicated for progressive hip subluxation in patients with CP. However, it is unclear whether unilateral bony surgery and musculotenduous release is effective in cases in which the contralateral hip is well seated. The purpose of this study is to describe the fate of the original and the contralateral hip of severely involved patients with CP, GMFCS III to V, with unilateral hip subluxation or dislocation treated by unilateral femoral osteotomy with or without pelvic osteotomy along with unilateral or bilateral soft tissue release when the contralateral hip was well seated followed to skeletal maturity. Methods: A continuous group of GMFCS III to V CP patients with unilateral hip subluxation or dislocation who underwent soft tissue release (adductor and iliopsoas) and unilateral intertrochanteric varus, rotation and shortening osteotomy with or without pelvic osteotomy are included. All patients were clinically and radiologically followed from the time of presentation until skeletal maturity. Results: Twenty-seven children and adolescents with GMFCS level III, IV, and V met the inclusion criteria. Two patients (7.4%) were GMFCS III, 5 (18.5%) were GMFCS IV and 20 (74.1%) GMFCS V. The male: female ratio was almost 1 (13 boys and 14 girls). At the time of chart and radiograph review, the average age of this patient group was 20.4 years (range: 14 to 25y).Twelve patients (44%) required subsequent bony surgical management of the contralateral hip for subluxation or dislocation after the index procedure. Initially, in all cases there was pelvic obliquity with the operative side higher, which reversed in cases in which the contralateral hip deteriorated, and did not reverse when the contralateral hip remained stable. Nine of them were treated with femoral varus osteotomy alone and 3 underwent a combination of femoral and pelvic osteotomy. Three of these 12 (25%) patients had revision of the first hip and bony correction of the contralateral hip. Age at surgery did not seem to have a significant effect on maintaining reduction or in preventing the contralateral hip to deteriorate. Conclusions: The rates of recurrence of the original hip and contralateral hip subluxation and dislocation after unilateral bony surgery in GMFCS III to V spastic patients are higher than those of other earlier series. However, in this series patients were followed until skeletal maturity. It is prudent to warn families of the possibility of long-term subluxation or dislocation of the original hip and development of the hip dysplasia requiring surgery on the contralateral side. Consideration should be given to adductor and iliopsoas release and bony surgery on the contralateral side in a GMFCS level III to V child undergoing surgery for hip displacement, even when the hip seem radiologically normal. If unilateral bony surgery is carried out, close radiological follow-up of both hips is recommended. It also seems that unilateral hip surgery alters the forces maintaining pelvic alignment, which can lead to destabilization of the contralateral hip.