Recurrent hip instability after hip reconstruction in cerebral palsy children with spastic hip disease.

BACKGROUND: Migration percentage (MP) is widely used to evaluate hip stability in children with spastic cerebral palsy (CP). Orthopedic surgeons need more objective information to make a proper hip reconstruction surgical plan and predict the outcome. METHODS: Medical records and plain radiographs of children with CP who underwent the hip reconstruction procedure for dysplasia were reviewed retrospectively. RESULTS: In total, 253 operated hips (140 patients; 11.7 ± 3.3 years old) were included in this study. MP at pre-operative (Tpre) was 35.3 ± 22.5%; at immediate follow-up (Tpost) was 5.9 ± 9.5%; at last follow-up (Tfinal) was 9.8 ± 10.8% (4.5 ± 2.3 years post-operative at age 16.3 ± 2.8 years). In hips with Melbourne Cerebral Palsy Hip Classification Scale (MCPHCS) grade 3 (n = 78), around 30-45% had an unsatisfactory outcome at Tpost and Tfinal. However, hips categorized as other grades showed only 2.1-9.1% of unsatisfactory outcome. In less affected hips (pre-operative MP<30%, n = 122), 109 hips (89.3%) had varus derotation osteotomy only, the other 13 hips (10.7%) were combined with a pelvic osteotomy. In more severely affected hips (pre-operative MP ≥ 30%, n = 131), 26 hips (19.8%) had varus derotation osteotomy only, the other 105 hips (80.2%) were combined with a pelvic osteotomy. CONCLUSIONS: Hips with pre-operative MP between 15 and 29% (MCPHCS grades 3) can be a higher risk group of recurrent hip instability after hip reconstruction surgery. Multiple indications beyond MP should be considered when indicating pelvic osteotomy or hip muscle release as combined procedures with varus femoral osteotomy for hip reconstruction in this milder group to achieve a consistent long-term satisfactory outcome.