Objective
Hip deformity is one of the common problems in children with cerebral palsy. And it is important to detect hip subluxation or dislocation as early as possible. The purpose of this study is to find the incidence of hip subluxation in early childhood in patients with cerebral palsy.

Method
We reviewed clinical and radiological records of children with cerebral palsy under 36 months of age. We measured migration index, acetabular index, center edge angle and neck shaft angle from hip X-ray of patients.

Results
Total 76 patients were included in this study. The mean of migration index was 4.5⁑7.5% at 8∼12 months, 10.9⁑11.9% at 13∼24 months, and 18.2⁑13.0% at 25∼36 months (p＜0.05). Twenty one patients (27.6%) were above 25% on the migration index. The neuromotor type of cerebral palsy in 21 patients with hip subluxation, were spastic in 20 (95.2%) except one child. The incidence of hip subluxation was 25.0% (8/32) for quadriplegia, 29.6% (8/27) for diplegia and 50.0% (4/8) for hemiplegia. The acetabular index was significantly higher and the center edge angle was lower in the subluxated hip group than in the non-subluxated hip group, though no significant difference in the neck shaft angle.

Conclusion
We concluded that the hip subluxation in cerebral palsy can occur under 36 months of age with a relatively high incidence. Therefore, it is recommended to evaluate the hip of cerebral palsy with radiological as well as clinical examination in early childhood. (J Korean Acad Rehab Med 2002; 26: 514-518)