To determine reliability and clinical use of two methods of migration index (MI) in CP patients with or without hip dysplasia.
The materials included radiographs of 200 hips of children with cerebral palsy. Conventional anteroposterior radiographs of the pelvis were taken with the child in the supine position with standardized methods. Two rehabilitation doctors measured the migration index using two methods. In the classic method, the lateral margin of the acetabular roof was used as a landmark and in the modified method the lateral margin of the sourcil was used as a landmark. Each rater measured the migration index at three separate times with a time interval of at least one week. Intraclass correlation (ICC) was used to test the inter- and intra-rater reliability.
MI shows excellent intra-rater reliability in both the classic and modified methods, but the inter-rater reliability was higher in the classic method than in the modified method. When categorized according to the sourcil classification, inter-rater reliability was higher in the normal sourcil type and lower in the dysplastic sourcil types.
Generally, the classic method showed higher reliability than the modified method, even though the reliability of the MI measurement was relatively high with both methods.
Citations
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)