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Reliability of hip migration index in children with cerebral palsy: the classic and modified methods
Sun Mi Kim1, Eun Geol Sim, Seong Gyu Lim
1Department and Research Institute of Rehabilitation Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea.
Insights
The classic method for measuring the hip migration index (MI) in cerebral palsy (CP) patients demonstrated higher reliability than the modified method. Both methods showed excellent intra-rater reliability for clinical use.
Area of Science:
- Orthopedics
- Pediatric Rehabilitation
- Medical Imaging Analysis
Background:
- Cerebral palsy (CP) often involves hip complications, including dysplasia.
- Accurate measurement of hip migration is crucial for managing CP patients.
- The migration index (MI) is a key metric, but its reliability across different measurement methods needs evaluation.
Purpose of the Study:
- To assess the reliability and clinical utility of two distinct methods for calculating the migration index (MI).
- To compare the inter- and intra-rater reliability of a classic versus a modified MI measurement technique in children with CP.
Main Methods:
- Radiographs of 200 hips from children with CP were analyzed.
- Two rehabilitation doctors measured the MI using conventional anteroposterior pelvic radiographs.
- Measurements were performed three times per rater using a classic (acetabular roof landmark) and modified (sourcil landmark) method.
- Intraclass correlation (ICC) was employed to determine inter- and intra-rater reliability.
Main Results:
- Both classic and modified MI methods exhibited excellent intra-rater reliability.
- The classic MI method showed higher inter-rater reliability compared to the modified method.
- Inter-rater reliability was superior for normal sourcil types versus dysplastic types in the modified method.
Conclusions:
- The classic method for MI measurement offers higher reliability than the modified approach in CP patients.
- Despite differences, both MI measurement methods demonstrate relatively high reliability, supporting their clinical use.
- Reliability is influenced by sourcil morphology, particularly in dysplastic hips.
Objective:
To determine reliability and clinical use of two methods of migration index (MI) in CP patients with or without hip dysplasia.
Method:
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.
Results:
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.
Conclusion:
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.
