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Head-shaft angle is a risk factor for hip displacement in children with cerebral palsy
Maria Hermanson1, Gunnar Hägglund, Jacques Riad
1Department of Clinical Science, Orthopedic Surgery, Skåne University Hospital, Lund.
Insights
A higher head-shaft angle (HSA) increases the risk of hip displacement in children with cerebral palsy (CP). This finding highlights HSA as a key indicator for monitoring hip health in CP patients.
Area of Science:
- Pediatric Orthopedics
- Cerebral Palsy Research
- Biomechanical Analysis
Background:
- Hip dislocation is a significant complication in children with cerebral palsy (CP).
- Standardized hip monitoring, including migration percentage (MP), is crucial in CP management.
- Head-shaft angle (HSA) is a measurable parameter of femoral head alignment.
Purpose of the Study:
- To investigate the head-shaft angle (HSA) as a predictive risk factor for hip displacement in children with cerebral palsy (CP).
- To quantify the association between HSA and the development of hip displacement.
Main Methods:
- Radiographic data from the Swedish follow-up program for CP (CPUP) were analyzed.
- Children with Gross Motor Function Classification System (GMFCS) levels III-V and initial MP < 40% were followed for 5 years.
- Multiple Poisson regression was used to calculate the risk ratio for hip displacement per degree of HSA, adjusting for age, MP, and GMFCS level.
Main Results:
- A cohort of 145 children with CP was included, with 51 developing hip displacement.
- A 1-degree increase in HSA was associated with a 1.05 times higher risk of hip displacement (p < 0.001).
- A 10-degree difference in HSA resulted in a 1.6-times higher risk of hip displacement in children with higher HSA, controlling for other factors.
Conclusions:
- Elevated head-shaft angle (HSA) is a significant risk factor for hip displacement in children with cerebral palsy (CP).
- HSA measurement can aid in identifying children with CP at higher risk for hip displacement, informing monitoring and intervention strategies.
Background And Purpose:
Hip dislocation in children with cerebral palsy (CP) is a common and severe problem. The Swedish follow-up program for CP (CPUP) includes standardized monitoring of the hips. Migration percentage (MP) is a widely accepted measure of hip displacement. Coxa valga and valgus of the femoral head in relation to the femoral neck can be measured as the head-shaft angle (HSA). We assessed HSA as a risk factor for hip displacement in CP.
Patients And Methods:
We analyzed radiographs of children within CPUP from selected regions of Sweden. Inclusion criteria were children with Gross Motor Function Classification System (GMFCS) levels III-V, MP of < 40% in both hips at the first radiograph, and a follow-up period of 5 years or until development of MP > 40% of either hip within 5 years. Risk ratio between children who differed in HSA by 1 degree was calculated and corrected for age, MP, and GMFCS level using multiple Poisson regression.
Results:
145 children (73 boys) with a mean age of 3.5 (0.6-9.7) years at the initial radiograph were included. 51 children developed hip displacement whereas 94 children maintained a MP of < 40%. The risk ratio for hip displacement was 1.05 (p < 0.001; 95% CI 1.02-1.08). When comparing 2 children of the same age, GMFCS level, and MP, a 10-degree difference in HSA results in a 1.6-times higher risk of hip displacement in the child with the higher HSA.
Interpretation:
A high HSA appears to be a risk factor for hip displacement in children with CP.
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