The head-shaft angle of the hip in early childhood: a comparison of reference values for children with cerebral palsy and normally developing hips.
The recognition of hips at risk of displacement in children with cerebral palsy (CP) is a difficult problem for the orthopaedic surgeon. The Gross Motor Function Classification System (GMFCS) and head-shaft angle (HSA) are prognostic factors for hip displacement. However, reference values for HSA are lacking. This study describes and compares the development of HSA in normal hips and children with CP. We selected 33 children from a retrospective cohort with unilateral developmental dysplasia of the hip (DDH) (five boys, 28 girls) and 50 children (35 boys, 15 girls) with CP with GMFCS levels II to V. HSA of normal developing hips was measured at the contralateral hip of unilateral DDH children (33 hips) and HSA of CP children was measured in both hips (100 hips). Measurements were taken from the radiographs of the children at age two, four and seven years. The normal hip HSA decreased by 2° per year (p < 0.001). In children with CP with GMFCS levels II and III HSA decreased by 0.6° (p = 0.046) and 0.9° (p = 0.049) per year, respectively. The HSA did not alter significantly in GMFCS levels IV and V. Between the ages of two and eight years, the HSA decreases in normal hips and CP children with GMFCS level, II to III but does not change in GMFCS levels IV to V. As HSA has a prognostic value for hip displacement, these reference values may help the orthopaedic surgeon to predict future hip displacement in children with CP.
Research Institute MOVE VU University Medical Center, De Boelelaan 1117, P.O. Box 7057, 1081 HV Amsterdam, The Netherlands.
J P
JP
van der List
Research Institute MOVE VU University Medical Center, De Boelelaan 1117, P.O. Box 7057, 1081 HV Amsterdam, The Netherlands.
M M
MM
Witbreuk
Research Institute MOVE VU University Medical Center, De Boelelaan 1117, P.O. Box 7057, 1081 HV Amsterdam, The Netherlands.
A I
AI
Buizer
Research Institute MOVE VU University Medical Center, De Boelelaan 1117, P.O. Box 7057, 1081 HV Amsterdam, The Netherlands.
J A
JA
van der Sluijs
D000375:Aging / Q000473:pathology; D002547:Cerebral Palsy / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006617:Hip Dislocation / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology; D006621:Hip Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000254:growth & development* / Q000473:pathology; D006801:Humans; D008297:Male; D011379:Prognosis; D011859:Radiography; D012016:Reference Values; D012189:Retrospective Studies
head-shaft angle; HSA; Southwick angle; femoral head; hip displacement; hip dislocation; hip subluxation; Cerebral Palsy