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Journal of Bone and Joint Surgery - British Volume, Vol 90-B, Issue 10,
1372-1379.
doi: 10.1302/0301-620X.90B10.20733 Copyright © 2008 by British Editorial Society of Bone and Joint Surgery Proximal femoral geometry in cerebral palsyA POPULATION-BASED CROSS-SECTIONAL STUDYJ. Robin, MBBS(Hons), Orthopaedic Registrar1; H. Kerr Graham, MD, FRCS(Ed), FRACS, Professor of Orthopaedic Surgery1; P. Selber, MD, Orthopaedic Surgeon1; F. Dobson, PhD, BSc, Senior Physiotherapist2; K. Smith, BSc, Biomedical Statistician3; and R. Baker, PhD, CEng, CSci, Biomechanical Engineer2
1 Orthopaedic Department Correspondence should be sent to Dr J. Robin; e-mail: jonorobin{at}yahoo.com
There is much debate about the nature and extent of deformities in the proximal femur in children with cerebral palsy. Most authorities accept that increased femoral anteversion is common, but its incidence, severity and clinical significance are less clear. Coxa valga is more controversial and many authorities state that it is a radiological artefact rather than a true deformity. We measured femoral anteversion clinically and the neck-shaft angle radiologically in 292 children with cerebral palsy. This represented 78% of a large, population-based cohort of children with cerebral palsy which included all motor types, topographical distributions and functional levels as determined by the gross motor function classification system. The mean femoral neck anteversion was 36.5° (11° to 67.5°) and the mean neck-shaft angle 147.5° (130° to 178°). These were both increased compared with values in normally developing children. The mean femoral neck anteversion was 30.4° (11° to 50°) at gross motor function classification system level I, 35.5° (8° to 65°) at level II and then plateaued at approximately 40.0° (25° to 67.5°) at levels III, IV and V. The mean neck-shaft angle increased in a step-wise manner from 135.9° (130° to 145°) at gross motor function classification system level I to 163.0° (151° to 178°) at level V. The migration percentage increased in a similar pattern and was closely related to femoral deformity. Based on these findings we believe that displacement of the hip in patients with cerebral palsy can be explained mainly by the abnormal shape of the proximal femur, as a result of delayed walking, limited walking or inability to walk. This has clinical implications for the management of hip displacement in children with cerebral palsy.
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