Musculo-skeletal   [back to the Category]

Dysplasia of the hip   [read the french version]

Author :   Docteur Anne Thiescé

The morphology of the hip can be determined using radiography. It measures the depth of the acetabulum and, in this way, checks for dysplasia. It differentiates between deep hips with covering acetabulum and exposed hips with short acetabulum or acetabulum with dysplasia, Fig 1. It also measures the cervico-diaphyseal angle: a wide angle characterises coxa valga, a narrow angle characterises coxa vara.
The mobility of the hip and the risk of secondary osteoarthritis is partly based on this morphological data.

Front view, pelvis X-rays of teenagers aged between 9 and 20 years, who do ballet with the aim of becoming professional ballet dancers, show the dancers' hips' clear tendency towards sub-dysplasia. The external coverage angle found in children who dance is inferior to that established in a test population and it does not change with age as it does in the trials.

This lack of coverage promotes coxofemoral mobility especially for abduction movements: is it a natural selection factor of young dancers or the result of the stretching exercises that are part of the intensive training programme during the initial years?

In any event, 80% of dancers with coxarthrosis were found to have badly covered hips and 54.3% to have genuine dysplasia. These percentages are far superior to those recorded for the general population which vary between 26 and 40%.


Bibliography:

Judet T., Combelles J., Thiescé A. - Devenir de la hanche de la danseuse. Colloque "Médecine de la danse" 25 mars 1995, Festival international de la danse de Cannes.

Thiescé A. - Hanche et Danse professionnelle. Thèse Med., Cochin, 1987.