Bony morphology of the hip in professional ballet dancers compared to athletes
To compare hip bony morphology between ballet dancers and a sporting control group and to determine the relationship with hip pain.
Thirty-three professional ballet dancers and 33 age- and sex-matched athletes completed questionnaires, including the Copenhagen Hip and Groin Outcome Score (HAGOS), and underwent clinical testing and 3.0-T magnetic resonance imaging to measure acetabular coverage with lateral centre edge angles, femoral head-neck junction concavity with alpha angles at anterior and superior positions, femoral neck-shaft angles, and acetabular version angles.
Bony morphological measures fell within normal ranges. Dancers had higher neck-shaft angles (dancers 134.6 ± 4.6°/athletes130.8 ± 4.7°, p = 0.002), lower acetabular version angles (13.5 ± 4.7°/17.1 ± 4.7°, p = 0.003), lower superior alpha angles (38.9 ± 6.9°/46.7 ± 10.6°, p < 0.001), similar anterior alpha angles (43.6 ± 8.1/46 ± 7°, p = 0.2), and similar lateral centre edge angles (28.8 ± 4.6°/30.8 ± 4.5°, p = 0.07) compared to athletes. Abnormal morphology was detected in dancers: 3% acetabular dysplasia (athletes 0), 15% borderline dysplasia (6%), 24% cam morphology (33%), 24% coxa valga (6%), and 21% acetabular retroversion (18%). The HAGOS pain scores correlated moderately with acetabular version (r = -0.43, p = 0.02) in dancers, with no other correlation between pain and morphological parameters in either group.
Professional ballet dancers have hip bony morphology that differentiates them from athletes. Hip pain correlated poorly with bony morphology.
• Ballet dancers have hip bony morphology that may allow extreme hip motion.
• Morphological parameter means fell within normal reference intervals in dancers.
• Bony morphology correlates poorly with hip pain.
• The risk of hip injury due to abnormal morphology requires prospective studies.
KeywordsAcetabular dysplasia Neck-shaft angle Acetabular version Femoroacetabular impingement Hip pain
Abbreviations and acronyms
Lateral centre edge angle
Anterior alpha angle
Superior alpha angle
Acetabular version angle
Copenhagen Hip and Groin Outcome Score
Body Mass Index
Range of movement
Magnetic resonance imaging
Field of view
Proton density weighted
Picture archive and communication system
The scientific guarantor of this publication is Jill Cook. The authors of this manuscript declare relationships with the following companies: Susan Mayes is employed by The Australian Ballet. The other authors declare that they have no competing interests. Funding from the Eirene Lucas Foundation, ANZ Trustees, Friends of The Australian Ballet (SA), Inc., and the Duncan Leary Charitable Trust is gratefully acknowledged. Prof. Cook was supported by the Australian Centre for Research into Sports Injury and its Prevention, which is one of the International Research Centres for Prevention of Injury and Protection of Athlete Health supported by the International Olympic Committee (IOC). Prof. Cook is an NHMRC practitioner fellow (ID 1058493). One of the authors has significant statistical expertise. Institutional Review Board approval was obtained. Written informed consent was obtained from all subjects (patients) in this study. Some study subjects or cohorts have been previously reported in ‘Similar Prevalence of Acetabular Labral Tear in Professional Ballet Dancers and Sporting Participants’ CJSM 2016 and ‘Atraumatic tears of the ligamentum teres are more frequent in professional ballet dancers than a sporting population’ Skeletal Radiol 2016.
Methodology: case-control study, performed at one institution.
The authors sincerely thank the past and present dancers of The Australian Ballet who participated in the study. We thank the staff of MIA East Melbourne Radiology for their support in image acquisition. We thank S. Emery for assisting in data acquisition and collation. We thank P. Baird-Colt, P. Stellar, S. Black, J. Carr, J. Pugh, and W. Tardif for their assistance in collection of clinical data. We thank G. Scott and E. Scase for assisting in participant recruitment and J. Gildea for assistance in manuscript preparation.
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