Dr. Courtney has received an honorarium from Merck, Sharp, and Dohme (less than $10,000).
Nonspherical femoral head shape (pistol grip deformity), neck shaft angle, and risk of hip osteoarthritis: A case–control study
Version of Record online: 29 SEP 2008
Copyright © 2008 by the American College of Rheumatology
Arthritis & Rheumatism
Volume 58, Issue 10, pages 3172–3182, October 2008
How to Cite
Doherty, M., Courtney, P., Doherty, S., Jenkins, W., Maciewicz, R. A., Muir, K. and Zhang, W. (2008), Nonspherical femoral head shape (pistol grip deformity), neck shaft angle, and risk of hip osteoarthritis: A case–control study. Arthritis & Rheumatism, 58: 3172–3182. doi: 10.1002/art.23939
- Issue online: 29 SEP 2008
- Version of Record online: 29 SEP 2008
- Manuscript Accepted: 27 JUN 2008
- Manuscript Received: 19 FEB 2008
- John Monk Hip Foundation
- Infrastructure support for Academic Rheumatology
- University of Nottingham
- Arthritis Research Campaign, UK. Grant Number: ICAC grant 14851
- Genetics of Osteoarthritis and Lifestyle (GOAL)
- AstraZeneca, Macclesfield, UK
To determine whether 2-dimensional measures of femoral head shape and angle are associated with hip osteoarthritis (OA).
We compared cases with symptomatic radiographic hip OA with asymptomatic controls with no radiographic hip OA. On anteroposterior pelvis radiographs, we measured “pistol grip deformity” for each hip (visually categorized as nonspherical, indeterminate, or spherical), the femoral head–to–femoral neck ratio as an interval measure of femoral head shape, and the femoral neck shaft angle. The relative risk of hip OA associated with each feature was estimated using odds ratios (ORs) and 95% confidence intervals (95% CIs), adjusted for possible confounders using a logistic regression model.
Of 1,007 cases, 965 had definite radiographic hip OA; of 1,123 controls, 1,111 had no radiographic OA. The prevalence of pistol grip deformity in at least 1 hip was 3.61% in controls and 17.71% in cases (OR 6.95 [95% CI 4.64–10.41]), and the prevalence of abnormal femoral head–to–femoral neck ratio in at least 1 hip was 3.70% in controls and 24.27% in cases (OR 12.08 [95% CI 8.05–18.15]). The risk of hip OA increased as the femoral head–to–femoral neck ratio decreased (P for trend < 0.001) and with each extreme of neck shaft angle (P < 0.05). In cases with unilateral hip OA, the prevalence of abnormal femoral head–to–femoral neck ratio in the unaffected hip was 2 times greater than that in controls (OR 1.82 [95% CI 1.07–3.07]); in contrast, an abnormally low, but not abnormally high, neck shaft angle was more common in unaffected hips than in controls (OR 1.79 [95% CI 1.03–3.14]).
Our findings indicate that pistol grip deformity is associated with hip OA. The increased prevalence of pistol grip deformity and an abnormally low neck shaft angle in unaffected hips of cases with unilateral OA suggests that they are risk factors for development of hip OA. However, both a nonspherical head shape and an increase in neck shaft angle may occur as a consequence of OA.