Characterization of individual radiographic features of hip osteoarthritis in African American and White women and men: the Johnston County Osteoarthritis Project.

OBJECTIVE: To describe differences in radiographic features of hip osteoarthritis (OA) between African American and white men and women.
METHODS: We conducted a cross-sectional analysis of radiographic hip OA using baseline data from the Johnston County Osteoarthritis Project, using Kellgren/Lawrence (K/L) grade, and the presence, location, and severity of 4 individual radiographic features (joint space narrowing [JSN], subchondral cysts, sclerosis, and osteophytes). Sex-specific logistic regression was used to evaluate associations between race and individual radiographic features, adjusting for age, body mass index, education, and prior hip injury. Robust variance estimators via generalized estimating equations were used to account for correlation between hips from the same individual.
RESULTS: The sample (n = 2,739) comprised 57% women and 31% African American participants. Among women, African Americans and whites had a similar prevalence of hip OA, defined as K/L grade > or =2 (23% versus 22%), but African American women were significantly more likely to have superior or medial JSN, moderate or severe axial JSN, medial or lateral osteophytes, and subchondral cysts. Among men, 21% of African Americans and 17% of whites had hip OA; African American men were more likely to have superior or medial JSN and lateral osteophytes, but were less likely to have axial JSN.
CONCLUSION: Individual radiographic features and patterns of hip OA differed by race among women and men, suggesting the possibility of anatomic and/or developmental variation in the hip joint. African Americans have an increased frequency of features that have been predictive of hip replacement in other populations, a finding worthy of further study.