29024801

PMC5732866

Objective

To provide the first prevalence estimates of different radiographic hip morphologies relevant to dysplasia and femoroacetabular impingement in a well-characterized U.S. population-based cohort.

Methods

Cross-sectional data were from the baseline examination (1991–1997) of a large population-based prospective longitudinal cohort study (The Johnston County Osteoarthritis Project). HipMorf software (Oxford, UK) was used to assess hip morphology on AP pelvis radiographs. Weighted, sex-stratified prevalence estimates and 95% confidence intervals for 4 key hip morphologies (AP alpha angle, triangular index sign, lateral center edge angle (LCEA), and protrusio acetabula) were derived and further stratified by age, race and BMI.

Results

A total of 5192 hips from 2596 individuals were included (31% African American, 43% male, mean age 63 years, mean BMI 29 kg/m2). Cam morphology was seen in more than 25% of men and 10% of women. Mild dysplasia was present in about 1/3 of men and women, while pincer morphology was identified in 7% of men and 10% of women. Femoral side (cam) morphologies were more common and more frequently bilateral among men, while pincer morphologies were more common in women; mixed morphologies were infrequent. African-Americans were more likely to have protrusio acetabula than whites.

Conclusion

We report the first population-based prevalence estimates of radiographic hip morphologies relevant to FAI and dysplasia in the U.S. These morphologies are very common, with ¼ men and 1/10 women having cam morphology, 1/3 of all adults having mild dysplasia, and 1/15 men and 1/10 women having pincer morphology in at least one hip.

CDC Public Access

HHSN268201000019C/HL/NHLBI NIH HHS/United States
K23 AR061406/AR/NIAMS NIH HHS/United States
P60 AR030701/AR/NIAMS NIH HHS/United States
U01 DP006266/DP/NCCDPHP CDC HHS/United States