Differences between race and sex in measures of hip morphology: a population-based comparative study

Abstract

s u m m a r yObjective: This paper aims to (i) identify differences in measures of hip morphology between four racial groups using anteroposterior (AP) hip x-rays, and (ii) examine whether these differences vary by sex. Methods: 912 hip x-rays (456 individuals) from four racial groups (European Caucasians, American Caucasians, African Americans and Chinese) were obtained. Males and females (45e75 years) with no radiographic hip OA (Kellgren and Lawrence < Grade 2 or Croft < Grade 1) were included. Eleven features of hip joint morphology were analysed. Linear regression with generalised estimating equations (GEE) was used to determine race and sex differences in hip morphology. Post-hoc Bonferroni procedure was used to adjust for multiple comparisons. Results: The final analysis included 875 hips. Chinese hips showed significant differences for the majority of measures to other racial groups. Chinese were characterised by more shallow and narrow acetabular sockets, reduced femoral head coverage, smaller femoral head diameter, and a lesser angle of alignment between the femoral neck and shaft. Variation was found between other racial groups, but with few statistically significant differences. The average of lateral centre edge angle, minimum neck width and neck length differed between race and sex (p-value for interaction < 0.05). Conclusions: Significant differences were found in measures of morphology between Chinese hips compared to African Americans or Caucasian groups; these may explain variation in hip OA prevalence rates between these groups and the lower rate of hip OA in Chinese. Sex differences were also identified, which may further explain male-female prevalence differences for OA.

Morphological consistency of bilateral hip joints in adults based on the X-ray and CT data

“…However, the effect of demography on the morphology of femoral medullary cavity is still controversial [ 19 ]. Edwards et al [ 3 ] showed that the average of lateral center edge angle, minimum neck width and neck length differed between sex. The difference in conclusion may be due to the different sample population.…”

To Explain or to Predict: Important Aspect to Consider Also in Orthopaedics: Letter to the Editor

“…Previous literature has described well that these measures are related to BMI and gender. 3,5 Again, while using alpha angle as an exposure, gender is a confounding variable. But when exposure is gender, alpha angle is a mediator, and this may result in bias when the interest is a single regression coefficient.…”

“…This arises from treating secondary independent variables and the primary independent variable as having a total effect strictly on the outcome under question without accounting for intervariable interactions, such as those via direct effects. 2,3 The authors direct attention toward our multivariate linear regression assessing 5-year patientreported outcomes (PROs) to emphasize the potential for group status (high improvement [HI] vs low improvement [LI]) as possibly being a mediator or confounding variable rather than a primary exposure of the tested outcomes. They refer to trending differences in our Table 1 between the HI and LI groups in regard to demographics, suggesting that these differences in our subcohorts may dilute the conclusions drawn in our study.…”

The Genetic Epidemiology of Joint Shape and the Development of Osteoarthritis

“…They found low lateral centre-edge angles FHFNR femoral head to femoral neck ratio and FNLWR femoral neck length to width ratio; e MPFA modified proximal femoral angle and FNSA femoral neck-shaft angle suggesting dysplasia (< 20°) more often in the Chinese (22% of hips versus 7% in whites, p = 0.005), whilst low mean impingement angles (83.6° versus 87.0°, p = 0.03) and lateral centre-edge angles suggestive of impingement (23% versus 11%, p = 0.008) were more common in women of European descent. More recently, Edwards et al examined hip plain radiographic morphological characteristics in individuals of European descent, African Americans and Chinese men and women with no radiographic hip OA [104]. They found that the Chinese group had more shallow and narrow acetabular sockets, reduced femoral head coverage, smaller femoral head diameter, and a lesser femoral neck-shaft angle versus the other ethnic groups.…”