Edwards K, Leyland KM, Sanchez-Santos MT, et al. - Using anteroposterior (AP) 912 hip x-rays (456 people) from four racial groups (European Caucasians, American Caucasians, African Americans and Chinese), researchers identified differences in measures of hip morphology between four racial groups and ascertained if these differences vary by gender. Participants in the study were males and females, aged 45 to 75 years, with no radiographic hip OA (Kellgren and Lawrence < Grade 2 or Croft < Grade 1). Eight hundred seventy-five hips were included in the final analysis. The authors discovered significant differences in measures of morphology between Chinese hips vs African Americans or Caucasian groups. These could explain the difference in hip OA prevalence rates between these groups and the lower Chinese hip OA rate. Gender differences have also been reported, which can also explain differences in male-female OA prevalence.