Comparison of three knee positioning protocols for measuring knee morphology using dual energy X-ray absorptiometry.

Abstract

indicating the coverage of the acetabulum became larger in elderly population. Discussion: This study revealed that the frequency of FAI related radiographic features in non-asymptomatic Japanese population. We found that the coverage of acetabulum is larger in male population than female population. In addition, it is larger in elderly population compared to younger population, indicating that degenerative change such as osteophyte formation might affect to this result. Since this study is CT-based assessment of hip morphology, the result is much more reliable than X-ray-based studies that can be affected by the photographing position and the variety of pelvic tilt. We defined the cutoff line based on the previous reports from western countries. Based on these cutoff values, 37% of the participants showed at least 1 abnormal value and 10.1% of them showed more than 2 abnormal values. On the other hand, Chakraverty et al. has reported that 66% of the asymptomatic Caucasian population showed at least 1 abnormal value and 22% of the same population showed more than 2 abnormal values. These rates are much higher than our results from Japanese asymptomatic population. Although the evaluation is based on radiographs, Laborie et al. investigated 2081 healthy subject and reported that the majority of the subjects showed characteristic feature of the FAI. Because the age distribution or evaluation item was deferent, it can not make an easy comparison with our results, our result suggested FAI might not contribute to primary hip OA in Japanese population.