Letter re: Comparison of acetabular and femoral morphologies on hip, pelvic, and lumbar radiographs (Yun et al.)

Abstract

We read with interest the recent article by Yun et al. [1] comparing acetabular and hip measurements across pelvis, hip and lumbar spine radiographs. The authors assert that lumbar radiographs can be utilised in place of routine pelvis radiographs for these measurements. The example lumbar spine radiograph (figure 2) appears to be an abdominal image, with a contrast urogram. Indeed, standard texts [2,3] confirm that the anteroposterior lumbar spine radiograph should not include any coverage of the hips as appropriate collimation should limit the anatomy to T12 superiorly, lower sacrum inferiorly and the sacroiliac joints laterally, which would exclude the hip joints. Thus assessing any hip measurements on an appropriately collimated lumbar spine radiograph should not be possible. This is further compounded by the description of the centring point within their study (iliac crest), which varies from the internationally recognised standard of lower costal margin/L3 [2,3].