Analysis of Leg Bones from Whole Body DXA in the UK Biobank

We have developed a software system to locate the outlines of the femur and tibia in whole-body Dual-energy X-ray absorptiometry (DXA) images. This enabled us to make geometric measurements of subjects’ bones in the UK Biobank Imaging Study. Of the 72,362 bone images made available, we measured both femurs and tibia on 59,214 (82%). We did not include images where (i) one leg was not wholly imaged, (ii) hip or knee replacements were present, or (iii) search failures due to other severe abnormalities. We show distributions of the lengths of the bones and angles at the hip and knee for both males and females. The lengths of the bones for males and females each exhibited a normal distribution, and the lengths of the left and right bones were very similar for most individuals. We also show results of linear regression between a) the length of the tibia and the femur, b) the subject’s height and the femur length, c) height and tibia length, d) height and a linear combination of femur and tibia length. The latter three help predict bone height, something of interest to archaeologists and forensic scientists. This is by far the most extensive study of these relationships.