Bone Density by Specific Anatomic Location Using Hounsfield Samples of the Lower Extremity: A Multi-center Retrospective Analysis.

Understanding bone mineral density and its effects on patient outcomes is a useful tool for lower extremity surgeons. Historically, dual-energy X-ray absorptiometry scans have been the gold standard for quantifying bone mineral density. In this study, we look at an indirect way to measure bone mineral density using Hounsfield units on computed tomography. The aim of this study is to establish normal physiological Hounsfield ranges in specific bones of the foot by analyzing Hounsfield unit measurements and determining associated factors. We hypothesize that there will be a difference in density based on age, sex, and anatomic location. Patient data from January 2010 to January 2020 were retrospectively analyzed from 2 institutions. Nine anatomic locations (calcaneus, talar body, talar head, navicular, cuboid, medial cuneiform, head of first and fifth metatarsal, and base of first proximal phalanx) were measured for bone mineral density averages. In total, 137 patients were evaluated (71 males, 66 females) with an average age of 54 years. Significant differences in density were found between the 9 anatomic locations. Age was confirmed to be a significant covariate with inverse relation to Hounsfield units, p < .001. There were no density differences between sexes at any of the locations, except the talar head, p < .001. This is the first study to our knowledge to establish normal physiological ranges of bone density on computed tomography for specific anatomic locations of the foot. This quantitative approach to bone density and the established effect of age, sex, and location is pivotal for diagnostic and preoperative planning.