Calcaneus as a site for assessment of bone mineral density: evaluation in cadavers and healthy volunteers.

OBJECTIVE: The value of calcaneal dual-energy X-ray absorptiometry for monitoring changes in bone mineral density has not yet been established. Accordingly, the focus of this study was to determine the usefulness of the calcaneus as the site for bone mineral density measurement with dual-energy X-ray absorptiometry. SUBJECTS AND METHODS: Dual-energy X-ray absorptiometry of the calcaneus was performed in 19 specimens derived from 11 cadavers and 337 healthy volunteers to assess accuracy, in vivo precision, and age-related changes in bone mineral density. We also compared calcaneal bone mineral density determined by dual-energy X-ray absorptiometry with lumbar spine bone mineral density determined by dual-energy X-ray absorptiometry (L1-L4) or quantitative CT (L3). RESULTS: Studies of specimens showed that dual-energy X-ray absorptiometry had an error rate of 6%. In addition, strong correlations were found between bone mineral content and ash weight (r = .97, p < .0001) and between bone mineral density and ash density (r = .87, p < .0001). In vivo studies showed moderate correlations between calcaneal bone mineral density determined by dual-energy X-ray absorptiometry and lumbar spine bone mineral density determined by dual-energy X-ray absorptiometry (men, r = .77, p < .0001; women, r = .76, p < .0001) and lumbar spine bone mineral density by quantitative CT (men, r = .68, p < .0001; women, r = .68, p < .0001). Calcaneal bone mineral density measured by dual-energy X-ray absorptiometry and lumbar spine bone mineral density measured by quantitative CT continued to decrease throughout the postmenopausal period. However, lumbar spine bone mineral density determined by dual-energy X-ray absorptiometry did not show further decreases in subjects more than 70 years old. CONCLUSION: Taken together, these results suggest that the calcaneus can be used as an additional site for determining bone mineral density to assess osteopenia in patients when deformities of the spine make quantitative CT or other methods of density measurement impossible.