A new method of measuring bone density in the lower tibia of normal and postinjury limbs. A quantitative and comparative study.

In osteoporosis, a pathologic state of diminution of bone mass, radiography is the most widely used diagnostic method, but it is only descriptive and mainly depicts changes in the compacta. Based on the Compton photon-scattering phenomenon, a noninvasive yet quantitative measuring method for analyzing bone density was developed. The values of repeated measurements taken at identical locations did not vary by more than 2%. Using this technique, bone density of the lower tibia was measured in 39 men and 36 women; 14 had been affected by an injury to a knee or calf and immobilized five to eight years prior to this investigation. The measured values demonstrated an impressive equality between the tibiae of each individual and between the two sexes up to 50 years of age. However, these values correlated poorly with the bone density of the distal radius. In women older than 50 years of age, bone density decreased. Bone density was also low in all postinjury limbs. When compared with radiographic and bone mineral content (BMC) measurements of the same limb at the same location, the bone density measurements were useful and reduced the range of uncertainty of diagnosing osteoporosis by radiography only. Little or no correlation was found between bone density values and BMC measurements. The Compton scattering technique may become a precise and sensitive method for the clinical diagnosis of postinjury osteoporosis and quantitation of the long-term effects of limb injuries.