The relationship between densitometry of the radius and vertebral fractures.

In 105 postmenopausal women with clinical suspicion of osteoporosis single photon absorptiometry (SPA) of the forearm and fracture percentage of the thoracic and lumbar spine were estimated. SPA was performed on the commonly used mid-radius site as well as on a modified distal radius site where radius and ulna are separated by five mm. Spine fracture percentage was inversely correlated with mid-radius SPA (r = -0.49) but more closely with distal radius SPA (r = -0.61). With bone mineral density values above 0.400 g/cm2 on the distal radius, no fractures were found. Between 0.325 and 0.400 g/cm2, 35% of the patients showed vertebral fractures but only up to a maximum of 30%. Below 0.325 g/cm2, 89% of the women had crushed vertebrae, often more than 30% of those measured. In conclusion, these results indicate that modified distal radius densitometry is superior to the commonly used mid-radius measurement and has some predictive value for the presence of vertebral fractures.