Bone densitometry: A new, highly responsive region of interest in the distal forearm to monitor the effect of osteoporosis treatment

The bisphosphonates have been introduced as alternatives to hormone replace ment therapy (HRT) for the treatment and prevention of postmenopausal osteo porosis. The expected increasing application in at clinical practice demand s cost-effective and easily handled methods to monitor the effect on bone. The weak response at the distal forearm during antiresorptive treatment has restricted the use of bone densitometry at this region. We describe a new model for bone densitometry at the distal forearm, by which the response ob tained is comparable to the response in other regions where bone densitomet ry is much more expensive and technically complicated. By computerized iter ation of single X-ray absorptiometry forearm scans we defined a region with 65% trabecular bone. The region was analyzed in randomized, double-masked, placebo-controlled trials: a 2-year trial with alendronate (n = 69), a 1-y ear trial with ibandronate (n = 141) and a 2-year trial with HRT (n = 121). Bone mineral density (BMD) at the distal forearm revealed a highly statist ically significant dose-related response and increased 3-5% per year with 2 .5 mg ibandronate, 10 mg alendronate or HRT, whereas the decrease in the pl acebo groups was 1-3% (p < 0.001). The response at the distal forearm was s imilar to the response at the lumbar spine and hip. In conclusion, trabecul ar bone at the distal forearm is as responsive to antiresorptive treatment as trabecular bone in other skeletal regions. Bone densitometry at the new region of interest in the distal forearm has comparable performance charact eristics to more expensive and technically demanding methods. The method is more accessible clinically and potential as an alternative for monitoring bone changes during antiresorptive treatment.