Bone densitometry in the management of Colles' fractures: which site to measure?

This study assessed whether patients with Colles' fractures can be evaluated by measurement of peripheral bone mineral density (BMD) instead of the more established axial BMD technique. 205 consecutive patients who had sustained a recent Colles' fracture were invited to attend for BMD measurement at the lumbar spine, hip and forearm by dual energy X-ray absorptiometry (DXA) using a Hologic QDR4500C instrument. Hologic normal reference ranges were used for spine and ultradistal radius BMD, and the NHANES 111 reference range was used for the femoral neck. 158 patients attended, of whom only 61 had a T-score below -2.5 at one of the three measured sites (84 T<-2.0, 112 T<-1.5). 36 patients had bilateral forearm fractures and did not undergo a forearm measurement. After excluding these patients and using a T-score of -2.5 as a diagnostic threshold, a spine and hip measurement strategy missed 26% of osteoporotic patients and a forearm only strategy missed 33%. If a forearm strategy is adopted, with axial BMD performed only on those patients with an ultradistal radial T-score of <-1.5 and >-2.5, 27 further scans would be required and only four patients with T<-2.5 at the spine or hip would be undetected. Where axial BMD measurement is performed, this should be accompanied by forearm BMD measurement in some patients with Colles' fractures. A peripheral bone mineral densitometry strategy using forearm BMD alone will miss many individuals with osteoporosis. Therefore where forearm, and probably any peripheral scanning method, only is used for patient assessment there should be close liaison with an axial BMD centre with agreed joint protocols, as some patients should be advised to have an additional axial BMD measurement following their peripheral BMD measurement.