Radiographic Absorptiometry of the Phalanges as a Screening Instrument to Detect Osteoporosis of the Hip

Abstract

Objective: To determine the validity of radiographic absorptiometry (RA) of the phalanges in detecting osteoporosis of the femoral neck, measured by dual energy X-ray absorptiometry (DXA).

Material and Methods: In a group practice, 494 Causasian women aged 55 to 84 years were recruited. Hand radiographs and DXA measurements of the hip were performed in 449 women. 409 (91.1%) hand radiographs had sufficient quality for analysis by RA. Change of bone mass by age was obtained by using linear regression. Correlations between RA and DXA were calculated. Sensitivity and specificity of RA were calculated for several RA cut-off levels.

Results: The mean bone mineral density at the femoral neck was 0.866 g/cm and 92.57 arbitrary units at the phalanges. A moderate correlation of 0.53 (p<0.01) was found between RA and DXA. Depending on the cut-off level used, the sensitivity and specificity of RA in detecting osteoporosis at the femoral neck was 0.84–0.55 and 0.61–0.88, respectively.

Conclusion: RA may be used as a screening technique to detect osteoporosis, but confirmation is necessary in the subgroup with a positive outcome on RA.