Metacarpal radiogrammetry by computed radiography in postmenopausal women with Colles' fracture and vertebral crush fracture syndrome.

Based on the hypothesis that the underlying osteoporotic mechanism of Colles' fracture in postmenopausal women is similar to that of other osteoporotic fractures, that is, cortical bone resorption as opposed to cancellous bone resorption, the rate of corticoendosteal bone loss was compared in 40 normal postmenopausal women [average age 68.4 +/- 7.1 years; 20 +/- 4 years since menopause (YSM)], in 35 postmenopausal women with Colles' fracture (age 69.4 +/- 7.5 years, 22 +/- 8 YSM), in 35 normal postmenopausal women with vertebral crush fracture (age 69.4 +/- 7.5 years, 22 +/- 8 YSM, and in 35 normal premenopausal women (age 36.1 +/- 7.9 years). Radiogrammetry by digital radiography of the second metacarpal was used to measure external (ED) and internal (ID) diameter, cortical thickness (CCT), cortical area (CA), and the ratio of cortical area to total area (CA/TA). The ID values of the groups of postmenopausal women were subtracted from the ID value of the premenopausal women and the result was divided by YSM to obtain the rate of corticoendosteal resorption/year (DeltaC), CA resorption year (DeltaCA) and CA/TA resorption/year (DeltaCA/TA). ID, DeltaC, DeltaCA, and DeltaCA/TA all were larger in the postmenopausal women with Colles' and vertebral crush fractures than in the normal postmenopausal women (ANOVA: all P < 0.0001). ID, CCT, DeltaC, CA, DeltaCA, and DeltaCA/TA did not differ between the two groups of postmenopausal women with fractures. DeltaC was 87% greater in postmenopausal women with vertebral crush fracture and 116% greater in women with Colles' fracture than in normal postmenopausal women. These results indicate that the loss of cortical bone is an important factor in Colles' fracture in postmenopausal women.