The metacarpal index revisited: a brief overview.

Metacarpal index (MCI) is combined cortical thickness (both sides)) normalized with regard to outer bone diameter of the measuring site, the midshaft of the second metacarpal, or the three midmetacarpals of both hands. MCI is reduced with age, particularly in postmenopausal women. It correlates with axial bone mass in group studies. Measurement of the MCI in its modern version, digital X-ray radiogrammetry (DXR), requires only a plain analog radiograph, a PC, a film scanner, and reliable software. MCI can be used diagnostically and longitudinally for monitoring changes. MCI measured with DXR has few problems regarding accuracy and precision errors, and MCI is presently regaining lost territories among tests for quantification of bone mass and bone strength. It can be measured inexpensively and swiftly. MCI and other geometrical variables of bone can be measured on old radiographs, thus enabling estimation of cortical bone loss from the time of earlier recordings.