Morphometry of the proximal humeral.

The values of the flare index and the radii of curvature of the medullary canal of the humerus of 70 dried humeri have been calculated from standard radiographs. The spacial geometry of the proximal medullary canal of the same humeri has been studied by means of mathematical models applied to data obtained from CT axial scans and by £D reconstructions. The results obtained show that no precise information on the spacial geometry of the medullary canal can be derived from radiographic studies. We have also found that the proximal half of the canal is rectangular, and humeral head lies in recurvatum. In the frontal planethe upper half of the medullary canal curves medially. These changes are less marked than in femur. Hence, while it seem impossibleto improve beyond a certain point the "fill" of the humeral canal achieved by custom-made prostheses. This knowledge of normal morphometry of the humeral canal may lead to further improvements in the "fit" between the implant and the canal.