The anatomic features of the radial head and their implication for prosthesis design

Objective. To establish the anatomical features of the radial head of an average normal human being and to verify the hypothesis that no significant difference exists between the geometry of the left and right normal radial heads. Design. 17 proximal ends of the radius from the left and right forearms of fresh male (average age 50 and range 40–70) cadavers were measured. Background. A reconstruction of anatomical features of the normal bone is important for prosthesis design. Methods. A morphologic study of the radial head was performed using a co-ordinate measuring machine integrated with a computer aided design system. For comparative purposes, a statistical analysis including linear regression and correlation was performed. Results. The maximum diameter (mean 23.36 mm (SD, 1.14 mm)) and height (mean 10.14 mm (SD, 1.38 mm)) of the radial head as well as the depth (mean 1.92 mm (SD, 0.32 mm)) and maximum radius (mean 20.27 mm (SD, 4.61 mm)) of the concave articulate surface are the most important anatomical features, which should be implicated in prosthesis design. The inclinations mean 2.50° (SD, 0.41°) and mean 9.50° (SD, 0.52°) and shift (mean 1.71 mm (SD, 0.35 mm)) of the radial head relative to its neck should also be taken into account in prosthetic design. Conclusions. The results of the study showed that “left is equal to right” (no significant differences between sides were obtained, for probability value P>0.05).