An anthropometric study of the radial head: implications in the design of a prosthesis.

The dimensions of the native radial head were measured in 28 cadaveric upper extremities and radiographs of the contralateral elbows of 40 patients who had received a radial head replacement. The mean difference between the maximum and minimum radial head diameters was 1.7 +/- 0.7 mm (range, 0.12-3.27 mm). This variability suggests that although the native radial head is not circular, it does not have a consistently elliptic shape. The native radial head also is variably offset from the axis of the neck (4.2 +/- 2.5 mm), suggesting that a radial head hemiarthroplasty that precisely replicates normal anatomy would be difficult to achieve. There was a poor correlation between the radial head diameter and the medullary canal of the radial neck, suggesting that a modular implant system should be considered.