Comparison of anatomical shoulder prostheses and the proximal humeri of Chinese people.

Reconstruction of normal anatomy is important to a successful proximal humeral arthroplasty, in which the surgeon needs to know multiple measured anatomical parameters during the surgery. Based on three-dimensional computed tomography scanning data, computer models of the proximal humeri of 180 Chinese people were built. They came from 77 males and 103 females; their ages ranged from 19 to 86 years. Anatomical parameters including the curvature diameter of the head, the head height, the inclination, and the retroversion were measured using the software in these three-dimensional proximal humerus models. The methodology was valid and the measured results showed marked variations in all those parameters. On average, the curvature diameter of the head was 44.6 mm, ranging from 36.4 to 55.5 mm. The head height was located at 16.7 +/- 1.9 mm (minimum, 12.4 mm; maximum, 22.0 mm). The inclination angle ranged from 122.35 degrees to 147.09 degrees (mean, 132.4 +/- 4.7 degrees). The proximal humeral retroversion was found to be extremely variable, ranging from -4.71 degrees to 52.46 degrees, and has a mean of 21.11 degrees. Then these measured results were compared with four commonly used anatomical prostheses. The wide range of variation in the normal values makes it difficult to restore anatomical characteristics individually. Thus, the use of an accurate three-dimensional model to guide surgery preoperatively can improve the outcome of some serious cases, such as gross degenerative change and large-bone-loss surgery.