Variation in neck-shaft angle: influence in prosthetic design.

Surgeons performing anatomical reconstruction of the shoulder during prosthetic replacement should consider the size of the humeral head and the placement of the head within the humerus. Prosthetic systems with a wide range of modular head sizes, eccentric tapers, and adjustable neck-shaft angles and versions help surgeons to better adapt a prosthesis to a patient's bone anatomy. Surgical technique remains critical for proper placement of the prosthesis and for correction of other soft-tissue and bony abnormalities associated with the pathology. In this article, we review some principles of prosthetic design and surgical technique to anatomically reconstruct the humeral head. We also review the clinical consequences of prosthetic humeral head malpositioning.