Fixation strength of the ulnar component of total elbow replacement

After clinical failure of ulnar component fixation by olecranon fracture occurred, this study examined different component designs to find the strongest type. Components requiring square cuts or rounded cuts to prepare the proximal ulna with short or long stems of polyethylene or metal were implanted in paired cadaver bones and tested to failure. Loads were applied through the articular surface in an anterior-posterior direction, causing bending fracture of the olecranon. The main findings were a higher strength if the bone was prepared to take a rounded rather than a square-shaped prosthesis body, a slightly higher strength with a metal component compared with a similarly shaped polyethylene component, and slightly less strength if a longer stem was used. We recommend the use of a polyethylene component with a rounded shape and short stem, because it will be thinner, entailing less bone excavation. Additionally, it is less costly than a metal-backed design.