Kinematics and constraint of total elbow arthroplasty.

Total elbow arthroplasty has been a valuable procedure for patients with rheumatoid arthritis, posttraumatic arthritis, osteoarthritis, and failed reconstructive procedures of the elbow. Many of the original designs were simple hinge joints, in which intrinsic complete constraint of the articulation predictably resulted in failure by loosening. Subsequently, the development of elbow prostheses diverged into 2 general types: loose hinge (linked) and resurfacing (unlinked). The main concern with such development is instability, which is attributable to numerous factors including prosthesis design, ligament integrity, and position of the prosthesis. A series of studies have been performed to examine the intrinsic constraint of various total elbow arthroplasty designs, as well as the joint laxity after implantation in cadaveric specimens.