The elbow is one of the few remaining joints for which the orthopedic surgeon does not possess the expertise or the information necessary to adequately select the patients amenable to joint replacement, or more importantly, the optimum implant for a given circumstance. The overall goal of the proposed study is to address the remaining problems associated with elbow reconstruction and replacement. The investigation will include implants that appear to have some promising applications: capitellocondylar resurfacing device (Ewald), ERS Surface Replacement System (Pritchard), Norway Elbow (Risung), and Souter Strathclyde Arthroplasty (U.K.). The continuing problem with the resurfacing device is instability, and thus both static and dynamic elements of their function will be assessed. Kinematic and tendon excursion data from cadaveric elbow specimens with prosthetic replacements will be collected under various muscle loading and valgus varus and axial rotational stresses. Joint constraints and laxity with different levels of soft tissue reconstruction and variations in implant placement will also be evaluated. Moment arm changes throughout the arc of motion will be obtained for three major flexors and extensors about the prosthetic elbow joint. Three hypotheses will be tested. The first is that the stability of the resurfacing arthroplasty is highly dependent on the capsuloligamentous condition. The second is that implant component malalignment will increase laxity of the joint. The third is that the moment arm balance of flexor and extensor muscles after implant replacement will be the same as those of the anatomic joint. It is anticipated that information obtained from this study will directly affect surgical guidelines for patient selection with reference to quality of bone and the presence or absence of static stabilizing elements. Furthermore, it will provide the surgeon with a basis for making a selection from the currently available implant designs. Finally, and of particular importance, the proposed studies should provide a standard for judging the degree of success of surgical techniques reported by various surgeons and centers throughout the world.