[Endoprosthesis implantation in the elbow joint]

Previously used total elbow prostheses were mainly constrained hinged implants. Their early clinical results were favourable but they failed due to a high rate of loosening already a few years after implantation. The cause for the early loosening was the great forces across the elbow joint which were directly transmitted to the prosthesis-bone interface in these implants. Therefore, these implants were abandoned. Afterwards, unlinked, semiconstrained or non-constrained resurfacing devices were introduced. In these devices, the soft tissues constrain the joint and therefore absorb part of the transmitted forces. The rates of loosening were significantly improved and rarely the cause of early failure. But resurfacing implants require intact condyles and collateral ligaments. These implants can, therefore, only be used in a limited number of indications, and postoperative instabilities are known complications. The currently most frequently used device is the semiconstrained Coonrad-Morrey prosthesis. It is a floppy hinge which allows valgus-varus and rotational laxities. Therefore, a part of the forces across the elbow joint are absorbed by the soft tissues. The loosening rate is not a clinical problem any more, and is with 4% 10 years after implantation (rheumatoid arthritis) similar to that of total hip or knee replacement. Furthermore, this device is stabilised with a small anterior flange to the anterior cortex of the humeral shaft. Condyles and collateral ligaments are therefore not necessary neither for short nor for long-term stability. The Coonrad-Morrey total elbow prosthesis can therefore be used for almost every indication, such as severe destruction of the elbow joint and even in case of complete loss of the distal humerus. The long-term outcome with this prosthesis for the treatment of rheumatoid arthritis is favourable with 96% of very good and good results. Function is restored with an average flexion of 131 degrees, a mean loss of extension of 28 degrees, and an unrestricted pronation and supination. The rate of complications for patients with rheumatoid arthritis is 10%. Similarly, the results for Coonrad-Morrey total elbow replacement for posttraumatic arthrosis are favourable with 83% of satisfactory results. Most patients consider their elbow as improved compared to preoperatively, but pain relief is obtained only in three quarters of the patients. The rate of complications is high with 30%, indicating the total elbow replacement is contraindicated for strenuous labour and sports activities.