Schaftfreier Humeruskopfersatz

[Shoulder arthroplasty]

Arthroplasty of the shoulder joint leads to excellent clinical results if the indications are valid and the implantation is technically correct. Taking anatomical requirements and mechanical functions as well as material properties and developments in surgical techniques into account, articulations and anchoring systems have been developed which, as modular systems enable successful restoration of the biomechanics and consider the importance of the surrounding soft tissues. Scientific data show promising medium-term and long-term results in terms of functionality and pain reduction. Nevertheless, due to the limited bone stock for implant anchoring, especially loosening of the prosthesis or instability of the glenoid joint component, revision arthroplasty remains challenging. This review article summarizes the relevant aspects of shoulder arthroplasty.

[Options and limits of stemless shoulder prostheses]

Currently there are five manufacturers offering stemless implants for shoulder joint replacement. A total number of almost 10,000 stemless implants have been used in shoulder arthroplasty since 2004. There are two different types of metaphyseal anchorage, one obtained by impaction of a fin system and in the other implant system cage screw fixation is used. Regarding revision surgery the different types of implants show varying advantages and disadvantages in terms of secondary approach to the glenoid and the metaphyseal component. Because of the small number of cases and short period of observation at the present time none of the implant systems show a decisive superiority. In sclerotic bone the cage screw system seems to be advantageous whereas impaction using the fin system seems to be preferable in osteoporotic bone and conditions with defects of the bone. A prerequisite for all types of stemless shoulder implants is good quality bone. There should not be bony defects under the surface of the area of head resection. Stemless implants are not indicated for acute fractures.

[Short stem shoulder prosthesis : concept and first results]

The trend in shoulder arthroplasty is moving away from long stemmed, cemented humeral components to cementless, stemless and metaphyseal fixed implants and to humeral resurfacing. The cementless short stem prosthesis presents a concept that combines the advantages of a bone-saving implantation with a straightforward revision option. Furthermore, the stem may serve as a carrier for a convertible anatomic and reversed modular system. The concept consists of a stabile proximal fixation of the prosthesis by compaction of metaphyseal cancellous bone. After 1 year follow-up the short stem prosthesis proved to be an implant with few complications and clinical results comparable to those of established prosthetic systems.