The management and outcome of treatment in 42 patients (49 shoulders) with an infected shoulder prosthesis was reviewed in a retrospective multicentre study of 2343 prostheses. The factors which were analysed included the primary diagnosis, the delay between the diagnosis of infection and treatment and the type of treatment. Treatment was considered to be successful in 30 patients (71%). Previous surgery and radiotherapy were identified as risk factors for the development of infection. All patients with an infected prosthesis had pain and limitation of movement and 88% showed radiological loosening. In 50% of the shoulders, the antibiotics chosen and the length of treatment were considered not to be optimal. The mean follow-up was 34 months. Antibiotics or debridement alone were ineffective. In acute infection, immediate revision with excision of all infected tissue and exchange of the prosthesis with appropriate antibiotic therapy gave the best results. Multidisciplinary collaboration is recommended.
We have studied the three-dimensional geometry of the proximal humerus on human cadaver specimens using a digitised measuring device linked to a computer. Our findings demonstrated the variable shape of the proximal humerus as well as its variable dimensions. The articular surface, which is part of a sphere varies individually in its orientation as regards inclination and retroversion, and it has variable medial and posterior offsets. These variations cannot be accommodated by the designs of most contemporary humeral components. Although good clinical results can be achieved with current modular and non-modular components their relatively fixed geometry prevents truly anatomical restoration in many cases. To try to restore the original three-dimensional geometry of the proximal humerus, we have developed a new type of humeral component which is modular and adaptable to the individual anatomy. Such adaptability allows correct positioning of the prosthetic head in relation to an individual anatomical neck, after removal of the marginal osteophytes. The design of this third-generation prosthesis respects the four geometrical variations which have been demonstrated in the present study. These are inclination, retroversion, medial offset and posterior offset.