[Periprosthetic humeral fractures: from osteosynthesis to prosthetic replacement].

OBJECTIVE: Stabilization of the humeral shaft and the restoration of shoulder function dependent on the osseous integrity of the prosthetic stem component.

INDICATIONS: In cases of a stable prosthesis stem, an isolated plate osteosynthesis is possible. Prosthesis stem replacement is indicated in cases of a loose stem. With sufficient bone stock of the proximal humeral segment, a change to a shorter humeral shaft component with subsequent plate fixation of the fracture is possible. If the bone stock is poor, conversion to a long revision stem is necessary.

CONTRAINDICATIONS: Inoperability of the patient due to serious comorbidities. Advanced age and low demands on shoulder function are relative contraindications for complex prosthesis replacements.

SURGICAL TECHNIQUE: Plate osteosynthesis can be done through an anterior or posterior approach, stem replacement only from anterior deltopectoral approach. When changing humeral shaft components, the loose shaft and all cement residues are removed, the fracture is reduced and, if possible, a shorter shaft is implanted with subsequent plate osteosynthesis of the fracture. When changing to a long revision stem, additional osteosynthesis with cerclages wires is usually sufficient. In case of poor bone stock, an additive autologous or allogenic bone grafting can be performed. An instable anatomical prosthesis with poor shoulder function may require conversion to an inverse prosthesis.

POSTOPERATIVE MANAGEMENT: In cases of an isolated plate osteosynthesis with an otherwise stable prosthesis, immediate active rehabilitation of the upper limb is advocated. When a prosthesis replacement and conversion to an inverse prosthesis is performed the shoulder is immobilized in 30° abduction for 6 weeks. Passive and after 3 weeks active-assistive shoulder movement up to 90° abduction and flexion is allowed.

RESULTS: In 40 patients with a periprosthetic humeral fracture, an isolated plate osteosynthesis was performed in 30 cases and a prosthesis replacement in 10 cases. Complications included 3 infections and 3 temporary radial nerve palsies. Revisions due to pseudarthrosis were necessary in 2 cases.