Allograft-prosthesis composite reconstruction of the proximal part of the humerus: surgical technique.

BACKGROUND:
Limb salvage following resection of a tumor in the proximal part of the humerus poses many challenges. Reconstructive options are limited because of the loss of periarticular soft-tissue stabilizers of the glenohumeral joint in addition to the loss of bone and articular cartilage. The purpose of this study was to evaluate the functional outcome and survival of the reconstruction following use of a humeral allograft-prosthesis composite for limb salvage.

METHODS:
An allograft-prosthesis composite was used to reconstruct a proximal humeral defect following tumor resection in thirty-six consecutive patients at one institution over a sixteen-year period. The reconstruction was performed at the time of a primary tumor resection in thirty cases, after a failure of a reconstruction following a previous tumor resection in five patients, and following excision of a local recurrence in one patient. The mean duration of follow-up of the living patients was five years. Glenohumeral stability, function, implant survival, fracture rate, and union rate following the reconstructions were measured. Functional outcome and implant survival were analyzed on the basis of the amount of deltoid resection, whether the glenohumeral resection had been extra-articular or intra-articular, and the length of the humerus that had been resected.

RESULTS:
One patient sustained a glenohumeral dislocation. Deltoid resection (partial or complete) resulted in a reduced postoperative range of motion in flexion and abduction but had no effect on the mean Musculoskeletal Tumor Society score. Extra-articular resections were associated with lower Musculoskeletal Tumor Society scores. All patients had either mild or no pain and normal hand function at the time of final follow-up. The overall estimated rate of survival of the construct, with revision as the end point, was 88% at ten years. There were three failures due to progressive prosthetic loosening that necessitated removal of the construct. Four patients required an additional bone-grafting procedure to treat a delayed union of the osteosynthesis site.

CONCLUSIONS:
An allograft-prosthesis composite used for limb salvage following tumor resection in the proximal part of the humerus is a durable construct associated with an acceptable complication rate. Deltoid preservation and intra-articular resection are associated with a greater range of shoulder motion and a superior functional outcome, respectively.