HUMERAL FRACTURES AFTER SHOULDER ARTHROPLASTY

Nine humeral fractures occurred subsequent to 499 shoulder arthroplast ies that had been performed between December 1978 and November 1987 at the Mayo Clinic. The time from the arthroplasty to the fracture avera ged thirty-nine months (range, eight to 101 months). Seven patients we re women and two were men, and the average age was seventy years (rang e, forty-five to eighty-five years). The arthroplasties were performed for rheumatoid arthritis in five patients and for the sequelae of tra uma in four. Six patients had advanced osteopenia, and two had had an ipsilateral total elbow arthroplasty Six of the fractures were centere d at the tip of the prosthesis; one fracture (type A) extended proxima lly, and five (type B) did not. The three remaining fractures (type C) involved the humeral shaft distal to the implant and extended into th e distal humeral metaphysis. Four fractures healed with non-operative treatment. Two fractures that had unacceptable alignment were treated successfully with operative intervention. Three fractures that were tr eated with immobilization in a splint failed to heal; two of those fra ctures eventually united after a revision of the prosthesis and bone-g rafting was performed, and one fracture remained ununited. Radial nerv e palsy developed postoperatively in two patients, and it resolved wit hin three months. Five patients had poor active motion before the frac ture, and two of them had even less motion after the fracture was trea ted. Our experience suggests that long oblique and spiral fractures ca n be successfully treated non-operatively, provided that the skeletal alignment is acceptable. Operative treatment should be considered for transverse or short oblique fractures that are at the level of the dis tal end of the stem or that are associated with a loose prosthesis. Au togenous bone-grafting should be used in conjunction with operative in tervention.