Association of intra-operative metaphyseal fractures with prosthesis size during hemiarthroplasty of the hip.

PURPOSE To study the possible causes of intra-operative metaphyseal fractures in elderly patients undergoing hemiarthroplasty for displaced intracapsular femoral neck fracture. METHODS 36 men and 228 women aged 61 to 89 years with 273 displaced femoral neck fractures underwent hemiarthroplasty using a hydroxyapatite ceramic-coated Furlong bipolar prosthesis. Anteroposterior and lateral radiographs were taken immediately after surgery to evaluate the presence and type of any intra-operative fractures (classified according to the Vancouver system) and their effect on stem stability or osseointegration. Pain and clinical outcomes were evaluated using a visual analogue scale and the Harris Hip Score. RESULTS Regarding the 273 surgeries for displaced femoral neck fracture, 28 (10%) were associated with intra-operative metaphyseal fracture (21 Vancouver type AL and 7 type AG). There was a correlation between intra-operative metaphyseal fractures and stem size. A size-9 stem was used in 64 surgeries without any fracture. A size-10 stem was used in 129 surgeries in which 11 (9%) sustained fractures, and a size-12 stem was used in 80 surgeries in which 17 (21%) sustained fractures. Postoperatively, 25 cases developed hip-related problems (thigh pain=14 and periprosthetic fractures=8) after 3 to 18 months. No patient whose metaphyseal fracture was fixed had hip problems. CONCLUSION In elderly women with compromised bone quality, extra care is needed to achieve better fitting so as to avoid iatrogenic metaphyseal fractures. Under-sizing or cementing of the prosthesis is recommended when encountering difficulties.