Management and outcome of interprosthetic femoral fractures

Introduction Interprosthetic femoral fractures following ipsilateral hip and knee arthroplasty are a rare but serious complication in clinical practice. In most cases, adequate management of these injuries might constitute a challenging problem. However, the literature provides only few data regarding the treatment and outcome of interprosthetic femoral fractures, and there are only few classifications available, which might assist in finding an appropriate treatment concept. The purpose of this study was to analyse our experience in the management of interprosthetic femoral fractures following ipsilateral hip and knee joint replacement. Materials and methods We reviewed the clinical and radiographic records of 23 patients (15 female and eight male, average age: 79.2 years) with an interprosthetic fracture after ipsilateral hip and knee joint replacement between 1992 and 2008. For the classification of interprosthetic femoral fractures, the fractures were divided into three types, depending on the fracture site and the adjacency to the prostheses. All patients underwent operative stabilisation, either by lateral plate fixation ( n = 19), by revision arthroplasty using a long stem ( n = 2) or by plate fixation and revision arthroplasty ( n = 2). Results Referring to the clinical outcome, 16 patients returned to their pre-injury activity level and were satisfied with their clinical outcome. In six patients, we saw a relevant decrease of hip or knee function and severe limitations in gait and activities of daily living. We had a mean Harris Hip Score (HHS) of 78.4 points, and a mean Knee injury and Osteoarthritis Outcome Score (KOOS) of 71.8 points. Relating to the radiographic outcome, successful fracture healing was achieved in 19 of 22 patients (86%) within 6 months. Failures of reduction and fixation were noted in four (18%) of 22 patients. Conclusion We had a satisfactory outcome following individualised treatment of interprosthetic femoral fractures following ipsilateral hip and knee joint replacement. Compared to the rare data in current literature, we had promising functional result and high rate of bony fusion. Regarding the complexity and challenges in many of these cases, interprosthetic fractures require an adequate analysis of the fracture aetiology and a suitable transfer into the best possible treatment concept.