Abstract
We report on a series of long-stemmed femoral components used in revision total hip replacements which fractured, and were subsequently revised.
Methods
All explanted stems were analysed in respect of the reasons for failure. The patient's serial radiographs and clinical records were also analysed.
Results
All stems demonstrated some fixation distally. They all showed little proximal osteo-integration. A biomechanical analysis confirmed the vulnerability of these long stemmed modular prostheses in respect of mechanical failure. The resultant unprotected lever-arms led to local stresses in the prosthesis constructs which were above the failure threshold resulting in prosthesis fractures. These fractures all occurred at points where the prostheses were structurally most vulnerable.
Conclusions
We make recommendations in respect of the use of these long-stemmed prostheses, including surgical technique modifications which may protect these implants. While these prostheses rely on distal fixation, their long-term survival probably depends on some proximal bone support and integration. We also make recommendations in respect of the design rationale which should be used when selecting these prostheses. The proximal metaphyseal design of these implants needs to accommodate large bony deficiencies, and also encourage osteo-integration.
NO DISCLOSURES
