[Femoral fractures in subjects with total prostheses of the hip or knee].

Thirty three fractures of the shaft of the femur, which occurred after 28 total hip replacements and 8 total knee replacements, are reviewed. Fracture occurred adjacent to the femoral component of the hip prosthesis in 5 cases, distal to the femoral component in 8, at the tip of the femoral component in 12 hips and 5 knees and between the femoral components of hip and knee replacements in 3 cases. Treatment was by fixation with a plate in 29 cases, revision of a total hip replacement in 2 and traction in the other 2. The mean follow up was 2.5 years. Fractures healed in 3-4 months and function was usually restored. Aseptic loosening of a total arthroplasty after plating of a fracture did not occur. Two prostheses became infected, requiring removal of a hip and revision of a knee. Aetiological factors are stress-raisers in the femoral shaft after revision arthroplasty, defects in the cortex, and modification of shaft elasticity between the stems of hip and knee prostheses. Detection of a cortical defect during revision arthroplasty and bone grafting may help to prevent fracture. Fixation with a plate seems to be the best treatment, but if there is evidence of loosening revision with a long-stemmed component is indicated.