SUBTROCHANTERIC STRESS-FRACTURE OF THE FEMUR FOLLOWING TOTAL KNEE ARTHROPLASTY

This study reports the first case of a subtrochanteric stress fracture of the femur after total knee arthroplasty. A 61-year-old obese woman was treated by right total knee arthroplasty for osteoarthrosis. Four months after the surgery and 1 month after full weight baring. she co mplained of tenderness ill the right groin and proximal thigh. There w as no history of trauma. Radiographs of the right hip and of the right proximal femur were interpreted as unremarkable, and nonsteroid anti- inflammatory drugs were administered. Three months later, she had a su dden onset of increased pain with instability and giving way of the ri ght leg. Radiographs revealed a subtrochanteric transverse fracture of the right femur, Histologic workup of the bone and tissue specimen ta ken at open reduction, as well as the laboratory data were consistent with the radiologic and clinical diagnosis of a stress fracture. It is most likely that a decrease in the tension band effect of the iliotib ial tract in combination with coxa vara and changes in static and dyna mic forces of the femur and an increased level oi activity after a per iod of relative inactivity secondary to the knee arthroplasty are resp onsible for this very uncommon fracture type.