Stress fracture of the hip. An unusual complication of total knee arthroplasty.

Stress fracture of the hip is a rare complication of total knee arthroplasty (TKA). Only eight cases seem to have been reported in the literature. A ninth case is reported in the present study. A 76-year-old obese woman was treated by right TKA for osteoarthrosis with cementing of the tibial component because of insufficient primary fixation. One year after TKA, she complained of tenderness above the right adductor tendons. There was no history of trauma. One month later, bone scintigrams and roentgenograms demonstrated a stress fracture of the femoral neck. Conservative management was successful. Etiologic factors such as rheumatoid arthritis, osteoporosis, steroid medication, or changes in static or dynamic forces of the hip secondary to knee arthroplasty could not be demonstrated in this patient. The increase in activity after TKA may be a factor in the incidence of these stress fractures of the hip. Radionuclear-type bone scan is helpful in diagnosis. The foci of increased isotope uptake are not always seen at the site of the stress fracture and only later visualized by roentgenograms.