Avascular necrosis of the femoral head after intertrochanteric fractures

OBJECTIVE: To determine factors that may influence the appearance of avascular necrosis after intertrochanteric fractures. DESIGN: Retrospective. SETTING: University hospital. PATIENTS: Twelve patients between the ages of fifty-nine and eighty-eight who had developed avascular necrosis of the femoral head after treatment of an intertrochanteric femur fracture at our institution between 1976 and 1995. Fractures were classified according to Kyle and Gustilo. There were three Type I, two Type II, six Type III, and one Type IV fractures. MAIN OUTCOME MEASURES: Risk factors for osteonecrosis, fracture pattern, surgical influence, location of the nail within the femoral head, and valgus malalignment. RESULTS: All fractures healed. Five patients had risk factors for osteonecrosis. Intertrochanteric fractures with a proximal fracture line appeared in five patients. The nail tip was situated in every quadrant of the femoral head. Valgus malalignment occurred in three cases. CONCLUSIONS: Avascular necrosis of the femoral head is an uncommon complication after intertrochanteric fractures. The pathogenesis is unknown, but in patients developing pain who have had intertrochanteric fractures, osteonecrosis should be included in the differential diagnosis, especially in cases with risk factors for osteonecrosis or a proximal intertrochanteric fracture line that perhaps disrupts the vascular anastomotic ring at the base of the femoral neck.