We reported on 7 cases of avascular necrosis of the femoral head after trea
tment of an unstable intertrochanteric fracture with the Asian Pacific gamm
a-nail. The incidence was about 1.16% (7 of 604) in our series. Good reduct
ion and good implant position were achieved in all 7 men. Avascular necrosi
s was found about 6 months to 3 years after the initial operation, and all
the fractures were solidly united at the final diagnosis. The possible etio
logies were initial high energy trauma and combining basal neck fracture an
d iatrogenic damage of the blood supply to the femoral head.