We have treated 30 cases of unstable intertrochanteric fractures of the femur with hip compression screw and side plate from Jan. 1990 to Dec. 1992. We compared the collapse amount of facture site between anatomic reduction and medial displacement(medialization), and analysed the site of lag screw in femoral head and rediographic result.

1. The degree of fracture site collapse was measured as 3.83mm(mean) in anatomic reduction cases and 5.13mm(mean) in medial displacement cases.

2. The lag screws position in femoral head was as followed 6 cases(20%) in cranial position, 16 cases(53%) in central position, 8 cases(27%) in caudal position on anteroposterior view ; 3 cases(10%) in anterior position, 15 cases(50%) in central position, 12 cases(40%) in posterior position on lateral view.

3. The union rate was 100 percent. But the penetration of lag screw into the joint occured in three cases, in which the lag screw was located in cranial position on anteroposterior view.

There was no difference in union rate and degree of fracture site collapse between anatomic reduction and medial displacement cases. But the best result was obtaned by central positioning of lag screw and firm internal fixation.