Thrust plate prosthesis for osteonecrosis of the femoral head: short-term results of 15 patients followed 2-6 years.

BACKGROUND

The thrust plate prosthesis is an implant with a metaphyseal fixation at the proximal femur that transmits the load forces of the hip onto the femoral neck.

METHODS

In this prospective study, 15 patients (8 women, 7 men) with 19 cementless thrust plate prostheses because of femoral head necrosis were examined. A clinical and radiologic evaluation was performed preoperatively, at 3, 6, 12, 18, and 24 months postoperatively, and every year thereafter. The mean follow-up period was 44 (range, 24-72) months. The average age at the time of surgery was 49 (27-70) years. The pathogenesis of femoral head necrosis included alcoholism (6 joints of 3 cases), Gaucher disease (1 joint of 1 case), Sheehan syndrome (2 joints of 1 case), and idiopathic (10 joints of 10 cases).

RESULTS

The Harris hip score increased from 53 (range, 15-71) to 97 (92-100) points on the final evaluation. Although mean preoperative hip flexion and abduction were 78 degrees (45 degrees -110 degrees ) and 24 degrees (10 degrees -45 degrees ), respectively, these increased to 114 degrees (75 degrees -125 degrees ) and 47 degrees (45 degrees -50 degrees ) 12 months after surgery and remained stable up to the latest follow-up. None of the patients displayed mechanical problems, and revision was not necessary in any case.

CONCLUSIONS

The thrust plate prosthesis shows midterm results comparable to those of the cementless stemmed prosthesis and supplies advantages, especially for younger patients with femoral head necrosis, because of its metaphyseal bone-preserving fixation.