[The femoral neck prosthesis CUT. Three- to six-year results]

As the number of younger patients undergoing total hip arthroplasty is growing steadily, bone-saving implantation techniques are increasingly gaining in importance.

Fifty-six femoral neck prostheses (type CUT, ESKA Implants, Lübeck, Germany) were implanted in 50 patients between 1999 and 2002 (average age 49 years). After a mean follow-up of 4.9 years (min.: 3.2, max.: 6.5), we determined the state of all the prostheses. Forty-four patients with 50 prostheses were examined clinically with the Harris hip score and were assessed radiologically.

The average Harris hip score improved from 48 points preoperatively to 93 points at the most recent follow-up examination. Of the 56 CUT prostheses, 6 (10.7%) had been revised. Four of these six cases (7.1%) required revision because of aseptic loosening. The radiological evaluation of these four cases revealed in three cases progressive horizontal migration with varization of the prosthesis, although the stem had been correctly positioned in primary surgery, with the femoral neck resected too widely or completely. After 4.9 years, the survival rate of the CUT prostheses is 88.4% according to Kaplan-Meier for a necessary exchange of the CUT prostheses as an endpoint.

The use of the CUT prosthesis can lead to good clinical and radiological results, but shows a higher loosening rate as compared with cementless standard stems. Further studies are necessary to determine if the CUT prosthesis is a real alternative to cementless standard stems.