[Implantation technique for the CUT-type femoral neck endoprosthesis].

OBJECTIVE: Total hip replacement with maximum preservation of femoral neck. Restoration of pain-free joint function.

INDICATIONS: Coxarthrosis, femoral head necrosis in younger patients with intact femoral neck.

CONTRAINDICATIONS: Joint infection. Coxa valga (caput-collum-diaphysis [CCD] angle > 150 degrees ). Coxa vara (CCD angle < 110 degrees ). Body mass index > 30 (relative contraindication). Ongoing chemotherapy. Osteoporosis.

SURGICAL TECHNIQUE: Transgluteal or anterolateral approach. Resection of two thirds of the femoral head. Implantation of uncemented acetabular component. Revitalization of the femoral neck with special rasps for the CUT prosthesis. Trial reduction with bone rasp and modular cone in place (10 degrees or 20 degrees angle). Uncemented stem implantation.

RESULTS: From 2002 to 2006, 49 uncemented CUT prostheses were implanted in 36 patients. Average age was 45.1 years (20-60 years). Inpatient stay amounted to 10.8 days and operating time to 74 min. Average blood loss through drainage was 795 ml, an average of 297 ml transfused back. Transfusion was necessary in ten patients. There were no cases of postoperative infection, nerve lesion, or hip dislocation. Patients were examined preoperatively and followed up at 6 weeks and 1 year. Harris Hip Score improved from 46.1 points preoperatively to 81.6 points at 6 weeks and 95.7 points at 1 year. Average leg length discrepancy of 0.7 cm (minimum -0.8, maximum 2.2 cm) was determined radiologically in 31 of 49 patients. It became necessary to replace two of the 49 stems due to aseptic loosening, in the first case at 19 months (femoral head osteonecrosis, lupus erythematosus, and taking cortisone), and in the second case 3 years after implantation (steroid-induced femoral head necrosis related to Crohn's disease and azathioprine [Imurek] therapy). One cone and head component had to be revised 1 month after implantation due to impingement syndrome. One ceramic head fractured 2.5 years after implantation so that cone and head required revision. The overall follow-up time was 37 months on average (minimum 12, maximum 55 months).