Cementless Total Hip Arthroplasty Using the COREN Hip System: A Minimum Five-Year Follow-up Study

Abstract

Purpose: This study presents the clinical and radiological outcomes of cementless total hip arthroplasty using the COREN hip system after a minimum duration of follow-up of 5 years.

Materials and methods: We evaluated the results of a consecutive series of the first 200 primary total hip arthroplasties that had been performed in our hospital in 169 patients between February 2007 and April 2011. Six patients (6 hips) had died within 5 years, and 12 patients (13 hips) had been lost to follow-up, leaving a total of 151 patients (181 hips) available for the study. All patients were evaluated clinically and radiologically with special attention to thigh pain, implant fixation, radiolucent line and osteolysis around implants.

Results: The mean Harris hip score improved from 59.4 preoperatively to 97.2 postoperatively. No patient complained of thigh pain. All implants demonstrated radiographic evidence of stable fixation by bone ingrowth without any change in position. No implant was loose radiographically or was revised. Eleven hips (7.7%) had a radiolucent line around the femoral stem. Focal osteolytic area was detected in 3 cases (2.1%). An osteolytic lesion was stabilized in 1 case and further observation was needed in 2 cases in which the lesions were detected several years after surgery. Stress shielding was observed in 80.3% of cases (first degree, 35.9%; second degree, 44.4%); there were no cases of third or fourth degree stress shielding. One case was complicated by bacterial infection and repeated dislocation.

Conclusion: Mid-term results of total hip arthroplasty using the COREN hip system are very encouraging clinically and radiologically.

Keywords: COREN hip system; Cementless total hip arthroplasty; Hip.

Fig. 1. A 21-year-old male patient underwent total hip arthroplasty for osteonecrosis of the femoral head. (A) Early postoperative radiograph shows well-implanted joint components. (B) Anteroposterior radiograph taken 1 year after index arthroplasty revealed an osteolytic lesion in zone 1, a radiolucent line in zone 7 and rounding of the most proximal medial edge of the cut femoral neck. (C) Anteroposterior radiograph taken 7.5 years after arthroplasty demonstrates no remarkable changes in the osteolytic lesion or radiolucent line, and the loss of the medial cortical density of the proximal femur.

Fig. 2. A 49-year-old male patient suffered from osteonecrosis of the femoral head. (A) Anteroposterior radiograph taken 4 years after surgery shows stably fixed implants. (B) Anteroposterior radiograph taken at 5 years after surgery demonstrates osteolytic lesions in zones 1 and 7. (C) Anteroposterior radiograph taken 7 years after surgery shows no marked change in the size of the osteolytic lesions, but their margins became sclerotic.

Fig. 3. A 46-year-old male patient had total hip arthroplasty because of degenerative arthritis secondary to acetabular dysplasia. (A) Anteroposterior radiograph taken at 1 year after arthroplasty shows stably fixed implants and mild rounding of the medial edge of the cut femoral neck. (B) Anteroposterior radiograph taken 6 years after arthroplasty demonstrates no marked changes. (C) Anteroposterior radiograph taken 9 years after arthroplasty shows osteolytic lesions in zones 1 and 7.

Fig. 4. Photograph of the alumina-on-alumina COREN hip system (Corentec, Seoul, Korea).