The mid-term result of total hip replacement with a proximally hydroxyapatite-coated femoral component

Abstract

Objective To summarize the mid-term result of total hip replacement with a proximally hydroxyapatite-coated femoral component. Methods From February 2000 to February 2001, 65 cases (70 hips) underwent uncement total hip replacement with a proximally hydroxyapatite-coated femoral component. There were twenty males and forty-five females with average of 63 years. The diagnosis included femoral neck fractures in 30 cases, osteoarthritis in 15 cases, avascular necrosis of the femoral head in 9 cases, loos-ening of artificial femoral head in 8 cases, rheumatoid arthritis in 2 cases, and arthrodesis in 1 case. Clinical and radiographic evaluations were performed postoperatively, at one week, three, six, twelve months, and yearly thereafter. Results Four patients died before the latest follow-up. Among the 61 cases (66 hips), the average follow-up was 7.5 years. At the latest follow-up, the mean Harris hip score was 96 points. 3 patients (4.5%) reported mild thigh pain, no ease need revision. By the measurement of the X-ray, 7 stems had less than 1.5 mm of subsidence within the 1 year follow-up. The remainer stems had no subsidence. Radiographic evaluation demonstrated all stems to get bone ingrowths fixation with evidence of spot welds, cancellous con-densation and cortical hypertrophy visible around Gruen zone 2 and zone 6 at 3 to 6 months postoperatively, including patients aged more than 70 years and of Dorr type C. Reactive lines covered the noncoated zone of the femoral stems for some eases. No hip had extensive proximal end osteolysis or distal intramedullary oste-olysis, and loosening. Conclusion Hydroxyapatite-coating on femoral implants is able to enhance the initial fixation of implants, to accelerate bone ingrowths and osseous fixation of the femoral component, to seal the interface between the implant and bone and to prevent ingress of polyethylene particles. So it is good to im-prove mid-term clinical results of the eementless total hip replacement. Key words: Arthroplasty; replacement; hip; Hip prosthesis; Hydroxyapatites