The early results of total hip replacement with a proximally hydroxyapatite-coated femoral component / 中华创伤骨科杂志

ABSTRACT

Objective To summarize the early results of total hip replacement with a proximally hydroxyapatite-coated femoral component. Methods From February 2000 to October 2003, 65 cases (70 hips) underwent uncemented total hip replacement with a proximally hydroxyapatite-coated femoral component (U2, United Orthopedic Corporation, Taiwan, China). The diagnosis included femoral neck fractures in 30 cases, osteoarthritis in 15 cases, avascular necrosis of the femoral head in 9 cases, loosening of artificial femoral head in 8 cases, rheumatoid arthritis in 2 cases, and arthrodesis in 1 case. Clinical and radiographic evaluations were performed at 1 week, 3 and 6 months postoperatively, and yearly afterwards. Bone mineral density (BMD) of the proximal femur was measured with dual-energy X-ray Absorptiometry (DEXA) for 44 cases. Results Postoperative X-ray films showed that the initial fixation was excellent or good in all the stems. The follow-ups averaged 3 years (2 to 5.5 years). The mean preoperative Harris hip score was 32 (25 to 52) points, which were improved to 96 points at the latest follow-ups. There was no reported incidence of thigh pain at any time throughout our study. And no case needed revision. By the measurements on the X-ray films taken within 1 year postoperatively, 7 of the 70 stems had subsidence of less than 1.5 mm. No hip experienced extensive proximal end osteolysis, intramedullary osteolysis, or loosening. DEXA showed that the BMD values decreased after operation, and then returned rapidly to the normal or near normal ones 3 to 6 months after operation, especially in zones Ⅱand Ⅵwhere the increase was even more significant than at the control side. All the stems were radiographically stable with evidence of osseous ingrowth typically seen in HA-coated zones, according to the criteria proposed by Engh et al. Conclusions Since HA-coating on femoral implants can enhance the initial fixation of implants, accelerate bone ingrowth and osseous fixation of the femoral component, and seal the interface between the implant and bone to prevent ingress of polyethylene particles, it is helpful in improving clinical results of the cementless total hip replacement.