The effect of component size and orientation on the concentrations of metal ions after resurfacing arthroplasty of the hip
D. J. Langton, MRCS, Orthopaedic Research Register1; S. S. Jameson, MRCS, Specialist Registrar, Trauma and Orthopaedics1; T. J. Joyce, MSc, PhD, MA, BEng, Lecturer in Bioengineering2; J. Webb, MRCS, Specialist Registrar, Trauma and Orthopaedics1; and A. V. F. Nargol, FRCS(Tr & Orth), Consultant Orthopaedic Surgeon1
1
Joint Replacement Unit, University Hospital of
North Tees, Hardwick, Stockton-on-Tees TS19 8PE,
UK.
2 Newcastle University, Claremont
Road, Newcastle upon Tyne NE1 7RU, UK.
Increased concentrations of metal ions after metal-on-metal resurfacing arthroplasty of the hip remain a concern. Although there has been no proven link to long-term health problems or early prosthetic failure, variables associated with high metal ion concentrations should be identified and, if possible, corrected. Our study provides data on metal ion levels from a series of 76 consecutive patients (76 hips) after resurfacing arthroplasty with the Articular Surface Replacement. Chromium and cobalt ion concentrations in the whole blood of patients with smaller 51 mm) femoral components were significantly higher than in those with the larger 53 mm) components (p < 0.01). Ion concentrations in the former group were significantly related to the inclination (p = 0.01) and anteversion (p = 0.01) of the acetabular component. The same relationships were not significant in the patients with larger femoral components (p = 0.61 and p = 0.49, respectively). Accurate positioning of the acetabular component intra-operatively is essential in order to reduce the concentration of metal ions in the blood after hip resurfacing arthroplasty with the Articular Surface Replacement implant.
