The effect of component size and orientation on the concentrations of metal ions after resurfacing arthroplasty of the hip 2008
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.