|
Journal of Bone and Joint Surgery - British Volume, Vol 91-B, Issue 10,
1287-1295.
doi: 10.1302/0301-620X.91B10.22308 Copyright © 2009 by British Editorial Society of Bone and Joint Surgery Blood metal ion concentrations after hip resurfacing arthroplastyA COMPARATIVE STUDY OF ARTICULAR SURFACE REPLACEMENT AND BIRMINGHAM HIP RESURFACING ARTHROPLASTIESD. J. Langton, Orthopaedic Research Registrar1; A. P. Sprowson, Specialist Registrar2; T. J. Joyce, Senior Lecturer in Bioengineering3; M. Reed, MD, FRCS(Tr & Orth), Consultant, Trauma & Orthopaedics4; I. Carluke, FRCS(Tr & Orth), Consultant, Trauma & Orthopaedics4; P. Partington, FRCS(Tr & Orth), Consultant, Trauma and Orthopaedics4; 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. Correspondence should be sent to Mr D. J. Langton; e-mail: djlangton22{at}doctors.org.uk
There have been no large comparative studies of the blood levels of metal ions after implantation of commercially available hip resurfacing devices which have taken into account the effects of femoral size and inclination and anteversion of the acetabular component. We present the results in 90 patients with unilateral articular surface replacement (ASR) hip resurfacings (mean time to blood sampling 26 months) and 70 patients with unilateral Birmingham Hip Resurfacing (BHR) implants (mean time 47 months). The whole blood and serum chromium (Cr) and cobalt (Co) concentrations were inversely related to the size of the femoral component in both groups (p < 0.05). Cr and Co were more strongly influenced by the position of the acetabular component in the case of the ASR, with an increase in metal ions observed at inclinations > 45° and anteversion angles of < 10° and > 20°. These levels were only increased in the BHR group when the acetabular component was implanted with an inclination > 55°. A significant relationship was identified between the anteversion of the BHR acetabular component and the levels of Cr and Co (p < 0.05 for Co), with an increase observed at anteversion angles < 10° and > 20°. The median whole blood and serum Cr concentrations of the male ASR patients were significantly lower than those of the BHR men (p < 0.001). This indicates that reduced diametral clearance may equate to a reduction in metal ion concentrations in larger joints with satisfactory orientation of the acetabular component.
|
|


