|
The exercise-related rise in plasma
cobalt levels after metal-on-metal
hip
resurfacing
arthroplasty 2008
M. Khan, MRCS, PhD Student, Clinical
Research Fellow1; J.-H. Kuiper, PhD, Lecturer in
Biomechanics1; and J. B. Richardson, MD, FRCS,
Professor of Orthopaedics1
1 Institute of
Orthopaedics The Robert Jones and Agnes Hunt Orthopaedic
Hospital, Gobowen, Shropshire SY10 7AG, UK.
Wear of metal-on-metal bearings
causes elevated levels of cobalt and chromium in
blood and body fluids. Metal-on-metal bearings
have two distinct wear phases. In the early phase, the wear
rate is high. Later, it decreases and the bearing
enters a steady-state phase. It is expected that
as the wear rates decline, the level of cobalt
detected in plasma will also decrease. We studied
the baseline and exercise-related cobalt rise in 21 patients
(13 men and eight women) with a mean age of 54 years
(38 to 80) who had undergone successful
hip
resurfacing
at a mean of 44 months (10 to 96) earlier. Our
results showed that circulating baseline cobalt
levels were not significantly correlated with the
time since implantation (r = 0.08, p = 0.650). By contrast,
the exercise-related cobalt rise was directly
correlated with the inclination angle of the
acetabular component (r = 0.47, p = 0.032) and
inversely correlated with the time since implantation
(r = –0.5, p = 0.020).
|
