The interpretation of metal ion levels in unilateral and bilateral hip resurfacing study 2012
August 2012 Van Der Straeten C1, Grammatopoulos G, Gill HS, Calistri A,
Campbell P, De Smet KA.
Read Complete Study Here:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3549185/pdf/11999_2012_Article_2526.pdf
The interpretation of metal ion concentrations and their role in clinical
management of patients with metal-on-metal implants is still controversial.
We questioned whether patients undergoing hip resurfacing with no clinical
problems could be differentiated from those with clinical (pain, loss of
function) and/or radiographic (component malpositioning, migration, bone loss),
problems based on metal ion levels, and if there was a threshold metal level
that predicted the need for clinical intervention…
We retrospectively identified 453 unilateral and 139 bilateral patients with
ion measurements at minimum follow-up of 12 months (mean, 4.3 years; range,
1 – 12.9 years)…
Well-functioning group ions were lower than the poorly functioning group ion
levels. The acceptable upper levels were: chromium (Cr) 4.6 μg/L, cobalt (Co)
4.0 μg/L unilateral and Cr 7.4 μg/L, Co 5.0 μg/L bilateral. The specificity of
these levels in predicting poor function was high (95%) and sensitivity was low
(25%). There were more males in the well-functioning group and more females and
smaller femoral components in the poorly functioning group.
Metal levels higher than these proposed safe upper limits can predict
problems with metal-on-metal resurfacings and are important parameters in the
management of at-risk patients.