Effects of Cobalt and Chromium Levels Following Modular Hip Stem Total Hip Arthroplasty.

Abstract

Due to the increased number of revision total hip arthroplasties (THAs) to correct pain secondary to fretting from modular hip stems, this study was conducted in an effort to correlate objective findings of serum cobalt (Co) levels, serum chromium (Cr) levels, and/or reactive tissue seen on metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) with a patient's need for revision THA. The study group comprised 66 patients, 18 of whom received MARS MRI. Serum Co levels, serum Cr levels, and standard numeric rating scale for pain were documented for all patients. Statistical analysis was then performed to determine whether there was a correlation between the aforementioned variables and the need for revision THA. Serum Cr levels were higher in patients with positive reactive tissue findings on MARS MRI, although this only approached significance (P=.083). Serum Co levels were higher in those undergoing revision THA, but this also only approached significance (P=.076). Pain scores were significantly different between those undergoing revision and those not (P<.001). It is the opinion of the authors that there is no objective finding in this study that can be used to identify patients who require revision THA secondary to fretting of a modular hip stem prosthesis. Only a patient's stated pain level can assist a surgeon in the decision-making process regarding the need for revision THA secondary to fretting. [Orthopedics.2016; 39(5):288-292.].