Detection of cobalt in synovial fluid from metal-on-metal hip prosthesis: correlation with the ion haematic level

Abstract

Hip replacement with large metal-on-metal (MoM) coupling has recently been under attention for its metal ions release, inducing several disorders. Since the blood level toxicity threshold for cobalt is known, the aim of this work is to determine whether Co serum and blood levels correlate with the synovial fluid level. Beside this, the synovial fluid Co from patients without prosthesis has also been measured. Co has been determined in 54 samples (32 unilateral MoM and 22 controls) with inductively coupled plasma mass spectrometry in the three matrices. In the prosthesized group, cobalt was significantly higher compared with controls and in the synovial fluid it strongly correlated with whole blood Co (p = 0.847) and serum (p = 0.855). Moreover, the Co levels into whole blood and serum were significantly different. In conclusion, haematic Co concentration correctly reflects Co local level.

• Articular capsule
• metal exposure
• toxicity

Acknowledgements

Dr Milva Battaglia of Diagnostic Sonography of Rizzoli Institute is gratefully acknowledged for her contribution to synovial fluid sample collection, as well as the nursing staff of the operating room (Orthopaedic-Traumatology and Prosthetic Surgery and Revisions of Hip and Knee Implants) for their technical contributions, and Dr Lucia Mancini for her support in revising this article.