Chromium and Nickel Concentrations in Subjects with a Stainless Steel Metal-on-Metal Cervical Disc Arthroplasty: Results from a Prospective Longitudinal Study with 7 Years Follow-Up

Vaneet Singh; Anastasia K. Skipor; Abdulhafez A. Selim; Joshua J. Jacobs

doi:10.14444/5055

ABSTRACT

Background Cervical disc arthroplasty (CDA) has emerged as an alternative to anterior cervical discectomy and fusion for degenerative cervical disc disease. The artificial discs provide intervertebral motion using multicomponent articulation and thus tend to generate particulate debris and soluble metal ions. Limited information is available on the long-term metal concentrations and associated systemic adverse events observed in metal-on-metal CDA. Serum chromium (Cr) and nickel (Ni) concentrations were assessed in patients implanted with ball-in-trough stainless steel–based cervical disc through 7 years.

Methods A prospective, nonrandomized longitudinal study was conducted that included 25 patients following rigorous exclusion criteria that included no previous permanent metal implants and no professional exposure to metal particles. Blood serum Cr and Ni concentrations were assayed preoperatively and at 3, 6, 12, 24, 36, 60, and 84 months postoperatively using high-resolution inductively coupled plasma–mass spectrometry. Longitudinal statistical comparisons were made using the Friedman test with statistical significance at P < .05.

Results Median serum concentrations determined preoperatively and at 3, 6, 12, 24, 36, 60, and 84 months postoperatively were 0.074, 0.106, 0.132, 0.170, 0.172, 0.274, 0.192, and 0.203 ng/mL for Cr and 0.085, 0.178, 0.222, 0.175, 0.205, 0.284, 0.181, and 0.194 ng/mL for Ni. The serum Cr concentrations were statistically higher for all postoperative time periods compared to preoperative concentration (Friedman P <.01), whereas serum Ni concentration was statistically higher at the 84-month postoperative time period than the preoperative concentration (Friedman P <.01) and then the concentration at 3, 12, 24, and 60 months postoperatively (Friedman P < .03).

Conclusions The Cr concentrations detected at all postoperative times were statistically higher than preoperative concentrations, whereas Ni concentration was statistically higher than the preoperative concentration only at 84 months.

Footnotes

Disclosures and COI: Vaneet Singh and Abdulhafez A. Selim are employees of Medtronic, Inc. Joshua J. Jacobs received research grant from Medtronic, Inc., to conduct this metal concentration work. Dr. Jacobs was also a paid consultant for Medtronic Corporation during the time of this study. For the remaining authors, none were declared. This study was funded by Medtronic, Inc. This study was conducted under a US Food and Drug Administration–approved investigational device exemption (G010188) and was approved by the institutional review board of each participating site, and all participants signed an informed consent prior to their inclusion in the study.