Saturday, December 29, 2012

Serum cobalt and chromium levels elevated after metal disc arthroplasty


Gornet MF. Eur Spine J. 2012. doi:10.1007/s00586-012-2581-8.

Blood samples for 24 patients with a single-level all-metal total lumbar disc arthroplasty prosthesis collected through 36 months postoperatively showed higher serum cobalt and chromium levels of the same order of magnitude as those seen at similar time points in patients with well-functioning metal-on-metal hip implants.

"In general, these results indicated that serum Co [cobalt] and Cr [chromium] levels are elevated at all postoperative time points," Matthew F. Gornet, MD, and colleagues wrote in their study abstract.
The 13 men and 11 women included in the study had an average age of 41 years when they had a Maverick Lumbar Disc (Medtronic; Memphis, Tenn.) implanted at either L4/5 (eight patients) or L5/S1 (16 patients).

Investigators conducted this prospective longitudinal study using high-resolution inductively-coupled plasma-mass spectometry for the serum assay. They found median serum Co levels of 0.10 ng/mL and Cr levels of 0.06 ng/mL, preoperatively. However, median 36-month postoperative serum measurements reached 0.52 ng/mL for Co and 0.50 ng/mL for Cr, according to the abstract.
Gornet and colleagues noted in the discussion section of the study that the median Co and Cr serum levels they measured were one-third those in some total disc arthroplasty studies in the literature, and the median serum Cr levels they reported were the same as or lower than in studies of patients with stainless steel posterior spine instrumentation.

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