Abstract | December 16, 2022
Cobalt Toxicity in Patient with Metal-on-Metal Hip Replacement
Learning Objectives
- Identify the risk factors for Cobalt toxicity.
- Recognize the neurologic presentation of Cobalt toxicity and be able to diagnose this condition.
Introduction: Cobalt toxicity can result from chronic low-level exposure and presents various neurological symptoms. We present a case of systemic cobalt toxicity from a prior total hip arthroplasty.
Case presentation: A 47-year-old male with a past medical history significant for ankylosing spondylitis and previous metal-on-metal right total hip arthroplasty performed 14 years prior presented to his primary care doctor with a 3-day history of neuropathic pain in bilateral hands and feet. He also endorsed sleep disturbances and night sweats. His vitals were stable and physical examination, including a complete neurologic examination, was unremarkable. The initial workup was unrevealing, including a complete blood count, comprehensive metabolic panel, Hemoglobin A1c, Vitamin B12, Iron, Ferritin, Thyroid function, and HIV testing. The cause of his neuropathic pain was suspected to be due to ankylosing spondylitis.
A year later, he was evaluated by an orthopedic surgeon for right hip pain. His neurological symptoms persisted with new symptoms of diarrhea, headaches, memory problems, and anxiety. His ESR was 25, and his CRP was 1.36. Given his neurological symptoms and hip pain, the cobalt level was checked and found to be elevated at 11.5 mcg/L, and his chromium level was 7.8 mcg/L. The X-ray of his right hip showed a vertically displaced acetabular component of his total hip arthroplasty with osteolysis.
Final diagnosis: He was diagnosed with Cobalt toxicity.
Follow up: He underwent revision of his right total hip arthroplasty with the placement of a ceramic acetabulum. Bacterial and fungal joint cultures, obtained intraoperatively, were negative. His neurologic symptoms completely resolved over the coming months.
The mechanism of cobalt toxicity remains unclear; proposed mechanisms include enzymatic inhibition and direct cytotoxicity. The diagnosis depends on a combination of history and laboratory confirmation with cobalt levels. Management of cobalt toxicity has not been well documented. Therefore, management should focus on eliminating cobalt exposure and providing supportive care.
References:
- Cheung, A. C., Banerjee, S., Cherian, J. J., Wong, F., Butany, J., Gilbert, C., Overgaard, C., Syed, K., Zywiel, M. G., Jacobs, J. J., &; Mont, M. A. (2016). Systemic cobalt toxicity from total hip arthroplasties. The Bone & Joint Journal, 98-B(1), 6–13. https://doi.org/10.1302/0301-620x.98b1.36374
