Case report: cobalt toxicity following implantation of a metal hip prosthesis

March 31, 2012, 12:36 am

★★½☆☆

Severe cobalt intoxication following hip replacement revision: Clinical features and outcome. Pelclova D et al. Clin Toxicol 2012 Apr;50:262-265.

Abstract

This case report, from the Czech Republic, describes a 56-year-old man who developed manifestations of severe cobalt intoxication after having ceramics-on-ceramics hip implant revised with insertion of a metal head containing cobalt, chromium, and titanium.

As TPR has reported before, cobalt can cause hypothyroidism, cardiomyopathy, and neurotoxicity. Neurological manifestations include:

  • optic nerve damage and retinopathy with decreased visual acuity
  • bilateral nerve deafness and tinnitus
  • polyneuropathy (sensory and motor)
  • cognitive impairment and memory loss
  • tremor

Twenty month’s after this patient’s hip revision, he presented with hip dislocation. Work-up revealed that 40% of the metal head had abraded, apparently from contact with abrasive ceramic particles. He also had a large pericardial effusion, subclinical hypothyroidism, sensorimotor polyneuropathy of upper and lower extremities, and severe hearing loss. Serum cobalt level was 506 mcg/L  (reference value < 0.9 mcg/L). After prolonged chelation with DMPS (Unithiol), most of his symptoms had improved although his cobalt level remained elevated. However, audiology tests showed severe damage, with complete deafness of the right ear and 83% hearing impairment on the left.

This authors note that DMPS had not previously been used to chelate cobalt for toxicity caused by a hip transplant. They admit, however, that it is unclear whether this treatment improved clinical outcome.

The important take-home lesson for clinicians is to suspect cobalt toxicity whenever a patient with a metal hip prosthesis presents with unexplained cardiac or neurological dysfunction.

Related posts:

Cognitive decline in patients with metal-on-metal hips: think cobalt toxicity

Neurological changes and hip prosthesis: think cobalt toxicity