We discuss the underlying pathomechanism of the visual loss from cobalt toxicity and review the debate of metallic hip prosthesis.Ī 59-year-old female presented to our institution for evaluation of bilateral visual loss. We present a case of systemic cobalt toxicity in the setting of multiple total hip arthroplasty revision surgeries resulting in both an optic neuropathy and retinopathy in addition to hearing loss, thyroid dysfunction and cardiac conduction defect. According to a review published in 2018, the most frequently materials used for total hip arthroplasty were cobalt-chromium alloys due to favorable strength and wear characteristics. However, due to polyethylene wear particles playing a role in osteolysis and loosening, alternative materials including CoC and CoP were developed. In the 1970s, MoP implants became widespread. 19 MoM hip implants were initially introduced in 1950 but lost popularity due to concern for metallosis. 6, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18 Four main types of materials are employed for total hip arthroplasty: MoM, metal-on-polyethylene (MoP), ceramic-on-ceramic (CoC), and ceramic-on-polyethylene (CoP). Specifically, ocular cobalt toxicity, although uncommon, has seen an increase in the number of published cases due to rising use of cobalt-chromium hip implantations. 1, 2 Systemic toxicity associated with excessive levels of cobalt include peripheral neuropathy, vision loss, sensorineural hearing loss, cognitive decline, cardiomyopathy, hypothyroidism, weakness, fatigue and polycythemia ( Table 1). 5, 6 Post-arthroplasty metallosis with systemic cobalt toxicity is a rare complication, but the morbidity and mortality related to this complication is extremely high. femoral head) due to retained ceramic particles from a failed ceramic femoral head prosthesis, causing the release of cobalt and chromium metal ions into the systemic circulation. 5 More recently, systemic cobalt toxicity has been associated with metal-on-metal (MoM) total hip arthroplasty or the grating down of the cobalt-chromium ball (i.e. In the past, cobalt toxicity was predominantly seen in the form of pulmonary disease in industrial workers who inhaled large amounts of cobalt dust while drilling hard metal or polishing diamonds. Although not firmly established, it is believed that adverse effects related to cobalt toxicity typically only occur at levels of 7 μg/L or more. 3 However, excessive cobalt can produce systemic toxicity affecting multiple organ systems. 1, 2 Normal daily dietary intake ranges from 5 to 50 μg with normal plasma concentrations of <0.2 μg/L. cobalamin) that is involved in the production and regulation of red blood cells, platelet, DNA as well as fatty acid synthesis and energy production. OCT showed retinal nerve fiber thinning and persistent GCLIPL thinning in both eyes.Ĭobalt, an essential trace element with an atomic number of 27, is a key component of vitamin B12 (i.e. One month after surgery, she had significant improvement in visual acuity (20/150 right eye, 20/250 left eye), Goldmann visual field testing, and mfERG. Four days after surgery, cobalt serum levels had significantly decreased to 378 ng/mL. She underwent a total hip revision arthroplasty with extensive debridement of “black sludge” found within a pseudocapsule. Goldmann visual field testing demonstrated bilateral central scotomas, optical coherence tomography (OCT) showed severe ganglion cell layer-inner plexiform layer (GCLIPL) thinning and multifocal electroretinography (mfERG) demonstrated decreased amplitudes in both eyes. There was bilateral temporal optic disc pallor. Visual acuity was 20/600 in the right and 20/800 in the left eye. The possibility of the patient's symptoms being due to cobalt toxicity from her hip prosthesis was proposed and she was found to have a serum cobalt level >1000 μg/L (normal 0–0.9 ng/mL). A few months after surgery, she began experiencing blurred and “white, spotty” vision in both eyes in addition to hypothyroidism, cardiomyopathy and neuropathy. The year prior, she had failure of the hip implant necessitating revision surgery with placement of a chrome-cobalt head. A 59-year-old female with a history of multiple left hip arthroplasties presented to our clinic with bilateral visual loss.

Cobalt toxicity symptoms