Unusual presentation of cobalt hypersensitivity in a patient with a metal-on-metal bearing in total hip arthroplasty.

Pain after hip arthroplasty is less likely to be attributed to dermal sensitivity from orthopedic implants. Unexplained persistent pain after hip arthroplasty typically leads to further investigation, occasionally revealing a metal sensitivity. Our case study presents an unusual finding of a delayed type IV cobalt hypersensitivity in a patient several years after use of cobalt in the contralateral hip. Recognition and a high index of suspicion are needed for timely treatment of metal allergy when it presents as persistent pain after hip arthroplasty.