Metal sensitivity as a cause of groin pain in metal-on-metal hip resurfacing.

We describe 4 patients pooled from our patient populations who presented with groin pain at different periods postoperatively after implantation of a metal-on-metal hip resurfacing. Each patient underwent exploratory surgery after radiographic imaging, hematologic testing, and microbiological assessment of joint aspirations failed to explain their symptoms. Samples of periprosthetic tissues revealed extensive amounts of lymphocytic infiltrates that were suggestive of an immunologic reaction. The patients obtained complete resolution of symptoms subsequent to revision surgery. The incidence of implant failures resulting from metal sensitivity is unknown owing to the difficulty in making a confirmed diagnosis. The possibility that this is the source of groin pain should be considered when other reasons for symptoms of pain and/or joint effusion in hips with metal-on-metal resurfacing arthroplasties have been discounted.