Normalization of chromium and cobalt values after femoral head replacement

• A patient with MoM THA presented ARMD with worsening paresthesias.
• Elevated Cr–Co values, worsening clinical picture, prosthetic revision was considered.
• Acetabular cup and femoral stem were found correctly osteointegrated.
• Only prosthetic metallic head was replaced with a polyethylene one.
• Cr and Co decreased and normalized 3 months after surgery.

IntroductionAdverse reaction to metal debris (ARMD) can be caused by metal-on-metal total hip arthoplasty. We treated a case of ARMD in a 61-year-old patient by limited prosthetic revision, replacing the metal head with a polyethylene one.Presentation of caseTwo years after metal-on-metal total arthoplasty of the left hip, radiographic control showed osteolysis of the patient’s greater trochanter. He underwent surgical curettage and the application of demineralized bone matrix. After a few months, blood Co and Cr increased, and at clinical evaluation, the patient had worsening paresthesias. He agreed to prosthetic revision after 14 months.DiscussionDuring surgery, the acetabular cup and femoral stem appeared correctly osteointegrated; therefore, the cup was maintained, while the prosthetic femoral head was removed and replaced with a 50 mm polyethylene head.ConclusionBlood Cr and urinary Cr and Co decreased and normalized 3 months after surgery, and the patient no longer suffered paresthesias. Blood Co normalized 7 months after revision. Radiographic follow-up showed no change after 30 months post-operatively. We believe this case report could be a starting point for a future randomized clinical trial to test the efficacy of the procedure used compared with complete implant revision.