Periimplant Histology and Cytokine Pattern in Metal-Allergic Knee Arthroplasty Patients with Improvement After Revision with Hypoallergenic Materials

In knee arthroplasty patients with complications not explained by classical mechanisms, like infection or malalignment/malposition, the role of hypersensitivity to implant materials may be questioned. In 10 such patients with and 5 without metal sensitization, a combined evaluation of periimplant histology and cytokine expression, and microbiological analysis was done. In the 10 metal allergics, outcome after revision with alternative “hypoallergenic” materials (9×titanium-based, 1×oxinium-based) was evaluated. In the metal-allergic patients, scattered, partly dense T-lymphocytes were seen in periimplant tissue and there were no signs of infection. Predominant IFN-γ expression and the improvement in the postoperative WOMAC scores (mean preoperative score, 40.4; postoperative score, 55.58) supported hypersensitivity as the symptoms elicitor.