Abstract
As part of a prospective RSA study into a new design of short-stem, trabecular metal, Co-Cr femoral components with modular necks and metal on polyethylene articulation, three patients presented with almost identical symptoms of pain and a large avascular mass within the operated hip. All three cases came to exploration and similar findings of a solid pseudotumour within the hip joint were found in all thee cases. Infection was not present. All cases were submitted to histology and reviewed by a pathologist with specific interest in tissue reactions to foreign materials. All three cases showed histological features classical of published descriptions of ALVAL (Aseptic Lymphocyte-dominated Vasculitis Associated Lesion). A consistent finding was fretting corrosion of the neck-stem junction. These cases demonstrate that Co and Cr ions can provoke adverse tissue reactions even in the absence of metal/metal articulations. This has design implications for all modular Co-Cr necks. The stem used in this study has been voluntarily withdrawn from the Australian market but is still being implanted in Europe. We make recommendations that modular trunnion-style Co-Cr necks not be used and alternative materials and design solutions be sought.
