Metallosis and elevated serum levels of tantalum following failed revision hip arthroplasty— a case report

A 70-year-old woman had a primary cemented total arthroplasty of her right hip performed elsewhere in 1967 for developmental hip dysplasia. The arthroplasty failed in 1977, due to aseptic loosening and since then the patient has undergone 3 revision procedures including 2 acetabular cup revisions. In 2006, a porous tantalum acetabular augment (PTAA) (Zimmer, Warsaw, IN) was used to support a hemispherical cementless acetabular centroid Hilock cup (SYMBIOS Orthopédie, Yverdon-les-Bains, Switzerland) made of titanium alloy (Ti6Al4V) with a porous titanium and hydroxyapatite dual coating. At that time, no cement was interpositioned between the cup and augment—as instructed by the manufacturers. 6 years later, the patient was unable to walk and suffered severe pain, and she was referred to us for an additional revision. The preoperative radiographs showed a peculiar “halo formation” surrounding the acetabular component (Figure 1). Extensive metallosis of this surrounding tissue was found intraoperatively. Black pigmentation was also found in the overlying skin (Figure 2). Following the removal of the loose Hilock cup, the tantalum augment was found to be non-osseointegrated, severely worn, and broken (Figure 3). Debridement and synovectomy was performed and a modified cup-cage construct technique was used to address the existing pelvic discontinuity.