Microscopic Metallic Wear and Tissue Response in Failed Titanium Hallux Metatarsophalangeal Implants: Two Cases

The membranes present at the implant-bone interface were retrieved from two patients with titanium single stem hallux implants that had failed. Both patients had pain and valgus deformity of the hallux, and radiographs showed a radiolucent shadow around the implant stem, with thinning of the dorsal cortex of the proximal phalanx in one patient. After removal of the implants, arthrodesis of the first metatarsophalangeal (MP) joint was performed. Histologic analysis of the membrane tissue at the implant-bone interface showed a synovial-like appearance. There was a fibrous tissue stroma adjacent to the bone surface, with multiple regions of scalloping covered by mononuclear cells. Fine metallic debris was seen throughout the fibrous tissue. Multinucleated foreign body giant cells were sparsely observed associated with fine particulate metallic wear debris similar to observations from failed total hip arthroplasties. The histologic appearance is evidence that foreign-body granulomatous infiltration associated with metallic wear debris may be a causative factor of peri-implant osteolysis leading to aseptic loosening and failure of titanium single stem hallux implants.