Metal Concentration in Synovial Fluids of Patients with Prosthetic Knee Arthroplasty

Significant levels of the major components of metal prostheses in total knee arthroplasty were measured in the synovial fluids from patients with these implants. Cobalt (Co), Chromium (Cr), and Nickel (Ni) concentrations were determined by atomic absorption spectrophotometry on 26 synovial fluid samples from 18 patients with hinged (metal-on-metal) prostheses and eight patients with nonhinged (metal-on-polyethylene) prostheses. Concentrations of Co, Cr, and Ni were significantly higher in synovial fluids from hinged knees, as were Ni concentrations in fluids from nonhinged knees. Of the three metals, Ni showed some evidence of increases solubility. The metal debris did not appear to provoke a leukocyte response, insofar as surprisingly low numbers of neutrophils were present in these fluids, all of which were obtained from nonseptic knees. However, significant numbers of lymphocytes and large mononuclear cells were present in the fluids.