Particulate titanium and cobalt-chrome metallic debris in failed total knee arthroplasty. A quantitative histologic...

Histologic examination of synovial tissue from the revisions of six cobalt-chrome and six titanium alloy total knee arthroplasties was made. Aseptic polyethylene wear-through had resulted in metal-on-metal contact of bearing surfaces and was the primary indication for revision surgery in all knees. The cobalt-chrome alloy prostheses failed at the femorotibial articulation at a mean of 92 months, while the titanium prostheses experienced patellofemoral failure at a mean of 39 months after implantation. Neither alloy was associated with any meaningful inflammatory infiltrate, and cement debris was comparable in both groups. Titanium alloy knees generated significantly more metallic debris than the cobalt-chrome alloy knees (P < .001). Cobalt-chrome alloy knees had more polyethylene debris (P < .01) and a greater number of histiocytes (P < .005). Titanium and polyethylene debris were associated with a prominent giant cell reaction. Titanium exhibited greater abrasive wear and elicited a different cellular response than cobalt-chrome under conditions of polyethylene failure allowing metal-on-metal contact. The variability of this foreign body reaction may be due to important differences in particle size and number, as well as in the material properties of the two alloys.