CHARACTERIZATION OF DEBRIS ADJACENT TO FAILED KNEE IMPLANTS OF 3 DIFFERENT DESIGNS

Wear debris particles have been associated with bone resorption and lo osening of total joint implants. To characterize the wear particles ar ound failed knee prostheses, tissues ad. jacent to 47 implants of 3 di fferent designs were evaluated: 29 were posterior cruciate ligament re tention type (Group I), 12 were posterior cruciate ligament sacrificin g or substituting (Total Condylar, Insall-Burstein), (Group II), and 6 were mobile bearing (posterior cruciate ligament retaining LCS), (Gro up III), Wear particles were isolated and evaluated using electronic p article quantitation and scanning electron microscopy. Tile correspond ing implants were also evaluated, and the surface damage quantified. T he number of particles smaller than 10 mu m ranged from 8.9 to 45.8 x 10(9) per gram of tissue (dry weight), Particle number directly correl ated with duration of implantation, Group I implants had larger partic les, and showed greater surface damage than the other 2 designs, Polye thylene surface damage significantly correlated with particle size mor e than 10 mu m in length. Particle number showed a significant inverse correlation with the thickness of the polyethylene. These results sup port previous mechanical and retrieval studies suggesting that increas ed wear may be associated with thinner polyethylene, and there are dif fering degrees and patterns of wear based on implant design.