COMPARISON AND QUANTITATION OF WEAR DEBRIS OF FAILED TOTAL HIP AND TOTAL KNEE ARTHROPLASTY

To compare the physical properties of debris particles associated with failed total hip and total knee arthroplasty, we applied a recently d eveloped assay to electronically characterize the size, number, and co mposition of debris particles isolated from tissues adjacent to failed implants. We identified 21 samples (from 20 patients) of hip synovia and 35 samples (from 32 patients) of knee tissues that had been obtain ed at the time of revision arthroplasty. There were 12 females and 9 m ales in the hip group, and 16 females and 19 males in the knee group. Primary arthroplasty was performed for osteoarthritis (OA, 15 cases) o r rheumatoid arthritis (RA, 6 cases) in the hip, and for OA (23) or RA (12) in the knee. Patients ranged in age from 23 to 85 (mean 59 years ) for total hip, and from 27 to 84 (mean 61 years) for total knee arth roplasty. Implantation duration was from 5 to 123 months (mean 37.8) f or total hip, and from 11 to 123 months (mean 63.1) for total knee art hroplasty. All of the implants were composed of cobalt-chromium alloy articulating with ultrahigh-molecular-weight polyethylene. The number of particles smaller than 10 mu m ranged from 1.04 x 10(8)/g to 1.91 x 10(10)/g in the hip, and from 6.69 x 10(8)/g to 2.13 x 10(10)/g in th e knee. Energy-dispersive X-ray spectroscopy and polarized light analy sis showed both polyethylene and metal particles in most cases. The me an diameter of particles smaller than 10 mu m was 0.72 +/- 0.2 mu m in the hip, and 0.74 +/- 0.1 mu m in the knee. Evaluation of particles l arger than 10 mu m showed a larger range of particle size in knee tiss ues (maximum 6.1 mm, mean 283 mu m), than in the hip tissues (maximum 826 mu m, mean 81 mu m) (p < 0.001). Very small particles are common i n both groups, but it appears that a larger range of particle sizes is present adjacent to failed knee than to failed hip prostheses. The hi gher frequency of large particles in failed knee prostheses probably r eflects the perceived higher rate of delamination and fragmentation of tibial and patellar compared to that of acetabular polyethylene. (C) 1996 John Wiley & Sons, Inc.