Preparation and characterization of wear debris of orthopedic materials for biocompatibility studies

✍ Scribed by Wagner, C. N. J. ;Shabaik, A. H. ;Schurman, D. J. ;Amstutz, H. C.

• Publisher: John Wiley and Sons
• Year: 1976
• Tongue: English
• Weight: 920 KB
• Volume: 10
• Category: Article
• ISSN: 0021-9304
• DOI: 10.1002/jbm.820100503

✦ Synopsis

In order to test the biocompatibility of wear debris of orthopedic materials, a method has been developed to produce artificial debris of stainless steel, cobalt-chromium alloy, and high-density polyethylene. I n this process, called the accelerated rubbing process, two cylindrical blocks of the same alloy were held under normal pressure in triply distilled water. One block remained stationary while the other rotated a t -4000 rpm. The water with the metal debris was recirculated between the rubbing surfaces. To prepare debris from polyethylene, a stainless steel block was rubbed over a polyethylene block submersed in liquid nitrogen.

The shape .of the metal debris was granular, whereas the polyethylene debris had a shred-like shape. The size distributions were determined from scanning electron micrographs, and it was found that the particles of the metal debris (stainless steel or cobalt-chrome alloy) ranged in sizes from 0.1-10 p with 75% of all particles < 2 p in diameter. The size of polyethylene debris, expressed as the volume of an ellipsoid, ranged from 10-20,000 pa with 45% of all particles in the range of 400-2500 pa.

The x-ray diffraction pattern revealed that the debris of stainless steel consisted primarily of the face-centered cubic (fcc) alloy with small amounts of body-centered cubic (bcc) alloy and Fe30r, whereas the cobalt-chrome debris consisted of the fcc alloy with a small amount of Cr203.

The structure of the polyethylene debris was quite similar to that of the solid sample used in its preparation. The percent crystallinity P , and the size of the crystalline regions D were slightly s m a l p in the debris than in the solid sample, i.e., P, = 52 and 55%, D = 90 and 130 A, in the debris and the solid, respectively.