Transmission electron microscopy of intracellular particles of polyethylene from joint replacement prostheses: size distribution and cellular response

The objectives of this transmission electron microscopy study of peri-impla nt tissues retrieved at revision arthroplasty were to (1) determine the siz e distribution of intracellular polyethylene particles, and (2) assess the cellular response to phagocytosed polyethylene particles as revealed by the condition of the cellular organelles. The frequency distributions of intra cellular polyethylene particle sizes for 15 cases of total hip replacement showed that more than 75% of the particles had lengths of less than 0.5 mum . More than 90% of the particles were less than 1.0 mum in size. In compari son, the frequency distribution for the particles in cells comprising tissu e retrieved from three total knee replacement prostheses showed that only 4 3% of the particles were less than 0.5 mum in length and 72% were less than 1 mum in size. There was no statistically significant difference in the me an particle length between the specimens from the hip and knee patients. Th e majority of the cells containing polyethylene were without signs of degen eration. The cytoplasmic and nuclear membranes were intact. Several electro n lucent voids which once contained polyethylene particles were seen surrou nded by several healthy appearing mitochondria, which displayed sharp membr anes and intact cristae. There were no signs of a cytotoxic response to pol yethylene at the ultrastructural level. (C) 2001 Elsevier Science Ltd. All rights reserved.