Untitled

Abstract

In 18 sheep the anterior cruciate ligament was replaced by an alloplastic ligament of polyetheretherketone (PEEK). Histological examination 18-36 months after implantation revealed the presence of wear particles with a size of 0.6-9.5 µm (mean size, 2.78 µm) in 57.5% of the 1448 evaluated lymph nodes from various sites in the body. The PEEK wear particles were found both in the operated right knee as well as in the non-operated left knee. Although the density of particles on the left side was generally lower than on the operated right side, these findings can only be explained in the context of distribution phenomena through the lymphatic system. The number of macrophages containing particles per lymph node and the particle density per macrophage decreased in both sides from the periphery towards the centre. There was a time-related change in the foreign body distribution pattern from right to left: while on the right there was rapid accumulation of positive macrophages, a quantitative re-distribution towards the left occurred only gradually. No evidence was found for successive re-distribution within the lymph nodes from the cortex towards the marrow. In the synovia of the hind legs, particles had accumulated only in the right leg. In the left no PEEK degradation products were