The biochemical and histological effects of artificial ligament wear particles: In vitro and in vivo studies

Growing evidence suggests that biochemical mecha nisms play a role in the pathogenesis of arthritis. Car tilaginous wear particles have been shown to induce destructive enzymes and cytokines. To assess the biocompatibility of artificial ACL replacements, the ef fects of wear particles from the following ligaments were analyzed biochemically and histologically: GORE- TEX, Stryker Dacron Ligament Prosthesis, Versigraft carbon, Kennedy LAD, Xenograft, Leeds-Keio, and hu man patellar tendon allograft. Ligaments were frozen and ground to produce wear particles similar to those seen clinically and were added to lapine synovial cell cultures. The resulting conditioned medium was ana lyzed for collagenase, gelatinase, and chondrocyte ac tivating factor (CAF) production. All of the ligaments induced significantly elevated enzyme and CAF production by the synoviocytes, with Xenograft and carbon inducing significantly higher en zyme levels than those of the other five ligaments. Five milligrams of wear particles were injected into the knees of 4 kg to 5 kg rabbits that were analyzed histologically after 14 weeks. Wear particles accumu lated in the periarticular synovial folds and induced modest to severe macrophage infiltration in the syno vium. A hypothetical model explaining the role of artifi cial ligament wear particles in the pathogenesis of arthritis is presented.