Permeation from the synovial fluid as nutritional pathway for the anterior cruciate ligament in rabbits

The anterior cruciate ligament of the knee receives its nutrition from a direct vascular supply and by permeation of nutrients from synovial fluid. In order to quantitate the relative importance of these two routes and to compare the anterior cruciate ligament with the medial collateral ligament, we injected [3H]methyl-glucose as a tracer intravenously or directly into the knee in rabbits. Tracer concentrations in plasma, synovial fluid, the anterior cruciate ligament and the medial collateral ligament were analysed by a pharmacokinetic compartment model developed for this study. The contribution of [3H]methyl-glucose permeation from the synovial fluid was calculated at 59.7% in the anterior cruciate ligament and at 18.1% in the medial collateral ligament. We concluded from these results that the nutrition for the medial collateral ligament, which is an extraarticular structure, is provided mainly by its vascular supply. In contrast, synovial fluid permeation is an important transport route for small molecules for the normal anterior cruciate ligament.