Dependency of meniscus mechanical properties on glycosaminoglycan content and its regional variation

The meniscus is a complex structure of collagen fibers which plays a major role in the mechanical function of the knee. Knee joints are subjected to high forces; up to five times body weight during normal activity whereby 75%... [ view full abstract ]

The meniscus is a complex structure of collagen fibers which plays a major role in the mechanical function of the knee. Knee joints are subjected to high forces; up to five times body weight during normal activity whereby 75% is transferred through the meniscus. As a result of these forces and its avascular structure, the meniscus is prone to irreparable damage. Meniscectomy was once a common procedure for damaged menisci, however approaches for meniscus regeneration are now being developed to restore the mechanical function of the meniscus. Therefore, the compressive properties of the meniscus are of paramount importance to provide a design criteria for researchers to develop scaffolds with appropriate properties for meniscus regeneration. Previous studies have been conducted on the bulk compressive properties of the meniscus. However limited studies have examined the meniscus structure function relationship. This study correlates the major constitute of the meniscus extracellular matrix, glycosaminoglycan’s (GAG), and its role on the mechanical properties of the meniscus. Furthermore, to the authors knowledge this is the first study to analyse the GAG distribution and mechanical properties with regards to depth and region within the meniscus. Biopsies were taken from twelve bovine meniscus zones and were analysed for GAG content, phosphate buffered saline (PBS) absorption and mechanical properties. Results showed that the medial zone of the meniscus had a significantly larger quantity of GAG compared to the peripheral zone. The tibial and femoral layers displayed higher quantity of GAG over the middle layer, with no significant difference between central and outer section being observed. These results correlate well with PBS absorption and compressive properties which suggests that the hydrophilic nature of these molecules play a role in the absorption of interstitial fluid which acts to support the meniscus under compressive loads.