Energy storing tendons such as the equine superficial digital flexor tendon (SDFT) stretch and recoil with each stride and therefore require a high degree of compliance compared to tendons with a purely positional function, such as the equine common digital extensor tendon (CDET). This extra extensibility is provided by a specialised interfascicular matrix (IFM), which provides greater sliding and recoil between adjacent fascicles in energy storing tendons. However, the composition of the IFM remains largely undefined. We hypothesised that the IFM in the SDFT has a distinct composition, with a greater abundance of proteoglycans and elastin which facilitate extension and recoil. Transverse and longitudinal sections were cut from the mid-metacarpal regions of SDFTs and CDETs from 5 horses aged 3–7 years. Sections were stained using Alcian blue/Periodic acid Schiff to detect proteoglycans, elastic Van Giesson's to detect elastin, and immunohistochemistry was performed using antibodies for decorin, biglycan, fibromodulin, lumican and lubricin. Resultant images were graded by blinded observers to assess staining intensity in the IFM and fascicular matrix (FM), and statistical significance determined using ANOVA.Introduction
Materials and Methods
