The enthesis describes the anatomic site where bone and tendon join. Contractile forces of the muscle are transmitted to the bone and skeletal system. The anchorage of the tendon withstands high forces that exceed a multiple of the body weight under varying angles. The goal of the project is to investigate the microstructure and force dependent deformation of the tissue.
We will first screen for a reproducible way of labeling collagen fibers in combination with a nuclear stain. We will image how cells and collagen fibers are distributed in the enthesis and neighboring tissue in three dimensions. Here, confocal microscopy and nanoscopy (STED) will be employed to cover the range between 500 Dm down to 50 nm.
In a second step, we compare the structure of the tissue before and after force application to the tendon. From these measurements, we will gain a clearer picture of how entheses manage to stay intact and do their job under repetitive and high load applied in various angles.
From preliminary experiments we hypothesize that the tenocyte columns are surrounded by a tube of collagen fibers, which enable a very effective force transduction mechanism. This will be the basis for the development of quantitative mechanical models, which may lead to important implications for the treatment of enthesiopathies or reconstructive surgery, with improvements for the fixation of tendons to endoprosthesis. The unraveled force transduction mechanisms could also result in the development of new composite materials outside the medical field.