Multi-parameter topographical analysis of the subchondral bone in healthy and osteoarthritic human patellae

Unlike other joints, the PFJ has only recently generated interest in the scientific community. Consequently, the knowledge about any physiological or pathological distribution of both, structural parameters as well as mechanical ones is still sparse. In particular, the distribution of mechanical strength fields across the SBP and a method of evaluation in vivo will be of benefit for a better understanding of the long-term load distribution and the alteration through pathological processes. Regular load distribution could be evaluated, pathologies could be detected and an alteration process could be monitored over time. Apart from the above-mentioned, the trabecular system of the patella has only been investigated on 2D cuttings and requires further investigation. Full detail about the 3D arrangement is still missing. Of special interest is the trabecular arrangement in in dependence to the long-term load intake of the SBP. This way, it could be evaluated how the SBP distributes the load to 14 the inside of the bone and how areas of high and low load intake are structured as sign of adaptation. The changes within the SBP and trabecular structure could provide conclusive information concerning OA of the PFJ and the pathological mechanism it initiates. So far it is understood that the properties of joint cartilage change as to maintain tissue homeostasis. Next to matrix remodelling, the cartilage adapts by cell proliferation and the pressure distribution is altered, however the mechanism of adaptation of the structures beneath the cartilage is not understood. Therefore, we aim to investigate the Osteochondral Unit of the human patella and show that the anatomical architecture represents a direct adaptation to the loading history. The three main investigations will include: • the analyses of mechanical properties of the SBP in regards to its density distribution; • the investigation of the subarticular bone for its structural and numerical parameters of trabecular network; and • the changes occurring in above mentioned systems in degenerated samples