Abstract
The principal goal of this work was to test the hypothesis that the joint should not be viewed as a composite structure consisting of a number of different and distinct connective tissue layers, but rather as an “organ” that is made up of functionally related tissues that share many characteristics
... read more
and reaction patterns. A second aim, more practical in character, was to identify pathology-driven changes in this entity of functionally related tissue layers and in synovial fluid that might be classified as early signs of OA.
To realise the main goals of this thesis, i.e. to determine whether there is indeed a functional connection between articular cartilage, subchondral and trabecular bone, an extensive comparative biochemical analysis was performed to assess the normal biochemical composition in mature animals without signs of disease (Chapter II). The strong influence of biomechanical loading on local tissue characteristics led to the study of two differently loaded sites.
The main question in Chapter III is to what extent the functional adaptation to loading is a generalised phenomenon across all layers in the joint and also whether differences exist in the age at which site differences develop between the organic and inorganic (mineral) components of subchondral or trabecular bone. This area has not been previously explored, but is of great interest in the equine industry given the high incidence of bone-related problems in horses that are strenuously trained at a young age.
Chapter IV compares normal tissue specimens with specimens from horses showing signs of (early) OA. Are these changes more evident or more extensive in one layer than in the other? Without the pretension of providing the definitive answer, it could be expected that, if such differences were to exist, they might at last give an indication on the origin of OA.
In Chapter V the matter of early OA is pursued further. This chapter can be seen as complimentary to the other four given the role of synovial fluid as a reflection of what happens at tissue level.
Chapter VI returns to the tissue level, but uses new and so far unexplored parameters for the detection of pathological processes in the three layers of tissue that make up the load bearing surface of the joint. In this chapter attention is focused on nitrite as a measure for the highly volatile NO, and on nitrotyrosine, a metabolite of NO. The combination of the two may give information on both metabolic and disease status of tissues.
In Chapter VII the key word is load and the crucial question regards the way the horse, or more specifically the equine musculoskeletal system, copes with load. As the last chapter of this thesis, it places the main findings of the work in this perspective. The chapter further tries to relate these findings to other recent work in the horse and in other species, as the general concepts of articular (patho)biology have a much wider application than a single species.
show less
