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In the present research the joint capsules from 30 knee- and hip joints were his tologically examined and compared to each another. The evaluation based on the anamnesis, the pathologicalanatomical and microbiological results as well as the simultaneous occurrence in several bones. The criteria for the histological evaluation are described and explained in detail. The dogs, comming into the Institute for Veterinary Pathology of the FU Berlin for necropsy, belonged to differentmidle to large seize breeds.The histological examination lead to the result, that the joint capsules of joints with degenerated structures surprisingly often show inflammatory changes, especially in form of lymphoplasmacellular infiltrates. The inflammatory cells are located scattered or in lymph follicles. Remarkablyoften are similar changes occur in several joints of individual dogs. These features could be an indication for an immunological component in the pathogenesis
of degenerative joint diseases.In order to prove this hypothesis, the lymphocytes were differentiated immunhistochemically in a representative part of synovial membranes. It became obvious, that the T-lymphocyte represents the leading inflammatory cell in the reactive synovial membrane, whereas an increase amount of Blymphocytes only occurre in a few individual dogs. The B-lymphocytes are suspected to be of great diagnostic and prognostic value, especially as their presence in the joint capsule is described in connection with rheumatoid arthritis. Their proof of presence in cases of an appropriate suspicion seems to be significant.Beside the above mentioned results, the present investigation material made clear, that kneeand hip joints showed a different inflammatory reaction. This is closely connected to the prevailing type of synovial membrane in the joint. The knee joint consists of an areolic synovial type with a very good blood supply, where as the hip joint represents almost exclusively a fibrose capsule type. The latter is substantially less supplied with blood. Consequently the joint capsule and cartilage of the hip joint react very sensitively upondisturbances, that arise from a reduced blood supply. This explains the chrondroid metaplasia of the joint capsule, which prevails in advanced cases of hip displasia.On the other hand, in the knee joint the inflammatory cell infiltrates dominate because of the better blood supply. The better blood supply enables an easier aggregation of inflammatory mediators and cells, as well as the accumulation of pathogens or immunologically active factors.It becomes obvious in the present work, that an examination of the synovial membrane could provide a further hint for the pathenogenesis of degenerative joint changes. This presupposes a routine taking of synovial membrane samples during surgical operations, to broaden the findings margin and therefore improve the diagnosis in a single animal. The described methods can all be
carried out on formalin fixated synovial membrane preparations, which allows that the sample taking can be accomplished under practice surgery conditions without any graeter effort.