Oertzenweg 19 b
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From 1997 to 1999, at the clinic and polyclinic for small domestic animals at the Free University Berlin (Germany), 74 stifle joints of 37 dogs of different breed, age and sex, were examined. The clinical degrees of patellar luxation of the pelvic limbs were determined. Lateral radiographs were made with a microfocus X-ray tube using the direct magnification technique for an indirect evaluation of the trochlear depth and for measuring the patellar thickness. The measured parameters on the microfocus radiographs were used to figure out the quotient of the trochlear depth and the patellar thickness. The Q-angle was measured on ventrodorsal pelvic radiographs. The results of the measured parameters were compared with the clinical degrees of patellar luxation. While the results of the Q-angle corresponded with previously reported values, there was no agreement with the literature in relation to the values of the quotient of trochlear depth and patellar thickness. In this work, the ascertained quotients were much lower than those reported in the existing literature. A definite relation between trochlear depth and the clinical degrees of patellar luxation could not be established. However, it was possible to explain patellar instability in dogs with congenital unilateral luxation by the indirect evaluation of the trochlear depth in combination with the Q-angle. In consideration of the clinical examination, both parameters make a pre-operative planning of the surgical corrections at the skeleton possible, which might lead to a better prognosis.