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Abstract
Experiments were conducted to study 2 topics. In Part I, studies were undertaken in a logical progression to determine if radionuclide joint imaging could detect degenerative joint disease (DJD) in the canine, and, specifically, if the technique could be used to detect canine hip dysplasia (CHD). In Part II, the objective was to measure diffusion of uncharged molecules in articular cartilage.
There were 3 phases of experimentation for Part I. In Experiment I, 5 skeletally-mature dogs were studied by radionuclide joint imaging and radiographic techniques before the after induction of an experimental induced DJD of the hip joint. The distribution of the bone imaging agent ('99m)technetium methylene diphosphonate was measured by a rectilinear scanner. DJD was induced by an intra-articular injection of papain. At the conclusion, all dogs were euthanized and the hip joints were examined for gross pathological lesions.
In Experiment II, 6 immature dogs were used in another study of papain induced joint disease. The same methods for investigation were followed as in Experiment I. The initial studies were begun when the dogs were 11 weeks of age, the intra-articular injection of papain was made at 16 weeks of age, and the experiment was terminated at 29 weeks of age.
In Experiment III, 32 immature dogs were sequentially studied to detect CHD. Initial studies began when the dogs were 9-12 weeks of age. Studies were discontinued when a dog was considered abnormal radiologically or at an age when the dog was deemed to be unaffected by CHD. Twenty-nine dogs have been subjected to post-mortem pathological examination.
In Part II of this research, the diffusion coefficients of 3 molecules were measured in normal, adult, bovine and equine articular cartilage. The molecules were ('14)C-glucose (180 M.W.), ('3)H-inulin (5000 M.W.), and ('3)H-dextran (20,000 avg. M.W.). Cartilage samples were taken from medial and lateral surfaces of patellae.
The studies were conducted in vitro at 37(DEGREES)C. Labelled molecules were added to Hanks Balanced Salt Solution. Movement of molecules was studied from the solution, across the articular surface, and into the matrix of the cartilage. A semi-infinite solution of the diffusion equation was applied to the data. The interface concentration and the diffusion coefficient were estimated by non-linear regression. Biochemical composition of cartilage was assayed by the use of tests for total hexosamine, uronic acid, and hydroxyproline content. A histological examination was conducted to detect pathological degeneration or autolysis.
In Part I it was concluded that radionuclide joint imaging could be used to detect DJD even in the presence of active growth centers in bone. It was found that canine hip dysplasia could be diagnosed by radionuclide joint imaging, and it was more accurate than the radiologic diagnosis when both were compared to the post-mortem pathologic diagnosis.
In Part II, a new approach to diffusion measurements in cartilage was described. The estimated diffusion coefficients were 4.2, 1.4, and 1.0 x 10('-6) cm('2)/s for glucose, inulin, and dextran respectively. While biochemical composition varied according to the species and site sampled, the diffusion coefficients were unaffected by this variation. The ratio of the diffusion rate in cartilage to the rate in free water was found to be greater for inulin rather than glucose. Diffusion in cartilage was considered to be similar to gel filtration in that large molecules that are partially excluded may move disproportionately faster than smaller molecules.
