Experimental Production of Synovitis and Marginal Articular Exostoses in the Knee Joints of Dogs ‡

In osteoarthritis the peripheral secondary changes of synovitis, effusion, stiffness, marginal exostoses, and muscular atrophy are usually responsible for the patient's symptoms, whereas the early primary degeneration of the articular cartilage may be largely asymptomatic. Since the relationship between these two categories is largely unknown, the authors have attempted to produce an experimental model simulating certain aspects of the primary process to determine whether the secondary changes would be produced. It is well known that a considerable amount of cartilage debris is worn away from chrondromalacic articular surfaces.`' Experimental work has shown that intra-articular injections of finely divided hyaline cartilage will produce a fibroblastic and round cell type of synovitis similar to that seen in clinical osteoarthritis."2 A single injection produces mild transient synovitis; repeated injections of autogenous or homologous cartilage once or twice a month for six or seven months resulted in a marked synovitis with increased capsular thickness and moderate muscular atrophy.2 The effects of autogenous and homologous cartilage did not differ greatly except that the latter was less rapidly absorbed. No lesions were noted in cartilage or bone except for needle damage at the site of injection. In the present study, we have repeated the above work of Hulten and Gellerstedt,2 but have given the intraarticular injections of autogenous cartilage homogenate more frequently, and over a longer period of time.