The Biology of Degenerative Joint Disease

THE BIOLOGY OF DEGENERATIVE JOINT DISEASE LEON SOKOLOFF* ... the inciting conditions ofthe disease must be sought for separately for each diseased joint, for the general or systemic influences in osteoarthritis ... are either rare or seemingly unimportant.—D. H. Collins [i] The woods decay, the woods decay and fidi, The vapours weep their burthen to the ground, Man comes and tills the field and lies beneath, And after many a summer dies the swan. Tennyson (Tithonus) "The Kharkov Veterinary Institute accepted a work by V. N. Zemlyansky, presented for the degree ofDoctor ofBiology. Its title was: 'Concerning Certain Patterns in the Biomechanics ofthe Gait and Carriage ofthe Horse as Factors Influencing Its Basic Productivity .' [Stir in the Hall. Laughter.] These are the conclusions the author ofthis doctoral dissertation arrived at: '(i) The rapidity ofa horse's movement, one ofthe indices of its work usefulness, depends chiefly on the length and frequency of the stride. [Stir in the hall. Laughter.] (2) Trotters at various stages oftraining have strides with the following phases: at high speed—a hold phase, a shift phase and two phases offree suspension .' [Stir in the hall. Laughter.] Apparently, the author of the dissertation was awarded a Doctor's degree, and our statistics on the number ofscientists in theSoviet Union were increased by one. I don't know—let the scientists not condemn me for this—perhaps this 'suspension' is needed but I am convinced that a 'scientific' work like this one will do no good." [Applause.]—N. S. Khrushchev [2] The purpose ofthis essay is to inquire whether there may be important systemic contributions to the development ofdegenerative joint disease. Osteoarthritis is generally regarded as a wear and tear phenomenon, and presents well many ofthe theoretical difficulties one encounters in trying to clarify the nature ofsenescence ofanimal tissues. Although an affirmative answer to the question posed may ultimately not be forthcoming, pessimism at the present time is premature. As the subject of increasing study, it seems desirable to distinguish between some assumptions, often poorly founded, and what actually is known about the genesis of the disease. * Laboratory ofExperimental Pathology, National Institute ofArthritis and Metabolic Diseases Bethesda 14, Md. 94 Leon Sokoloff· The Biology ofDegenerativeJoint Disease Perspectives in Biology and Medicine · Autumn 1963 I. Comparative Pathology This exceedingly common disorder occurs not only in man but in many mammalian species regardless oftheir position in the taxonomic scale [3]. The lesions have been recorded in fossil reptiles as far back as the Mesozoic period [4], and their frequency may perhaps be gauged by the fact that changes ofthis sort have been found in six ofeleven extant specimens of caudal vertebrae ofthe giant sauropod dinosaur Diplodocus [5]. In ancient man, too, there is ample paleontologie evidence of osteoarthritis. Advanced cervical spondylosis was present in the La Chapelle-aux-Saints Neanderthal man [6]. Vertebral osteophytosis and ankylosis, presumably oftraumatic-degenerative type, occur with some frequency in animals that swim (cetaceans) [7] as well as in those that bear weight on their extremities. It would be ofsome interest to know whether species that fly or hang rather than walk develop osteoarthritis. Professor John S. Hall of Albright College has graciously permitted me to examine two little brown bats, recaptured in the wild nineteen years after having been banded [8]; no osteoarthritis was present in them. Little is known of the occurrence of articular degeneration in nonmammalian vertebrates. Birds do not ordinarily achieve longevity except under protected conditions. In 48 captive birds ranging in age from 4 to 32 years, there were 15 instances ofapparently primary osteoarthritis [9]. Although these avian lesions were much less conspicuous than in most mammals, the significance ofthis finding is partly vitiated by two conditions : the potential longevity of the birds may theoretically be considerably greater than was actually attained in this material, and normal locomotion was restricted in most instances by pinioning the wings. Isolated instances ofdegenerativejoint disease have been recorded in contemporary reptiles, but the lesions have not been studied systematically in these particularly long-lived species. Osteoarthritis in species other than man is ofmore than academic interest since it causes a considerable loss in several branches oflivestock commerce . The medical literature has recently been graced by...