As an aid to the differentiation of gouty from non-gouty forms of arthritis skiagraphy has scarcely fulfilled the somewhat optimistic claims at one time made on its behalf. As to acute gout, radiography reveals nothing abnormal in the bones, though Tousey holds that this of itself at once enables us to exclude osteomyelitis, which, he says, “these cases sometimes resemble.”
Turning now to chronic articular gout, Huber in 1896 drew attention to certain focal areas of rarefaction, or diminished density, in the distal extremities of the phalanges. These localised transparent areas in the bone-ends are discrete, circular, or oval in shape. When located near the edges of the bones, they are of segmental contour, and, viewed in profile, give the appearance of small punched-out holes, simulating syphilitic dactylitis. Despite their proximity to the diseased joints, they apparently do not communicate with the articular cavities.
These bony changes Huber held distinctive of gout, and Koehler, Drinberg, and Jacobsohn and other subsequent writers confirmed Huber’s findings, and, like him, held these areas of rarefaction to be the result of uratic deposits at their sites. Strangeways has dissected bones in which these transparent areas were demonstrated by X-rays. The examination revealed that the bone was definitely excavated, filled with a gelatinous-looking substance, and in advanced cases of gout, moreover, a characteristic deposit of urates clung, as it were, to the margins of the cavities.
Similar focal areas of decreased density were noted by Strangeways in certain cases of rheumatoid arthritis, and both he and Burt found it impossible on the X-ray findings to differentiate between these and gout, i.e., without invoking the aid of clinical data.
Radiographs of the Foot and Hand, showing extensive bony and other changes in long-standing Gout.
Apart from these transparent areas, Wynne many years ago pointed out that small nodes or bony deposits are sometimes met with flanking the sides of the phalanges. More recently Ironside Bruce by radiography has again drawn attention to these bony outgrowths near the extremities of the phalanges (Bruce’s nodes). At first these were thought by Bruce to be composed of urates, but Strangeways from a study of macerated specimens has demonstrated their true bony nature, and also that uratic deposits are not opaque to X-rays, as was formerly thought.
In skiagrams of chronic gout all stages of ankylosis may be seen in the interphalangeal joints. In some it is merely fibrous, in others merging therefrom into bony, and not infrequently true synostosis is observed. Deflections or subluxations are frequent features, due either to the thrust of tophi or small bony outgrowths or to peri-articular contractures.
So much for the skiagraphic findings in chronic gout, and now to discuss their valency as aids to diagnosis of this arthritic disorder. The chief controversy centres around the significance of the focal areas of rarefaction which have been found in the bones of the wrists, hands, ankles, and feet of gouty subjects. Here we may comment on one grave handicap, viz., the lack of certainty as to whether the cases radiographed by different observers were true instances of gouty arthritis.
To justify our expression of doubt we may take, for example, the series reported by Drinberg and Jacobsohn. The said “transparent areas” were present in all the eighteen cases, but the presence of tophi was only established in three. Now, as McClure and McCarty rightly contend, “since the tophus is the only universally accepted pathognomonic sign of gout, for studies of that disease only those patients should be chosen in whom tophi are found, and sodium urate crystals from them microscopically demonstrated.” No one can, I think, gainsay the legitimacy of this stipulation.