The diagnosis of villous synovitis should not be considered complete without skiagraphy being undertaken to reveal or exclude osteophytic outgrowths. For the subjective symptoms and signs of early osteoarthritis are practically identical with those of villous arthritis, and although the presence of osteoarthritic lesions elsewhere would be suggestive, skiagraphy alone will enable us to effect a differentiation with certainty. Indeed, Bassett Jones and myself are strongly of the opinion that the life history of osteoarthritis involves two stages: (1) a primary or pre-osteophytic phase, often of prolonged duration, whose clinical characteristics are those of villous hypertrophy; (2) a secondary or terminal stage, in which bony and cartilaginous outgrowths make their appearance.
Other symmetrical disorders of the knees that may be wrongly ascribed to gout are hydrarthrosis and gummatous synovitis.
Bilateral Hydrarthrosis.—Given effusion into both knees which is passive, copious, and persistent rather than recurrent, then its possible infective origin must be carefully canvassed. The common sources are gonorrhœa, syphilis, and tubercle. The history or presence of an urethral discharge and detection of the gonococcus will identify the first named. In syphilis the existence of other lesions, the response to Wassermann’s test and specific treatment are the points on which to rely, and in tubercle, the detection of visceral foci and the sero-reaction will give the clue.
As to the intermittent type of hydrarthrosis, the remarkable periodicity in incidence of the effusion will suffice to obviate any possibility of confusion.
Peri-synovial and Peri-bursal Gummata.—Affecting as they do commonly the knee joints of adults, these may, in the absence of a history of infection, be a source of error. The uneven and nodular swelling may quite easily be confounded with uratic deposits. Pain is slight and mobility but little impaired. The presence of neighbouring scars, a positive Wassermann reaction, and a favourable response to anti-syphilitic therapy will clear up the diagnosis.
Chronic Gout of Polyarticular Distribution
The clinical portrait of tophaceous gout when of widespread distribution is one of the most striking to be met with in the whole domain of medicine, but for the broad outlines of the picture presented we would refer the reader to the chapter dealing with the clinical description of chronic articular gout.
In these polyarticular forms the most distinctive joint deformities are those met with in the hands or feet, more particularly the former. The excrescences produced are the outcome of successive uratic deposits. These latter when massive can scarcely be confused with any other disorder, for the superjacent skin, distended by the ever-increasing underlying uratic deposits, becomes thinned and purplish red in hue, and occasionally ulcerates. I have at present in my wards a case of this nature, and the subject hoards up the exuding “chalk” in a small bottle.
Fortunately such marked examples are relatively rare, though easily recognised; but it is the less marked types that occasion difficulty in diagnosis. The point at issue of course is the differentiation of moderate-sized or small tophaceous swellings from bony outgrowths. Frequently the task is impossible of achievement without resorting to puncture, when, if anything can be withdrawn, microscopic examination may reveal the presence of biurate crystals.