For the rest, attention to the following points will prove helpful in enabling us to differentiate clinically between gouty arthritis and other chronic joint disorders attended by deformities:—
(1) Tophi when of recent incidence are soft, and when of long standing are never so dense or so hard as bony outgrowths.
(2) The overlying skin is thin, and through its substance the subjacent white concretions may sometimes be discerned. It may be adherent, or the seat of ulcers.
(3) Uratic deposits are not located exactly at the level of the articulation. They do not adapt themselves to the contour or shape of the bone-ends.
(4) Unlike osseous growths, they may be slightly movable in lateral directions.
(5) Tophi may soften or disappear after exacerbations of arthritis.
Differential Diagnosis
The conditions likely to be confused with chronic polyarticular gout are osteoarthritis, rheumatoid arthritis, and the multiple arthropathies met with in affections of the central nervous system.
Osteoarthritis
Its chief characteristics may be summarised as follows:—It is a disease rarely met with under forty years of age. The mode of onset is generally insidious, never really acute. In this respect it contrasts with gout, the initial outbreak of which is invariably acute. Osteoarthritis attacks both sexes equally. Although it may be polyarticular, its specific tendency is towards a mono- or, more accurately speaking, oligo-articular distribution, with no marked leaning to symmetry. It has a pronounced predilection for attacking the hip, the shoulder, and the spine—sites rarely, if ever, attacked by gout.