If the pain and tenderness be located on the posterior surface of the os calcis, or in the tendo Achillis, the following should be excluded before assigning the trouble to “gout”:—
(1) Post-calcaneal Bursitis.—Inflammation of the bursa lying between the os calcis and the tendo Achillis is not uncommon. It may be uni- or bi-lateral, and in the majority of instances is attributable to violent exercise, or chafing of the heel by ill-fitting boots. The local swelling and tenderness at the site of the inflamed bursa and its aggravation by plantar flexion of the foot will afford a clue to its true nature. (An exostosis projecting from the hinder surface is sometimes a cause of post-calcaneal bursitis.)
(2) Synovitis of the Tendo Achillis.—Symptoms very similar to those above described have been met with in a teno-synovitis of the tendo Achillis, as evidenced by swelling of the sheath, tenderness, and silky crepitus.
Gout in the Sole
There is a wide disposition to regard all painful or unpleasant sensations in the sole of the foot as evidences of “goutiness.” It may be recalled that Strabo, according to Plutarch, apostrophised heat or itching of the feet at night as “the lisping of the gout.” Duckworth, too, emphasised the frequency of this symptom in the gouty, and Sir Charles Scudamore also held heat and dryness of the sole as frequent harbingers of acute attacks. Now, did we but confine our hazards as to gout only to cases marked by heat or itching in the sole, possibly little harm might result; but unfortunately there is a flippant readiness to relegate all obscure pains or abnormal sensations in the sole to the “gouty” category. Needless to say, this is quite unjustifiable. We need not reiterate the bounden necessity of excluding all static foot deformities, but we should in addition recall the various types of plantar neuralgia.
Plantar Neuralgia.—Occasionally, as we have pointed out elsewhere, the pain is of almost unendurable severity. It constitutes one of the types of so-called partial sciatica, the pain and paræsthesia being confined to the plantar nerves. Indeed, pain, numbness, hyperæsthesia, or sweating of the sole are often symptomatic of a definite neuritis. Such may follow typhoid fever or caisson disease, and in this latter be of aggravated type. When we realise that the pain in these cases may be limited to the tips of the toes or the ball of the great toe, we see how readily it may be confused with “gout.” Fortunately plantar neuralgia is exceptionally rare; but even after exclusion of the foregoing causes we should, before pronouncing any such neuralgia to be “gouty,” recollect that plantar neuralgia or hyperæsthesia is very common in alcoholism and hysteria.
Erythromelalgia.—Among the exceptional cases that find their way to spas are examples of this rare disorder. Almost invariably they come under the diagnosis of “gout” or “rheumatism.” When we reflect that in the majority of instances the initial burning pain typical of the disease is located in some part of the sole of one foot, and that the associated redness and vascularity may be delimited to the ball of the great toe, the heel, or outer or inner side of the foot, we see the danger of its being too easily referred to “gout.”
If seen at the zenith of an attack, the severe pain, the local heat, the intense purplish redness, the distension of the veins, and in some instances œdema, how close the resemblance to gout! Precisely also, as in gout, the simulation of a deep-seated inflammatory process is very pronounced. Indeed, in not a few examples of erythromelalgia fruitless incisions have been made. Accordingly in all cases of pain, redness, and swelling in the sole of the foot, we should canvass the possibility that we may be face to face with an instance of erythromelalgia, a disorder which, like gout, is most frequently met with in men of middle age.
In drawing to a close our remarks on the diagnosis of acute gout in the foot, we would emphasise the fact that in all such cases the bare feet should be thoroughly examined. For, apart from infective and traumatic lesions, the frequency with which the various static foot deformities are confused with “gout” is incredibly common. That gout may co-exist with hallux valgus or other distortion we readily admit, but this does not absolve us of our responsibility—correction of the static deformity. Combine this, if you will, with constitutional treatment if there be evidence, i.e., tophi, of a “gouty” diathesis, but, we repeat, correct the mechanical defect. For gout may come and go, but static errors remain. In so doing, the victim will be saved much preventable suffering, and, for aught known to the contrary, the removal of irritation and local congestion may haply minimise the chances of subsequent gouty outbreaks.