#Other Diseases of Bursae# are associated with gonorrhoeal infection, and with rheumatism, especially that following scarlet fever, and are apt to be persistent or to relapse after apparent cure.  In the gouty form, urate of soda is deposited in the wall of the bursa, and may result in the formation of chalky tumours, sometimes of considerable size (Fig. 114).

[Illustration:  FIG. 114.—­Section through Bursa over external malleolus, showing deposit of urate of soda. (Cf.  Fig. 117.)]

Tuberculous disease of bursae closely resembles that of tendon sheaths.  It may occur as an independent affection, or may be associated with disease in an adjacent bone or joint.  It is met with chiefly in the prepatellar and subdeltoid bursae, or in one of the bursae over the great trochanter.  The clinical features are those of an indolent hydrops, with or without melon-seed bodies, or of uniform thickening of the wall of the bursa; the tuberculous granulation tissue may break down into a cold abscess, and give rise to sinuses.  The best treatment is to excise the affected bursa, or, when this is impracticable, to lay it freely open, remove the tuberculous tissue with the sharp spoon or knife, and treat the cavity by the open method.

Syphilitic disease is rarely recognised except in the form of bursal and peri-bursal gummata in front of the knee-joint.

New growths include the fibroma, the myxoma, the myeloma or giant-celled tumour, and various forms of sarcoma.

#Diseases of Individual Bursae.#—­The olecranon bursa is frequently the seat of pyogenic infection and of traumatic or trade bursitis, the latter being known as “miner’s” or “student’s elbow.”

[Illustration:  FIG. 115.—­Tuberculous Disease of Sub-deltoid Bursa.

(From a photograph lent by Sir George T. Beatson.)]

The sub-deltoid or sub-acromial bursa, which usually presents a single cavity and does not normally communicate with the shoulder-joint, is indispensable in abduction and rotation of the humerus.  When the arm is abducted, the fixed lower part or floor of the bursa is carried under the acromion, and the upper part or roof is rolled up in the same direction, hence tenderness over the inflamed bursa may disappear when the arm is abducted (Dawbarn’s sign).  It is liable to traumatic affections from a fall on the shoulder, pressure, or over-use of the limb.  Pain, located commonly at the insertion of the deltoid, is a constant symptom and is especially annoying at night, the patient being unable to get into a comfortable position.  Tenderness may be elicited over the anatomical limits of the bursa, and is usually most marked over the great tuberosity, just external to the inter-tubercular (bicipital) groove.  When adhesions are present, abduction beyond 10 degrees is impossible.  Demonstrable effusion is not uncommon, but is disguised by the overlying tissues.  If