#Tuberculous Disease of Tendon Sheaths.#—­This is a comparatively common affection, and is analogous to tuberculous disease of the synovial membrane of joints.  It may originate in the sheath, or may spread to it from an adjacent bone.

The commonest form—­hydrops—­is that in which the synovial sheath is distended with a viscous fluid, and the fibrinous material on the free surface becomes detached and is moulded into melon-seed bodies by the movement of the tendon.  The sheath itself is thickened by the growth of tuberculous granulation tissue.  The bodies are smooth and of a dull-white colour, and vary greatly in size and shape.  There may be an overgrowth of the fatty fringes of the synovial sheath, a condition described as “arborescent lipoma.”

The clinical features vary with the tendon sheath affected.  In the common flexor sheath of the hand an hour-glass-shaped swelling is formed, bulging above and below the transverse carpal (anterior annular) ligament—­formerly known as compound palmar ganglion.  There is little or no pain, but the fingers tend to be stiff and weak, and to become flexed.  On palpation, it is usually possible to displace the contents of the sheath from one compartment to the other, and this may yield fluctuation, and, what is more characteristic, a peculiar soft crepitant sensation from the movement of the melon-seed bodies.  In the sheath of the peronei or other tendons about the ankle, the swelling is sausage-shaped, and is constricted opposite the annular ligament.

The onset and progress of the affection are most insidious, and the condition may remain stationary for long periods.  It is aggravated by use or strain of the tendons involved.  In exceptional cases the skin is thinned and gives way, resulting in the formation of a sinus.

Treatment.—­In the common flexor sheath of the palm, an attempt may be made to cure the condition by removing the contents through a small incision and filling the cavity with iodoform glycerine, followed by the use of Bier’s bandage.  If this fails, the distended sheath is laid open, the contents removed, the wall scraped, and the wound closed.

A less common form of tuberculous disease is that in which the sheath becomes the seat of a diffuse tuberculous thickening, not unlike the white swelling met with in joints, and with a similar tendency to caseation.  A painless swelling of an elastic character forms in relation to the tendon sheath.  It is hour-glass-shaped in the common flexor sheath of the palm, elongated or sausage-shaped in the extensors of the wrist and in the tendons at the ankle.  The tuberculous granulation tissue is liable to break down and lead to the formation of a cold abscess and sinuses, and in our experience is often associated with disease in an adjacent bone or joint.  In the peronei tendons, for example, it may result from disease of the fibula or of the ankle-joint.