In all of these conditions, examination of the bones with the X-rays gives valuable information and often disclose unsuspected metastases.

Cancer of Bone resulting from Direct Extension from Soft Parts.—­In this group there are also two clinical types.  The first is met with in relation to epithelioma of a mucous surface—­for example, the palate, tongue, gums, antrum, frontal sinus, auditory meatus, or middle ear.  They will be described under these special regions.

The second type is met with in relation to epithelioma occurring in a sinus, the sequel of suppurative osteomyelitis, compound fracture, or tuberculous disease.  The patient has usually had a discharging sinus for a great number of years:  we have known it to last as many as fifty.  The epithelioma originates at the skin orifice of the sinus, and spreads to the bone and into its interior, where the progress of the cancer is resisted by dense bone, which obliterates the medullary canal.  Although its progress is slow, the infiltration of the bone is usually more extensive than appears externally.  It is recognised clinically by the characteristic cauliflower growth at the orifice of the sinus, and by the offensive nature of the discharge.  A similar epithelioma may arise in connection with a chronic ulcer of the leg.  The cancer may infect the femoral lymph glands.  The operative treatment is influenced by the extent of the disease in the soft parts overlying the bone, and consists in wide removal of the diseased tissues and resection of the bone, or in amputation.

#Cysts of Bone.#—­With the exception of hydatid cysts, cysts in the interior of bone are the result of the liquefaction of solid tissue; this may be that of chondroma, myeloma, or sarcoma, but more commonly of the marrow in osteomyelitis fibrosa.

CHAPTER XXI

DISEASES OF JOINTS

Definition of terms—­Ankylosis.  DISEASES:  Errors of
    development—­Bacterial diseases:  Pyogenic; Gonorrhoeal;
    Tuberculous; Syphilitic; Acute rheumatism—­Diseases
    associated with certain constitutional conditions:  Gout; Chronic
    articular rheumatism; Arthritis deformans;
    Haemophilia—­Diseases associated with affections of the nervous
    system:  Neuro-arthropathies; Charcot’s disease—­Hysterical or
    mimetic affections of joints—­Tumours and cysts—­Loose bodies.

#Definition of Terms.#—­The term synovitis is applied to any reaction which affects the synovial membrane of a joint.  It is usually associated with effusion of fluid, and this may be serous, sero-fibrinous, or purulent.  As the term synovitis merely refers to the tissue involved, it should always be used with an adjective—­such as gouty, gonorrhoeal, or tuberculous—­which indicates its pathological nature.