ligature from within outward. In Sir Astley Cooper's ligation the inguinal canal is laid open.

The Gluteal Artery.-This vessel is a continuation of the posterior division of the internal iliac. It emerges from the pelvis at the upper border of the pyriformis muscle. It rests upon the gluteus minimus and divides into three branches, and is covered by the gluteus maximus muscle. The superior gluteal nerve lies inferior to the artery (Fig. 64).

Ligation.-Patient is prone. The surgeon stands to the outside. The incision corresponds to a line drawn from the posterior superior iliac spine to the upper border of the great trochanter. Divide the skin, fascia, gluteus maximus muscle, and fascia over the gluteus medius, retract the gluteus medius upward. Feel for the great sacrosciatic foramen, and at this point the artery is found above the pyriformis muscle. Clear the vessel and pass the needle from below upward (see Kocher).

The Sciatic Artery.-This artery is the larger of the terminal branches of the anterior division of the internal iliac artery. It passes to the lower portion of the great sacrosciatic foramen, lying back of the internal pudic artery, and resting upon the sacral plexus and pyriformis muscle (Gray). It leaves the pelvis between the pyriformis and coccygeus muscles and passes downward between the ischial tuberosity and great trochanter. It is covered by the gluteus maximus muscle, rests upon the gemelli, internal obturator and quadratus femoris muscles, and has the great sciatic nerve external to it, and the small sciatic nerve external and posterior (Fig. 64).

Ligation.-Patient lies prone. Surgeon stands to outside. Incision "corresponds to the middle two-thirds of a line extending from the posterior inferior iliac spine to the base of the great trochanter." Cut the skin, fat, fascia, and gluteus maximus muscle. Find the artery at the lower border of the pyriformis muscle and trace it to its point of emergence from the pelvis. Pass the ligature from without inward.

Internal Pudic Artery.-Is one of the terminal branches of the anterior trunk of the internal iliac. It runs to the lower margin of the great sacrosciatic foramen, and leaves the pelvis between the pyriformis and coccygeus muscles, crosses the ischial spine and again enters the pelvis by the lesser sacrosciatic foramen. The vessel is accompanied by the internal pudic nerve (Fig. 64).

Ligation. Position and incision as in ligation of sciatic. 1 Kocher's Operative Surgery, by Stiles.

The artery is found below the ischial spine. Pass the needle. from below upward to avoid the nerve.

XIX. DISEASES AND INJURIES OF BONES AND

JOINTS.

1. DISEASES OF THE BONES.

Atrophy of bone is a diminution in the amount of bony matter without change in osseous structure. It arises from want of use (as seen in the wasting of the bone of a stump) or from pressure (as seen in the destruction of the sternum by an aneurysm of the aorta). Eccentric atrophy is the thinning of a long bone from within, the outer surface being unchanged. It is usually a senile change. Concentric atrophy means a thinning of the outer surface of the shaft, causing a lessened diameter. It is usually linked with eccentric atrophy.

Hypertrophy of bone may be due to increased bloodsupply (as is seen in chronic epiphyseal inflammation), the bone growing much more than does its fellow. It may arise from excessive use or from strain, as is seen in the increased size of the fibula when the tibia is congenitally absent (Bowlby).

Tumors of Bone.-Bones give origin to both innocent and malignant tumors. Myeloid sarcoma takes origin in the endosteum and expands the bone. The fasciculated sarcoma is a periosteal growth. Besides these growths we find osteomata, chondromata, and secondary deposits of cancer and sarcoma. Primary cancer of bone does not exist. A bone may become cystic, and occasionally the cysts are due to hydatids. Gummata are the commonest growths found springing from bone.

Actinomycosis of Bone.-Most usual in the jaw, but may attack the orbit, ribs, sternum, or limbs (p. 183).

Tubercle of Bone.-Tends especially to appear in the cancellous ends of long bones. Is apt to caseate and destroy large amounts of bone. The bone does not sclerose, but undergoes alterations of an osteoporotic nature (see p. 154). Osteitis, Periostitis, and Osteoperiostitis.-Osteitis, or inflammation of bone, may be due to traumatism, to a constitutional malady or diathesis, to the extension of inflammation from some other structure, or to infection. In inflammation of bone the exudation flows into the Haversian canals and spaces and the canaliculi, the corpuscles of

the exudate and the bone-corpuscles proliferate, embryonic tissue forms, the bone undergoing thinning (rarefaction), not because of pressure, but because of absorption by voracious leukocytes and osteoclasts. This process of rarefaction enlarges all the bony spaces, and by destroying septa throws many of the spaces into one. If the surface of a bone inflames, the periosteum will more or less be separated by the exudation and the bone will be covered with little pits or Inflamed bone is so soft that it can readily be cut

with a knife.

In

Osteitis may terminate in resolution or it may terminate in sclerosis, the exudate being converted first into fibrous tissue and next into dense bone with only a few small cancellous spaces. If the exudation is under the periosteum, the bone will be thickened at this point, bone stalactites marking the points of passage of the vessels. Osteitis may terminate in suppuration, this condition being known as "caries. tubercular osteitis caseation of the inflammatory products is very apt to arise (tubercular or strumous caries). Acute osteitis may terminate in necrosis. Osteitis is usually associated with more or less periostitis. A simple acute periostitis without involvement of the bone can arise from traumatism, but in all severe cases of periostitis, in all chronic cases, in all cases due to syphilis, rheumatism, measles, scarlatina, or enteric fever the bone is involved at the same time or subsequently. In syphilitic states gummatous degeneration frequently ensues.

Symptoms of Osteitis and Osteoperiostitis.-As a chronic process the symptoms of osteitis are commonest in the femur. Its history usually exhibits a record of a cold or an injury. Pain is severe, boring or aching in character, deepseated, worse at night, and aggravated by a dependent position of the part. The symptoms closely resemble those of periostitis, with which disease it is almost sure to be linked. Tenderness exists on percussion, and sometimes on pressure. Subperiosteal swelling, fusiform in shape, is noted; cutaneous. edema and discoloration are observed if a superficial bone be involved. In syphilis, atrophic osteitis may attack the cranial bones and produce softening or even perforation, or osteophytic osteitis may arise, exostoses being formed. Osteoperiostitis may be acute or chronic, circumscribed or diffused, and may terminate in resolution, organization, or suppuration. It arises from cold, blows, wounds, strains, the spread of adjacent inflammation, specific febrile maladies, pyogenic infection, syphilis, rheumatism, or tubercle. The

symptoms are pain (which is worse at night and which is aggravated by motion, pressure, or a dependent position), swelling, edema, and discoloration of the soft parts. Pain in the syphilitic form is not so severe as in other varieties. Acute necrosis or diffuse periostitis, a septic inflammation of bone and periosteum, is commonest in boys about the age of puberty. It is usually due to cold, a specific fever, or injury, and generally affects the tibia or femur; the symptoms locally are severe; redness, swelling, and pain are marked; constitutionally there are rigors, fever, or convulsions. Necrosis is apt to result. Pyemia is common. Some fever always exists. In simple acute periostitis a swelling is felt upon the osseous surface. The swelling is firmly fixed and is very tender, but the bone itself is not enlarged. There is some local heat, discoloration, often fever, and the patient complains of an aching pain, which is worse at night.

Treatment of Osteitis and Osteoperiostitis.-In syphilitic forms the treatment consists of rest, elevation of the part, the local use of iodin and mercurial ointment, and bandaging. Specific treatment is by the stomach or hypodermatically. Operation is rarely justifiable. In other forms, if the case be recent and severe, put the patient to bed, place the limb in a splint and elevate it, apply leeches, cold, and lead-water and laudanum, use a bandage, and order salines and iodid of potassium. Morphin is used for pain. If these means fail, order counterirritation by iodin and blue ointment or blisters, and use heat locally. In severe cases take a tenotome and slit the periosteum subcutaneously to relieve tension; this procedure often instantly relieves the pain. Some cases demand a longitudinal osteotomy, which is performed by taking Hey's saw and dividing the bone. longitudinally into the medullary canal. If pus forms, drain

at once.

Diffuse osteoperiostitis requires early and free incisions, antiseptics, drainage, rest and elevation of the limb, and strong supporting and stimulating treatment. Amputation is sometimes demanded, as when the patient grows weaker and weaker even after incision, and when a joint is seriously involved. If the necrosis affects the entire shaft, which separates from its epiphyses, and new bone has not yet formed from the periosteum, make a subperiosteal resection of the shaft.

Chronic periostitis is usually syphilitic. A node is a chronic inflammation of the deep periosteal layers. Nodes occurring early in the secondary stage remain soft and soon

pass away, but those occurring two years or more after infection are apt to cause a bony deposit. A node may suppurate, leaving a sinus at the bottom of which is a piece of dead bone. Gumma of the periosteum is one form of node which is apt to produce caries or necrosis.

Osteoplastic periostitis accompanies chronic osteitis and causes the deposit of new bone which undergoes sclerosis. The chief symptom is aching pain, which is worse when warm in bed, and is aggravated by damp and wet. A swelling is found at the seat of pain (often over the tibia, ulna, clavicle, or sternum). The soft parts are uninflamed and move freely unless softening or suppuration has occurred. Tenderness is manifest.

Treatment. For the nodes of early syphilis use mercurial treatment; for the nodes of late syphilis give mercury and large advancing doses of iodid of potassium. Blisters, blue ointment, and iodin used locally, and subcutaneous division of periosteum, are of value. If suppuration occurs, open antiseptically.

It

Abscess of bone is due to tubercular infection. is always chronic, never acute. A very acute inflammation, such as is induced by pyogenic organisms, causes acute necrosis rather than an acute abscess. After a chronic abscess begins mixed infection may take place, the seat of abscess being a point of least resistance. Chronic abscess of bone was first described by Sir Benjamin Brodie, and is often called "Brodie's abscess." It occurs in the cancellous structure of the ends of bones-usually in the head of the tibia, sometimes in the femur or humerus. The cause of bone-abscess is injury which induces osteitis; bonerarefaction forms a cavity, the inflammatory products caseate and sometimes suppurate, and the surrounding bone thickens and hardens because of growth from the periosteum. The abscess is apt to break into a joint, as the jointsurface is not covered by periosteum and no barrier of bone is there formed. Brodie's abscess may induce necrosis.

Symptoms. The symptoms are like those of osteoperiostitis, only they are localized and persistent. These symptoms are thickening of bone and soft parts, edema and discoloration of skin, tenderness, constant pain (subject to violent exacerbations and made worse by motion, pressure, or a dependent position), and attack after attack of synovitis in the nearest joint. Fever and sweats may be noted.

Treatment. In treating bone-abscess, trephine the bone