Lesions of Bone in Inherited Syphilis.—Craniotabes, in which the flat bones of the skull undergo absorption in patches, was formerly regarded as syphilitic, but it is now known to result from prolonged malnutrition from any cause. Bossing of the skull resulting in the formation of Parrot's nodes is also being withdrawn from the category of syphilitic affections. The lesions in infancy—epiphysitis, bossing of the skull, and craniotabes—have been referred to in the chapter on inherited syphilis.

Epiphysitis or Syphilitic Perichondritis.—The first of these terms is misleading, because the lesion involves the ossifying junction and the shaft of the bone, and the epiphysis only indirectly. The young bone is replaced by granulation tissue, so that large clear areas are seen with the X-rays. The symptoms are referred to the joint, because it is there that the muscles are inserted and drag on the perichondrium when movement occurs; swelling is most marked in the vicinity of the joint, and it may be added to by effusion into the synovial cavity. The baby, usually under six months, is noticed to be feverish and fretful and to cry when touched. The mother discovers that the pain is caused by moving a particular limb, usually the arm, as the humerus, radius, and ulna are the bones most commonly affected; the limb, moreover, hangs useless at the side as if paralysed, and the condition was formerly described as syphilitic pseudo-paralysis.

The lesions met with later correspond to those of the tertiary period of the acquired disease, but as they affect bones which are still actively growing, the effects are more striking. Gummatous disease may come and go over periods of many years, with the result that the external appearance and architectural arrangement of a long bone come to be profoundly altered. In the tibia, for example, the shaft is bowed forward in a gentle curve, which is compared to the curve of a sabre—"sabre-blade" deformity (Fig. 132). The diffuse thickening all round the bone obscures the sharp margins so that the bone becomes circular in section and the anterior and mesial edges are blunted, and the comparison to a cucumber is deserved. In some cases the tibia is actually increased in length as well as in girth.



The contrast between the grossly enlarged and misshapen tibia and the normal or even attenuated fibula is a striking one.

Treatment is carried out on lines similar to those recommended in the acquired disease. When curving of the tibia causes disability in walking, the bone may be straightened by a cuneiform resection.

Syphilitic dactylitis is met with chiefly in children. It may affect any of the fingers or toes, but is commonest in the first phalanx of the index-finger or of the thumb. Several fingers may be attacked at the same time or in succession. The lesion consists in a gummatous infiltration of the soft parts surrounding the phalanx, or a gummatous osteomyelitis, but there is practically no tendency to break down and discharge, or to the formation of a sequestrum as is so common in tuberculous dactylitis.

The finger becomes the seat of a swelling, which is more evident on the dorsal aspect, and, according to the distribution and extent of the disease, it is acorn-shaped, fusiform, or cylindrical. It is firm and elastic, and usually painless. The movements are impaired, especially if the joints are involved. In its early stages the disease is amenable to anti-syphilitic treatment, and complete recovery is the rule.

HYDATID DISEASE

This rare disease results from the lodgment of the embryos of the taenia echinoccus, which are conveyed to the marrow by the blood-stream. The cysts are small, usually about the size of a pin-head, and they are present in enormous numbers scattered throughout the marrow. The parts of the skeleton most often affected are the articular ends of the long bones, the bodies of the vertebrae, and the pelvis.

As the cysts increase in number and in size, the framework of the bone is gradually absorbed, and there result excavations or cavities. The marrow and spongy bone first disappear, the compact tissue then becomes thin, and pathological fracture may result. The bone becomes expanded, and the cysts may escape through perforations into the surrounding cellular tissue, and when thus freed from confinement may attain considerable dimensions. Suppuration from superadded pyogenic infection may be attended with extensive necrosis, and lead to disorganisation of the adjacent joint.

Clinical Features.—The patient complains of deep-seated pains. In superficial bones, such as the tibia, there is enlargement, and it may be possible to recognise egg-shell crackling, or unequal consistence of the bone, which is hard in some parts, and doughy and elastic in others. The disease may pursue an indolent course during months or years until some complication occurs, such as suppuration or fracture. With the occurrence of suppuration the disease becomes more active, and abscesses may form in the soft parts and in the adjacent joint. In the vertebral column, hydatids give rise to angular deformity and paraplegia. In the pelvis, there is usually great enlargement of the bones, and when suppuration occurs it is apt to infect the hip-joint and to terminate fatally.

Examination with the X-rays shows the characteristic excavations of the bone caused by the cysts. The disease is liable to be mistaken for central tumour, gumma, tuberculosis, or abscess of bone.

The treatment consists in thorough eradication of the parasite by operation. The bone is laid open and scraped or resected according to the extent of the disease, and the raw surfaces swabbed with 1 per cent. formalin. In advanced cases complicated with spontaneous fracture or with suppuration, amputation affords the best chance of recovery.

The lesions in the bones resulting from actinomycosis and from mycetoma, have been described with these diseases.

CONSTITUTIONAL DISEASES ATTENDED WITH LESIONS IN THE BONES

These include rickets, scurvy-rickets, osteomalacia, ostitis deformans, osteomyelitis fibrosa, fragilitas ossium, and diseases of the nervous system.

RICKETS

Rickets or rachitis is a constitutional disease associated with disturbance of nutrition, and attended with changes in the skeleton. The disease is most common and most severe among the children of the poorer classes in large cities, who are improperly fed and are brought up in unhealthy surroundings. There is evidence that the most important factors in the causation of rickets are ill-health of the mother during pregnancy, and the administration to the child after its birth of food which is defective in animal fat, proteids, and salts of lime, or which contains these in such a form that they are not readily assimilated. The occurrence of the disease is favoured, and its features are aggravated, by imperfect oxygenation of the blood as the result of a deficiency of fresh air and sunlight, want of exercise, and by other conditions which prevail in the slums of large towns.

Pathological Anatomy.—The most striking feature is the softness (malacia) of the bones, due to excessive absorption of osseous tissue, and the formation of an imperfectly calcified tissue at the sites of ossification. The affected bones lose their rigidity, so that they are bent under the weight of the body, by the traction of muscles, and by other mechanical forces.

The periosteum is thick and vascular, and when detached carries with it plates and spicules of soft porous bone. The new bone may be so abundant that it forms a thick crust on the surface, and in the flat bones of the skull this may be heaped up in the form of bosses or ridges resembling those ascribed to inherited syphilis.

In the epiphysial cartilages and at the ossifying junctions, all the processes concerned in ossification, excepting the deposition of lime salts, occur to an exaggerated degree. The cartilage of the epiphysial disc proliferates actively and irregularly, so that it becomes softer, thicker, and wider, and gives rise to a visible swelling, best seen at the lower end of the radius and lower end of the tibia, and at the costo-chondral junctions where the series of beaded swellings is known as the "rickety rosary."

The ossifying zone is increased in depth; the marrow is abnormally vascular; and the new bone that is formed is imperfectly calcified. The result is that the bones may never attain their normal length, and they remain stunted throughout life as in rickety dwarfs (Fig. 133), or the shafts may grow unequally and come to deviate from their normal axes as in knock-knee and bow-knee.



These changes are well brought out in skiagrams; instead of the well-defined narrow line which represents the epiphysial cartilage, there is an ill-defined, blurred zone of considerable depth.

In the shafts of the long bones, owing to the excessive absorption of bone, the cortex becomes porous, the spongy bone is rarefied, and the bones readily bend or break under mechanical influences. When the disease is arrested, a process of repair sets in which often results in the bones becoming denser and heavier than normal. In the flat bones of the skull, the absorption may result in the entire disappearance of areas of bone, leaving a membrane which dimples like thin cardboard under the pressure of the finger—a condition known as craniotabes.

Changes in the Skeleton before the Child is able to walk.—The fontanelles remain open until the end of the second year or longer, and the frontal and parietal eminences are unduly prominent. There is sometimes hydrocephalus, and the head is characteristically enlarged. The jaws are altered so that while the upper jaw is contracted into the shape of a V, the lower jaw is square instead of rounded in outline, and the teeth do not oppose one another. In the thorax, the chief feature may be the beading at the costo-chondral junctions, principally of the fifth and sixth ribs or its walls may be contracted, particularly if respiration is interfered with as a result of bronchial catarrh or adenoids. The contraction may take the form of a vertical groove on each side, or of a horizontal groove at the level of the upper end of the xiphi-sternum; when the sternum and cartilages form a projection in front, the deformity is known as "pigeon-breast."

The spine may be curved backwards—kyphosis—throughout its whole extent or only in one part; or it may be curved to one side—scoliosis.

In the limbs, the prominent features are the deficient growth in length of the long bones, the enlargements at the epiphysial junctions, and the bending, and occasional greenstick fracture, of the shafts. The degree of enlargement of the epiphysial junctions is directly proportionate to the amount of movement to which the bone is subjected (John Thomson). The curves at this stage depend on the attitude of the child while sitting or being carried—for example, the arm bones become bent in children who paddle about the floor with the aid of their arms; and in a child who lies on its back with the lower limbs everted, the weight of the limb may lead to curvature of the neck of the femur—coxa vara. The clavicle or humerus may sustain greenstick fracture from the child being lifted by the arms; the femur, by a fall. From the extreme laxity of the ligaments, the joints can be moved beyond the normal limits, and the child is often observed to twist its limbs into abnormal attitudes.

In Children who have walked.—In these children the most important deformities occur in the spine, pelvis, and lower extremities, and result for the most part from yielding of the softened bones under the weight of the body. Scoliosis is the usual type of spinal curvature, and in extreme cases it may lead to a pronounced form of hump-back. The pelvis may remain small (justo-minor pelvis), or it may be contracted in the sagittal plane (flat pelvis); when the bones are unusually soft, the acetabular portions are pushed inwards by the femora bearing the weight of the body, and the pelvis assumes the shape of a trefoil, as in the malacia of women. The shaft of the femur is curved forwards and laterally; the bones of the leg laterally as in bow-leg, or forwards, or forwards and laterally just above the ankle. The deformities at the knee (genu valgum, genu varum, and genu recurvatum), and at the hip (coxa vara), will be described in the volume dealing with the Extremities.

The majority of cases seen in surgical practice suffer from the deformities resulting from rickets rather than from the active disease. The examination of a large series of children at different ages shows that the deformities become less and less frequent with each year. Those who recover may ultimately show no trace of rickets, and this is especially true of children who grow at the average rate; in those, however, in whom growth is retarded, especially from the fifth to the seventh year, the deformities are apt to be permanent. It may be noted that the scoliosis due to rickets has little tendency towards recovery.

Treatment.—The treatment of the disease consists in regulating the diet, improving the surroundings, and preventing deformity. Phosphorus in doses of 100th grain may be given dissolved in cod-liver oil, and preparations of iron and lime may be added with advantage. To avoid those postures which predispose to deformities, the child should lie as much as possible. In the well-to-do classes this is readily accomplished by the aid of a nurse and the use of a perambulator. In hospital out-patients the child is kept off its feet by the use of a light wooden splint applied to the lateral aspect of each lower extremity, and extending from the pelvis to 6 inches beyond the sole.

When deformities are already present, the treatment depends upon whether or not there is any prospect of the bone straightening naturally. Under five years of age this may, as a rule, be confidently expected; the child should be kept off its feet, and the limbs bathed and massaged. In children of five or six and upwards, the prospect of natural straightening is a diminishing one, and it is more satisfactory to correct the deformity by operation. In rickety curvature of the spine, the child should lie on a firm mattress, or, to allow of its being taken into the open air, upon a double Thomas' splint extending from the occiput to the heels; the muscles acting on the trunk should be braced up by massage and appropriate exercises.

Late Rickets or Rachitis Adolescentium is met with at any age from nine to seventeen, and is generally believed to be due to a recrudescence of rickets which had been present in childhood. The disease is not attended with any disturbance of the general health; the pathological changes are the same as in infantile rickets, but are for the most part confined to the ossifying junctions, especially those which are most active during adolescence, for example at the knee-joint. The patient is easily tired, complains of pain in the bones, and, unless care is taken, deformity is liable to ensue. There can be no doubt that adolescent rickets plays an important part in the production of the deformities which occur at or near puberty, especially knock-knee and bow-knee.

Scurvy-Rickets or Infantile Scurvy.—This disease, described by Barlow and Cheadle, is met with in infants under two years who have been brought up upon sterilised or condensed milk and other proprietary foods, and is most common in the well-to-do classes. The haemorrhages, which are so characteristic of the disease, are usually preceded for some weeks by a cachectic condition, with listlessness and debility and disinclination for movement. Very commonly the child ceases to move one of his lower limbs—pseudo-paralysis—and screams if it is touched; a swelling is found over one of the bones, usually the femur, accompanied by exquisite tenderness; the skin is tense and shiny, and there may be some oedema. These symptoms are due to a sub-periosteal haemorrhage, and associated with this there may be crepitus from separation of an epiphysis, rarely from fracture of the shaft of the bone. X-ray photographs show enlargement of the bone, the periosteum being raised from the shaft and new bone formed in relation to it. Haemorrhages also occur into the skin, presenting the appearance of bruises, into the orbit and conjunctiva, and from the mucous membranes.

The treatment consists in correcting the errors in diet. The infant should have a wet nurse or a plentiful supply of cow's milk in its natural state. Anti-scorbutics in the form of orange, lemon, or grape juice, and of potatoes bruised down in milk, may be given.

Osteomalacia.—The term osteomalacia includes a group of conditions, closely allied to rickets, in which the bones of adults become soft and yielding, so that they are unduly liable to bend or break.

One form occurs in pregnant and puerperal women, affecting most commonly the pelvis and lumbar vertebrae, but sometimes the entire skeleton. The lime salts are absorbed, the bones lose their rigidity and bend under the weight of the body and other mechanical influences, with the result that gross deformities are produced, particularly in the pelvis, the lumbar spine, and the hip-joints.

Neuropathic forms occur in certain chronic diseases of the brain and cord; in some cases the bones lose their lime salts and bend, in others they become brittle.

Osteomalacia associated with New Growths in the Skeleton.—When secondary cancer is widely distributed throughout the skeleton, it is associated with softening of the bones, as a result of which they readily bend or break, and after death are easily cut with a knife. In the disease known as multiple myeloma, the interior of the ribs, sternum, and bodies of the vertebrae is occupied by a reddish gelatinous pulp, the structure of which resembles sarcoma; the bones are reduced to a mere shell, and may break on the slightest pressure; the urine contains albumose, a substance resembling albumen but coagulating at a comparatively low temperature (140 F.), and the coagulum is re-dissolved on boiling, and it is readily precipitated by hydrochloric acid (Bence-Jones).

Ostitis Deformans—Paget's Disease of Bone.—This rare disease was first described by Sir James Paget in 1877. In the early stages, the marrow is transformed into a vascular connective tissue; its bone-eating functions are exaggerated, and the framework of the bone becomes rarefied, so that it bends under pressure as in osteomalacia. In course of time, however, new bone is formed in great abundance; it is at first devoid of lime salts, but later becomes calcified, so that the bones regain their rigidity. This formation of new bone is much in excess of the normal, the bones become large and bulky, their surfaces rough and uneven, their texture sclerosed in parts, and the medullary canal is frequently obliterated. These changes are well brought out in X-ray photographs. The curving of the long bones, which is such a striking feature of the disease, may be associated with actual lengthening, and the changes are sometimes remarkably symmetrical (Fig. 135). The bones forming the cranium may be enormously thickened, the sutures are obliterated, the distinction into tables and diploe is lost, and, while the general texture is finely porous, there may be areas as dense as ivory (Fig. 134).



Clinical Features.—The disease is usually met with in persons over fifty years of age. It is insidious in its onset, and, the patient's attention may be first attracted by the occurrence of vague pains in the back or limbs; by the enlargement and bending of such bones as the tibia or femur; or by a gradual increase in the size of the head, necessitating the wearing of larger hats. When the condition is fully developed, the attitude and general appearance are eminently characteristic. The height is diminished, and, owing to the curving of the lower limbs and spine, the arms appear unnaturally long; the head and upper part of the spine are bent forwards; the legs are held apart, slightly flexed at the knees, and are rotated out as well as curved; the whole appearance suggests that of one of the large anthropoid apes. The muscles of the limbs may waste to such an extent as to leave the large, curved, misshapen bones covered only by the skin (Fig. 135). In the majority of cases the bones of the lower extremities are much earlier and more severely affected than those of the upper extremity, but the capacity of walking is usually maintained even in the presence of great deformity. In a case observed by Byrom Bramwell, the patient suffered from a succession of fractures over a period of years.



The disease may last for an indefinite period, the general health remaining long unaffected. In a considerable number of the recorded cases one of the bones became the seat of sarcoma.

Osteomyelitis Fibrosa.—This comparatively rare disease, which was first described by Recklinghausen, presents many interesting features. Because of its causing deformities of the bones and an undue liability to fracture, and being chiefly met with in adolescents, it is regarded by some authors as a juvenile form of Paget's disease. It may be diffused throughout the skeleton—we have seen it in the skull and in the bones of the extremities—or it may be confined to a single bone, usually the femur, or, what is more remarkable, the condition may affect a portion only of the shaft of a long bone and be sharply defined from the normal bone in contact with it.



On longitudinal section of a long bone during the active stage of the disease, the marrow is seen to be replaced by a vascular young connective tissue which encroaches on the surrounding spongy bone, reducing it to the slenderest proportions; the formation of bone from the periosteum does not keep pace with the absorption and replacement going on in the interior, and the cortex may be reduced to a thin shell of imperfectly calcified bone which can be cut with a knife. The young connective tissue which replaces the marrow is not unlike that seen in osteomalacia; it is highly vascular and may show haemorrhages of various date; there are abundant giant cells of the myeloma type, and degeneration and liquefaction of tissue may result in the formation of cysts, which, when they constitute a prominent feature, are responsible for the name—osteomyelitis fibrosa cystica—sometimes applied to the condition.

It would appear that most of the recorded cases of cysts of bone owe their origin to this disease, while the abundance of giant cells with occasional islands of cartilage in the wall of such cysts is responsible for the view formerly held that they owed their origin to the liquefaction of a solid tumour, such as a myeloma, a chondroma, or even a sarcoma. Although the tissue elements in this disease resemble those of a new growth arising in the marrow, they differ in their arrangement and in their method of growth; there is no tendency to erupt through the cortex of the bone, to invade the soft parts, or to give rise to secondary growths.

Clinical Features.—The onset of the disease is insidious, and attention is usually first directed to it by the occurrence of fracture of the shaft of one of the long bones—usually the femur—from violence that would be insufficient to break a healthy bone. Apart from fracture, the great increase in the size of one of the long bones and its uneven contour are sufficiently remarkable to suggest examination with the X-rays, by means of which the condition is at once recognised. A systematic examination of the other long bones will often reveal the presence of the disease at a stage before the bone is altered externally.

Symmetrical bossing of the skull was present in the case shown in Figs. 136 and 137, and there were also scattered patches of brown pigmentation of the skin of the face, neck, and trunk, similar to those met with in generalised neuro-fibromatosis. Apart from fracture, the disease is recognised by the thickening and usually also by the curving of the shafts of the long bones. It is easy to understand the curvature of bones that have passed through a soft stage and also of those that have been broken and badly united, but it is difficult to account for the curvatures that have no such cause; for example, we have seen marked curve of the radius in a forearm of which the ulna was quite straight. The curvature probably resulted from exaggerated growth in length.



The X-ray appearances vary with the stage of the malady, not estimated in time, for the condition is chronic and may become stationary, but according to whether it is progressive or undergoing repair. The shadow of the bone presents a poor contrast to the soft parts, and no trace of its original architecture; in extreme cases the shadow of the femur resembles an unevenly filled sausage (Fig. 137); there is no cortical layer, the interior shows no trabecular structure, and some of the many clear areas are probably cysts. The condition extends right up to the articular cartilage, or, in the case of adolescent bones, up to the epiphysial cartilage.

Prognosis.—The condition does not appear to affect the general health. The future is concerned with the local conditions, and, especially in the case of the femur, with its liability to fracture; so far as we know there is no time limit to this.

Treatment is confined to protecting the affected bone—usually the femur—from injury. Operative treatment may be required for lameness due to a badly united fracture.

Neuropathic Atrophy of Bone.—The conditions included under this heading occur in association with diseases of the nervous system.

Most importance attaches to the fragility of the bones met with in general paralysis of the insane, locomotor ataxia, and other chronic diseases of the brain and spinal cord. The bones are liable to be fractured by forces which would be insufficient to break a healthy bone. In locomotor ataxia the fractures affect especially the bones of the lower extremity, and may occur before there are any definite nerve symptoms, but they are more often met with in the ataxic stage, when the abrupt and uncontrolled movements of the limbs may play a part in their causation. They may be unattended with pain, and may fail to unite; when repair does take place, it is sometimes attended with an excessive formation of callus. Joint lesions of the nature of Charcot's disease may occur simultaneously with the alterations in the bones. In syringomyelia pathological fracture is not so frequent as in locomotor ataxia; it is more likely to occur in the bones of the upper extremity, and especially in the humerus. In some cases of epilepsy the bones break when the patient falls in a fit, and there is usually an exaggerated amount of comminution.

In these affections the bones present no histological or chemical alterations, and the X-ray shadow does not differ from the normal. It is maintained, therefore, that the disposition to fracture does not depend upon a fragility of the bone, but on the loss of the muscular sense and of common sensation in the bones, as a result of which there is an inability properly to throw the muscles into action and dispose the limbs so as to place them under the most favourable conditions to meet external violence.

Osteogenesis Imperfecta, Fragilitas Ossium, or Congenital Osteopsathyrosis.—These terms are used to describe a condition in which an undue fragility of the bones dates from intra-uterine life. It may occur in several members of the same family. In severe cases, intra-uterine fractures occur, and during parturition fresh fractures are almost sure to be produced, so that at birth there is a combination of recent fractures and old fractures united and partly united, with bendings and thickenings of the bones. Large areas of the cranial vault may remain membranous.

After birth the predisposition to fracture continues, the bones are easily broken, the fractures are attended with little or no pain, the crepitus is soft, and although union may take place, it may be delayed and be attended with excess of callus. Cases have been observed in which a child has sustained over a hundred fractures.

The bones show a feeble shadow with the X-rays, and appear thin and atrophied; the medullary canal is increased at the expense of the cortex.

In young infants in whom multiple fractures occur the prognosis as to life is unfavourable, and no satisfactory treatment of the disease has been formulated. If the patient survives, the tendency to fracture gradually disappears.

Hypertrophic Pulmonary Osteo-Arthropathy.—This condition, which was described by Marie in 1890, is secondary to disease in the chest, such as chronic phthisis, empyema, bronchiectasis, or sarcoma of the lung. There is symmetrical enlargement and deformity of the hands and feet; the shafts of the bones are thickened, and the soft tissues of the terminal segments of the digits hypertrophied. The fingers come to resemble drum-sticks, and the thumb the clapper of a bell. The nails are convex, and incurved at their free ends, suggesting a resemblance to the beak of a parrot. There is also enlargement of the lower ends of the bones of the forearm and leg, and effusion into the wrist and ankle-joints. Skiagrams of the hands and feet show a deposit of new bone along the shafts of the phalanges.

TUMOURS OF BONE

New growths which originate in the skeleton are spoken of as primary tumours; those which invade the bones, either by metastasis from other parts of the body or by spread from adjacent tissues, as secondary. A tumour of bone may grow from the cellular elements of the periosteum, the marrow, or the epiphysial cartilage.

Primary tumours are of the connective-tissue type, and are usually solitary, although certain forms, such as the chondroma, may be multiple from the outset.

Periosteal tumours are at first situated on one side of the bone, but as they grow they tend to surround it completely. Innocent periosteal tumours retain the outer fibrous layer as a capsule. Malignant tumours tend to perforate the periosteal capsule and invade the soft parts.

Central or medullary tumours as they increase in size replace the surrounding bone, and simultaneously new bone is formed on the surface; as this is in its turn absorbed, further bone is formed beneath the periosteum, so that in time the bone is increased in girth, and is said to be "expanded" by the growth in its interior.

Primary Tumours—Osteoma.—When the tumour projects from the surface of a bone it is called an exostosis. When growing from bones developed in membrane, such as the flat bones of the skull, it is usually dense like ivory, and the term ivory exostosis is employed. When derived from hyaline cartilage—for example, at the ends of the long bones—it is known as a cartilaginous exostosis. This is invested with a cap of cartilage from which it continues to grow until the skeleton attains maturity.

An exostosis forms a rounded or mushroom-shaped tumour of limited size, which may be either sessile or pedunculated, and its surface is smooth or nodulated (Figs. 138 and 139). A cartilaginous exostosis in the vicinity of a joint may be invested with a synovial sac or bursa—the so-called exostosis bursata. The bursa may be derived from the synovial membrane of the adjacent joint with which its cavity sometimes communicates, or it may be of adventitious origin; when it is the seat of bursitis and becomes distended with fluid, it may mask the underlying exostosis, which then requires a radiogram for its demonstration.



Clinically, the osteoma forms a hard, indolent tumour attached to a bone. The symptoms to which it gives rise depend on its situation. In the vicinity of a joint, it may interfere with movement; on the medial side of the knee it may incapacitate the patient from riding. When growing from the dorsum of the terminal phalanx of the great toe—subungual exostosis—it displaces the nail, and may project through its matrix at the point of the toe, while the soft parts over it may be ulcerated from pressure (Fig. 107). It incapacitates the patient from wearing a boot. When it presses on a nerve-trunk it causes pains and cramps. In the orbit it displaces the eyeball; in the nasal fossae and in the external auditory meatus it causes obstruction, which may be attended with ulceration and discharge. In the skull it may project from the outer table, forming a smooth rounded swelling, or it may project from the inner table and press upon the brain.

The diagnosis is to be made by the slow growth of the tumour, its hardness, and by the shadow which it presents with the X-rays (Fig. 138).

An osteoma which does not cause symptoms may be left alone, as it ceases to grow when the skeleton is mature and has no tendency to change its benign character. If causing symptoms, it is removed by dividing the neck or base of the tumour with a chisel, care being taken to remove the whole of the overlying cartilage. The dense varieties met with in the bones of the skull present greater difficulties; if it is necessary to remove them, the base or neck of the tumour is perforated in many directions with highly tempered drills rotated by some form of engine, and the division is completed with the chisel.



Multiple Exostoses.—This disease, which, by custom, is still placed in the category of tumours, is to be regarded as a disorder of growth, dating from intra-uterine life and probably due to a disturbance in the function of the glands of internal secretion, the thyreoid being the one which is most likely to be at fault (Arthur Keith). The disorder of growth is confined to those elements of the skeleton where a core of bone formed in cartilage comes to be encased in a sheath of bone formed beneath the periosteum. To indicate this abnormality the name diaphysial aclasis has been employed by Arthur Keith at the suggestion of Morley Roberts.

Bones formed entirely in cartilage are exempt, namely, the tarsal and carpal bones, the epiphyses of the long bones, the sternum, and the bodies of the vertebrae. Bones formed entirely in membrane, that is, those of the face and of the cranial vault, are also exempt. The disorder mainly affects the ossifying junctions of the long bones of the extremities, the vertebral border of the scapula, and the cristal border of the ilium.

Clinically the disease is attended with the gradual and painless development during childhood or adolescence of a number of tumours or irregular projections of bone, at the ends of the long bones, the vertebral border of the scapula, and the cristal border of the ilium. They exhibit a rough symmetry; they rarely attain any size; and they usually cease growing when the skeleton attains maturity—the conversion of cartilage into bone being then completed. While they originate from the ossifying junctions of the long bones, they tend, as the shaft increases in length, to project from the surface of the bone at some distance from the ossifying junction and to "point" away from it. They may cause symptoms by "locking" the adjacent joint or by pressing upon nerve-trunks or blood vessels.

In a considerable proportion of cases, the disturbance of growth is further manifested by dwarfing of the long bones; these are not only deficient in length but are sometimes also curved and misshapen, which accounts for the condition being occasionally confused with the disturbances of growth resulting from rickets. In about one-third of the recorded cases there is a dislocation of the head of the radius on one or on both sides, a result of unequal growth between the bones of the forearm.



In early adult life, one of the tumours, instead of undergoing ossification, may take on active growth and exhibit the features of a chondro-sarcoma, pressing injuriously upon adjacent structures (Fig. 140) and giving rise later to metastases in the lungs.

The X-ray appearances of the bones affected are of a striking character; apart from the outgrowths of bone or "tumours" there is evident a widespread alteration in the internal architecture of the bones, which suggests analogies with other disturbances of ossification such as achondroplasia and osteomyelitis fibrosa. The condition is one that runs in families, sometimes through several generations; we have more than once seen a father and son together in the hospital waiting-room.

As regards treatment, there is no indication for surgical interference except when one or other tumour is a source of disability as by pressing upon a nerve-trunk or by locking a joint, in which case it is easily removed by chiselling through its neck.



Diffuse Osteoma, Leontiasis Ossea.—This rare affection was described by Virchow, and named leontiasis ossea because of the disfigurement to which it gives rise. It usually commences in adolescence as a diffuse overgrowth first of one and then of both maxillae; these bones are enlarged in all directions and project on the face, and the nasal fossae and the maxillary and frontal sinuses become filled up with bone, which encroaches also on the orbital cavities. In addition to the hideous deformity, the patient suffers from blocking of the nose, loss of smell, and protrusion of the eyes, sometimes followed by loss of sight. The condition is liable to spread to the zygomatic and frontal bones, the vault of the skull, and to the mandible. The base of the skull is not affected. The disease is of slow progress and may become arrested; life may be prolonged for many years, or may be terminated by brain complications or by intercurrent affections. In certain cases it is possible to remove some of the more disfiguring of the bony masses.

A less aggressive form, confined to the maxilla on one side, is sometimes met with, and, in a case of this variety under our own observation, the disfigurement, which was the only subject of complaint, was removed, after reflecting the soft parts, by paring away the excess of bone; this is easily done as the bone is spongy, and at an early stage, imperfectly calcified.

A remarkable form of unilateral hypertrophy and diffuse osteoma of the skull, following the distribution of the fifth nerve, has seen described by Jonathan Hutchinson and Alexis Thomson.

Chondroma.—Cartilaginous tumours, apart from those giving rise to multiple exostoses, grow from the long bones and from the scapula, ilium, ribs, or jaws. They usually project from the surface of the bone, and may attain an enormous size; sometimes they grow in the interior of a bone, the so-called enchondroma.

The hyaline cartilage composing the tumour frequently undergoes myxomatous degeneration, resulting in the formation of a glairy, semi-fluid jelly, and if this change takes place throughout the tumour it comes to resemble a cyst. On the other hand, the cartilage may undergo calcification or ossification. The most important transition of all is that into sarcoma, the so-called malignant chondroma or chondro-sarcoma, which is associated with rapid increase in size, and parts of the tumour may be carried off in the blood-stream and give rise to secondary growths, especially in the lungs.

Cases have been met with in which certain parts of the skeleton—only those developed in cartilage—were so uniformly permeated with cartilage that the condition has been described as a "chondromatosis" and is regarded as dating from an early period of foetal life. Unlike the condition known as multiple cartilaginous exostoses, it is a malignant disease.



The chondroma is met with as a slowly growing tumour which is specially common in the bones of the hand, often in a multiple form (Figs. 142 and 144). The surface is smooth or lobulated, and in consistence the tumour may be dense and elastic like normal cartilage, or may present areas of softening, or of bony hardness. The skin moves freely over it, except in relation to the bones of the fingers, where it may become adherent and ulcerate, simulating the appearance of a malignant tumour. Large tumours growing from the bones of the extremities may implicate the main vessels and nerves, either surrounding them or pressing on them.

Portions of a chondroma, which have undergone calcification or ossification, throw a dark shadow with the X-rays; unaltered cartilage and myxomatous tissue appear as clear areas.



Treatment.—It is necessary to remove the whole tumour, and in chondromas growing from the surface of the bone, especially if they are pedunculated, this is comparatively easy. When a bone, such as the scapula or mandible, is involved, it is better to excise the bone, or at least the part of it which bears the tumour. In the case of central tumours the shell of bone is removed over an area sufficient to allow of the enucleation of the tumour, or the affected portion of bone is resected. Should there be evidence of malignancy, such as increased rate of growth, a tube of radium should be inserted, and in advanced cases with destruction of tissue, amputation may be called for.



In multiple chondromas of the hand in young subjects, it was formerly the custom to amputate the limb; an attempt should be made to avoid this by shelling out the larger tumours individually, and persevering with the application of the X-rays or of radium to inhibit the growth of the smaller ones.

Chondromas springing from the pelvic bones usually arise in the region of the sacro-iliac joint; they project into the pelvis and press on the bladder and rectum, and on the sciatic and obturator nerves; sometimes also on the iliac veins, causing oedema of the legs. They are liable to take on malignant characters, and rarely lend themselves to complete removal by operation.

Fibroma is met with chiefly as a periosteal growth in relation to the mouth and pharynx, the simple epulis of the alveolar margin and the naso-pharyngeal polypus being the most common examples. We have met with a fibroma in the interior of the lower end of the femur of an adult, causing expansion of the bone with decided increase in girth and liability to pathological fracture; it is possible that this represents the cured stage of osteomyelitis fibrosa.

Myxoma, lipoma, and angioma of bone are all rare.

Myeloma.—The myeloid tumour, which is sometimes classified with the sarcomas, contains as its chief elements large giant cells, like those normally present in the marrow. On section these tumours present a brownish-red or chocolate colour, and, being highly vascular, are liable to haemorrhages, and therefore also to pigmentation, and to the formation of blood cysts. Sometimes the arterial vessels are so dilated as to impart to the tumour an aneurysmal pulsation and bruit. The enlargement or "expansion" of the bone results in the cortex being represented by a thin shell of bone, which may crackle on pressure—parchment or egg-shell crackling.

The myeloma is most often met with between the ages of twenty-five and forty in the upper end of the tibia or lower end of the femur. It grows slowly and causes little pain, and may long escape recognition unless an examination is made with the X-rays. Although these tumours have been known to give rise to metastases, they are, as a rule, innocent and are to be treated as such. When located in the shaft of a long bone, pathological fracture is liable to occur.

Diagnosis and X-ray Appearances of Myeloma.—The early diagnosis of myeloma is made with the aid of the X-rays: the typical appearance is that of a rounded or oval clear area bounded by a shell of bone of diminishing thickness (Fig. 145). The inflammatory lesions at the ends of the long bones—tubercle, syphilitic gumma, and Brodie's abscess, that resemble myeloma, are all attended with the formation of new bone in greater or lesser amount. The myeloma is also to be diagnosed from chondroma, from sarcoma, and from osteomyelitis fibrosa cystica.



Treatment.—In early cases the cortex is opened up to give free access to the tumour tissue, which is scraped out with the spoon. Bloodgood advises the use of Esmarch's tourniquet, and that the curetting be followed by painting with pure carbolic acid and then rinsing with alcohol; a rod of bone is inserted to fill the gap. In advanced cases the segment of bone is resected and a portion of the tibia or fibula from the other limb inserted into the gap; a tube of radium should also be introduced.

The coexistence of diffuse myelomatosis of the skeleton and albumosuria (Bence-Jones) is referred to on p. 474. Myeloma occurs in the jaws, taking origin in the marrow or from the periosteum of the alveolar process, and is described elsewhere.

Sarcoma and endothelioma are the commonest tumours of bone, and present wide variations in structure and in clinical features. Structurally, two main groups may be differentiated: (1) the soft, rapidly growing cellular tumours, and (2) those containing fully formed fibrous tissue, cartilage, or bone.

(1) The soft cellular tumours are composed mainly of spindle or round cells; they grow from the marrow of the spongy ends or from the periosteum of the long bones, the diploe of the skull, the pelvis, vertebrae, and jaws. As they grow they may cause little alteration in the contour of the bone, but they eat away its framework and replace it, so that the continuity of the bone is maintained only by tumour tissue, and pathological fracture is a frequent result. The small round-celled sarcomas are among the most malignant tumours of bone, growing with great rapidity, and at an early stage giving rise to secondary growths.

(2) The second group includes the fibro-, osteo-, and chondro-sarcomas, and combinations of these; in all of them fully formed tissues or attempts at fully formed tissues predominate over the cellular elements. They grow chiefly from the deeper layer of the periosteum, and at first form a projection on the surface, but later tend to surround the bone (Fig. 150), and to invade its interior, filling up the marrow spaces with a white, bone-like substance; in the flat bones of the skull they may traverse the diploe and erupt on the inner table. The tumour tissue next the shaft consists of a dense, white, homogeneous material, from which there radiate into the softer parts of the tumour, spicules, needles, and plates, often exhibiting a fan-like arrangement (Fig. 151). The peripheral portion consists of soft sarcomatous tissue, which invades the overlying soft parts. The articular cartilage long resists destruction. The ossifying sarcoma is met with most often in the femur and tibia, less frequently in the humerus, skull, pelvis, and jaws. In the long bones it may grow from the shaft, while the chondro-sarcoma more often originates at the extremities. Sometimes they are multiple, several tumours appearing simultaneously or one after another. Secondary growths are met with chiefly in the lungs, metastasis taking place by way of the veins.



Clinical Features.—Sarcoma is usually met with before the age of thirty, and is comparatively common in children. Males suffer oftener than females, in the proportion of two to one.

In periosteal sarcoma the presence of a swelling is usually the first symptom; the tumour is fusiform, firm, and regular in outline, and when it occurs near the end of a long bone the limb frequently assumes a characteristic "leg of mutton" shape (Fig. 146). The surface may be uniform or bossed, the consistence varies at different parts, and the swelling gradually tapers off along the shaft. On firm pressure, fine crepitation may be felt from crushing of the delicate framework of new bone.



In central sarcoma pain is the first symptom, and it is usually constant, dull, and aching; is not obviously increased by use of the limb, but is often worse at night. Swelling occurs late, and is due to expansion of the bone; it is fusiform or globular, and is at first densely hard, but in time there may be parchment-like or egg-shell crackling from yielding of the thin shell. The swelling may pulsate, and a bruit may be heard over it. In advanced cases it may be impossible to differentiate between a periosteal and a central tumour, either clinically or after the specimen has been laid open.

Pathological fracture is more common in central tumours, and sometimes is the first sign that calls attention to the condition. Consolidation rarely takes place, although there is often an attempt at union by the formation of cartilaginous callus.



The soft parts over the tumour for a long time preserve their normal appearance; or they become oedematous, and the subcutaneous venous network is evident through the skin. Elevation of the temperature over the tumour, which may amount to two degrees or more, is a point of diagnostic significance, as it suggests an inflammatory lesion.

The adjacent joint usually remains intact, although its movements may be impaired by the bulk of the tumour or by effusion into the cavity.

Enlargement of the neighbouring lymph glands does not necessarily imply that they have become infected with sarcoma for the enlargement may disappear after removal of the primary growth; actual infection of the glands, however, does sometimes occur, and in them the histological structure of the parent tumour is reproduced.

To obtain a reasonable prospect of cure, the diagnosis must be made at an early stage. Great reliance is to be placed on information gained by examination with the X-rays.



X-ray Appearances.—In periosteal tumours that do not ossify, there is merely erosion of bone, and the shadow is not unlike that given by caries; in ossifying tumours, the arrangement of the new bone on the surface is characteristic, and when it takes the form of spicules at right angles to the shaft, it is pathognomic.

In soft central tumours, there is disappearance of bone shadow in the area of the tumour, while above and below or around this, the shadow is that of normal bone right up to the clear area. In many respects the X-ray appearances resemble those of myeloma. In tumours in which there is a considerable amount of imperfectly formed new bone, this gives a shadow which barely replaces that of the original bone, in parts it may even add to it—the resulting picture differing widely in different cases; but it is usually possible to differentiate it from that caused by bacterial infections of the bone and from lesions of the adjacent joint.



Skiagraphy is not only of assistance in differentiating new growths from other diseases of bone, but may also yield information as to the situation and nature of the tumour, which may have important bearings on its treatment by operation.

When fracture of a long bone takes place in an adolescent or young adult from comparatively slight violence, disease of the bone should be suspected and an X-ray examination made.

In difficult cases the final appeal is to exploratory incision and microscopical examination of a portion of the tumour; this should be done when the major operation has been arranged for, the surgeon waiting until the examination is completed.

The prognosis varies widely. In general, it may be said that periosteal tumours are less favourable than central ones, because they are more liable to give rise to metastases. Permanent cures are unfortunately the exception.

Treatment.—When one of the bones of a limb is involved, the usual practice has been to perform amputation well above the growth, and this may still be recommended as a routine procedure. There are reasons, however, which may be urged against its continuance. High amputation is unnecessary in the more benign sarcomas, and in the more malignant forms is usually unavailing to prevent a fatal issue either from local recurrence or from metastases in the lungs or elsewhere. Following the lead of Mikulicz, a considerable number of permanent cures have been obtained by resecting the portion of bone which is the seat of the tumour, and substituting for it a corresponding portion from the tibia or fibula of the other limb. In a cellular sarcoma of the humerus of a boy we resected the shaft and inserted his fibula ten years ago, and he shows no sign of recurrence. When resection is impracticable, a subcapsular enucleation is performed, followed by the insertion of radium.

Pulsating Haematoma or Aneurysm of Bone.—A limited number of these are innocent cavernous tumours dating from a congenital angioma. The majority would appear to be the result of changes in a sarcoma, endothelioma, or myeloma. The tumour tissue largely disappears, while the vessels and vascular spaces undergo a remarkable development. The tumour may come to be represented by one large blood-containing space communicating with the arteries of the limb; the walls of the space consist of the remains of the original tumour, plus a shell of bone of varying thickness. The most common seats of the condition are the lower end of the femur, the upper end of the tibia, and the bones of the pelvis.

The clinical features are those of a pulsating tumour of slow development, and as in true aneurysm, the pulsation and bruit disappear on compression of the main artery. The origin of the tumour from bone may be revealed by the presence of egg-shell crackling, and by examination with the X-rays.

If the condition is believed to be innocent, the treatment is the same as for aneurysm—preferably by ligation of the main artery; if malignant, it is the same as for sarcoma.

Secondary Tumours of Bone.—These embrace two groups of new growth, those which give rise to secondary growths in the marrow of bones and those which spread to bone by direct continuity.

Metastatic Tumours.—Excepting certain cancers which give rise to metastases by lymphatic permeation (Handley), the common metastases arising in the bone-marrow reach their destination through the blood-stream.



Secondary cancer is a comparatively common disease, and, as in metastases in other tissues, the secondary growths resemble the parent tumour. The soft forms grow rapidly, and eat away the bone, without altering its shape or form. In slowly growing forms there may be considerable formation of imperfectly formed bone, often deficient in lime salts; this condition may be widely diffused throughout the skeleton, and, as it is associated with softening and bending of the bones, it is known as cancerous osteomalacia. Secondary cancer of bone is attended with pain, or it suddenly attracts notice by the occurrence of pathological fracture—as, for example, in the shaft of the femur or humerus. In the vertebrae, it is attended with a painful form of paraplegia, which may involve the lower or all four extremities. On the other hand, the disease may show itself clinically as a tumour of bone, which may attain a considerable size, and may be mistaken for a sarcoma, unless the existence of the primary cancer is discovered.

The cancers most liable to give rise to metastasis in bone are those of the breast, liver, uterus, prostate, colon, and rectum; hyper-nephroma of the kidney may also give rise to metastases in bone.

Secondary tumours derived from the thyreoid gland require special mention, because they are peculiar in that neither the primary growth in the thyreoid nor the secondary growth in the bones is necessarily malignant. They are therefore amenable to operative treatment.

Secondary sarcoma, whether derived from a primary growth in the bone or in the soft parts, is much rarer than secondary cancer. Its removal by operation is usually contra-indicated, but we have known of cases terminating fatally in which the section revealed only one metastasis, the removal of which would have benefited the patient.

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.

The terms hydrops, hydrarthrosis, and chronic serous synovitis are synonymous, and are employed when a serous effusion into the joint is the prominent clinical feature. Hydrops may occur apart from disease—for example, in the knee-joint from repeated sprains, or when there is a loose body in the joint—but is met with chiefly in the chronic forms of synovitis which result from gonorrhoea, tuberculosis, syphilis, arthritis deformans, or arthropathies of nerve origin.

Arthritis is the term applied when not only the synovial membrane but the articular surfaces, and it may be also the ends of the bones, are involved, and it is necessary to prefix a qualifying adjective which indicates its nature. When effusion is present, it may be serous, as in arthritis deformans, or sero-fibrinous or purulent, as in certain forms of pyogenic and tuberculous arthritis. Wasting of the muscles, especially the extensors, in the vicinity of the joint is a constant accompaniment of arthritis. On account of the involvement of the articular surfaces, arthritis is apt to be followed by ankylosis.

The term empyema is sometimes employed to indicate that the cavity of the joint contains pus. This is observed chiefly in chronic disease of pyogenic or tuberculous origin, and is usually attended with the formation of abscesses outside the joint.

Ulceration of cartilage and caries of the articular surfaces are common accompaniments of the more serious and progressive forms of joint disease, especially those of bacterial origin. The destruction of cartilage may be secondary to disease of the synovial membrane or of the subjacent bone. When the disease begins as a synovitis, the synovial membrane spreads over the articular surface, fuses with the cartilage and eats into it, causing defects or holes which are spoken of as ulcers. When the disease begins in the bone, the marrow is converted into granulation tissue, which eats into the cartilage and separates it from the bone. Following on the destruction of the cartilage, the articular surface of the bone undergoes disintegration, a condition spoken of as caries of the articular surface. The occurrence of ulceration of cartilage and of articular caries is attended with the clinical signs of fixation of the joint from involuntary muscular contraction, wasting of muscles, and starting pains. These starting pains are the result of sudden involuntary movements of the joint. They occur most frequently as the patient is dropping off to sleep; the muscles becoming relaxed, the sensitive ulcerated surfaces jar on one another, which causes sudden reflex contraction of the muscles, and the resulting movement being attended with severe pain, wakens the patient with a start. Advanced articular caries is usually associated with some abnormal attitude and with shortening of the limb. It may be possible to feel the bony surfaces grate upon one another. When all its constituent elements are damaged or destroyed, a joint is said to be disorganised. Should recovery take place, repair is usually attended with union of the opposing articular surfaces either by fibrous tissue or by bone.

Conditions of Impaired Mobility of Joints.—There are four conditions of impaired mobility in joints: rigidity, contracture, ankylosis, and locking. Rigidity is the fixation of a joint by involuntary contraction of muscles, and is of value as a sign of disease in deep-seated joints, such as the hip. It disappears under anaesthesia.

Contracture is the term applied when the fixation is due to permanent shortening of the soft parts around a joint—muscles, tendons, ligaments, fasciae, or skin. As the structures on the flexor aspect are more liable to undergo such shortening, contracture is nearly always associated with flexion. Contracture may result from disease of the joint, or from conditions outside it—for example, disease in one of the adjacent bones, or lesions of the nerves.

Ankylosis is the term applied when impaired mobility results from changes involving the articular surfaces. It is frequently combined with contracture. Three anatomical varieties of ankylosis are recognised—(a) The fibrous, in which there are adhesions between the opposing surfaces, which may be in the form of loose isolated bands of fibrous tissue, or may bind the bones so closely together as to obliterate the cavity of the joint. The resulting stiffness, therefore, varies from a mere restriction of the normal range of movement, up to a close union of the bones which prevents movement. Fibrous ankylosis may follow upon injury, especially dislocation or fracture implicating a joint, or it may result from any form of arthritis. (b) Cartilaginous ankylosis implies the fusion of two apposed cartilaginous surfaces. It is often found between the patella and the trochlear surface of the femur in tuberculous disease of the knee. The fusion of the cartilaginous surfaces is preceded by the spreading of a vascular connective tissue, derived from the synovial membrane, over the articular cartilage. Clinically, it is associated with absolute immobility, (c) Bony ankylosis or synostosis is an osseous union between articulating surfaces (Figs. 154 and 155). It may follow upon fibrous or cartilaginous ankylosis, or may result from the fusion of two articular surfaces which have lost their cartilage and become covered with granulations. In the majority of cases it is to be regarded as a reparative process, presenting analogies with the union of fracture.



The term arthritis ossificans has been applied by Joseph Griffiths to a condition in which the articular surfaces become fused without evident cause.

The occurrence of ankylosis in a joint before the skeleton has attained maturity does not appear to impair the growth in length of the bones affected; ankylosis of the temporo-maxillary joints, however, greatly impairs the growth of the mandible. When there is arrest of growth accompanying ankylosis, it usually depends on changes in the ossifying junctions caused by the original disease.

To differentiate by manipulation between muscular fixation and ankylosis, it may be necessary to anaesthetise the patient. The nature and extent of ankylosis may be learned by skiagraphy; in osseous ankylosis the shadow of the two bones is a continuous one. In fibrous as contrasted with osseous ankylosis mobility may be elicited, although only to a limited extent; while in osseous ankylosis the joint is rigidly fixed, and attempts to move it are painless.



The treatment is influenced by the nature of the original lesion, the variety of the ankylosis, and the attitude of the joint. When there is restriction of movement due to fibrous adhesions, these may be elongated or ruptured. Elongation of the adhesions may be effected by manipulations, exercises, and the use of special forms of apparatus—such as the application of weights to the limb. It may be necessary to administer an anaesthetic before rupturing strong fibrous adhesions, and this procedure must be carried out with caution, in view of such risks as fracture of the bone—which is often rarefied—or separation of an epiphysis. There is also the risk of fat embolism, and of re-starting the original disease. The giving way of adhesions may be attended with an audible crack; and the procedure is often followed by considerable pain and effusion into the joint, which necessitate rest for some days before exercises and manipulations can be resumed.

Operative treatment may be called for in cases in which the bones are closely bound to one another by fibrous or by osseous tissue.

Arthrolysis, which consists in opening the joint and dividing the fibrous adhesions, is almost inevitably followed by their reunion.

Arthroplasty.—Murphy of Chicago devised this operation for restoring movement to an ankylosed joint. It consists in transplanting between the bones a flap of fat-bearing tissue, from which a bursal cavity lined with endothelium and containing a fluid rich in mucin is ultimately formed.

Arthroplasty is most successful in ankylosis following upon injury; when the ankylosis results from some infective condition such as tuberculosis or gonorrhoea, it is liable to result in failure either because of a fresh outbreak of the infection or because the ankylosis recurs.

When arthroplasty is impracticable, and a movable joint is desired—for example at the elbow—a considerable amount of bone, and it may be also of periosteum and capsular ligament, is resected to allow of the formation of a false joint.

When bony ankylosis has occurred with the joint in an undesirable attitude—for example flexion at the hip or knee—it can sometimes be remedied by osteotomy or by a wedge-shaped resection of the bone, with or without such additional division of the contracted soft parts as will permit of the limb being placed in the attitude desired.

Bony ankylosis of the joints of a finger, whether the result of injury or disease, is difficult to remedy by any operative procedure, for while it is possible to restore mobility, the new joint is apt to be flail-like.

Locking.—A joint is said to lock when its movements are abruptly arrested by the coming together of bony outgrowths around the joint. It is best illustrated in arthritis deformans of the hip in which new bone formed round the rim of the acetabulum mechanically arrests the excursions of the head of the femur. The new bone, which limits the movements, is readily demonstrated in skiagrams; it may be removed by operative means. Locking of joints is more often met with as a result of injuries, especially in fractures occurring in the region of the elbow. In certain injuries of the semilunar menisci of the knee, also, the joint is liable to a variety of locking, which differs, however, in many respects from that described above.

Errors of Development.—These include congenital dislocations and other deformities of intra-uterine origin, such as abnormal laxity of joints, absence, displacement, or defective growth of one or other of the essential constituents of a joint. The more important of these are described along with the surgery of the Extremities.

DISEASES OF JOINTS

Bacterial Diseases.—In most bacterial diseases the organisms are carried to the joint in the blood-stream, and they lodge either in the synovial membrane or in one of the bones, whence the disease subsequently spreads to the other structures of the joint. Organisms may also be introduced through accidental wounds. It has been shown experimentally that joints are among the most susceptible parts of the body to infection, and this would appear to be due to the viscid character of the synovial fluid, which protects organisms from bactericidal agents in the tissues and fluids.

PYOGENIC DISEASES

The commoner pyogenic diseases are the result of infection of one or other of the joint structures with staphylococci or streptococci, which may be demonstrated in the exudate in the joint and in the substance of the synovial membrane. The mode of infection is the same as in the pyogenic diseases of bone, the metastasis occurring most frequently from the mucous membrane of the pharynx (J. B. Murphy). The localisation of the infection in a particular joint is determined by injury, exposure to cold, antecedent disease of the joint, or other factors, the nature of which is not always apparent.

The effects on the joint vary in severity. In the milder forms, there is engorgement and infiltration of the synovial membrane, and an effusion into the cavity of the joint of serous fluid mixed with flakes of fibrin—serous synovitis. In more severe infections the exudate consists of pus mixed with fibrin, and, it may be, red blood corpuscles—purulent or suppurative synovitis; the synovial membrane and the ligaments are softened, and the surface of the membrane presents granulations resembling those on an ulcer; foci of suppuration may develop in the peri-articular cellular tissue and result in abscesses. In acute arthritis, all the structures of the joint are involved; the articular cartilage is invaded by granulation tissue derived from the synovial membrane, and from the marrow of the subjacent bone; it presents a worm-eaten or ulcerated appearance, or it may undergo necrosis and separate, exposing the subjacent bone and leading to disintegration of the osseous trabeculae—caries. With the destruction of the ligaments, the stability of the joint is lost, and it becomes disorganised.

The clinical features vary with the extent of the infection. When this is confined to the synovial and peri-synovial tissues—acute serous and purulent synovitis—there is the usual general reaction, associated with pyrexia and great pain in the joint. The part is hot and swollen, the swelling assuming the shape of the distended synovial sac, fluctuation can usually be elicited, and the joint is held in the flexed position.

When the joint is infected by extension from the surrounding cellular tissue, the joint lesion may not be recognised at an early stage because of the swollen condition of the limb, and because there are already symptoms of toxaemia. We have observed a case in which both the hip and knee joints were infected from the cellular tissue.

If the infection involves all the joint structures—acute arthritis—the general and local phenomena are intensified, the temperature rises quickly, often with a rigor, and remains high; the patient looks ill, and is either unable to sleep or the sleep is disturbed by starting pains. The joint is held rigid in the flexed position, and the least attempt at movement causes severe pain; the slightest jar—even the shaking of the bed—may cause agony. The joint is hot, tensely distended, and there may be oedema of the peri-articular tissues or of the limb as a whole. If the pus perforates the joint capsule, there are signs of abscess or of diffuse suppuration in the cellular tissue. The final disorganisation of the joint is indicated by abnormal mobility and grating of the articular surfaces, or by spontaneous displacement of the bones, and this may amount to dislocation. In the acute arthritis of infants, the epiphysis concerned may be separated and displaced.

When the joint is infected through an external wound, the anatomical features are similar to those observed when the infection has reached the joint by the blood-stream, but the destructive changes tend to be more severe and are more likely to result in disorganisation.

The terminations vary with the gravity of the infection and with the stage at which treatment is instituted. In the milder forms recovery is the rule, with more or less complete restoration of function. In more severe forms the joint may be permanently damaged as a result of fibrous or bony ankylosis, or from displacement or dislocation. From changes in the peri-articular structures there may be contracture in an undesirable position, and in young subjects the growth of the limb may be interfered with. The persistence of sinuses is usually due to disease in one or other of the adjacent bones. In the most severe forms, and especially when several joints are involved, death may result from toxaemia.

The treatment is carried out on the same principles as in other pyogenic infections. The limb is immobilised in such an attitude that should stiffness occur there will be the least interference with function. Extension by weight and pulley is the most valuable means of allaying muscular spasm and relieving intra-articular tension and of counteracting the tendency to flexion; as much as 15 or 20 pounds may be required to relieve the pain.

The induction of hyperaemia is sometimes remarkably efficacious in relieving pain and in arresting the progress of the infection. If the fluid in the joint is in sufficient quantity to cause tension, if it persists, or if there is reason to suspect that it is purulent, it should be withdrawn without delay; an exploring syringe usually suffices, the skin being punctured with a tenotomy knife, and, as practised by Murphy, 5 to 15 c.c. of a 2 per cent. solution of formalin in glycerin are injected and the wound is closed. In virulent infections the injection may be repeated in twenty-four hours. Drainage by tube or otherwise is to be condemned (Murphy). A vaccine may be prepared from the fluid in the joint and injected into the subcutaneous cellular tissue.

Suppuration in the peri-articular soft parts or in one of the adjacent bones must be looked for and dealt with.

When convalescence is established, attention is directed to the restoration of the functions of the limb, and to the prevention of stiffness and deformity by movements and massage, and the use of hot-air and other baths.

At a later stage, and especially in neglected cases, operative and other measures may be required for deformity or ankylosis.

Metastatic Forms of Pyogenic Infection

In pyaemia, one or more joints may fill with pus without marked symptoms or signs, and if the pus is aspirated without delay the joint often recovers without impairment of function.

In typhoid fever, joint lesions result from infection with the typhoid bacillus alone or along with pyogenic organisms, and run their course with or without suppuration; there is again a remarkable absence of symptoms, and attention may only be called to the condition by the occurrence of dislocation.

Joint lesions are comparatively common in scarlet fever, and were formerly described as scarlatinal rheumatism. The most frequent clinical type is that of a serous synovitis, occurring within a week or ten days from the onset of the fever. Its favourite seat is in the hand and wrist, the sheaths of the extensor tendons as well as the synovial membrane of the joints being involved. It does not tend to migrate to other joints, and rarely lasts longer than a few days. It is probably due to the specific virus of scarlet fever.

At a later stage, especially in children and in cases in which the throat lesion is severe, an arthritis is sometimes observed that is believed to be a metastasis from the throat; it may be acute and suppurative, affect several joints, and exhibit a septicaemic or pyaemic character.

The joints of the lower extremity are especially apt to suffer; the child is seriously ill, is delirious at night, develops bed-sores over the sacrum and, it may happen that, not being expected to recover, the legs are allowed to assume contracture deformities with ankylosis or dislocation at the hip and flexion ankylosis at the knees; should the child survive, the degree of crippling may be pitiable in the extreme; prolonged orthopaedic treatment and a series of operations—arthroplasty, osteotomies, and resections—may be required to restore even a limited capacity of locomotion.

Pneumococcal affections of joints, the result of infection with the pneumococcus of Fraenkel, are being met with in increasing numbers. The local lesion varies from a synovitis with infiltration of the synovial membrane and effusion of serum or pus, to an acute arthritis with erosion of cartilage, caries of the articular surfaces, and disorganisation of the joint. The knee is most frequently affected, but several joints may suffer at the same time. In most cases the joint affection makes its appearance a few days after the commencement of a pneumonia, but in a number of instances, especially among children, the lung is not specially involved, and the condition is an indication of a generalised pneumococcal infection, which may manifest itself by endocarditis, empyema, meningitis, or peritonitis, and frequently has a fatal termination. The differential diagnosis from other forms of pyogenic infection is established by bacteriological examination of the fluid withdrawn from the joint. The treatment is carried out on the same lines as in other pyogenic infections, considerable reliance being placed on the use of autogenous vaccines.

In measles, diphtheria, smallpox, influenza, and dysentery, similar joint lesions may occur.

The joint lesions which accompany acute rheumatism or "rheumatic fever" are believed to be due to a diplococcus. In the course of a general illness in which there is moderate pyrexia and profuse sweating, some of the larger joints, and not infrequently the smaller ones also, become swollen and extremely sensitive, so that the sufferer lies in bed helpless, dreading the slightest movement. From day to day fresh joints are attacked, while those first affected subside, often with great rapidity. Affections of the heart-valves and of the pericardium are commonly present. On recovery from the acute illness, it may be found that the joints have entirely recovered, but in a small proportion of cases certain of them remain stiff and pass into the crippled condition described under chronic rheumatism. There is no call for operative interference.

Gonococcal Affections of Joints.—These include all forms of joint lesion occurring in association with gonorrhoeal urethritis, vulvo-vaginitis, or gonorrhoeal ophthalmia. They may develop at any stage of the urethritis, but are most frequently met with from the eighteenth to the twenty-second day after the primary infection, when the organisms have reached the posterior urethra; they have been observed, however, after the discharge has ceased. There is no connection between the severity of the gonorrhoea and the incidence of joint disease. In women, the gonorrhoeal nature of the discharge must be established by bacteriological examination.

As a complication of ophthalmia, the joint lesions are met with in infants, and occur more commonly towards the end of the second or during the third week.

The gonococcus is carried to the joint in the blood-stream and is first deposited in the synovial membrane, in the tissues of which it can usually be found; it may be impossible to find it in the exudate within the joint. The joint lesions may be the only evidence of metastasis, or they may be part of a general infection involving the endocardium, pleura, and tendon sheaths.

The joints most frequently affected are the knee, elbow, ankle, wrist, and fingers. Usually two or more joints are affected.

Several clinical types are differentiated. (1) A dry poly-arthritis met with in the joints and tendon sheaths of the wrist and hand, formerly described as gonorrhoeal rheumatism, which in some cases is trifling and evanescent, and in others is persistent and progressive, and results in stiffness of the affected joints and permanent crippling of the hand and fingers.

(2) The commonest type is a chronic synovitis or hydrops, in which the joint—very often the knee—becomes filled with a serous or sero-fibrinous exudate. There are no reactive changes in the synovial membrane, cellular tissue, or skin, nor is there any fever or disturbance of health. The movements are free except in so far as they are restricted by the amount of fluid in the joint. It usually subsides in two or three weeks under rest, but tends to relapse.

(3) An acute synovitis with peri-articular phlegmon is most often met with in the elbow, but it occurs also in the knee and ankle. There is a sudden onset of severe pain and swelling in and around the joint, with considerable fever and disturbance of health. The slightest movement causes pain, and the part is sensitive to touch. The skin is hot and tense, and in the case of the elbow may be red and fiery as in erysipelas.

The deposit of fibrin on the synovial membrane and on the articular surfaces may lead to the formation of adhesions, sometimes in the form of isolated bands, sometimes in the form of a close fibrous union between the bones.

(4) A suppurative arthritis, like that caused by ordinary pus microbes, may be the result of gonococcal infection alone or of a mixed infection. Usually only one joint is affected, but the condition may be multiple. The articular cartilages are destroyed, the ends of the bones are covered with granulations, extra-articular abscesses form, and complete osseous ankylosis results.

The diagnosis is often missed because the possibility of gonorrhoea is not suspected.

The denial of the disease by the patient is not always to be relied upon, especially in the case of women, as they may be ignorant of its presence. The chief points in the differential diagnosis from acute articular rheumatism are, that the gonorrhoeal affection is more often confined to one or two joints, has little tendency to wander from joint to joint, and its progress is not appreciably influenced by salicylates, although these drugs may relieve pain. The conclusive point is the recognition of a gonorrhoeal discharge or of threads in the urine.

The disease may persist or may relapse, and the patient may be laid up for weeks or months, and may finally be crippled in one or in several joints.

The treatment—besides that of the urethral disease or of the ophthalmia—consists in rest until all pain and sensitiveness have disappeared. The pain is relieved by salicylates, but most benefit follows weight extension, the induction of hyperaemia by the rubber bandage and hot-air baths; if the joint is greatly distended, the fluid may be withdrawn by a needle and syringe. Detoxicated vaccines should be given from the first, and in afebrile cases the injection of a foreign protein, such as anti-typhoid vaccine, is beneficial (Harrison).

Murphy has found benefit from the introduction into the joint, in the early stages, of from 5 to 15 c.c. of a 2 per cent. solution of formalin in glycerin. This may be repeated within a week, the patient being kept in bed with light weight extension. In the chronic hydrops the fluid is withdrawn, and about an ounce of a 1 per cent. solution of protargol injected; the patient should be warned of the marked reaction which follows.

After all symptoms have settled down, but not till then, for fear of exciting relapse or metastasis, the joint is massaged and exercised. Stiffness from adhesions is most intractable, and may, in spite of every attention, terminate in ankylosis even in cases where there has been no suppuration. Forcible breaking down of adhesions under anaesthesia is not recommended, as it is followed by great suffering and the adhesions re-form. Operation for ankylosis—arthroplasty—should not be undertaken, as the ankylosis recurs.

TUBERCULOUS DISEASE

Tuberculous disease of joints results from bacillary infection through the arteries. The disease may commence in the synovial membrane or in the marrow of one of the adjacent bones, and the relative frequency of these two seats of infection has been the subject of considerable difference of opinion. The traditional view of Konig is that in the knee and most of the larger joints the disease arises in the bone and in the synovial membrane in about equal proportion, and that in the hip the number of cases beginning in the bones is about five times greater than that originating in the membrane. This estimate, so far as the actual frequency of bone lesions is concerned, has been generally accepted, but recent observers, notably John Fraser, do not accept the presence of bone lesions as necessarily proving that the disease commenced in the bones; he maintains, and we think with good grounds, that in many cases the disease having commenced in the synovial membrane, slowly spreads to the bone by way of the blood vessels and lymphatics, and gives rise to lesions in the marrow.

Morbid Anatomy.—Tuberculous disease in the articular end of a long bone may give rise to reactive changes in the adjacent joint, characterised by effusion and by the extension of the synovial membrane over the articular surfaces. This may result in the formation of adhesions which obliterate the cavity of the joint or divide it into compartments. These lesions are comparatively common, and are not necessarily due to actual tuberculous infection of the joint.

The infection of the joint by tubercle originating in the adjacent bone may take place at the periphery, the osseous focus reaching the surface of the bone at the site of reflection of the synovial membrane, and the infection which begins at this point then spreads to the rest of the membrane. Or it may take place in the central area, by the projection of tuberculous granulation tissue into the joint following upon erosion of the cartilage (Fig. 156).



Changes in the Synovial Membrane.—In the majority of cases there is a diffuse thickening of the synovial membrane, due to the formation of granulation tissue, or of young connective tissue, in its substance. This new tissue is arranged in two layers—the outer composed of fully formed connective or fibrous tissue, the inner of embryonic tissue, usually permeated with miliary tubercles. On opening the joint, these tubercles may be seen on the surface of the membrane, or the surface may be covered with a layer of fibrinous or caseating tissue. Where there is greater resistance on the part of the tissues, there is active formation of young connective tissue which circumscribes or encapsulates the tubercles, so that they remain embedded in the substance of the membrane, and are only seen on cutting into it.

The thickened synovial membrane is projected into the cavity of the joint, filling up its pouches and recesses, and spreading over the surface of the articular cartilage "like ivy growing on a wall." Wherever the synovial tissue covers the cartilage it becomes adherent to and fused with it. The morbid process may be arrested at this stage, and fibrous adhesions form between the opposing articular surfaces, or it may progress, in which case further changes occur, resulting in destruction of the articular cartilage and exposure of the subjacent bone.

In rare instances the synovial membrane presents nodular masses or lumps, resembling the tuberculous tumours met with in the brain; they project into the cavity of the joint, are often pedunculated, and may give rise to the symptoms of loose body. The fringes of synovial membrane may also undergo a remarkable development, like that observed in arthritis deformans, and described as arborescent lipoma. Both these types are almost exclusively met with in the knee.

The Contents of Tuberculous Joints.—In a large proportion of cases of synovial tuberculosis the joint is entirely filled up by the diffuse thickening of the synovial membrane. In a small number there is an abundant serous exudate, and with this there may be a considerable formation of fibrin, covering the surface of the membrane and floating in the fluid as flakes or masses; under the influence of movement it may assume the shape of melon-seed bodies. More rarely the joint contains pus, and the surface of the synovial membrane resembles the wall of a cold abscess.

Ulceration and Necrosis of Cartilage.—The synovial tissue covering the cartilage causes pitting and perforation of the cartilage and makes its way through it, and often spreads widely between it and the subjacent bone; the cartilage may be detached in portions of considerable size. It may be similarly ulcerated or detached as a result of disease in the bone.

Caries of Articular Surfaces.—Tuberculous infiltration of the marrow in the surface cancelli breaks up the spongy framework of the bone into minute irregular fragments, so that it disintegrates or crumbles away—caries. When there is an absence of caseation and suppuration, the condition is called caries sicca.

The pressure of the articular surfaces against one another favours the progress of ulceration of cartilage and of articular caries. These processes are usually more advanced in the areas most exposed to pressure—for example, in the hip-joint, on the superior aspect of the head of the femur, and on the posterior and upper segment of the acetabulum.

The occurrence of pathological dislocation is due to softening and stretching of the ligaments which normally retain the bones in position, and to some factor causing displacement, which may be the accumulation of fluid or of granulations in the joint, the involuntary contraction of muscles, or some movement or twist of the limb. The occurrence of dislocation is also favoured by destructive changes in the bones.

Peri-articular tubercle and abscess may result from the spread of disease from the bone or joint into the surrounding tissues, either directly or by way of the lymphatics. A peri-articular abscess may spread in several directions, sometimes invading tendon sheaths or bursae, and finally reaching the skin surface by tortuous sinuses.

Reactive changes in the vicinity of tuberculous joints are of common occurrence, and play a considerable part in the production of what is clinically known as white swelling. New connective tissue forms in the peri-articular fat and between muscles and tendons. It may be tough and fibrous, or soft, vascular, and oedematous, and the peri-articular fat becomes swollen and gelatinous, constituting a layer of considerable thickness. The fat disappears and is replaced by a mucoid effusion between the fibrous bundles of connective tissue. This is what was formerly known as gelatinous degeneration of the synovial membrane. In the case of the wrist the newly formed connective tissue may fix the tendons in their sheaths, interfering with the movements of the fingers. In relation to the bones also there may be reactive changes, resulting in the formation of spicules of new bone on the periosteal surfaces and at the attachment of the capsular and other ligaments; these are only met with where pyogenic infection has been superadded.

Terminations and Sequelae.—A natural process of cure may occur at any stage, the tuberculous tissue being replaced by scar tissue. Recovery is apt to be attended with impairment of movement due to adhesions, ankylosis, or contracture of the peri-articular structures. Caseous foci in the interior of the bones may become encapsulated, and a cure be thus effected, or they may be the cause of a relapse of the disease at a later date. Interference with growth is comparatively common, and may involve only the epiphysial junctions in the immediate vicinity of the joint affected, or those of all the bones of the limb. This is well seen in adults who have suffered from severe disease of the hip in childhood—the entire limb, including the foot, being shorter and smaller than the corresponding parts of the opposite side.

Atrophic conditions are also met with, the bones undergoing fatty atrophy, so that in extreme cases they may be cut with a knife or be easily fractured. These atrophic conditions are most marked in bedridden patients, and are largely due to disuse of the limb; they are recovered from if it is able to resume its functions.

Clinical Features.—These vary with the different anatomical forms of the disease, and with the joint affected.

Sometimes the disease is ushered in by a febrile attack attended with pains in several joints—described by John Duncan as tuberculous arthritic fever. This is liable to be mistaken for rheumatic fever, from which, however, it differs in that there is no real migration from joint to joint; there is an absence of sweating and of cardiac complications; and no benefit follows the administration of salicylates.

In exceptional cases, tuberculous joint disease follows an acute course resembling that of the pyogenic arthritis of infants. This has been observed in children, especially in the knee, the lesion being in the synovial membrane, and attended with an accumulation of pus in the joint. If promptly treated by incision and drainage, recovery is rapid, and free movement of the joint, may be preserved.

The onset and early stages of tuberculous disease, however, are more often insidious, and are attended with so few symptoms that the disease may have obtained a considerable hold before it attracts notice. It is not uncommon for patients or their friends to attribute the condition to injury, as it often first attracts attention after some slight trauma or excessive use of the limb. The symptoms usually subside under rest, only to relapse again with use of the limb.

The initial local symptoms may be due to the presence of a focus in the neighbouring bone, perhaps causing neuralgic pains in the joint, or weakness, tiredness, stiffness, and inability to use the limb, these symptoms improving with rest and being aggravated by exertion.

It is rarely possible by external examination to recognise deep-seated osseous foci in the vicinity of joints; but if they are near the surface in a superficial bone—such as the head of the tibia—there may be local thickening of the periosteum, oedema, pain, and tenderness on pressure and on percussion.

X-ray Appearances of Tuberculous Joints.—Gross lesions such as caseous foci in the marrow of the adjacent bone show as clear areas with an ill-defined margin; a sclerosed focus gives a denser shadow than the surrounding bone, and a sequestrum presents a dark shadow of irregular contour, and a clear interval between it and the surrounding bone.

Caries of the articular surface imparts a woolly appearance or irregular contour in place of the well-defined outline of the articular end of the bone. In bony ankylosis the shadow of the two bones is a continuous one, the joint interval having been filled up. The minor changes are best appreciated on comparison with the normal joint of the other limb.

Wasting of muscles is a constant accompaniment of tuberculous joint disease. It is to be attributed partly to want of use, but chiefly to reflex interference with the trophic innervation of the muscles. It is specially well seen in the extensor and adductor muscles of the thigh in disease of the knee, and in the deltoid in disease of the shoulder. The muscles become soft and flaccid, they exhibit tremors on attempted movement, and their excitability to the faradic current is diminished. The muscular tissue may be largely replaced by fat.

Impairment of the normal movements is one of the most valuable diagnostic signs, particularly in deeply seated joints such as the shoulder, hip, and spine. It is due to a protective contraction of the muscles around the joint, designed to prevent movement. This muscular fixation disappears under anaesthesia.

Abnormal attitudes of the limb occur earlier, and are more pronounced in cases in which pain and other irritative symptoms of articular disease are well marked, and are best illustrated by the attitudes assumed in disease of the hip. They are due to reflex or involuntary contraction of the muscles acting on the joint, with the object of placing it in the attitude of greatest ease; they also disappear under anaesthesia. With the lapse of time they not only become exaggerated, but may become permanent from ankylosis or from contracture of the soft parts round the joint.

Startings at night are to be regarded as an indication that there is progressive disease involving the articular surfaces.

The formation of extra-articular abscess may take place early, or it may not occur till long after the disease has subsided. The abscess may develop so insidiously that it does not attract attention until it has attained considerable size, especially when associated with disease of the spine, pelvis, or hip. The position of the abscess in relation to different joints is fairly constant and is determined by the anatomical relationships of the capsule and synovial membrane to the surrounding tissues. The bursae and tendon sheaths in the vicinity may influence the direction of spread of the abscess and the situation of resulting sinuses. When the abscess is allowed to burst, or is opened and becomes infected with pyogenic bacteria, there is not only the risk of aggravation of the disease and persistent suppuration, but there is a greater liability to general tuberculosis.

The sinuses may be so tortuous that a probe cannot be passed to the primary focus of disease, and their course and disposition can only be demonstrated by injecting the sinuses with an emulsion of bismuth and taking X-ray photographs.