Chapter XX: Diseases of Bone (2)

_Clinical Features._--As a rule, it is only in superficially placed bones, such as the tibia, ulna, clavicle, mandible, or phalanges, that tuberculous disease in the marrow gives rise to signs sufficiently definite to allow of its clinical recognition. In the vertebræ, or in the bones of deeply seated joints, such as the hip or shoulder, the existence of tuberculous lesions in the marrow can only be inferred from indirect signs--such, for example, as rigidity and curvature in the case of the spine, or from the symptoms of grave and persistent joint-disease in the case of the hip or shoulder.

With few exceptions, tuberculous disease in the interior of a bone does not reveal its presence until by extension it reaches one or other of the surfaces of the bone. In the shaft of a long bone its eruption on the periosteal surface is usually followed by the formation of a cold abscess in the overlying soft parts. When situated in the articular ends of bones, the disease more often erupts in relation to the reflection of the synovial membrane or directly on the articular surface--in either case giving rise to disease of the joint (Fig. 156).

(Photograph lent by Sir H. J. Stiles.)]

#Diffuse Tuberculous Osteomyelitis in the shaft of a long bone# is comparatively rare, and has been observed chiefly in the tibia and the ulna in children (Fig. 126). It commences at the growing extremity of the diaphysis, and spreads along the medulla to a variable extent; it is attended by the formation of vascular and porous bone on the surface, which causes thickening of the diaphysis; this is most marked at the ossifying junction and tapers off along the shaft. The infection not only spreads along the medulla, but it invades the spongy bone surrounding this, and then the cortical bone, and is only prevented from reaching the soft parts by the new bone formed by the periosteum. The bone is replaced by granulation tissue, and disappears, or part of it may become sclerosed and in time form a sequestrum. In the macerated specimen, the sequestrum appears small in proportion to the large cavity in which it lies. All these changes are revealed in a good skiagram, which not only confirms the diagnosis, but, in many instances, demonstrates the extent of the disease, the presence or absence of a sequestrum, and the amount of new bone on the surface. Finally the periosteum gives way, and an abscess forms in the soft parts; and if left to itself ruptures externally, leaving a sinus. The most satisfactory _treatment_ is to resect sub-periosteally the diseased portion of the diaphysis.

_In cancellous bones, such as those of the tarsus_, there is a similar caseous infiltration in the marrow, and this may be attended with the formation of a sequestrum either in the interior of the bone or involving its outer shell, as shown in Fig. 127. The situation and extent of the disease are shown in X-ray photographs. After the tuberculous granulation tissue erupts through the cortex of the bone, it gives rise to a cold abscess or infects adjacent joints or tendon sheaths.

(Specimen in Anatomical Museum, University of Edinburgh.)]

If an exact diagnosis is made at an early stage of the disease--and this is often possible with the aid of X-rays--the affected bone is excised sub-periosteally or its interior is cleared out with the sharp spoon and gouge, the latter procedure being preferred in the case of the _calcaneus_ to conserve the stability of the heel. When several bones and joints are simultaneously affected, and there are sinuses with mixed infection, amputation is usually indicated, especially in adults.

#Tuberculous dactylitis# is the name applied to a diffuse form of the disease as it affects the phalanges, metacarpal or metatarsal bones. The lesion presents, on a small scale, all the anatomical changes that have been described as occurring in the medulla of the tibia or ulna, and they are easily followed in skiagrams. A periosteal type of dactylitis is also met with.

The _clinical features_ are those of a spindle-shaped swelling of a finger or toe, indolent, painless, and interfering but little with the function of the digit. Recovery may eventually occur without suppuration, but it is common to have the formation of a cold abscess, which bursts and forms one or more sinuses. It may be difficult to differentiate tuberculous dactylitis from the enlargement of the phalanges in inherited syphilis (syphilitic dactylitis), especially when the tuberculous lesion occurs in a child who is the subject of inherited syphilis.

In the syphilitic lesion, skiagrams usually show a more abundant formation of new bone, but in many cases the doubt is only cleared up by observing the results of the tuberculin test or the effects of anti-syphilitic treatment.

Sarcoma of a phalanx or metacarpal bone may closely resemble a dactylitis both clinically and in skiagrams, but it is rare.

_Treatment._--Recovery under conservative measures is not uncommon, and the functional results are usually better than those following upon operative treatment, although in either case the affected finger is liable to be dwarfed (Fig. 129). The finger should be immobilised in a splint, and a Bier's bandage applied to the upper arm. Operative interference is indicated if a cold abscess develops, if there is a persistent sinus, or if a sequestrum has formed, a point upon which information is obtained by examination with the X-rays. When a toe is affected, amputation is the best treatment, but in the case of a finger it is rarely called for. In the case of a metacarpal or metatarsal bone, sub-periosteal resection is the procedure of choice, saving the articular ends if possible.

SYPHILITIC DISEASE

Syphilitic affections of bone may be met with at any period of the disease, but the graver forms occur in the tertiary stage of acquired and inherited syphilis. The virus is carried by the blood-stream to all parts of the skeleton, but the local development of the disease appears to be influenced by a predisposition on the part of individual bones.

Syphilitic diseases of bone are much less common in practice than those due to pyogenic and tuberculous infectious, and they show a marked predilection for the tibia, sternum, and skull. They differ from tuberculous affections in the frequency with which they attack the shafts of bones rather than the articular ends, and in the comparative rarity of joint complications.

_Evanescent periostitis_ is met with in acquired syphilis during the period of the early skin eruptions. The patient complains, especially at night, of pains over the frontal bone, ribs, sternum, tibiæ, or ulnæ. Localised tenderness is elicited on pressure, and there is slight swelling, which, however, rarely amounts to what may be described as a _periosteal node_.

In the later stages of acquired syphilis, _gummatous periostitis and osteomyelitis_ occur, and are characterised by the formation in the periosteum and marrow of circumscribed gummata or of a diffuse gummatous infiltration. The framework of the bone is rarefied in the area immediately involved, and sclerosed in the parts beyond. If the gummatous tissue degenerates and breaks down, and especially if the overlying skin is perforated and septic infection is superadded, the bone disintegrates and exhibits the condition known as _syphilitic caries_; sometimes a portion of bone has its blood supply so far interfered with that it dies--_syphilitic necrosis_. Syphilitic sequestra are heavier and denser than normal bone, because sclerosis usually precedes death of the bone. The bones especially affected by gummatous disease are: the skull, the septum of the nose, the nasal bones, palate, sternum, femur, tibia, and the bones of the forearm.

_In the bones of the skull_, gummata may form in the peri-cranium, diploë, or dura mater. An isolated gumma forms a firm elastic swelling, shading off into the surroundings. In the macerated bone there is a depression or an actual perforation of the calvaria; multiple gummata tend to fuse with one another at their margins, giving the appearance of a combination of circles: these sometimes surround an area of bone and cut it off from its blood supply (Fig. 130). If the overlying skin is destroyed and septic infection superadded, such an isolated area of bone is apt to die and furnish a sequestrum; the separation of the dead bone is extremely slow, partly from the want of vascularity in the sclerosed bone round about, and partly from the density of the sequestrum. In exceptional cases the necrosis involves the entire vertical plate of the frontal bone. Pus is formed between the bone and the dura (suppurative pachymeningitis), and this may be followed by cerebral abscess or by pyæmia. Gummatous disease in the wall of the orbit may cause displacement of the eye and paralysis of the ocular muscles.

On the inner surface of the skull, the formation of gummatous tissue may cause pressure on the brain and give rise to intense pain in the head, Jacksonian epilepsy, or paralysis, the symptoms varying with the seat and extent of the disease. The cranial nerves may be pressed upon at the base, especially at their points of exit, and this gives rise to symptoms of irritation or paralysis in the area of distribution of the nerves affected.

_In the septum of the nose, the nasal bones, and the hard palate_, gummatous disease causes ulceration, which, beginning in the mucous membrane, spreads to the bones, and being complicated with septic infection leads to caries and necrosis. In the nose, the disease is attended with stinking discharge (ozœna), the extrusion of portions of dead bone, and subsequently with deformity characterised by loss of the bridge of the nose; in the palate, it is common to have a perforation, so that the air escapes through the nose in speaking, giving to the voice a characteristic nasal tone.

_Syphilitic disease of the tibia_ may be taken as the type of the affection as it occurs _in the long bones_. Gummatous disease in the periosteum may be localised and result in the formation of a well-defined node, or the whole shaft may become the seat of an irregular nodular enlargement (Fig. 132). If the bone is macerated, it is found to be heavier and bulkier than normal; there is diffuse sclerosis with obliteration of the medullary canal, and the surface is uneven from heaping up of new bone--hyperostosis (Fig. 131). If a periosteal gumma breaks down and invades the skin, a syphilitic ulcer is formed with carious bone at the bottom. A central gumma may eat away the surrounding bone to such an extent that the shaft undergoes pathological fracture. In the rare cases in which it attacks the articular end of a long bone, gummatous disease may implicate the adjacent joint and give rise to syphilitic arthritis.

_Clinical Features._--There is severe boring pain--as if a gimlet were being driven into the bone. It is worst at night, preventing sleep, and has been ascribed to compression of the nerves in the narrowed Haversian canals.

The _periosteal gumma_ appears as a smooth, circumscribed swelling which is soft and elastic in the centre and firm at the margins, and shades off into the surrounding bone. The gumma may be completely absorbed or it may give place to a hard node. In some cases the gumma softens in the centre, the skin becomes adherent, thin, and red, and finally gives way. The opening in the skin persists as a sinus, or develops into a typical ulcer with irregular, crescentic margins; in either case a probe reveals the presence of carious bone or of a sequestrum. The health may be impaired as a result of mixed infection, and the absorption of toxins and waxy degeneration in the viscera may ultimately be induced.

A _central gumma_ in a long bone may not reveal its presence until it erupts through the shell and reaches the periosteal surface or invades an adjacent joint. Sometimes the first manifestation is a fracture of the bone produced by slight violence.

In radiograms the appearance of syphilitic bones is usually characteristic. When there is hyperostosis and sclerosis, the shaft appears denser and broader than normal, and the contour is uneven or wavy. When there is a central gumma, the shadow is interrupted by a rounded clear area, like that of a chondroma or myeloma, but there is sclerosis round about.

_Diagnosis._--The conditions most liable to be mistaken for syphilitic disease of bone are chronic staphylococcal osteomyelitis, tuberculosis, and sarcoma; and the diagnosis is to be made by the history and progress of the disease, the result of examination with the X-rays, and the results of specific tests and treatment.

_Treatment._--The general health is to be improved by open air, by nourishing food, and by the administration of cod-liver oil, iron, and arsenic. Anti-syphilitic remedies should be given, and if they are administered before there is any destruction of tissue, the benefit derived from them is usually marked.

Radiograms show the rapid absorption of the new bone both on the surface and in the marrow, and are of value in establishing the therapeutic diagnosis.

In certain cases, and particularly when there are destructive changes in the bone complicated with pyogenic infection, specific remedies have little effect. In cases of persistent or relapsing gummatous disease with ulceration of skin, it is often necessary to remove the diseased soft parts with the sharp spoon and scissors, and to gouge or chisel away the unhealthy bone, on the same lines as in tuberculous disease. When hyperostosis and sclerosis of the bone is attended with severe pain which does not yield to blistering, the periosteum may be incised and the sclerosed bone perforated with a drill or trephine.

#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.

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

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 tænia 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 vertebræ, 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.

(Anatomical Museum, University of Edinburgh.)]

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 hæmorrhages, 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 œdema. These symptoms are due to a sub-periosteal hæmorrhage, 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. Hæmorrhages 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 vertebræ, 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 vertebræ 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 diploë is lost, and, while the general texture is finely porous, there may be areas as dense as ivory (Fig. 134).

(Anatomical Museum, University of Edinburgh.)]

_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 hæmorrhages 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 fossæ 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.

(Photograph lent by Sir George T. Beatson.)]

#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 vertebræ. 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 maxillæ; these bones are enlarged in all directions and project on the face, and the nasal fossæ 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 fœtal 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.