Alexis Thomson

“ Regeneration of Bone.#--When bone has been lost or destroyed as a result of injury or disease, it is capable of being reproduced, the extent to which regeneration takes place varying under different conditions. The chief part in the regeneration of bone is played by the osteoblasts in the adjacent marrow and in the deeper layer of the periosteum. The shaft of a long bone may be reproduced after having been destroyed by disease or removed by operation. The flat bones of the skull and the bones of the face, which are primarily developed in membrane, have little capacity of regeneration ”

“ 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. ”

“ 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. ”

“ Where there are two parallel bones--as in the leg, for example--the growth of the diseased bone may be impaired, and the other continuing its normal growth becomes disproportionately long; less frequently the growth of the diseased bone is exaggerated, and it becomes the longer of the two. In either case, the longer bone becomes curved. An _obliquity_ of the bone may result when one half of the epiphysial cartilage is destroyed and the other half continues to form bone, giving rise to such deformities as knock-knee and club-hand. ”

“ 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. ”

“ 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. ”

“ 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_. ”

“ It follows from this that the implanting of living bone is to be preferred to the implanting of dead bone or of foreign material. We believe that transplanted living bone when placed under favourable conditions survives and becomes incorporated with the bone with which it is in contact, and does not merely act as a scaffolding. We believe also that the retention of the periosteum on the graft is not essential, but, by favouring the establishment of vascular connections, it contributes to the survival of the graft and the success of the transplantation. ”

“ When the infection becomes active, the contents of the cavity are transformed into a greenish-yellow pus from which the staphylococcus can be isolated, and the cavity is lined by a thin film of granulation tissue which erodes the surrounding bone and so causes the abscess to increase in size. If the erosion proceeds uniformly, the cavity is spherical or oval; if it is more active at some points than others, diverticula or tunnels are formed, and one of these may finally erupt through the shell of the bone or into an adjacent joint. ”

“ Amputation of the limb is reserved for grave cases, in which life is endangered by toxaemia, which is attributed to the primary lesion. It may be called for later if the limb is likely to be useless, as, for example, when the whole shaft of the bone is dead without the formation of a new case, when the epiphyses are separated and displaced, and the joints are disorganised.
Flat bones, such as the skull or ilium, must be trephined and the pus cleared out from both aspects of the bone. In the vertebrae, operative interference is usually restricted to opening and draining the associated abscess. ”

“ 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_. ”

“ If the periosteum has been extensively destroyed, new bone may only be formed in patches, or not at all. The dead bone is separated from the living by the agency of granulation tissue with its usual complements of phagocytes and osteoclasts, so that the sequestrum presents along its margins and on its deep surface a pitted, grooved, and worm-eaten appearance, except on the periosteal aspect, which is unaltered. Ultimately the dead bone becomes loose and lies in a cavity a little larger than itself; the wall of the cavity is formed by the new case, lined with granulation tissue. ”

“ 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. ”

“ 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 ”

“ 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. ”

“ 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. ”

“ The size of the abscess affords no indication of the extent of the bone lesion from which it originates. As the abscess reaches the surface, the skin becomes of a dusky red or livid colour, is gradually thinned out, and finally sloughs, forming a sinus. A probe passed into the sinus strikes carious bone. Small sequestra may be found embedded in the granulation tissue. The sinus persists as long as any active tubercle remains in the tissues, and is apt to form an avenue for pyogenic infection. ”

“ When there is widespread suppuration in the marrow, and the shaft is extensively bared of periosteum and appears likely to die, it may be resected straight away or after an interval of a day or two. Early resection of the shaft is also indicated if the opening of the medullary canal is not followed by relief of symptoms. In the leg and forearm, the unaffected bone maintains the length and contour of the limb; in the case of the femur and humerus, extension with weight and pulley along with some form of moulded gutter splint is employed with a similar object. ”

“ 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. ”

“ It may be less evident to the eye than to the fingers, and is best appreciated by gently stroking the bone from the middle of its shaft towards the end. The maximum thickening and tenderness usually correspond to the junction of the diaphysis with the epiphysis, and the swelling tails off gradually along the shaft. As time goes on there is redness of the skin, especially over a superficial bone, such as the tibia, the swelling becomes softer, and gives evidence of fluctuation. ”

“ The most common is an osteomyelitis commencing in the marrow exposed in a wound infected with pyogenic organisms. In amputation stumps, fungating granulations protrude from the sawn end of the bone, and if necrosis takes place, the sequestrum is annular, affecting the cross-section of the bone at the saw-line; or tubular, extending up the shaft, and tapering off above. The periosteum is more easily detached, is thicker than normal, and is actively engaged in forming bone. ”

“ Displacement or partial extrusion of the dead bone may cause complications, as when a sequestrum derived from the trigone of the femur perforates the popliteal artery or the cavity of the knee-joint, or a sequestrum of the pelvis perforates the wall of the urinary bladder. ”

“ 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 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. ”

“ Where there are one or more sinuses, the passage of a probe which strikes bare bone affords corroboration of the view that the bone has perished. When the dead bone has been separated from the living, the X-rays yield the most exact information. ”

“ While the swelling often remains quiescent for some time, it tends to increase in size, to become boggy or fluctuating, and to assume the characters of a cold abscess. The pus perforates the fibrous layer of the periosteum, invading and infecting the overlying soft parts, its spread being influenced by the anatomical arrangement of the tissues. ”

“ Acute osteomyelitis# is a suppurative process beginning in the marrow and tending to spread to the periosteum. The disease is common in children, but is rare after the skeleton has attained maturity. Boys are affected more often than girls, in the proportion of three to one, probably because they are more liable to exposure, to injury, and to violent exertion. ”

“ 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. ”