Bone is a living, dynamic organ, being continuously remodelled in response to external mechanical and chemical influences and acting as a large reservoir for calcium and phosphate.
Examples of fractures: the fibula (thin bone) has a simple fracture of its shaft and a comminuted fracture at its lower end; the tibia has a compound fracture of its shaft.
These occur when there is a break in the continuity of the bone either from violence or because the bone is unhealthy and unable to withstand normal stresses.
Fractures where the skin remains intact or merely grazed.
These fractures have at least one open wound which communicates with the fracture, meaning that bacteria can enter the fracture site and cause infection. A compound fracture is also more serious than a simple fracture because there is greater chance of blood loss. Compound fractures usually need hospital admission, antibiotics and careful reduction of the fracture. Debridement (cleaning and excising dead tissue) in a sterile theatre may also be necessary.
The type of fracture depends on the force which has caused it. An object hitting the bone may cause a transverse break horizontally across the bone. Indirect violence occurs, for example, when a twisting injury to the ankle breaks the tibia higher up. The break may be more oblique. A fall on an outstretched hand may cause a break at the wrist, in the humerus or at the collar-bone depending on the force of impact and age of the person.
These occur after the bone has been under recurrent stress. A typical example is the March fracture of a metatarsal, from which some army recruits suffer after long marches.
These occur in bone which is already diseased – for example, by OSTEOPOROSIS in post-menopausal women or by cancerous deposits. Such fractures are typically crush fractures of the vertebrae, fractures of the neck of the femur, and COLLES’ FRACTURES (of the wrist).
These occur in young children whose bones are soft and bend, rather than break, in response to stress. The bone tends to buckle on the side opposite to the force. Greenstick fractures heal quickly but still need any deformity corrected and plaster of Paris to maintain the correction.
These involve damage to important soft tissue such as nerves, blood vessels or internal organs. In these cases the soft-tissue damage needs as much attention as the fracture site.
A fracture with more than two fragments. It usually means that the injury was more violent and that there is more risk of damage to vessels and nerves. These fractures are unstable and take longer to unite. Rehabilitation tends to take a long time.
Most commonly found in skull fractures. A fragment of bone is forced inwards so that it lies lower than the level of the bone surrounding it. It may damage the brain beneath it.
These occur when the bone is broken but the force has not been severe enough to cause visible displacement. These fractures may be easily missed and even an X-ray may not initially reveal them.
The fracture site is usually painful, swollen and deformed. There is asymmetry of contour between limbs. The limb is held uselessly. If the fracture is in the upper limb, the arm is usually supported by the patient; if it is in the lower limb then the patient is not able to bear weight on it. The limb may appear short because of muscle spasm.
Depressed fracture of the skull (sagittal view).
Impacted fracture of neck of left femur.
Injury to the spine: compression fracture of 1st lumbar vertebra with no damage to spinal cord.
Injury to the spine: fracture/dislocation of 12th thoracic vertebra with damage to spinal cord.
Examination may reveal crepitus – a bony grating – at the fracture site. The diagnosis may be confirmed by X-ray.
Healing of fractures (union) begins with the clotted blood around the fracture being resorbed and new bone-producing cells and blood vessels migrating into the area. Within a couple of days they form a bridge of primitive bone across the fracture. This is called callus.
The callus is replaced by woven bone which gradually matures as the new bone remodels itself. Treatment of fractures is designed to ensure that this process occurs with minimal residual deformity to the bone involved.
Treatment is initially to relieve pain and may involve temporary splinting of the fracture site. Reducing the fracture means restoring the bones to their normal position; this is particularly important at the site of joints where any small displacement may considerably limit movement.
Reduction may be done under a general anaesthetic, which relaxes muscles and makes manipulation easier. Traction, which means sustained but controlled pulling on the bone, then restores the fragments of the fracture into their normal position: these are then kept in position with plaster of Paris. If closed traction does not work, open reduction of the fracture may be needed. This may involve fixing the fracture with internal-fixation methods, using metal plates, wires or screws to hold the fracture site in a rigid position with the two ends closely opposed. This allows early mobilisation after fractures and speeds return to normal use.
External fixators are usually metal devices applied to the outside of the limb to support the fracture site. They are useful in compound fractures where internal fixators are at risk of becoming infected.
Consolidation of a fracture means that repair is complete. The time taken for this depends on the age of the patient, the bone and the type of fracture. A wrist fracture may take six weeks, a femoral fracture three to six months in an adult.
Complications of fractures are fairly common. In non-union, the fracture does not unite – usually because there has been too much mobility around the fracture site. Treatment may involve internal fixation (see above). Malunion means that the bone has healed with a persistent deformity and the adjacent joint may then develop early osteoarthritis.
Myositis ossificans may occur at the elbow after a fracture. A big mass of calcified material develops around the fracture site which restricts elbow movements. Fractured neck of FEMUR typically affects elderly women after a trivial injury. The bone is usually osteoporotic. The leg appears short and is rotated outwards. Usually the patient is unable to put any weight on the affected leg and is in extreme pain. The fractures are classified according to where they occur:
subcapital where the neck joins the head of the femur.
intertrochanteric through the trochanter.
subtrochanteric transversely through the upper end of the femur (rare).
Most of these fractures of the neck of femur need fixing by metal plates or hip replacements, as immobility in this age group has a mortality of nearly 100 per cent. Fractures of the femoral shaft are usually the result of severe trauma such as a road accident. Treatment may be CONSERVATIVE or operative.
In fractures of the SPINAL COLUMN, mere damage to the bone – as in the case of the so-called compression fracture, in which there is no damage to the spinal cord – is not necessarily serious. If, however, the spinal cord is damaged, as in so-called fracture dislocation, the accident may be a very serious one, the possible result being paralysis of the parts of the body below the level of the injury. Therefore the higher up the spine is fractured, the more serious the consequences. The injured person should not be moved until skilled assistance is at hand; or, if he or she must be removed, this should be done on a rigid shutter or door, not on a canvas stretcher or rug, and there should be no lifting which necessitates bending of the back. In such an injury, an operation designed to remove a displaced piece of bone and free the spinal cord from pressure is often necessary and successful in relieving the paralysis. DISLOCATION or SUBLUXATION of the spine is not uncommon in certain sports, particularly rugby. Anyone who has had such an injury to the cervical spine (i.e. in the neck) should be strongly advised not to return to any form of body-contact or vehicular sport.
Simple fissured fractures and depressed fractures of the skull often follow blows or falls on the head, and may not be serious, though there is always a risk of damage which is potentially serious to the brain at the same time.
Compound fractures may result in infection within the skull, and if the skull is extensively broken and depressed, surgery is usually required to check any intracranial bleeding or to relieve pressure on the brain.
The lower jaw may be fractured by a blow on the face. Treatment is simple, the line of teeth in the upper jaw forming a splint against which the lower jaw is bound, with the mouth closed.
These are rare but may produce certain types of dwarfism or a susceptibility to fractures (osteogenesis imperfecta).
(osteomyelitis) may occur after an open fracture, or in newborn babies with SEPTICAEMIA. Once established, it is very difficult to eradicate. The bacteria appear capable of lying dormant in the bone and are not easily destroyed with antibiotics, so that prolonged treatment is required, as might be surgical drainage, exploration or removal of dead bone. The infection may become chronic or recur.
Osteomalacia (rickets) is the loss of minerals from bone rather than simple loss of bone mass, so it becomes soft and misshapen. It is caused by vitamin D deficiency and is probably the most important bone disease in the developing world. In the UK it is mostly seen in children from the Indian sub-continent. In sunlight the skin can synthesise vitamin D (see APPENDIX 5: VITAMINS), but osteomalacia is contributed to by a poor diet or by a failure to absorb food normally (malabsorption). In rare cases vitamin D cannot be converted to its active state due to the congenital lack of the specific enzymes and the rickets will fail to respond to treatment with vitamin D. Malfunction of the parathyroid gland or of the kidneys can disturb the dynamic equilibrium of calcium and phosphate in the body and severely deplete the bone of its stores of both calcium and phosphate.
A condition of low bone mass (osteopenia) due to excessive bone resorption. Sufferers are prone to bone fractures from relatively minor trauma. With bone DENSITOMETRY it is now possible to determine individuals’ risk of osteoporosis and monitor their response to treatment.
It may be classified as primary or secondary. Primary (or type 1) osteoporosis is due to accelerated trabecular bone loss, probably as a result of deficiency of OESTROGENS. This typically leads to crush fractures of vertebral bodies and fractures of the distal forearm in women in their 60s and 70s. Type 2 osteoporosis, by contrast, results from the slower, age-related cortical and trabecular bone loss that occurs in both sexes. It typically leads to fractures of the upper femur in elderly people.
Secondary osteoporosis accounts for about 20 per cent of cases in women and 40 per cent of cases in men. Subgroups include endocrine (THYROTOXICOSIS, primary HYPERPARATHYROIDISM, CUSHING'S SYNDROME and HYPOGONADISM); gastrointestinal (malabsorption syndrome, e.g. COELIAC DISEASE, or liver disease, e.g. primary biliary CIRRHOSIS); rheumatological (RHEUMATOID ARTHRITIS or ANKYLOSING SPONDYLITIS); malignancy (multiple MYELOMA or metastatic CARCINOMA); and drugs (CORTICOSTEROIDS, HEPARIN). Additional risk factors for osteoporosis include smoking, high alcohol intake, physical inactivity, thin body-type and heredity.
Individuals at risk of osteopenia, or with an osteoporosis-related fracture, need investigation with spinal radiography and bone densitometry. A small fall in bone density results in a large increase in the risk of fracture, which has important implications for preventing and treating osteoporosis.
With established osteoporosis, the aim of treatment is to relieve pain (with analgesics and physical measures, e.g. lumbar support) and reduce the risk of further fractures: improvement of bone mass, the prevention of falls, and general physiotherapy, encouraging a healthier lifestyle with more daily exercise. Specific treatment has to be based on the person's age, their risk factors for fractures and bone density measurements. The risks that have to be considered include having had a fracture, drinking more than 4 units of alcohol daily, rheumatoid arthritis and certain illnesses that reduce mobility. In women over 70, a bisphosphonate drug (identifiable by its ending, -onate) is often prescribed, or strontium if the former is not tolerated. There is no evidence that calcium supplementation is useful in this condition.
(see also separate entry) is a common disease of bone in the elderly, caused by overactivity of the osteoclasts (cells concerned with removal of old bone, before new bone is laid down by osteoblasts). The bone affected thickens and bows and may become painful. Treatment with calcitonin and bisphosphonates may slow down the osteoclasts, and so hinder the course of the disease, but there is no cure.
If bone loses its blood supply (avascular necrosis) it eventually fractures or collapses. If the blood supply does not return, bone's normal capacity for healing is severely impaired.
For the following diseases see separate articles: RICKETS; ACROMEGALY; OSTEOMALACIA; OSTEOGENESIS IMPERFECTA.
These can be benign (non-cancerous) or malignant (cancerous). Primary bone tumours are rare, with secondary spread from carcinoma of the breast, prostate and kidneys being more common. They may form cavities in a bone, weakening it until it breaks under normal load (a pathological fracture). The bone eroded away by the tumour may also produce problems by causing high levels of calcium in the plasma.
is a malignant growth affecting long bones, particularly the tibia (calf-bone). The presenting symptoms are a throbbing pain in the limb and a high temperature. Treatment is combined surgery, radiotherapy and chemotherapy.
is a generalised malignant disease of blood cells which produces tumours in bones which have red bone marrow, such as the skull and trunk bones. These tumours can cause pathological fractures.
is a harmless small growth which can occur in any bone. Its pain is typically removed by aspirin.
is a malignant tumour of bone with a peak incidence between the ages of ten and 20. It typically occurs around the knee, causing a warm tender swelling. Removal of the growth with bone conservation techniques can often replace amputation as the definitive treatment. Chemotherapy can improve long-term survival.