1 TYPE OF BONE

2 PATIENT AGE

In children, union of fractures is rapid. The speed of union decreases as age increases until skeletal maturity is reached. There is then not a great deal of difference in the rate between young adults and the elderly. For example, in a child, union may be expected in a fractured femur a little after the number of weeks equivalent to its numerical age have passed: viz. a fractured femur in a child of 3 years is usually united after 4 weeks; a fractured femur in a child of 8 years is usually sound after 9 weeks. In contrast, a fracture of the femoral shaft in an adult may take 3–6 months to unite.

Apart from great rapidity of union it should be noted that children have remarkable powers of remodelling fractures. These powers are excellent as far as displacement is concerned, and are often good for slight to moderate angulation. Remodelling is poor in the case of axial rotation in both adults and children. The power to remodel decreases rapidly once adolescence is reached and epiphyseal fusion is imminent.

3 MOBILITY AT THE FRACTURE SITE

Excessive mobility persisting at the fracture site (due, for example, to poor fixation) may interfere with vascularisation of the fracture haematoma; it may lead to disruption of early bridging callus and may prevent endosteal new bone growth. One of the main aims of all forms of internal and external splintage is to reduce mobility at the fracture site, and hence encourage union. Absolute rigidity, however, may discourage external callus formation, so that reliance is placed on the internal fixation device – typically a plate – until the long process of endosteal union is complete. Nevertheless, if splintage is inadequate, union may be delayed or prevented.

4 SEPARATION OF BONE ENDS

1 Supracondylar fracture of humerus with soft tissue between bone ends.

Union will be delayed or prevented if the bone ends are separated, for this interferes with the normal mechanisms of healing. (The converse is also true, namely that compression of the fracture facilitates union.) Separation may occur under several circumstances:

5 BONE LOSS

This is comparatively rare, with the tibia and femur being most commonly affected; even less common is significant loss in the humerus and forearm bones. The main causes are bone extrusion in open fracture at the site of the causal incident or during transport, bone removal occurring during debridement procedures, and injuries due to gunshots or explosions. Loss most commonly affects the diaphysis; loss of metaphyseal or articular bone is generally associated with high-energy dissipation injuries.

If the loss is substantial then treatment will be prolonged and difficult, and because of the mechanism of injury many of these cases have accompanying problems with skin loss, tissue contamination, and accompanying neural and vascular damage. Other factors such as the patient’s age and medical state, and other injuries will influence the management of the case. The first decision that must be made is therefore whether amputation is the best approach. This is not always easy, and the general view is that this must be decided on a completely individual assessment of the factors involved. While use of the Mangled Extremity Severity Index (see p. 51) may help in taking all the important factors into account, it has been shown to be somewhat unreliable in evaluating those cases where it indicates that amputation should be performed.

Where it has been decided not to amputate, an appropriate method of fixation of the fracture must be chosen. The procedure to be adopted depends on the site and extent of the bone loss, and other local factors. In the femur, tibia and humerus (unless there is any contraindication), locked intramedullary nails generally give the best support for losses up to 6 cm, and at the later stages, with the newer devices, may allow bone lengthening procedures to be carried out. Autogenous bone grafting may also be required. In the forearm, and also in the case of the humerus, plates and screws are usually employed. External fixators may also be used, although unilateral frames do not give sufficient support where there is a significant segmental defect in the leg. In this case, the Ilizarov and other circular frames are of particular value, especially when subsequent bone lengthening is planned, and may be employed where the defect exceeds 6 cm.

The general approach is to fix the fracture at its true length, paying particular attention to rotation. However, where the skin poses a problem it is often useful to allow initial shortening of the limb while aiming to correct this later with a subsequent limb lengthening procedure.

There are many other approaches to dealing with the vagaries of these injuries. These include calcium phosphate cement which may be used for small metaphyseal or calcaneal defects; allografts, particularly in young patients with loss of a portion of a joint surface; vascularised fibular grafts, especially in the forearm; the creation of a one-bone forearm or lower leg; the use of bone substitutes and bone growth factors; and joint replacement procedures where there is a substantial loss of articular surfaces.

6 INFECTION

2 Chronic bone infection and failure of union of tibia following plating (plate removed).

Infection in the region of a fracture may delay or prevent union. This is especially the case if, in addition, movement is allowed to occur at the fracture. Infection of the fracture site is extremely rare in conservatively treated closed fractures; infection, if it occurs, follows either an open injury or one treated by internal fixation. Where infection becomes well established in the presence of an internal fixation device, it is often difficult to achieve healing without removal of the device which acts as a foreign body and a nidus for persisting infection. This is especially the case if there is breakdown of the overlying skin and the establishment of a sinus. Not infrequently the situation arises where cast fixation alone is unable to provide the degree of fixation necessary for union if the device is removed, and where infection is likely to remain if it is not. In such circumstances it is usually wiser to retain the fixation device until union is reasonably well advanced, or to consider using an external fixator. In some cases where sound healing can be obtained and maintained after removal of an internal fixation device, it may be possible to repeat the internal fixation in the sterile environment that has been obtained.

7 DISTURBANCE OF BLOOD SUPPLY

It is obvious that for the normal multiplication of bone cells and their precursors an adequate blood supply is required. Where the blood supply to an area is reduced, or where there is interference with the blood supply to both major fragments – e.g. in radionecrosis of bone – healing may be interfered with. On the other hand, reduction of the blood supply to one fragment, especially if cancellous bone is involved, may not interfere with union; indeed, in some situations it may apparently stimulate it. The most striking examples of this are fractures of the femoral neck and scaphoid, where the phenomenon of avascular necrosis is most frequently discovered in soundly united fractures. Interference with the blood supply to one fragment at the time of injury leads to immediate bone death; this is frequently followed by sound union of the fracture. Collapse of necrotic bone beyond the level of union is observed at a later date.

Again, a bulky internal fixation device may in itself interfere with the local blood supply and the fracture haematoma, delaying union. Where possible this should be avoided by choosing the most appropriate device.

8 PROPERTIES OF THE BONE INVOLVED

Fracture healing is also affected by a number of imperfectly understood factors which lead to variations in the speed of union. The clavicle is a spectacular example; non-union is extremely rare, the time to clinical union is unexcelled by any other part of the skeleton, yet movement at the fracture site cannot be controlled with any efficiency. Union of the tibia is often slow to a degree that is difficult to explain even when the influence of its nutrient artery and fracture mobility are taken into account.

9 OTHER FACTORS

In closed fractures, and as a general rule, conservative methods of treatment are to be preferred wherever possible. Nevertheless, infections occurring in cases treated by internal fixation appear to be due mainly to contamination rather than an impaired immunity response, and open methods may be pursued so long as strict attention is paid to asepsis and careful tissue handling. Prophylactic antibiotics in the form of a first generation cephalosporin have been recommended by Harrison.²

In open fractures, if internal fixation is used, the rate of infection is often unacceptably high, and this line of treatment should be avoided where possible. In the case of the tibia an external fixator may be used, although an increase in pin-track infections should be anticipated. It need hardly be stated that in every case the strictest precautions must be taken to avoid the operator being exposed to the infected tissues and serum of the patient.

In any fracture case if there is an increase in the rate of non-union, it may generally be dealt with successfully by internal fixation and bone grafting.

1 COMPLICATIONS OF MAJOR TRAUMA

These include:

Major tissue trauma activates cell defence mechanisms which combat infection, remove damaged tissue and facilitate tissue repair. These processes may be affected by systemic mediators which might cause an imbalance. This may be towards a generalised pro-inflammatory state (systemic inflammatory response syndrome or SIRS) accompanied by cell damage with increased cell wall permeability, or to suppression of inflammation (compensatory anti-inflammatory response syndrome or CARS) which may lead to a susceptibility to infection. Such imbalances are said to be the result either of particularly severe trauma or a particular individual response.³ The acute respiratory distress syndrome (ARDS) is regarded as being a local manifestation of SIRS, and in those who survive, the cause of multiple organ dysfunction (MODS). This may include cardiac, gastrointestinal, renal, hepatic, haematological and cerebral failure.

Hypoxia and acute respiratory insufficiency are common after trauma, and the causes include upper airway obstruction, chest injury (e.g. due to pneumothorax) and circulatory failure. Most respond to treatment of the underlying cause and the administration of oxygen, but if this fails other reasons, ARDS or the fat embolism syndrome (FES) must be suspected.

After most fractures some fat is released into the circulation and causes no problem. In FES however, the situation is different, and this may be related to the quantity of fat involved. The presence of fat in the pulmonary circulation may result in respiratory problems similar to those found in ARDS. Fat particles may, however, also enter the systemic circulation through pulmonary capillaries and shunts, or through a patent foramen ovale, producing very distinctive features which merit the title ‘fat embolus’. This is seen most often after fractures of the femoral shaft and pelvis.

In both ARDS and FES there is no evidence of cardiac failure; chest radiographs show bilateral ‘snowstorm’ lungs, and there is disturbance of the PaO₂/FiO₂ ratio (the arterial oxygen concentration divided by the fractional inspired oxygen concentration). Where there has been a fat embolism the most distinctive features (which may appear 2 or 3 days after the injury) are:

2 COMPLICATIONS OF PROLONGED RECUMBENCY

These include:

Factors in risk assessment include:

Where the risks are judged to be more than trivial, the following may be considered:

Mechanical measures, such as:

Chemical prophylaxis: Where the risks are considered to be high, chemical prophylaxis should be considered. It would seem advantageous to continue this for 4–5 weeks, even although the patient has been allowed home in the interim. Careful consideration must be given as to when the medication should be commenced: the earlier it is started, the more effective it is – but too early, and haemorrhage may ensue. A number of agents, of varying efficacy, are in current use. These include:

Avoiding these complications as well as the costs of protracted in-patient treatment are the main reasons for the continuing trend towards the operative management of many fractures. In the case of multiple injuries, internal fixation is of considerable help to the nursing staff in their care of the patient.

3 COMPLICATION OF ANAESTHESIA AND SURGERY

These include:

4 COMPLICATIONS PECULIAR TO FRACTURES

These include:

This last group will be considered in more detail.