An introduction to fractures

the Executive Committee of the Association of Orthopaedic Chartered Physiotherapists

This chapter looks at some basic facts and concepts about fractures but should not be seen as a definitive guide to fracture management. Suggested further reading is included at the end of the chapter.

Definition and classifications

Definition

A fracture is an interruption in the continuity of bone. The terms fracture and break mean the same thing in medicine. The symbol # (hash) represents a fracture.

Classification of fractures

There are numerous different ways of classifying fractures and this will vary depending on country, hospital or consultant preference. Although it is helpful to categorise common fracture types and mechanisms, any bone may break in a variety of ways, so no two fractures will be exactly alike. Obviously, the type of fracture will affect the initial management and treatment.

Fractures may be classified as open or closed (Figure 22.1). Open or compound types of fracture occur when the bone-end or some other object has pierced the skin. These fractures are an additional cause for concern because of the possibility of the introduction of microorganisms, leading to bone infection (osteomyelitis). With closed fractures the skin remains intact. Another common classification includes displaced or un-displaced.

Figure 22.1 (a) Closed fracture. (b) Open or compound fracture. (Adapted from Dandy and Edwards 1998, with permission.)

Figure 22.2 shows some further classifications. Spiral fractures commonly occur from a twisting injury. A direct blow could give a transverse or oblique fracture depending on the angle of the force and whether the limb is fixed or moving at the time of the trauma. Longitudinal forces tend to result in compression or crush fractures. In some cases there are a number of fragments of bone and this is termed a ‘comminuted’ fracture (not to be confused with ‘compound’). Loose fragments of bone are known as ‘butterfly fragments’.

Figure 22.2 Classification: (a) spiral; (b) transverse; (c) oblique; (d) compression; (e) comminuted; (f) greenstick; (g) pathological; (h) avulsion; (i) impacted.

A greenstick fracture is a type of fracture sustained by young children whose bones are still relatively malleable; therefore, fractures are more likely to present as an incomplete fracture – a greenstick fracture. (The analogy is attempting to break a green twig, which will bend and split but not snap.) Avulsion fractures occur when a bit of bone is pulled off owing to its attachment to soft tissues (e.g. ligaments). Impacted fractures are generally compressed and therefore more stable.

The causes of fractures

Trauma

Most fractures are a result of some form of injury. This might be a direct blow, a fall from a height or a weight falling onto a part of the body. Other fractures may be caused by indirect trauma, such as falling on an outstretched hand leading to the transmission of force up the arm causing a fracture of the clavicle. Twisting forces may result in fractures of the tibia and fibula, for example during soccer or skiing when the weight of the body rotates on a fixed foot. Stress or fatigue fractures are caused by repeated minor trauma, which can occur after walking or running long distances, and often affect the foot metatarsals.

Pathological fractures

These occur as the result of a disease that weakens the composition of the bone itself, making it liable to fracture as the result of a relatively trivial injury. There are a number of such diseases but those most commonly seen clinically are osteoporosis, Paget’s disease, carcinoma, osteomyelitis or osteogenesis imperfecta (brittle bone disease).

Clinical features of fractures

Clinical features vary depending on the cause and nature of the injury, and range from unconsciousness to the patient being able to use the limb, although complaining of pain – such as following fatigue fractures and some impacted or crack fractures. Most will be diagnosed by X-ray. Some fractures, for example fractures of the scaphoid bone, are sometimes not detected upon initial X-ray and can be misdiagnosed as wrist sprain. The clinical features of fractures are summarised below.

Fracture healing

Healing of compact bone

Bone has the incredible ability to replace itself with new bone, not scar tissue. Healing starts within seconds of a fracture being sustained and will still be ongoing years later – this makes ascribing a healing timescale difficult.

Wolff’s law states that bone responds to the stresses that are imposed upon it by rearranging its internal architecture to best withstand the stresses. In other words, bone is laid down where it is needed and absorbed where it is not. It is important to understand this concept when dealing with people who have sustained fractures. Bone is a living tissue, not the brittle, chalky specimens that students may be familiar with. It is continually in a dynamic equilibrium of growth and reabsorption. Figure 22.3 shows the process of fracture healing in compact bone taken through five stages.

Haematoma

As a result of the tearing of blood vessels within seconds of the injury, a haematoma forms at the fracture site. Very small portions of bone immediately adjacent to the fracture die and are gradually absorbed.

Periosteal and endosteal proliferation

There is a proliferation of cells from the deep surface of the periosteum adjacent to the fracture site. These cells are precursors of the osteoblasts and form around each fragment of bone. At the same time cells proliferate from the endosteum in each fragment and this tissue gradually forms a bridge between the bone ends. During this stage the haematoma is gradually reabsorbed.

Callus formation

The proliferating cells mature as osteoblasts or, in some instances, as chondroblasts. The chondroblasts form cartilage and are found in varying amounts at a fracture site. Osteoblasts lay down an intercellular matrix of collagen and polysaccharide which then becomes impregnated with calcium salts forming the immature bone called callus or woven bone. This is visible on X-ray and gives evidence that healing is taking place.

Consolidation

Osteoblastic activity results in the change of primary callus to bone, which has a lamellar structure, and at the end of this stage union is complete. New bone forms a thickened mass at the fracture site and obliterates the medullary cavity. The amount of this new bone varies for a number of reasons. It tends to be more extensive if there has been a large haematoma or it has been impossible to obtain exact apposition of the bone fragments.

Remodelling

The lamellar structure is changed and the bone adapts by strengthening along the lines of stress imposed upon it. The surplus bone formed during healing is gradually removed and eventually the bone structure appears very similar to the original. In children, healing is usually very good and it is difficult to see the fracture site on a radiograph. In adults there may be a permanent area of thickening, which might be felt or seen, in a superficial bone.

Healing of cancellous bone

This follows a different pattern from that described above. As with compact bone, a haematoma will form, but as there is no medullary cavity, the second stage differs. Cancellous bone has a greater area of contact between the fragments of bone and penetration of the bone-forming tissue is facilitated by the open arrangement of trabeculae as it grows out from both fragments. Osteogenic cells lay down intercellular matrix, which calcifies to form woven bone. The process of remodelling then continues to form the cancellous bone.

When is a fracture healed?

One of the most common questions asked by patients is ‘When will my fracture be healed?’ Unfortunately, the answer to this question is not always straightforward and depends upon many factors, including the type of bone fractured, the type of fracture sustained, the age of the person, the treatment undergone and the nutritional status of the person.

The current mainstay for evaluating when a fracture is healed is still based upon a combination of clinical judgement, X-ray evaluation and historical knowledge on specific fracture behaviours. A fracture is considered to be clinically healed based upon the combination of physical findings and symptoms over time.

The following suggest complete healing:

• absence of pain on weight-bearing, lifting or movement;

• no tenderness on palpation at the fracture site;

• blurring or disappearance of the fracture line on X-ray;

• full or near full functional ability (Hoppenfeld and Urthy 1999).

Time for a fracture to unite

The time it takes for a fracture to unite depends on a number of factors.

• Type of bone. Cancellous bone heals more quickly than compact bone. Healing of long bones depends on their size so that bones of the upper limb unite earlier (3–12 weeks) than do those of the lower limb (12–18 weeks).

• Revascularisation of devitalised bone and soft tissues adjacent to the fracture site.

• The mechanical environment of the fracture (Marsh and Li 1999).

• Classification of the fracture. It is easier to obtain good apposition of bone ends with some fractures than with others. This may depend on the initial position of the fragments before reduction and the effect of muscle pull on the fragments.

• Blood supply. Adequate blood supply is essential for normal healing to take place. Certain fractures can be notoriously slow to heal (e.g. fractures of the lower third of tibia). This part of the bone has a poor blood supply owing to the fact that under normal circumstances it does not require one as there is little muscle bulk here, therefore little demand for nutrients and oxygen.

• Fixation. Adequate fixation prevents impairment of the blood supply which may be caused by movement of the fragments. It also maintains the reduction thus preventing deformity and consequent loss of function. Interestingly, if a fracture is rigidly immobilised, the stimulus for callus to form is lost, so a small amount of movement at a fracture site actually encourages fracture healing.

• Age. Union of a fracture is quicker in children and consolidation may occur at between 4 and 6 weeks. Age makes little difference to union in adults unless there is accompanying pathology.

• It has been suggested that certain drugs such as non-steroidal anti-inflammatory drugs may interfere with fracture healing; however, evidence remains inconclusive (Bandolier 2004).

• Smoking. There are increased rates of delayed union and non-union in people who smoke who have sustained open tibial fractures (Adams et al. 2001).

• Ultrasound. Recent work has suggested that low-intensity ultrasound may accelerate fracture healing (Azuma et al. 2001).

Complications of fractures

Critical blood disorders

Pulmonary embolism and deep vein thrombosis are two possible complications of a fracture. Shock may be caused by hypovolaemia or loss of blood. Femoral shaft fractures may bleed as much as three pints (1.7 litres) and pelvic fractures may lose six pints (22.4 litres). Clinical signs of this are tachycardia (rapid heart rate), pallor from reduced peripheral perfusion, hypoxia (decreased oxygen saturation), confusion, and a state of semi-consciousness.

Infection and tetanus are threats, especially following open or compound fractures. Most people are now immunised against tetanus or given booster tetanus injections if they have a large open wound. Bone infection (osteomyelitis) can be stubborn to respond to treatment.

Fat embolism (acute respiratory distress syndrome)

If a person sustains multiple fractures of large bones or crushing injuries, or if large amounts of marrow become exposed, there may be leakage of microscopic fat globules into the circulatory system. These may become trapped in the lungs. Symptoms include respiratory distress, shortness of breath, drowsiness, a decrease in saturation of oxygen levels and petechiae (tiny haemorrhages which appear on the chest). Acute respiratory distress syndrome (ARDS) is potentially fatal.

Skin plaster sores

Reassure the patient that large amounts of dry flaky skin following removal of plaster is normal. Reddened areas or sores caused by plaster or splints must be reported to the relevant team member.

Muscle damage and atrophy

Muscle fibres may be torn, crushed or ruptured as a result of the injury and this will cause additional bleeding and swelling. Tendons may be severed, particularly in the case of open fractures, or sometimes there may be a rupture following a fracture. Surgical intervention is usually necessary to repair a rupture.

Compartment syndrome

If muscles become damaged or inflamed at the time of injury, and intramuscular pressure builds up with no means of release, death (necrosis) of the tissues from ischaemia (lack of blood supply) may result. It is defined as the condition in which high pressure within a closed fascial sheath reduces capillary blood perfusion below the level necessary for tissue viability. Compartment syndrome is seen most commonly in the anterior tibial muscles or forearm muscles.

Clinical signs of a limb with compartment syndrome are the five P’s:

Treatment revolves primarily around accurate diagnosis. Check colour, sensation and movement after any injury or surgery, elevate and cool the limb. Surgical decompression (fasciotomy) may be necessary as an emergency procedure.

Avascular necrosis

Bone receives its blood supply by the soft tissue structures attached to it or by intra-osseous vessels. In certain instances one part of the bone is very dependent on the intra-osseous (within the bone) vessels for its blood supply and if this is interrupted because of a fracture, avascular necrosis may occur (part of the fractured bone may die). It can occur in fractures of the neck of femur leading to avascular necrosis of the head, and in fractures of the scaphoid bone where the proximal pole may be affected. This may be a cause of non-union of the fracture and as the fragment usually includes an articular surface it can lead to osteoarthritis.

Problems with union

Delayed union may occur if the gap between the bone ends is too big, the blood supply is poor (lower third of the tibia), the area is infected or if internal fixation is used (this sometimes removes the stimulus for callus formation).

There may be distinct pathological changes and radiological evidence of non-union. There appears to be no callus formation and the fractured ends of bone become dense and the outline clear-cut. The gap between the bone fragments may be filled with fibrous tissue and form a pseudo-arthrosis. The lower third of the tibia has notoriously poor healing capabilities, even occasionally in the young and healthy.

A fracture may heal in a less than perfect position – malunion. Overlapping of the fragments could lead to shortening and this would affect function. Angulation or rotation of the fragments may impair function because of the resulting altered biomechanics.

Growth disturbance

In younger people there may be growth disturbance if the fracture includes the epiphysis (growth plate).

Complex regional pain syndrome I (CRPS I)

The term complex regional pain syndrome (also sometimes known as Sudeck’s atrophy, reflex sympathetic dystrophy (RSD), algodystrophy or causalgia) is now being used to describe these pathological states. Fortunately it is a rare complication. Patients complain of severe pain at rest, as well as on movement, out of proportion to the initial injury. The limb is swollen and the skin appears shiny and discoloured, and feels cold. In extreme cases this may lead to the limb becoming exquisitely tender and discoloured. Osteoporosis and permanent contractures may follow.

Management is difficult. When the lower limb is involved, weight-bearing is encouraged with the help of physiotherapy and pain control aids, such as transcutaneous electrical nerve stimulation (TENS). However, this is minor therapy compared with the use of other treatments such as sympathetic nerve blocks (Viel et al. 1999), vasodilator drugs (e.g. guanethedine) and local analgesia. All of them have variable results. Recovery is slow and may take several months.

Intra-articular fractures

Fractures involving the articular cartilage predispose the joint to osteoarthrosis in the future (e.g. fractures of the tibial plateau). This is owing to the area of roughness that inevitably results after a fracture and also because the immobilisation of the fracture results in cartilage death (see below). For the latter reason, some fractures are now treated aggressively by physiotherapists from an early stage.

Another problem with intra-articular fractures is that if callus is attempting to form within a joint cavity, it is constantly being washed away by synovial fluid.

Visceral injuries

A fractured pelvis may damage the bladder or urethra. A fractured rib may cause a pneumothorax. A skull fracture may cause brain injury. These are just three examples.

Adhesions

These may be within the joint (intra-articular) or around the joint (peri-articular). Adhesions are the price paid for immobilising a fracture. Intra-articular adhesions may occur when the fracture extends into the joint surface and there is a haemarthrosis, or bleeding within a joint cavity. If this is not absorbed, fibrous adhesions may form within the synovial membrane. Peri-articular adhesions may occur if oedema is not reduced and is allowed to organise in the surrounding tissues. This leads to adhesion formation between tissues such as the capsule and ligaments, and results in joint stiffness, which is less of a problem now that new techniques of fixation allowing early mobilisation have been developed.

Capsular adhesions are common, for example in the capsule of the shoulder joint which possesses dependent folds on its inferior aspect to permit the huge range of motion at this joint. These may stick together after fracture or injury causing limitation of movement.

Injury to large vessels

If a large artery is occluded in such a position as to cut off the blood supply to the limb, this may lead to gangrene or, if there is partial occlusion, an ischaemic contracture may develop. These injuries must be dealt with as an emergency by the surgical team.

Thrombosis of veins may occur in the area of the fracture. This presents as a sudden development of a cramp-like pain in the part, by an increase of swelling and by marked tenderness along the line of the vein. Anything that appears to be abnormal in the circulatory system must be reported to the surgeon immediately. Blood vessels may sustain damage, for example following supracondylar humeral fractures the brachial artery may be damaged.

Nerve injury

Certain fractures can lead to nerve palsy (e.g. radial nerve injury in mid-shaft fractures or the common peroneal nerve when a plaster is applied too tightly to the lower limb). Functional bracing (e.g. ankle foot orthosis or AFO) can be helpful while the nerve recovers. Sometimes bracing has to be used long-term if the nerve does not recover.

Oedema

Oedema may be apparent below the level of the plaster and it is often necessary to elevate the limb, exercise the fingers or toes not encased in plaster, and perform isometric contractions of the muscles within the cast in an attempt to encourage muscle pump activity (Tschakovsky et al. 1996; Sheriff and Van Bibber 1998). Once the plaster has been removed, atrophied muscles may not provide an adequate muscle pump on the veins, in which case swelling may reappear especially after activity or non-elevation.

Principles of fracture management

Once a fracture has been diagnosed, the most suitable treatment must be decided upon. This should be the minimum possible intervention that will safely and effectively provide the right environment for healing of the fracture. Interestingly, nature has devised a system by which a slight amount of movement at a fracture site is useful in stimulating callus formation so there is a balance to be made between immobilising a fracture but allowing enough movement to stimulate callus formation and healing (Figure 22.4; Cornell and Lane 1992).

This is a common dilemma in orthopaedics. In the same way that there is no recipe for the physiotherapy treatment of a fracture, there is no single recipe for the surgical management of fractures. This ‘see-saw’ will be referred to in the case study presented later in this chapter.

Reduction

Reduction means to realign into the normal position or as near to the normal anatomical position as possible (Figure 22.5). Reduction of a fracture may be either open or closed. Closed reduction means that no surgical intervention is used with the fracture being manipulated by hand under local or general anaesthesia. Open reduction means that the area has been surgically opened and reduced.

Figure 22.5 Reduction and healing of a fractured shaft of tibia showing the developing callus formation. (With thanks to Martin George, Superintendent Radiographer; Sue Evans, Senior Radiographer; Lynn Porter, Sonographer; Southport and Ormskirk Hospitals, UK.)

Reduction may not always be necessary, even when there is some displacement. For example, fractures of the clavicle may heal with a bump which may be a problem only in the cosmetic sense; function is the most important end-point.

However, when there is poor alignment of the fragments or the relative positions of the joints above and below the fracture are lost as a result of angulation or rotation of the bone ends, or if there is loss of leg length, then accurate anatomical reduction is necessary. X-rays are used to ascertain the exact position of the fragments before and after reduction. Real-time X-rays can now be taken using image intensifiers so that the surgeon can more accurately reduce. Improvements in computed tomography (CT) and magnetic resonance imaging (MRI) scanning mean that complex fractures can be studied in great detail pre-operatively, which assists the planning of surgery.

Immobilisation

The objectives of immobilising a fracture are:

• to maintain the reduction;

• to provide the optimal healing environment for the fracture;

• to relieve pain.

In some fractures where there is no likelihood of displacement, fixation may not be necessary or minimal fixation will suffice, for example buddy strapping for some finger fractures (Figure 22.6).

Figure 22.6 Double buddy strapping applied to both sound and damaged fingers to assist movement of the latter.

Common methods of fracture immobilisation

Plaster of Paris

This is a plaster-impregnated bandage that can be moulded to the part when wet, which sets in time. The standard method of external splinting is still plaster of Paris (Figure 22.7).

Synthetic materials are now used for splinting some fractures because of their light weight and waterproof qualities. Custom-made lightweight thermoplastics can be moulded to the limb and remoulded if swelling or atrophy cause changes in the limb contour. Some synthetic casting materials, however, are less malleable and cannot be moulded as effectively as plaster of Paris and they can occasionally cause allergies.

A plaster saw is needed to remove a cast. This special tool has an oscillating blade that will cut through the hard cast without damaging the skin.

The advantages and disadvantages of using plaster of Paris are listed in Table 22.1.

Table 22.1

The advantages and disadvantages of plaster of Paris

Advantages	Disadvantages
• No surgery or its complications • No infection risk • Quick to apply • Rapid patient discharge • Cheap, relatively easy to apply with training • New lightweight casts are an alternative • Radio translucent (bones can be X-rayed through the cast) • May absorb fluids or bleeding. The extent of bleeding can be traced on the cast itself and monitored daily • Can be moulded for several minutes before hardening	• It may not be possible to reduce the fracture correctly or maintain reduction • May require surgery at a later date • Plaster needs removal/or windowing (removal of a piece of the cast) to inspect the skin • May need removal in case of increased swelling or reapplication once swelling has subsided • Bad odour if it gets wet • Heavy • May crack • May rub the skin and cause sores

Advantages

Disadvantages

• No surgery or its complications

• No infection risk

• Quick to apply

• Rapid patient discharge

• Cheap, relatively easy to apply with training

• New lightweight casts are an alternative

• Radio translucent (bones can be X-rayed through the cast)

• May absorb fluids or bleeding. The extent of bleeding can be traced on the cast itself and monitored daily

• Can be moulded for several minutes before hardening

• It may not be possible to reduce the fracture correctly or maintain reduction

• May require surgery at a later date

• Plaster needs removal/or windowing (removal of a piece of the cast) to inspect the skin

• May need removal in case of increased swelling or reapplication once swelling has subsided

• Bad odour if it gets wet

• Heavy

• May crack

• May rub the skin and cause sores

Clinical note

Medical advice should be sought if any of the following occur to a limb that is in a plaster of Paris or similar splint:

• pale or blue coloration of the skin on the injured part;

• numbness, tingling or throbbing of the injured part;

• inability to move the fingers or toes;

• excessive pain in the injured part;

• swelling, bulging or puffiness around the edges of the cast;

• a foul smell from under the cast;

• if it becomes loose and slides around.

Functional bracing (cast bracing)

It has been found unnecessary to fix some fractures as rigidly as was thought necessary in the past. An example of this is cast (or functional) bracing. Functional braces have hinges to allow movement (see the case study towards the end of the chapter and Figure 22.24).

The soft tissues of the limb squeeze against the inside of the brace and, in conjunction with the use of a heel cup, permit weight to be taken through the substance of the brace. This has reduced many of the problems that were seen as a direct result of prolonged immobilisation. Another benefit of allowing movement of joints, provided that it does not unduly stress the fracture site, is that it may promote union by improving the area’s blood supply.

Internal fixation

Surgical intervention by applying a plate and screws to the fracture is known as open reduction and internal fixation, often abbreviated to ORIF (Figure 22.8).

Figure 22.8 Fracture of the tibia/fibula fixed by plate and screws.

Advantages of ORIF

It permits a detailed inspection and accurate surgical assessment of the site of injury and procedure to be undertaken.

Disadvantages of ORIF

• Surgery inevitably causes additional trauma and potential exposure to microorganisms.

• It can convert a closed fracture into an open fracture.

• It requires surgery with all its sequelae and potential complications. Ironically, rigid fixation may remove the stimulus for callus formation. The implants are usually left in unless they cause problems e.g. irritation, infection or protrusion. In the young, they will be removed if they will affect growth of the bone.

Intramedullary nailing

Here, a hollow metal rod is introduced at one end of a long bone, travels down the medullary canal and may be locked with screws distally and proximally (Figure 22.9). The proximal aspect of the nail is threaded and this permits a tool to be threaded onto the nail at a later date for its removal.

Figure 22.9 Intramedullary nailing. (a) ISKD nail. (b) Intramedullary skeletal kinetic distractor (ISKD) (With thanks to Dania Sorio, Customer Service International, Orthofix Srl and Grit Soboll, Communications Manager, Orthofix Srl, www.orthofix.it.)

Intramedullary nailing for fractures of long bones has revolutionised the management of many fractures, which, historically, would have been managed by prolonged bed rest. The trauma is less than with open techniques and results in a shorter hospital stay, more rapid patient mobilisation and rehabilitation with minimal risk of complications associated with immobility. The implant, rather than the bone, may take stresses and strains, and, for this reason, the surgeon may choose to remove the locking screws at a later stage. This permits the nail to move slightly and cause compaction of bone ends (dynamisation). It allows the bone to once again take its normal stresses and strains and adapt in accordance with Wolff’s law. The endosteal proliferation that occurs as part of the normal fracture healing process may be lost with certain types of internal fixation. Fractures of the shaft of tibia and humerus may also be nailed in this way.

The intramedullary skeletal kinetic distractor

The intramedullary skeletal kinetic distractor (ISKD) is a two-part metal rod that can be used for tibial or femoral lengthening. An osteotomy is performed to allow distraction to take place. The device can only rotate in one direction and requires the patient to perform a rotational movement to cause lengthening. A hand-held monitor that contains a magnetic sensor is able to detect a small magnet sealed inside the ISKD. As the ISKD lengthens, the magnet rotates through 360 degrees. The monitor detects these changes and is able to record measurements so that lengthening can be very accurately controlled. Patients take measurements regularly throughout the day. The duration of lengthening depends on how much length needs to be achieved. The average desired rate is usually 1 mm per day. Patients are generally non-weight-bearing during the distraction phase.

External fixation

Figure 22.10 shows fixation of a fractured tibia using an external fixator. Pins or wires are driven into the fragments and held by a piece of apparatus on the outside of the body. Figure 22.11 shows an external fixator for a comminuted intra-articular fracture of the distal radius. Figure 22.12 shows an external fixator for an unstable pelvic fracture.