Limb trauma

Vascular injury

Arterial injury is a limb- and (potentially) life-threatening emergency. Ischaemia times of 4 to 6 hours may result in permanent damage to tissues. Peripheral circulation and distal pulses must always be assessed and sides compared. All splints in transferred patients should be removed and underlying tissues and distal circulation assessed. High-risk patients include unconscious and shocked patients, as these states may mask local limb ischaemia.

In patients with active haemorrhage from an injured limb, focal pressure and haemostatic dressings should be applied and may be sufficient to control bleeding. Ongoing bleeding warrants the application of a tourniquet proximal to the injury, which should temporize the situation until definitive management can occur.

The presence of a distal pulse does not exclude arterial injury, which may be incomplete. Other signs to consider include the presence of a dislocation, limb deformity or open fracture in that limb, brisk bleeding from an open wound, reduced pulses compared with the other side (either clinically or on Doppler) and an expanding wound haematoma. Delayed signs include a false aneurysm or the presence of a bruit on examination.

Sites at specific risk of arterial injury include the following:

• Brachial artery in the upper limb

• Popliteal artery around the knee and adductor canal of the medial distal femur

• Deep femoral artery at the trochanter level of the femur

• The anterior tibial artery in the tibia

Computed tomography (CT) angiography (CTA) has largely replaced formal angiography as the investigation of choice; if a vascular injury is suspected, early discussion with a vascular surgeon is recommended.

Nerve injury

Nerve injury in limb trauma may be a direct result of laceration by foreign bodies or fracture fragments. Nerves may be crushed, bruised or stretched. Ischaemia must be excluded as a cause of neurological deficits. Nerve injury due to penetrating trauma should ideally be explored in the operating theatre.

Nerve injuries may be classified into three major groups:

• Neuropraxia. This is a transient change in conduction. It usually follows crush or contusion or stretching of a nerve. There is usually some return of function within days and complete return of function within 8 weeks.

• Axonotmesis. Complete denervation with an intact nerve sheath, usually as a result of blunt trauma causing severe bruising and stretching. Regeneration along the intact nerve sheath takes place over months.

• Neurotmesis. Complete division of a nerve and its sheath. Spontaneous regeneration is not expected and surgical repair is required. This represents the most severe end of the spectrum and full recovery cannot be guaranteed.

The neurovascular status of the injured limb should be assessed and documented before and after any manipulation and relocation. Specific nerve injury presentations include the following:

• Wrist drop from radial nerve injury of the middle or distal third of the humerus

• Foot drop from peroneal nerve injury to the proximal fibula

• Shoulder skin numbness and deltoid muscle weakness from axillary nerve injury in shoulder dislocation

• Lower limb numbness and weakness from sciatic nerve injury due to posterior dislocations of the hip

• Hand numbness and weakness from median nerve injury in distal fractures of the wrist and dislocations of the carpal bones

• Hand numbness and weakness from ulnar nerve injury in injuries to the medial forearm or humerus

History and examination

Injury history and pre-hospital care should be presented in the MIST format on arrival at hospital:

• Mechanism

• Injuries identified or suspected; specifically, estimates of external blood loss, limb deformity (and correction) or amputation

• Symptoms and signs: in particular vital signs, whether the patient mobilized at the scene, areas of limb weakness or numbness and pale or pulseless limbs

• Treatments commenced and the responses to them with a note made of all splints placed and their type (hard, soft or anatomic)

The general history should also include the patient’s normal state of health, medications and allergies, hand dominance, tetanus prophylaxis and fasting state. The history should be presented when the primary survey commences. Only when this is completed should a meticulous secondary survey start. All splints should be removed for limb trauma assessment, especially in patients transferred between hospitals, given the often long intervals before definitive assessment and treatment.

The assessment of limbs for trauma includes the following:

• Looking for deformity, bruising, open fractures, bleeding, skin blistering (which denotes soft tissues under pressure) and white or pressured skin. Comparison should always be made with the other limb.

• Feeling for local pain, crepitus or deformity.

• Active (patient-controlled) and passive (examiner-controlled) movement. Joints with a full active range of movement are almost never dislocated. Full active movement of the elbow may exclude an elbow fracture and straight leg raising a major pelvic fracture. Passive movement should include an assessment of ligament stability, although this can be difficult to assess in the acutely injured knee.

• Peripheral vascular assessment includes pulses and capillary refill.

• Peripheral neurological assessment includes motor power and sensation. The most accurate indicator of sensory function is two-point discrimination.

• Vascular injury should be suspected in elbow and knee dislocations regardless of whether the peripheral vascular examination is normal after reduction. Abnormal peripheral vascular signs include absent or decreased distal pulses, prolonged capillary refill, pale peripheries unilaterally, ongoing wound bleeding or an expanding haematoma.

Plain radiography

Plain x-rays constitute the investigation of choice in the diagnosis of limb fracture. They may be performed in the trauma bay where available or in the radiology area once the patient is stable for transfer.

Two views in two planes are required for accurate diagnosis and planning of reduction. The joints above and below the injury site should also be imaged.

Other indicators of injury that may alter management include the presence of air or foreign bodies around injury sites and joints and soft tissue swelling, such as the sail sign in distal humerus fractures. Joint injury may be indicated by soft tissue swelling and lipohaemarthroses, which may indicate an underlying fracture.

Joints and fractures should be x-rayed again after reduction. Timed repeated x-rays may be used in injuries where there is doubt about the presence of a fracture (e.g. the scaphoid in peripheral wrist injuries).