Vascular injuries

Vascular injuries are potentially catastrophic complications of supracondylar fractures. As such, any child presenting with a supracondylar fracture must undergo a careful vascular assessment prior to consideration of the bony injury. Presentations may include a diminished or absent pulse, pain on passive flexion/extension of the long flexors to the fingers, or a frankly ischaemic limb. The arterial injury itself can vary from a complete transection of the artery, an intimal tear or compression of the vessel. In addition, there is frequently damage to the venous drainage system.

Compartment syndrome occurs as a direct result of an increase in pressure within the closed compartments of the forearm. It results from disruption of the venous drainage in the presence of continued arterial input. Other factors that also contribute to its development include oedema, haematoma formation and compressive dressings or plaster casts.

Early diagnosis of vascular damage or impending compartment syndrome is essential and requires a thorough clinical examination not only at presentation but routinely thereafter at 15, 30 or 60 min intervals, depending on the severity of the injury.

A palpable, regular, radial pulse is important but may not exclude the diagnosis of compartment syndrome. A better method of assessment is passive and active extension of the fingers. If this is possible and painless it is highly unlikely that the patient has compartment syndrome. Examination of the neurological status of the hand should also be undertaken. Neural tissue as well as muscle is highly sensitive to ischaemia and impairment may be an indicator of ongoing vascular compromise. Conversely, the presence of a pulse together with painless passive finger extension and normal sensation in the fingers effectively excludes a major vascular injury.

Once it has been confirmed that the patient does not have limb-threatening vascular injuries it is appropriate to undertake anteroposterior and lateral radiographs of the elbow. These will reveal the nature of the bony injury and allow formulation of a management plan.

If the hand is obviously ischaemic, the arm should be immediately manipulated and splinted in an extended position. This will often restore the circulation to the hand but if this fails the child should be taken immediately to the operating room for closed reduction and pinning. The role of arteriography is controversial.^5,6 While plainly any information about the vascular status is helpful, undertaking the technique should not lead to undue delay with treatment. The rationale is that this is an emergency situation and, if the circulation does not return following reduction and pinning of the fracture, exposure of the brachial vessels should be performed. If the artery is trapped between bony fragments then the fixation should be taken down and the artery liberated. If the artery is crushed, transacted or has an intimal tear, reconstruction will be required, usually with help from a vascular or micro trained surgeon. In this situation it is also important to perform a fasciotomy of the deep fascia of the forearm, particularly if there has been significant ischaemia time.

The management of a limb that is initially ischaemic but becomes viable following reduction and internal fixation, or of a viable limb with a ‘deficient pulse’, is less controversial. In the absence of a radial pulse, but the presence of pink fingers with good capillary return and pain-free, passive and active finger movements, most clinicians would manage the patient conservatively, resting the arm in a splint at 20–30° of extension. If the pulse fails to return over the next 48–72 h, then an arteriogram should be performed, with further management being determined by the results of the investigation.

The initial symptoms of compartment syndrome are often subtle, or missed completely, resulting in a delay in diagnosis and treatment. The increase in pressure within the closed compartment ultimately results in anoxia of soft tissues, particularly muscle and nerve. Diagnosis is based on clinical awareness and should be made before the patient has severe pain, particularly on passive and active movement of the long flexor and extensor finger tendons. Other findings include paraesthesia and loss of capillary return to the finger tips. Loss of the radial/ulna pulse is frequently a late finding.

Treatment should be prompt, with elevation of the affected extremity and mobilization of the fingers, as appropriate. Any constrictive bandages should be removed. If clinical doubt exists, many clinicians undertake urgent pressure measurements within the flexor compartment. Several techniques have been described and there are now a number of propriety instruments that allow this to be undertaken. Controversy still exists, however, regarding the pressure that can be accepted before fasciotomy should be performed. Generally, if the pressure exceeds 30–35 mmHg, or if it is within 30 mmHg of the patient’s diastolic pressure, an emergency fasciotomy should be undertaken. If, however, facilities are not available to measure compartment pressure and clinical concern persists, an urgent fasciotomy should be performed.

Peripheral nerve injuries

The assessment of the peripheral nerves in a young child with a supracondylar fracture can be difficult owing to the natural reluctance to move the fingers and respond to appropriate testing. Indeed it is often impossible to undertake an adequate neurological examination immediately after injury. Generally, however, as pain reduces and recovery ensues, neurological evaluation becomes possible.

If on examination a nerve palsy is detected, the abnormal sensory and motor findings must be accurately recorded. The majority will be a neuropraxia and will spontaneously improve. In these cases, apart from reassurance and physiotherapy input to prevent contractures, little else is required. If, however, there are no signs of recovery at 3 months, nerve conduction studies should be performed. If these show no evidence of neurological recovery and muscle degeneration is taking place, then exploration of the nerve is indicated. Depending on the surgical findings a nerve release, repair or graft may be required. If, however, nerve conduction studies reveal subclinical recovery then an expectant policy can be adopted.

Malunion

Cubitus varus or valgus is assessed by measuring the carrying angle of the arm. This is the angle created by the medial border of the fully supinated forearm and the medial border of the humerus when the elbow is extended (Fig. 9.1). The angle typically varies between the sexes, with the normal range lying between 6° and 12°. It is generally greater in female than male patients and is best assessed by comparison with the contralateral side. In addition, as the normal elbow extends, the carrying angle increases, i.e. becomes more valgus. With malunions, however, hyperextension tends to accentuate a cubitus varus deformity, while a flexion contracture can create the appearance of cubitus valgus. Measurement of rotational deformity is more difficult but can be assessed by asking the child to bend forward such that the thoracolumbar spine is parallel to the ground. Each arm is then placed in turn behind the patient’s back and rotation measured as the angle between the forearm and the patient’s thoracolumbar spine when the arm is maximally rotated.

Figure 9.1 Cubitus varus deformity.

Fortunately, there are few if any symptoms or functional limitations as a result of cubitus varus or cubitus valgus deformity. The principal concern is cosmesis. Occasionally cubitus valgus may be associated with a flexion contracture and in extreme cases the patient may also complain of ulnar nerve symptoms. Conversely in cubitus varus flexion may be limited and occasionally symptoms of elbow instability are present. Rarely, however, does this loss of flexion or extension result in any deficit in activities of daily living.

Unfortunately, there is little potential for angular malunion of the distal humerus to remodel and, as such, the best treatment is prevention. Mild degrees of cubitus valgus and varus should be treated by simple reassurance. However, if the deformity is severe and there are significant cosmetic concerns or any functional restriction. surgical reconstruction should be undertaken.

Gurkan et al⁷ described posterior instability of the shoulder in three patients with cubitus varus deformity.

A less commonly reported complication of supracondylar fractures of the humerus in children is the dissolution of a portion of the trochlea at a variable time after fracture (Fig. 9.2). If this defect to the trochlea is severe it will allow migration of the ulnar proximally.⁸ A similar complication on the lateral side of the elbow was reported by Vocke-Hell et al.⁹ They noted that this could occur at any time between 1 and 4 years after the fracture and may result in secondary radial head dislocation.

Figure 9.2 Dissolution of a portion of the trochlea.

Stiffness