Chapter 13 Dislocations of the Elbow in Children

Introduction

‘Pity the young surgeon whose first case is a fracture around the elbow.’

Falls on the outstretched hand are common in childhood and occur in some toddlers on a daily basis. Approximately 65% of all fractures in children are to the upper limb, with the vast majority the result of indirect forces, following a fall on the outstretched hand (Fig. 13.1).² The most common site of injury is the wrist and hand, with the elbow region accounting for approximately 10% of the total. Although elbow dislocations are much less common than fractures,³ it is important to make a prompt diagnosis since in the majority of patients this will enable closed reduction and result in a rapid return of normal function and appearance of the elbow. Delayed diagnosis or inappropriate management may require open surgical management and result in permanent functional loss.

Figure 13.1 Typical mechanism of a child falling on an outstretched hand, which can result in various injuries to the upper limb.

Prevalence and associated injuries

A study of 1579 elbow injuries in skeletally immature individuals from Gothenberg, Sweden, found only 45 dislocations, giving a prevalence of only 3%.⁴ Subluxation of the radial head (pulled elbow) usually occurs in children aged between 2 and 4 years, while dislocations tend to occur around the time of physeal closure (12–14 years). The most common dislocation is posterior and may be accompanied by almost any fracture or combination of fractures, the most frequent being fracture separation of the medial epicondyle, fracture of the lateral condyle and fracture of the radial neck. Less common fractures occur to the coronoid and medial condyle. The Monteggia fracture dislocation is the most common fracture–dislocation combination in childhood (Fig. 13.2). Isolated dislocation of the radial head is uncommon.

Figure 13.2 (A) AP and (B) lateral radiographs of the left elbow of a girl involved in a motor vehicle accident, demonstrating multi-trauma in a single arm: a fracture of the distal humerus and a Bado type 1 Monteggia fracture–dislocation of the forearm.

When the elbow dislocates, the proximal radio-ulnar joint (PRUJ) may remain intact or may be disrupted. When it remains intact, the most common finding is a posterolaterally displaced radius and ulna in relation to the distal humerus. Much less common are posteromedial, medial, lateral or anterior dislocations. Divergent dislocations and translocation dislocations are even rarer and can only occur in association with disruption of the PRUJ.

Isolated elbow dislocations involving both the capitellar–radial and trochlear–ulnar joints are uncommon in children and more frequently the dislocation is associated with fractures about the elbow. Radial head dislocations occur in conjunction with ulnar fractures (the Monteggia fracture–dislocation), while proximal ulnar dislocations are very rare in the adult population, and have never been reported in children. In this chapter we will discuss the management of pulled elbow, elbow dislocations and the Monteggia fracture–dislocation of the radial head.

Summary Box 13.1

• The diagnostic calendar: physeal injuries to the distal humerus occur at 0–6 years, pulled elbow at 2–4 years, supracondylar fracture of the distal humerus at 5–10 years and elbow dislocations at 12–14 years.

• Prompt diagnosis and appropriate management of an elbow dislocation by simple closed means result in a rapid return of normal function and appearance in the majority of children.

• Accurate diagnosis in the majority of elbow injuries can be made by a combination of knowing what to look for at specific ages, a good history and good-quality AP and lateral radiographs.

Pulled elbow

Background/aetiology

Pulled elbow occurs in toddlers and children aged 1–6 years, with a peak incidence at age 2–4 years.⁵ The diagnosis is not tenable outside these narrow age limits. The injury is caused by longitudinal traction on the extended elbow, in a child young enough to have sufficient intrinsic elbow laxity to allow the radial head to slide partially out of the annular ligament. The toddler tries to go in one direction, while the parent pulls in another. As Mercer Rang wryly observed, the wonder is not that some children get a pulled elbow but that ‘it is remarkable that not all children experience a pulled elbow’.¹

The major predisposition is the laxity of the toddler’s annular ligament combined with their behaviour. There may be signs of generalized joint laxity in the child and in one or both parents. The injury is extremely common and, because the majority of pulled elbows are treated in emergency departments or the offices of paediatricians or GPs; the exact incidence is not known.

Originally it was thought that the injury occurred with the elbow extended and the forearm supinated. However, it is now widely believed that subluxation results when the pronated, extended forearm of an infant has forcible traction applied through the longitudinal axis. The typical scenario is a parent suddenly pulling their child by the arm. The annular ligament may simply be stretched or partially torn, and occasionally subluxates into the radiocapitellar joint (Fig. 13.3). The head of the radius subluxates distally but not beyond the equator, or maximal circumference, of the head. If it goes beyond this point, studies show that reduction becomes difficult, and these may go on to Monteggia type fracture–dislocations of the forearm with dislocation of the radial head.⁶

Figure 13.3 Longitudinal traction on a pronated forearm is the typical mechanism for subluxation of the radial head, commonly termed ‘pulled elbow’ or ‘nursemaid’s elbow’. Inset (right to left): the annular ligament may be stretched or torn, and once traction is discontinued may subluxate into the radiocapitellar joint.

Presentation, investigation and treatment options

The history is crucial, and familiarity with the typical mechanism is the most important element of diagnosis. Occasionally a snap is heard as the annular ligament tears, and although pain may initially be present this often rapidly subsides. The child holds the elbow in the extended position, typically not in any great distress, but refuses to move the affected limb, (the phenomenon of ‘pseudoparalysis’). Examination may reveal tenderness over the radial head and annular ligament.

A typical history and examination obviates the need for any investigations. Radiological examination is reserved for atypical presentations and failed primary treatment. Given that the injury is a minor subluxation of a largely cartilaginous radial head, plain radiographs are expected to show no abnormality. They are therefore useful only to exclude other injuries. Arthrography and ultrasonography are useful only when an alternative diagnosis is suspected or primary treatment has failed. The differential diagnosis includes other causes of ‘pseudoparalysis’, including other injuries around the elbow or elsewhere in the upper limb as well as septic arthritis and osteomyelitis.

Once diagnosed, the first step in treatment is to advise the child and the family that there will be a brief period of pain, followed almost immediately by relief and usage of the affected limb.

Management and rehabilitation

The child sits on the parent’s lap, and the affected limb is grasped at the wrist. The examiner gently supinates the child’s forearm with one hand and applies gentle pressure over the radial head with the other. Relocation is recognized by an audible or palpable snap, which may require elbow flexion in addition to supination. The child winces or cries and begins using the arm almost immediately. A transient synovitis may develop in patients with delayed presentation and in this circumstance a return of normal function of the arm can take up to 2 days. Parents should be warned about this, and of the need to seek further medical attention if considerable improvement is not evident within the first 24 h.

Outcome and literature review

The success rate of manipulation is very high and all pulled elbows appear eventually to self-relocate, without any long-term sequelae.⁷ Delayed presentation may result in failed manipulation. Failed manipulation or delayed return in using the arm should prompt a search for other injuries and include repeat examination and radiographs. Ultrasonography can provide inconsistent results⁸ and is very rarely used in our emergency department. Treatment of failed manipulation in a collar and cuff in flexion for a few days will result in successful relocation in all late-presenting cases and open reduction is very rarely necessary.⁹ A technique of forced pronation at the wrist, with or without flexion at the elbow, has been advocated by some authors. In a randomized control trial, parents perceived this technique to be less painful for their child.⁷

Recurrent episodes occur in 5–39% of children until the annular ligament becomes stronger and stiffer.^10,¹¹ Age at initial presentation of less than 24 months is a risk factor for recurrent subluxation,¹² and some advocate immobilizing all manipulated elbows in a flexed and supinated position for 2 days to ensure a successful outcome.¹³

Clinical Pearl 13.1

The typical history for a pulled elbow does not include unwitnessed falls in the hyperactive toddler. These are more likely to result in greenstick fractures that do not take kindly to manipulation!

Elbow dislocations

Background/aetiology

Posterolateral dislocation of the elbow is typically the result of indirect trauma and most frequently occurs as the result of a fall on the outstretched hand. The mechanism is thought to begin with the elbow in either the semi-flexed or hyperextended position. The medial structures of the elbow joint are integral to joint stability, and axial force from a fall is transmitted to the medial elbow by the medial crista of the trochlear, exaggerating the natural valgus carrying angle of the elbow. When this valgus force is applied to either the hyperextended or semi-flexed elbow, the medial collateral ligament is torn or the medial epicondyle and common flexor origin are avulsed. In addition, the coronoid process is also at risk of fracturing. The anterior capsule is commonly disrupted, exposing the articular surface and increasing the danger of soft tissue or neurovascular structures being interposed during reduction. Disruption of the posterior capsule may also occur and contribute to the risk of recurrent dislocation.¹⁴ The brachialis muscle, in its position between the anterior capsule and the more superficial neurovascular structures, is at risk during dislocation of the elbow but is particularly liable to be torn if hyperextension forces are applied in order to achieve reduction of the joint (Fig. 13.4). Tearing of the brachialis may expose the median nerve and brachial artery, which are then stretched directly over the trochlea. Median nerve entrapment may occur during reduction, as originally described by Hallet.¹⁵

Figure 13.4 Brachialis is at risk of rupture during dislocation, but also during relocation if the forearm is hyperextended to aid reduction.

Arterial damage to the main brachial trunk is rare.^16,¹⁷ However, complete rupture, an intimal tear or simple kinking into the elbow joint can occur because of the tethering effect of the collaterals and surrounding soft tissue restraints. Complete arterial rupture is more likely in open injuries. The most common vascular injury is a compartment syndrome resulting from swelling and secondary compromise to the brachial artery and collateral circulation. The risk factors are severe closed trauma, delay in treatment, closed reduction and immobilization in flexion in a complete cast. Severe ulnar nerve injury is less common now than previously described owing to the increasing recognition that entrapment of the medial epicondyle within the joint may also trap the ulnar nerve.¹⁸ Ulnar nerve injuries are usually transient.

Presentation, investigation and treatment options

Falling onto the outstretched hand in a child aged 12–14 years is a common cause of elbow dislocation. The child presents with a swollen elbow and limited movement. Clinical differentiation should be made between an elbow dislocation and an extension-type supracondylar fracture of the humerus by examining for the normal equilateral triangular relationship between the humeral epicondyles and the tip of the olecranon. This relationship is maintained in supracondylar fractures, but lost in elbow dislocations (the apex normally moving posterolaterally). Examination for associated fractures is essential even though it frequently proves difficult due to swelling and pain around the elbow. A complete neurovascular examination of the affected limb must also be completed and documented prior to manipulation, with particular reference to the distal vascular supply, and the sensorimotor distribution of the median and ulnar nerves.

Anteroposterior (AP) radiographs show the distal humerus superimposed distally over the proximal forearm, with the proximal radius and ulna usually displaced in a posterior and lateral direction. Lateral radiographs confirm a posterior dislocation of the elbow (Fig. 13.6A, B).

Given that more than 50% of elbow dislocations in children have associated fractures, the radiographs must be carefully examined for bony injuries (medial epicondyle, radial neck and coronoid).¹⁹ Less common fractures include lateral condyle, lateral epicondyle, medial condyle and olecranon.

Management and rehabilitation

The majority of elbow dislocations are managed by closed reduction. The principle of reduction is to counteract the muscle forces that are maintaining the dislocation. These are the brachialis and biceps anteriorly and the triceps posteriorly. These forces must be overcome so as to allow the coronoid process of the ulna and the radial head to pass unimpeded from posterior to anterior. Indeed, if not free to do so, these osseous landmarks are at risk of fracture. To unlock the radial head and coronoid process from behind the distal humerus, some authors have previously advocated initial hyperextension.²⁰ This, however, has been shown to produce excessive force on an already stretched brachialis, which can cause rupturing of the muscle and the anterior capsule. Hypersupination is more useful and is often the critical step to unlock the radial head from behind the distal humerus.¹⁸

Adequate analgesia and anaesthesia are always essential to permit a safe and effective reduction of the elbow. This allows the majority of uncomplicated, isolated dislocations to be reduced quickly and safely in the emergency department, provided that the procedure is undertaken by experienced staff. If a fracture has been identified or is suspected, access to fluoroscopy will normally dictate transfer to the operating theatre.

The two major techniques to reduce the elbow can be classified as ‘push’ and ‘pull’. First, traction longitudinally down the arm and supination of the forearm aids unlocking of the proximal radius and ulna. The now free radial and ulnar articular surfaces are then either pushed (from pressure on the olecranon) or pulled (via longitudinal traction on the forearm), enabling relocation of the joint. This is done while the elbow is being flexed, which helps maintain the reduction (Fig. 13.5).

Figure 13.5 (A) The posteriorly dislocated elbow is supinated (movement 1) to unlock the radial head from behind the capitellum. (B) The supinated forearm then has traction (2 and 3) applied to it via either a push (on the olecranon) or a pull technique. (C) The forearm is flexed (4) to maintain the reduction.

Reduction is first assessed clinically by the correction of the fixed deformity, restoration of range of motion and reformation of the normal posterior bony landmarks. The stability of reduction should also be confirmed and the position maintained by a posterior plaster slab, extending from below the shoulder to the metacarpophalangeal joints. This is maintained for a period of 3 weeks in the majority of first time dislocators. A collar and cuff are applied to support the plaster slab. Repeat radiographs must be undertaken to confirm the reduction and a repeat neurovascular examination performed after the child has fully recovered from sedation or anaesthesia (Fig. 13.6).

Figure 13.6 (A) AP and (B) lateral radiographs of the left elbow of a 7-year-old girl showing a typical posterolateral dislocation of the elbow, which was reduced in the emergency department under sedation. (C) AP and (D) lateral post-reduction radiographs showing an enlocated elbow joint.

After 3 weeks, the plaster slab is removed and the child is allowed to freely mobilize the elbow. Many children, however, find the collar and cuff helpful for about 1 week after removal of the plaster slab until confidence is regained and a functional range of motion obtained. Formal physiotherapy is not necessary for the majority of children, who will quickly regain normal motion and function. A shorter period of immobilization (1–2 weeks) can be considered in selected older children if there are concerns about elbow stiffness and a particular need to regain full elbow extension for occupational or sporting requirements.

Clinical Pearl 13.2

After plaster slab immobilization for 3 weeks, many children find the collar and cuff helpful for part-time use for about 1 week, until they regain confidence and a functional range of motion.

Closed reduction is successful in more than 90% of isolated posterior dislocations.¹⁹

Failure to obtain a satisfactory closed reduction is usually because of inadequate analgesia, sedation and muscular relaxation in the emergency department. This is usually easily rectified in the operating theatre under a general anaesthetic but better avoided in the first place. Failed closed reduction in the emergency department is distressing for children and parents.

Indications for open reduction include failed closed reduction. This may occur due to interposed tissue, of which incarceration of the medial epicondyle within the joint is by far the most common. Additional indications are the treatment of associated fractures, existing open injury or the investigation of neurovascular compromise. Primary ligament repair is not an appropriate indication as studies have shown that the outcome is inferior to closed treatment.^21,²²

Outcome and literature review

Closed reduction of a posterior dislocation of the elbow in children is effective in more than 90% of cases.¹⁹ A better outcome is expected in closed reduction versus open reduction, but the severity of associated injuries needs to be considered when interpreting these data.²³ Prompt reduction increases the success rate.²⁴ The majority of children will regain a near normal range of motion and full function. A loss of between 5° and 10° of elbow extension is quite common but the majority of children and parents will be unaware of this deficit.¹⁸ However, children and parents should always be advised about this risk when consent is being taken for reduction of the dislocation.

The common causes of more severe stiffness are delayed diagnosis, immobilization beyond 3 weeks, and vigorous and early physiotherapy, particularly if this involves passive stretching and missed incarceration of the medial epicondyle necessitating delayed open reduction.²⁵

Clinical Pearl 13.3

Children should not be referred for physiotherapy after elbow dislocations, and parents need to be explicitly warned not to seek any form of therapy which includes passive stretching.

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