Dislocations of the Elbow in Children

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Chapter 13 Dislocations of the Elbow in Children

Matthew G. Alexander, H. Kerr Graham

Introduction

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

Mercer Rang ¹

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!

Summary Box 13.2

• Pulled elbow has a peak incidence at age 2–4 years.

• The history is crucial, and familiarity with the typical mechanism is the most important element of diagnosis.

• A typical history and examination obviate the need for further investigations.

• Reduction is obtained by gently supinating the child’s forearm with one hand and applying gentle pressure over the radial head with the other. Flexion at the elbow may also be required.

• Early closed manipulation in the emergency department, without sedation, is the preferred treatment.

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.

Complications of treatment

Heterotopic ossification

Minor degrees of heterotopic ossification in the surrounding ligaments and soft tissues are quite common but do not have a significant impact on function.

Volkmann’s ischaemic contracture

This is the most serious complication but is fortunately uncommon. Various types of direct and indirect arterial injury may be implicated but the final common pathway is compartment syndrome. Damage to the brachial artery can occur in the form of complete rupture, an intimal tear or entrapment within the joint.²⁶ Arterial rupture is more common in open injuries. Unfortunately, the presence of a Doppler pulse at the wrist does not rule out arterial compromise,¹⁷ and if distal ischaemia is still suspected the cast and dressings should be removed, the elbow extended and an arteriogram considered. Prompt exploration and fasciotomy should, however, never be delayed if clinically compartment syndrome is suspected. It is important to remember that the collateral arterial supply may be disrupted in elbow dislocations and therefore cannot always be relied upon in the event of a brachial artery injury.²⁷

Neurological compromise

Assessment of neurological compromise in a child is often difficult because of fear, pain, limited comprehension and poor cooperation with formal testing. However, provided adequate analgesia is given the child can often perform active movements, and the thumb and fingers can be assessed for loss of sweating.

Three types of median nerve entrapment associated with elbow dislocation have been described by Hallet.¹⁵ Types 1 and 2 occur in association with a fracture of the medial epicondyle.

Type 1 median nerve entrapment occurs when the median nerve becomes displaced behind the avulsed medial epicondyle during dislocation and then becomes trapped within the joint during reduction. Compression within the joint results in complete nerve palsy and, the longer the nerve remains within the joint, the more severe is the compression injury. Delayed diagnosis is common and may result in such severe nerve injury that resection and cable grafting become necessary. Chronic entrapment may also result in a Matev sign: a depression on the posterior aspect of the medial epicondyle from chronic pressure by the median nerve. This is only seen on good-quality radiographs after chronic entrapment and quickly resolves when the nerve is released.

Type 2 entrapment is when the median nerve is displaced posteriorly during dislocation and becomes trapped between the fracture surfaces of the medial epicondyle during reduction. As the compression is less severe than in type 1, the nerve lesion may be incomplete. If not recognized and released the nerve becomes trapped by callus, resulting in the formation of a neo-foramen. In this situation a delayed release and nerve reconstruction may be required.

Type 3 entrapment is very rare. The nerve becomes trapped between the distal humerus and trochlea during reduction.

Median nerve entrapment can be difficult to diagnose, as there is often little associated pain, and neurological examination for sensorimotor loss in children can be unreliable. The combination of a medial epicondyle fracture and median nerve dysfunction is a strong indication for early exploration and neurolysis.²⁸

Ulnar nerve injury is seen in 5–10% of elbow dislocations in children. The most common injury is a mild traction injury in continuity. The usual symptoms are paraesthesia or numbness in the ulnar nerve distribution with absent or incomplete motor signs. Recovery is usually rapid and complete.

Ulnar nerve symptoms in association with a fracture of the medial epicondyle may be more serious and may require more active management. Incarceration of the medial epicondyle within the elbow joint after closed reduction requires open reduction and internal fixation. At the time of internal fixation, the ulnar nerve should be carefully inspected, decompressed within the cubital tunnel and protected during fixation of the medial epicondylar fragment. Fixation with a single 4 mm cannulated screw is preferred to K-wire fixation as the latter provides much less stable fixation and incidences of loss of position and non-union are higher.

Transposition of the ulnar nerve in the acute setting has been suggested by some ²⁶ but is rarely necessary.^29,³⁰

The management of ulnar nerve symptoms, in the presence of a fracture of the medial epicondyle, without incarceration is less clear. A good case can, however, be made for exploration, decompression of the ulnar nerve in the cubital tunnel and internal fixation of the medial epicondylar fracture.

Injury to the radial nerve, in association with elbow dislocation in children, is very rare and has not been recorded at our institution.

Recurrent dislocation

This is rare, but when it occurs the initial dislocation is thought to have happened in the paediatric age group.^23,³¹ Recurrent dislocations have been shown to be associated with deficiencies in the posterolateral soft tissues of the elbow joint. A technique to address these defects was proposed by Osborne and Cotterill.¹⁴ The same authors, however, along with others, caution against surgical intervention if the recurrent dislocations are infrequent.

Osteochondral injury

This may occur during dislocation of the elbow, particularly in association with fractures of the medial epicondyle and lateral condyle of the humerus, the radial head and neck and the coronoid process of the ulna. Relocation places the proximal radius and ulna at risk of fracture, as previously discussed.

Other patterns of dislocation

1. Medial and lateral

2. Anterior

3. Divergent dislocation

4. Proximal radio-ulnar translocation

5. Congenital dislocation.

Medial and lateral dislocations

Lateral dislocations are invariably posterolateral and are often incorrectly diagnosed on the basis of oblique radiographs. That is, the dislocation is posterior but appears lateral or posterolateral on oblique radiographs. There is no material difference between posterolateral and posterior dislocations in management or outcome. Medial dislocations have never been seen in our institution or reported in the literature.

Anterior dislocations

Anterior dislocations in children are very rare (<2%).²³ In contrast to posterior dislocations, the mechanism of injury may involve a direct blow to the semi-flexed elbow. Clinically, the elbow is locked in extension with severe pain and swelling. The incidence of neurovascular complications involving the brachial artery and median nerve is much higher than in posterior dislocations.

Various osteochondral injuries are also seen, the commonest being a partial triceps avulsion from the olecranon. Closed reduction is achieved by flexing the elbow and pushing the forearm bones proximally. Open reduction is reserved for failed closed reduction, arterial injury, open dislocations and for the treatment of concomitant fractures. Immobilization in a long posterior slab is required, in about 30° of flexion, for 3 weeks. The range of flexion recovers quickly following removal of the plaster slab. Recurrence is unknown.

Divergent dislocation

Divergent dislocations are a rare subgroup of elbow dislocation in children, involving all three articulations: humero-ulnar, radiocapitellar and radio-ulnar. The humerus is wedged between the proximal ulna and radius. Only significant soft tissue injury and disruption of the proximal radio-ulnar joint will allow such intrusion of the distal humerus between the proximal forearm bones (Fig. 13.7).

Figure 13.7 A 6-year-old boy presented after falling on an outstretched right hand. (A) AP and (B) lateral radiographs show an AP divergent dislocation of the elbow. Post-reduction films confirming reduction of the divergent dislocation in both the (C) AP and (D) lateral views.

The first radiologically documented case was reported by DeLee in 1981.³² Two distinct types of divergent dislocation have been proposed: mediolateral (transverse) and AP. These refer to the direction of dislocation of the two forearm bones.

The child typically presents with pain, swelling and an inability to move the elbow after a fall on the outstretched hand. The elbow is locked in about 30° of flexion. Good-quality AP and lateral radiographs are often difficult to obtain. Many of the views in published reports and in our own series are oblique.³³^–³⁵ The radius and ulna dislocate proximally and the distal humerus becomes interposed between them. For this to happen, the proximal radio-ulnar joint must be disrupted, along with a significant portion of the proximal interosseous ligament.

The severity of ligamentous and capsular damage in this injury is confirmed by the ease with which the dislocation is reduced. Longitudinal traction is applied to the semi-extended forearm, while the proximal radius and ulna are compressed together. The elbow is immobilized in 90° of flexion in a long-arm posterior plaster slab for 3 weeks. The long-term outcome of posterior divergent elbow dislocation is satisfactory.^33,³⁴ Recurrent instability is rare despite the severe associated soft tissue damage.

Summary Box 13.3

• The peak incidence for elbow dislocations is 12–14 years. Postero-lateral dislocations are most common.

• More than 50% of elbow dislocations in children have associated fractures.

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

• The majority of uncomplicated, isolated dislocations can be closed reduced quickly and safely in the emergency department by experienced staff.

• Neurovascular examination pre and post reduction, and pre-discharge is paramount.

The Monteggia fracture–dislocation

Background/aetiology

The Monteggia fracture–dislocation is a dislocation of the radial head accompanied by a fracture of the ulnar shaft. It occurs more commonly in children than in adults but unfortunately is a diagnosis that is often missed due to those who first see the child being unaware of this common childhood injury pattern.^40,⁴¹ Late diagnosis delays treatment, impairs the outcome and frequently leads to litigation. The injury complex occurs as the result of indirect forces when the child falls on the outstretched hand. In published series the peak age at presentation is 5–12 years, with usually more boys than girls and more injuries to the non-dominant upper limb.⁴²

This type of fracture dislocation was first described by Giovanni Monteggia in 1814. His name was given to the injury by Perrin in 1901. A further classification system based on the direction of the radial head dislocation and associated ulnar and radial fracture patterns was proposed by Jose Bado, of Uruguay, in the late 1950s.⁴³ It is this classification system of Monteggia fracture–dislocations that is widely used today.

As well as Bado’s four types of true Monteggia lesions, equivalent lesions have also been described. Bado’s classification system helps conceptualize the causal forces of the injury and hence identify the forces required to obtain reduction.

Table 13.1 Bado classification of Monteggia lesions, including equivalent lesions

Figure 13.8 Bado classification of Monteggia fracture dislocations. (A) Type 1. (B) Type 2. (C) Type 3. (D) Type 4.

Presentation, investigations and treatment options

Monteggia lesions usually occur following a fall when torsional and axial forces are applied to the forearm. The ulna fractures and as this occurs the radial head dislocates. The direction of the radial head dislocation is determined by the direction of the forces resulting in the ulnar fracture. Alternatively, excessive torsional force dislocates the radial head, with the ulna fracturing secondarily.

A direct blow may also cause a Monteggia injury. Again, the force and trajectory of the blow will dictate the direction and location of the ulnar fracture and the direction of the radial head dislocation. This mechanism is thought to occur in Bado type 2 lesions, where the radial head dislocates posteriorly.

In an acute injury pain is typical and the child is reluctant to use the affected elbow. Swelling and bruising should be noted, and focal tenderness may be present anteriorly. Range of motion of the elbow is markedly reduced, particularly pronation and supination. However, in younger children with joint laxity and a greenstick fracture or plastic bowing of the ulna, the physical signs may be relatively minor and settle quickly (Fig. 13.9). In the emergency department attention is often directed to the ulnar fracture, and it is important that the elbow is also carefully examined and adequate radiographs obtained.

Figure 13.9 (A) Bado type 1 acute Monteggia fracture–dislocation, the result of a fall on the outstretched hand. Clinical signs associated with this low-velocity injury are minimal and this is the type in which frequently there is a delay in diagnosis, resulting in progression to a chronic Monteggia lesion. (B) A line drawn along the subcutaneous border of the ulna confirms the mid-shaft anterior bowing. A line drawn through the midpoint of the radial head is not collinear with the line drawn through the midpoint of the capitellum, thus confirming the radial head dislocation.

Clinical Pearl 13.4

In younger children with joint laxity and a greenstick fracture or plastic bowing of the ulna, the physical signs may be relatively minor and settle quickly (Fig. 13.9). Attention is often directed to the ulnar fracture in the emergency department and the elbow may not be examined or adequate radiographs obtained.

A detailed neurovascular examination should take place, with particular attention given to the posterior interosseous nerve (PIN) of the forearm. This is at particular risk with an anterior radial head dislocation as the nerve passes between the two heads of the supinator. If there is any uncertainty as to whether the nerve is injured the clinical findings should be compared with the contralateral arm.

Radiological confirmation of the diagnosis relies on adequate AP and lateral views of the entire forearm, with additional views of the elbow and wrist. The ulnar fracture may be very subtle, with the radiographs revealing only bowing or plastic deformity of the normally straight ulnar border. It is also important to remember when the radiographs are examined that a line drawn through the radial head should bisect the capitellum on both the lateral and AP views. If this is not the case, then the radial head is not appropriately enlocated. If doubt exists computed tomography is indicated.

Management and rehabilitation

There are three principles that underpin management of the acute Monteggia lesion: reduction of the ulnar fracture, reduction of the radial head dislocation and positioning of the arm to neutralize the forces that could cause redislocation. The two anatomical factors that determine management are the Bado type and the morphology of the ulnar fracture.

Prior to treatment it is imperative classify the injury correctly in order to identify accurately the forces required to reduce the injury and maintain the reduction. Closed reduction is the management of choice in the majority of acute Monteggia lesions.⁴⁴ Reduction of the ulnar fracture, followed by flexion and supination of the elbow and forearm, usually results in reduction of the radial head unless the fracture reduction is unstable. In this situation the radial head may be difficult to reduce or unstable following reduction.

If an unstable fracture of the ulna and/or radius does not allow stable reduction of the radial head, then fixation of the ulna and/or radius is necessary. With adequate fracture fixation the radial head is rarely unstable, but if it is exploration of the radial head, open reduction and surgical stabilization are required. Once stable reduction has been achieved, the position in which the forearm is cast is determined by the Bado type. Type I and III lesions are best immobilized in elbow flexion of 90 to 120° with the forearm supinated. Flexion of the elbow above 90° may not be safe if reduction has been delayed and swelling of the elbow is severe. In such cases, flexion to 90° is recommended, with the option of changing the cast after 7–10 days, to increase flexion and ensure stability of the radial head reduction.

Type II lesions are immobilized in extension. Type IV lesions require intramedullary fixation of the forearm fractures to maintain satisfactory fracture alignment and stable reduction of the radial head, and are then immobilized in flexion. The recommended duration of immobilization in children is 6 weeks, after which an active range of motion exercises is instituted. When closed reduction is performed early, reduction of the radial head is usually stable. However, displacement and redislocation can occur. In order to monitor progress a spot lateral radiograph of the elbow is advised every week for the first 3 weeks. This will reveal any evidence of radial head displacement or redislocation and enable treatment to be instituted in a timely fashion. It is not sufficiently accurate to assess the radial head position on a lateral radiograph of the whole forearm that has been taken primarily to show the ulnar fracture.

Surgical techniques and rehabilitation

Management of the ulnar fracture is crucial. Plastic bowing and greenstick fractures are inherently stable and can be realigned by closed reduction. Displaced transverse fractures are best managed by intramedullary fixation with an elastic nail. The stability of the radial head dislocation depends on anatomical realignment of the ulnar fracture (Fig. 13.10).

Figure 13.10 (A) AP and (B) lateral radiographs showing Bado type 1 Monteggia fracture dislocation in a 6-year-old boy after a fall at school. The radial head was found to be reducible but unstable intraoperatively. The ulnar fracture underwent closed intramedullary nailing, and an intraoperative arthrogram and postoperative (C) AP and (D) lateral radiographs confirmed a stable radial head reduction.

Oblique, comminuted and severely displaced fractures of the ulna may require open reduction and plate fixation.

Indications for open reduction of the forearm fracture or radial head dislocation include an existing open injury, neurovascular compromise or failed closed reduction. Open reduction of the radial head dislocation requires a careful debridement of the torn annular ligament in order to permit accurate and stable radial head reduction. Repair of the annular ligament is rarely required and transcapitellar wires should be avoided. If the radial head dislocation can only be maintained with the use of a transcapitellar wire it usually means that the management of either the ulnar fracture or the radial head dislocation has been inadequate.

Outcome and literature review

Prompt diagnosis and appropriate closed treatment will result in normal appearance and function of the elbow in the majority of children.^23,^42,⁴⁵ Delayed diagnosis, however, results in an increased reliance on open reduction, and has suboptimal outcomes.⁴⁵ A recent study on the pathology of the annular ligament in acute Monteggia lesions has shown that it is interposed in the radiocapitellar joint in the majority of cases.⁴⁶ Despite this, excellent outcomes can be expected from closed reduction of the radial head provided that the associated fractures are appropriately treated.^5,⁴⁷^–⁴⁹ If open reduction of the radial head is required, there is an increased risk of functional deficit due to scarring and heterotopic ossification.⁴⁷

Complications of treatment

The most common complication of Monteggia lesions is late diagnosis.⁵⁰ The patient often presents fortuitously following a knock to the elbow, with mild and intermittent pain together with limited range of motion and stiffness. The carrying angle of the elbow is increased and the radial head is palpable as a lump on the anterolateral aspect of the elbow. Management is dictated by the interval between injury and presentation, the state of the radial head, the degree of malunion of the ulna, the age of the child, and the wishes of the parents and child. Early is better than delayed surgical reconstruction and younger patients have better outcomes. However, unlike the management of the acute lesion, which is predictably good, management of the chronic lesion is predictably unpredictable and has a high complication rate, even in expert hands.⁴⁵ The longer the interval between injury and reconstruction, the more likely it will be that an open reduction of the radial head will be required, with reconstruction of the annular ligament. The risk of redislocation, neurovascular injury, degenerative change and stiffness in this situation is substantial.⁴⁵ For this reason reconstruction of the chronic Monteggia lesion should be performed by surgeons with a special interest in the area.

Clinical Pearl 13.5

Chronic Monteggia lesions often present fortuitously after a knock to the elbow and an abnormal examination is noted.

Management of the chronic Monteggia lesion: options, outcomes and literature review

Chronic Monteggia lesions are defined as those presenting 3 or more months after an acute injury. Initially symptoms are mild and intermittent and include mild pain, slightly decreased range of motion and mild valgus deformity. Tardy ulnar nerve and posterior interosseous nerve palsies are uncommon initially but are seen as late features.⁵¹ Untreated, the dislocated radial head becomes hypertrophic and progressively convex in profile. The capitellum flattens and the range of elbow flexion and extension reduces.

Management of the chronic Monteggia lesion includes symptomatic treatment, radial head excision, repair or reconstruction of the annular ligament, closed or open reduction of the radial head and osteotomy of the ulna and/or radius.^44,⁵¹^–⁵⁴ Of these, the most successful reconstructions usually combine open reduction of the radial head with reconstruction of the annular ligament and corrective osteotomy of the ulnar deformity.⁵⁵ Earlier descriptions emphasized annular ligament reconstruction using imported local tissue, such as a strip of triceps fascia, as in the classical Bell Tawse procedure⁵⁶ and its variants.⁵⁷ Results of these older procedures were uncertain and had a high incidence of subluxation and stiffness. In long-term follow-up, notching of the radial neck was noted and suggested that the reconstructed annular ligament was either too tight or not isometric.⁵⁵ Although the annular ligament is considered the most important structure in maintaining the enlocation of the radial head,⁵⁸ recent literature suggests that without an ulnar osteotomy to correct the ulnar malunion it is likely that the radial head will redislocate.^50,⁵²

Other publications emphasize repair rather than replacement of the annular ligament,^48,⁵⁹ combined with a posterior, bending and lengthening osteotomy of the ulna. These newer procedures are associated with improved long-term results, although they do not abolish the risk of subluxation and degenerative change (Fig. 13.11).