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Elbow Injuries

Author: Clint Gomes, Richard Lowsby / Editor: Jason B Lee / Codes: C3AP1c / Published: 26/07/2013 / Review Date: 26/07/2017

 

Introduction

Context

Elbow injuries are common and acute elbow trauma accounts for 2-3% of all visits to the emergency department. Injury and fracture patterns in children tend to be different to the adult population due to nature of the developing bones. This module aims to provide an introduction to the common acute traumatic injuries that occur around the elbow joint, and to provide the emergency physician with an understanding of the assessment and initial management of these injuries.

Anatomy

The elbow is a hinge joint and consists of the humero-ulnar, humero-radial and proximal radio-ulnar articulations. The radial head articulates with the humeral capitellum whilst the trochlear notch of the ulna articulates with the humeral trochlea. Posteriorly the ulna forms the olecranon, which contacts the olecranon fossa of the humerus at full elbow extension.

The elbow joint allows 0 140 of flexion. Hyperextension may be possible and up to 15 is considered normal, especially in women. Movement at the proximal and distal radio-ulnar joints combine to produce 75 of pronation and 80 of supination. When fully extended the elbow joint forms a valgus angle, this is commonly referred to as the carrying angle and is generally greater in women.

Bony landmarks of the elbow palpable on examination are the:

  • medial and lateral humeral epicondyles
  • olecranon process and proximal ulnar shaft
  • head of radius

Figure 1: Bony anatomy of the elbow

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Web

The lateral and medial collateral ligaments provide joint stability. The nearby annular ligament attaches to the anterior and posterior margins of the radial notch on the ulna and forms a collar around the radial head.

Figure 2: Elbow ligaments

elbow_anatomy3

Elbow flexion results from the actions of the biceps brachii, brachialis, brachioradialis and pronator teres muscles, which cross the joint anteriorly. The triceps tendon inserts into the olecranon process posteriorly and together with the anconeus muscle is responsible for elbow extension.

Figure 3: Muscles surrounding the elbow joint

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Several muscles responsible for wrist and finger flexion have a common insertion into the medial epicondyle (flexor carpi radialis, palmaris longus, flexor carpi ulnaris and flexor digitorum superficialis). Similarly, several extensor muscles insert into the lateral epicondyle (extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi and extensor carpi ulnaris).

The cubital fossa is a triangular depression found anterior to the elbow joint and contains the median nerve, biceps tendon, brachial artery, and radial nerve (deep and superficial branches). The ulnar nerve crosses the elbow joint posteriorly, running behind the medial epicondyle in a groove adjacent to the olecranon. The olecranon bursa is located over the posterior aspect of the olecranon.

Figure 4: Nerves and artery running across the elbow joint

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elbow_anatomy6

 

Clinical assessment

History and examination

The initial assessment of the patient presenting with an elbow injury should consist of a history, key points of which include the:

  • mechanism of injury (particularly important in paediatric injuries when non-accidental injury should be considered)
  • onset and location of pain
  • associated symptoms including sensory disturbance and proximal or distal limb pain
  • history of previous elbow injury

Subsequently the examination routine should follow the sequence of look, feel, move and special tests

Look

This should also include the wrist and shoulder. Note any bruising, swelling or deformity. The medial and lateral epicondyles along with the olecranon should form a straight line in full extension and an equilateral triangle in flexion. Disturbance of this alignment should raise the suspicion of a fracture or dislocation.

Feel

The bony landmarks mentioned previously should be palpated (medial and lateral epicondyles, olecranon and radial head). Further palpation, particularly of the radial head, should occur during elbow movement as outlined below. Tenderness over the common flexor or extensor tendon insertions is suggestive of tendinopathy and can be confirmed with special tests.

Move

Passive and active range of elbow movement should be assessed and should include flexion, extension, supination and pronation. It is important to compare both sides in order to distinguish between normal and abnormal reduced range of movement.

Resisted elbow flexion and extension stresses the biceps and triceps tendons respectively and increased pain on testing may suggest a musculotendinous strain. Grossly reduced flexion or extension strength accompanied with pain and localised swelling/bruising might suggest a rupture of the biceps tendon or avulsion fracture of the triceps insertion.

Special tests

The medial and lateral collateral ligaments should be stressed with valgus and varus forces across the joint in 30 of flexion. Increased pain and/or laxity are suggestive of ligamentous sprain.

The common extensor tendon insertion should be palpated during resisted wrist extension with the forearm pronated, increased pain is suggestive of extensor tendinopathy, otherwise known as lateral epicondylosis or tennis elbow.

Similarly increased pain located at the common flexor tendon insertion during resisted wrist flexion with the forearm supinated is suggestive of flexor tendinopathy, also known as medial epicondylosis or golfers elbow.

As with all musculoskeletal injuries the neurovascular status of the distal limb should be assessed. Specifically median, radial and ulnar nerve sensory and motor function should be tested along with palpation of the radial and ulnar pulses.

 

Investigation Strategies

Imaging

Figure 5: Normal elbow xray

elbow_xray

Important Lines

Anterior Humeral Line

If a line is drawn along the anterior part of the humerus on the lateral radiograph, then it should intersect the middle third of the capitellum. Failure to do this indicates that the capitellum has been displaced. There is often posterior displacement in association with supracondylar fractures.

Figure 6: Normal (left) and abnormal (right) anterior humeral line

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elbow_anterior1

The Radio-Capitellar Line

A line drawn through the middle of the radius should always bisect the capitellum since the radial head articulates with the capitellum. This should occur in every direction, no matter which x-ray view is taken. If this is not the case suspect dislocation of the radial head and remember that this can sometimes be associated with ulna fractures (Monteggia fracture-dislocation).

Figure 7: Normal (left) and abnormal (right) radio-capitellar line

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elbow_capitellar2

Fat Pads

On a normal AP x-ray of the elbow an anterior fat pad is visible due to fat in the joint capsule. It is never normal to see a posterior fat pad because this is hidden in the intercondylar fossa. The diagram below shows a displaced anterior fat pad in association with a posterior fat pad. This is known as the sail sign because of its resemblance to the sails of a boat. In the setting of acute trauma it represents blood in the joint. In the non-trauma setting effusion may be due to an inflammatory cause. Note that if the fracture is extra-articular, then there may not be a joint effusion and therefore the fad pad sign will be absent.

Examine the radial head closely in these injuries as there is often a subtle fracture. Presence of a posterior fat pad has been associated with a 75% rate of occult fracture.

Figure 8: Positive Sail Sign

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Ossification Centres

There are six ossification centres in the elbow of a developing child and they occur in a fixed order at sequential times up to the age of 13 years, although these times are variable. It is the presence of these centres that make paediatric elbow x-rays notoriously difficult to interpret. Knowledge of these ossification centres and the age at which they appear will assist the observer in identifying whether a fracture is present or not. A well-known helpful pneumonic for this is CRITOL or CRITOE:

Capitellum 1 year
Radial head 3 years
Internal (medial) epicondyle 5 years
Trochlear 7 years
Olecranon 9 years
Lateral (External) epicondyle 11 years

Note that these ages vary but a broad guide of 1,3,5,7,9 and 11 years is easy to remember.

Figure 9: Ossification centres

elbow_ossification

Contours

Finally, it is important to analyse all 3 bones of the elbow joint and follow the contours looking for irregularities and steps that could indicate subtle disruptions and fractures in the cortex. Common subtle injuries that may be difficult to identify include undisplaced radial head fractures in adults and undisplaced supracondylar fractures in children.

 

Management

Injury Patterns

Elbow dislocation

This injury is seen in both children and adults and is usually caused by a fall onto the outstretched hand. It is more common in children than dislocation of the shoulder. Examination may reveal obvious deformity of the elbow. The triangular relationship of the epicondyles and olecranon will be disrupted. It is important to check the distal neurovascular status of the limb due to possible damage to the brachial artery or median and ulnar nerves. The dislocation is most commonly in a posterior or posterolateral direction and will be confirmed on x-ray, along with the presence of any associated fractures. Associated epicondylar fractures and fractures of the lateral condyle are known to occur in children.

Analgesia should be provided prior to attempts to reduce the dislocation. Procedural sedation (with full monitoring) is likely to be required. In some cases reduction under general anaesthetic may be necessary.

Figure 10: Posterior elbow dislocation

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Several techniques for reduction of a posteriorly dislocated elbow are recognised:

  • With the elbow flexed to 60 provide traction to the pronated forearm and counter-traction to the distal humerus.
  • Lever the olecranon forwards whilst traction is being provided to the forearm.
  • Position the patient prone with the abducted humerus resting upon the bed and pronated forearm hanging towards the floor. Provide traction to the forearm and downward pressure to the olecranon.

Reduction should be immediately followed by a further assessment of limb neurovascular status. Successful reduction is then confirmed by repeat x-ray. This will also enable assessment of the new position of any associated fractures.

The reduced elbow can be immobilised in a backslab in 90 of flexion. In cases where there are concerns over neurovascular impairment or significant elbow swelling a period of observation should follow. This is due to the possibility of compartment syndrome developing in the forearm fascia or biceps tendon. Outpatient orthopaedic review should subsequently be arranged. Myositis ossificans may later develop as a result of large elbow haemarthroses

Radial head fractures

These injuries usually follow a fall onto an outstretched wrist or direct trauma. Radial head fractures usually occur in adults and account for 30% of all adult elbow fractures. Examination may reveal local bruising and swelling. In some cases pain may only be evident with palpation of the radial head during passive forearm pronation. Elbow extension is usually restricted. Assessment of the wrist should be performed due to the possibility of an Essex-Lopresti fracture-dislocation, consisting of a comminuted radial head fracture with subluxation of the distal end of the ulna.

Radiography may reveal the fracture or merely the presence of a joint effusion. Undisplaced fractures can be managed with a collar and cuff sling and orthopaedic outpatient follow-up. Further management generally consists of early mobilization to prevent loss of elbow extension. Comminuted or displaced fractures may require manipulation under anaesthetic or internal fixation. Occasionally the radial head may need to be excised and replaced.

Radial neck fractures are seen more commonly in children and are managed similar to radial head fractures. Greater than 20 of angulation in the adult requires reduction.

Figure 11: Radial head fracture

elbow_radial-1

Olecranon fractures

The mechanism of injury is usually a fall onto the point of the elbow or onto a semi-flexed outstretched forearm. Examination will reveal swelling and tenderness over the posterior aspect of the elbow. Radiography will confirm the diagnosis and also reveal any displacement due to the pull of the triceps tendon. Identification of paediatric olecranon fractures may be complicated by the appearance of the olecranon ossification centre, which may be bifid. Undisplaced fractures can be managed with a backslab in 90 of elbow flexion and orthopaedic clinic follow-up. Displaced fractures (> 2mm) and those with comminution are more likely to require operative fixation and therefore warrant orthopaedic referral.

Figure 12: Olecranon Fracture

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Monteggia fracture-dislocation

This injury comprises dislocation of the radial head with an ulna fracture. It may result from a direct blow to the ulna or forced pronation. The radiographic appearance of a dislocated radial head (suspect if a line bisecting the radius longitudinally does not pass through the centre of the capitellum) should prompt further imaging of the forearm to exclude an ulna fracture. These injuries should be referred for reduction and internal fixation.

Paediatric Injuries

Supracondylar fractures

These account for 60% of all paediatric elbow fractures and typically follow a fall onto an outstretched hand. The peak incidence occurs between the ages of 5 and 8 years. Children are more prone to supracondylar fracture than adults due to the relatively thin trabeculae of the coronoid and olecranon fossae in this population. 90% of these fractures are caused by hyperextension injury due to ligament laxity. The force is transmitted up through the ulna and into the distal humerus.

Signs to look out for on x-ray include presence of fat pads and loss of normal anterior humeral alignment. Undisplaced fractures may only be identified by subtle disruption in the posterior cortex whereas displaced fractures will normally be obvious. These injuries have been classified by Gartland into 3 types. Type 1 is an undisplaced fracture which accounts for 25% of injuries. Type 2 represents a fracture with posterior displacement but with an intact posterior cortex. A Type 3 injury has posterior displacement with complete cortical disruption.

Figure 13: Type 2 Supracondylar fracture with posterior fat pad

elbow_fat_pad

Initial assessment should include provision of analgaesia and a search for associated neurovascular complications. Undisplaced fractures may be treated with a collar and cuff and can be followed up in fracture clinic. If there is significant pain, a back slab may be a better option. Displaced fractures should all be referred for manipulation, urgently if circulation is compromised.

Complications include:

  • Cubitus varus (gun stock deformity)
  • Malunion and stiffness
  • Myositis ossificans
  • Nerve injury (most commonly median nerve)
  • Brachial artery (due to stretch and posterior displacement)
  • Volkmanns ischaemic contracture (due to compartment swelling)

Lateral epicondyle epiphyseal injury

This is the second most common elbow fracture seen in children, usually between the ages of 4 and 10. It results from a varus force applied through the extended elbow, normally due to a fall on an outstretched hand. It is commonly displaced by the action of the forearm extensors. Appearance on x-ray may be subtle so an awareness of the possibility of this injury is necessary when interpreting films. Displaced fractures often need reduction whereas undisplaced fractures can be managed in a backslab with orthopaedic follow up.

Figure 14: Lateral epicondyle avulsion

elbow_avulsion

Medial epicondyle avulsion injury

These injuries tend to occur in adolescents due to valgus stress during a fall on an outstretched hand. There may be associated ulna nerve damage and sometimes dislocation. Undisplaced avulsions can be managed conservatively while displaced fragments should be referred for reduction.

Radial neck fracture

These injuries are more common in children due to weak metaphyseal bone and, as with radial head fractures, may be difficult to spot on an x-ray. Treatment is similar to that of radial head fractures and orthopaedic referral is recommended if there is greater than 30 degrees of angulation

Pulled elbow

This is also sometimes known as nursemaids elbow. There is often a history of traction on the arm of a child between 1 and 5 years, although this is not always the case. The parent may not be willing to volunteer the history or may not have been present when it occurred. The child will not be using the arm.

It results from subluxation of the radial head from its normal position encircled by the annular ligament. The x-ray is normal and therefore not necessary if clinical suspicion is high prior to attempted manipulation. Traditional reduction is achieved by flexing the elbow to 90 degrees and then fully supinating or pronating the forearm, there may often be an associated click and the child will begin using the arm a short time later.

Soft tissue injuries

Lateral epicondylosis / Tennis elbow

This condition occurs as a result of overuse of the forearm extensor tendons. Previously known as lateral epicondylitis the process is thought to be due to failed tendon healing rather than acute inflammation. The patient may complain of a diffuse ache located over the lateral aspect of the elbow. The diagnosis can be made clinically as described previously.

Management should consist of advice regarding relative rest, ice therapy and analgesia. The condition is often persistent and although corticosteroid injection reduces pain the effects do not appear to last beyond six weeks.

Physiotherapy has an established role, although results at 12 months are comparable with patients who have not received any intervention.

Medial epicondylosis / Golfers elbow

This condition is seen less commonly than lateral epicondylosis and is similarly an overuse injury, this time of the forearm flexor tendons, giving rise to pain over the medial aspect of the elbow. In 20% of cases there may be associated ulnar nerve symptoms, specifically paraesthesia in an ulnar nerve distribution. The diagnosis should again be made clinically. Management should follow that for lateral epicondylosis.

Olecranon bursitis

This is usually the result of direct trauma (such as a fall onto the outstretched elbow) or repetitive friction. It may be acute or chronic and can be associated with crystal arthropathy or inflammatory arthritis. Septic bursitis is most commonly due to Staphylococcus aureus infection and can arise directly from an overlying skin wound.

On examination there is localised swelling, tenderness and possible erythema over the posterior aspect of the elbow. Patients with septic bursitis may be systemically unwell with pyrexia, cellulitis and axillary lymphadenopathy.

Blood tests may reveal an elevated ESR, CRP and white cell count. Septic or crystal-induced bursitis can be confirmed with bursal aspiration and subsequent microscopy and Gram stain.

All cases are likely to require relative rest (may require a broad arm sling in severe cases) and analgesia. Septic bursitis requires antibiotics as per local policy (intravenous if systemically unwell).

 

Safety pearls and Pitfalls

  • A subtle fracture may be missed if insufficient attention is paid to the appearance of an elevated anterior fat pad
  • Radial head dislocation may not be obvious and should be excluded with use of the radio-capitellar line
  • A minimally displaced supracondylar fracture may not be obvious and should be excluded with use of the anterior-humeral line
  • Misinterpretation of the paediatric elbow x-ray may result from a lack of knowledge of the appearance of ossification centres
  • Associated injuries may be missed if the identification of one bony injury does not prompt a search for others with further radiography
  • Neurovascular compromise may be associated with supracondylar fractures and elbow dislocations and should always be assessed

 

References

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