Elbow—Proximal Radius and Ulna



Elbow—Proximal Radius and Ulna


Maya Pring

Vidyadhar Upasani



INTRODUCTION

For the purposes of this book, we have divided “elbow fractures” into those above the elbow (distal humerus—Chapter 8) and those below the elbow (proximal radius and ulna—this chapter). Although fractures of the proximal radius and ulna are less frequent than supracondylar fractures in young children, their prevalence increases with age as does severity of the fractures.

Many of these fractures and dislocations can be treated in a closed or percutaneous fashion, but caution is warranted as there is risk of poor outcomes if radial head dislocations are undertreated, and at the opposite extreme, there can be significant complications and poor outcome following open reduction of more severe radial head and neck fractures.

“Once you stop learning, you start dying”

Albert Einstein







Figure 9-1 The capsule and ligaments give stability to the elbow.


Anatomy

The elbow does not have inherent bony stability; it depends on the ligaments and capsule to maintain alignment of three joints: the ulnohumeral joint (stabilized by the ulnar collateral ligament and the lateral ulnar collateral ligament), the radio-humeral joint (stabilized by the radial collateral ligament), and the proximal radio-ulnar joint, stabilized by the annular ligament and the interosseous membrane. The three joints of the elbow allow motion in several dimensions: flexion, extension, pronation, and supination (Fig. 9-1).

Elbow x-rays can be difficult to read in young children as the radial head ossification center isn’t visible until around age 3, and the olecranon not until around 8 years in girls, 10 years in boys—fractures or physeal injury can be easily missed on x-ray. Ultrasound is being used more commonly for evaluation and treatment of pediatric elbow fractures as it does not expose the child to radiation and can give a better picture of unossified bone (Fig. 9-2). MRI arthrogram can also better delineate fractures and displacement around the elbow.






Figure 9-2 Lateral condyle fracture in a 5-year-old child. Ultrasound was used to determine the amount of displacement.






Figure 9-3 Triceps avulsion treated with a suture anchor.

In children, the proximal radial physis is intra-articular; fractures that are bathed in synovial fluid typically take longer to heal and may go on to non-union even if adequately reduced. The physis is also at risk for premature closure secondary to fracture, fracture reduction, and/or fixation that crosses the physis.

The olecranon has an apophysis at its proximal end that may develop chronic traction injuries in athletes. The triceps tendon, with or without the apophysis, can be completely avulsed with forceful triceps contraction (Fig. 9-3).

It is also important to note that the blood supply to the radial head is mainly from the periosteal blood vessels running from distal to proximal—this tenuous blood supply may be disrupted by fracture or surgical dissection, leading to avascular necrosis (AVN), which can have a long-term deleterious effect on elbow function and growth of the radius. Repetitive trauma to the elbow, as is seen in pitchers and gymnasts, can also disrupt radial head blood supply and cause abnormal growth of the radial head and an incongruent joint.


The brachial artery, median nerve, and radial nerve anterior to the elbow joint are at risk for stretch injury with a proximal forearm fracture or elbow dislocation. The ulnar nerve, running medially just behind the medial epicondyle, may be stretched, torn, or entrapped in the joint at the time of injury or during reduction. The posterior interosseous nerve, coursing anterior to the radial head and anterolateral to the radial neck, can easily be injured when the proximal radius is fractured or dislocated (Fig. 9-4).


Initial Exam

As discussed in the prior chapter, it can sometimes be difficult to distinguish between an injured and infected elbow in a young child. Be wary if you do not see a clear fracture but there is a “sail sign” or fluid in the joint on x-ray (Fig. 9-5). This may indicate an occult fracture, but the fluid creating the sail sign may also be a sign of infection (pus) in the joint. If there is any question, check bloodwork: CBC, sedimentation rate, and C-reactive protein. Putting an infected elbow in a cast for 3 weeks has resulted in disaster.

Once the area of concern is identified, a skin exam will rule out an open fracture, with the standard neuro-vascular exam then performed (see Chapter 8 for details). Do this portion of the exam before you touch the elbow; if the child starts screaming, the rest of the exam is very difficult if not impossible (Fig. 9-6). In a relaxed child, the fracture location can be estimated by gentle palpation and pronation/supination of the forearm.

Because additional fractures in the same limb are common, always check the joint above and below the area of concern. The contralateral elbow should be examined to determine the normal anatomy and motion for each individual. A child who has a more cubitus valgus due to normal anatomy or prior fracture is more likely to sustain a proximal radius fracture whereas a child with a varus carrying angle is more prone to lateral condyle fracture.



PULLED ELBOW SYNDROME (NURSEMAID’S ELBOW)

A pulled elbow is a common early childhood injury. The clinical picture is characteristic; a child between 1 and 4 years suddenly refuses to move an arm and holds the elbow slightly flexed with the forearm pronated. Often parents think the arm is paralyzed or broken, and they rarely mention that the problem began as the child was pulled along or lifted by the wrist—the usual cause in our fast-paced culture (Fig. 9-9). It is remarkable that all children do not experience a pulled elbow!

Salter and Zaltz found that when longitudinal traction is applied to the arm (with the forearm in pronation) the annular ligament partially tears at its attachment to the radius, allowing the radius to move distally, slipping under the annular ligament. When traction is released,
the ligament is carried up and becomes entrapped between the radius and capitellum (Fig. 9-10). After the age of 5 years, the attachment of the annular ligament to the neck of the radius strengthens and prevents displacement and radial head subluxation. Enlargement of the proximal radial epiphysis with growth may also improve stability.






Figure 9-9 The usual mechanism of a radial head subluxation in a fast-paced culture.

The diagnosis of nursemaid’s elbow is now well recognized by most primary care providers and is quickly treated in the office—rarely requiring referral to orthopedics. However, this condition may be confused for more complex problems. Conditions that we have had referred to our clinic that were initially treated with multiple attempts at reduction of a pulled elbow include



  • Septic elbow


  • Olecranon fracture


  • Radial head or neck fractures


  • Supracondylar fracture


  • Septic wrist

The child with a simple pulled elbow should have no swelling on presentation and should have immediate relief following reduction. If there is not relief following one attempt at reduction, another cause of elbow pain should be sought. X-rays of a pulled elbow are usually normal, but x-ray can rule out effusion, fracture, and true dislocation. CBC, CRP, and ESR can help rule out infection. Once the child is referred to orthopedics, pulled elbow should be a diagnosis of exclusion.


Treatment—Pulled Elbow

Fortuitous reduction can occur when the x-ray technician supinates the arm to obtain an AP x-ray. Because the x-rays are usually normal, you must rely on the history and your exam to reach the diagnosis. The classic teaching is to reduce by supinating the flexed elbow and you will feel a click as the subluxed radial head reduces. Often the elbow must be flexed above 90 degrees with firm supination to achieve reduction (Fig. 9-11). There are four “low quality” studies reviewed by Krul in the Cochrane Database of Systematic Reviews that looked at flexion and hyper-pronation of the pulled elbow as a less painful and more effective reduction technique; however, better studies need to be done before this becomes standard of care.

After the typical reduction, the child often stops crying, seems more comfortable, and starts to move the arm within a minute or two. No immobilization is required, but the parents should avoid pulling the child or lifting them by the arm for the next several years.

Recurrence is relatively common, and a child may have repeated subluxations in the first 3-4 years of life. Repeat injuries are treated in the same fashion as first-time subluxations, with the problem gradually
disappearing by age 5 years; the younger the child, the greater the risk for recurrent subluxation.






Figure 9-10 With longitudinal traction the annular ligament can partially tear allowing the radial head to move distally.






Figure 9-11 Nursemaid’s elbow reduction maneuver.






Figure 9-12 Apparent “dislocation” with transphyseal fracture seen on arthrogram.

“Do not mistake a transphyseal fracture for an elbow dislocation in a young child!”


Pitfalls—Pulled Elbow

A few times a year, one is faced with a case that does not seem to reduce despite ruling out other causes and utilizing the correct reduction maneuver. When convinced that we have a true unreducible nursemaid’s elbow (not an occult septic elbow or fracture), our approach includes casting the child in a position that technically will reduce the subluxation (elbow flexed to 100 degrees, full supination) for 3 weeks. This usually solves the problem.

There have been a few case reports in the literature of pulled elbows that were completely irreducible with closed means. In these cases, surgical exploration demonstrated that the annular ligament had slipped past the equator of the radial head and become trapped in the radiocapitellar joint. We have no experience with such cases.


DISLOCATIONS—ELBOW JOINT

Dislocations are rare in young children, becoming more common as they start doing more aggressive contact sports. If the distal humerus is not yet ossified, beware—a transphyseal fracture will look like a dislocation on x-ray. In children under 2 years, consider non-accidental trauma and use ultrasound or arthrogram to determine if there is a transphyseal fracture (Fig. 9-12).

In children, elbow dislocations without a fracture are uncommon. Whenever you encounter an elbow dislocation, assume an associated occult fracture (which may prevent reduction). The most common example is a medial epicondyle fracture, which frequently becomes entrapped in the joint (discussed in Chapter 8). The articular surface of the ulna or radial head can also fracture and prevent concentric reduction. A flap of articular cartilage and subchondral bone lifted off the articular surface may be barely perceptible on the x-ray. Crepitus and a restricted range of motion following reduction should alert you to possible osteochondral fragments in the joint.

A non-concentric reduction on x-ray should alert the examiner to a trapped fragment, which may be cartilage in younger children (the medial epicondyle ossifies around age 7 years), or bone in the adolescent (Fig. 9-13). Ultrasound, arthrogram, and MRI are useful diagnostic tests for locating a displaced fragment that is not yet ossified. If the fragment is ossified but it is unclear where it came from, contralateral elbow x-ray is very useful.







Figure 9-13 A, B. Child with elbow dislocation reduced elsewhere and referred to us for ulnar nerve palsy. The lateral view suggests non-concentric reduction. C, D. After open reduction, which revealed the ulnar nerve was trapped in the joint and was blocking reduction.

More obvious fractures associated with elbow dislocation include medial and lateral condyle, olecranon, coronoid, and radial head/neck injuries; these are easily identified on x-ray and are more straightforward in terms of management.

Dislocation puts the neurovascular structures, muscles, collateral ligaments, and capsule on extreme stretch and at risk of injury/tearing. Reduction of a dislocated joint should be done emergently to take tension off the soft tissues.


Classification—Elbow Dislocations

Elbow dislocations are described by the position of the radius and ulna in relation to the distal humerus (anterior, posterior, medial, or lateral). They are further classified based on whether or not the proximal radio-ulnar joint remains intact (Table 9-1). Posterolateral dislocations, by far the most common in reported series, are thought to be caused by a fall on the outstretched hand with the elbow extended. Typically the radio-ulnar articulation remains intact with only rare instances of divergent dislocation (radius and ulna separated).








Table 9-1 Classification—Elbow Dislocation
















Type I Proximal radio-ulnar joint intact


Type II Proximal radio-ulnar joint disrupted


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Most common—posterior Can also dislocate anteriorly, laterally, or medially


Anteroposterior divergent


Mediolateral (transverse) divergent


Radio-ulnar translocation








Figure 9-14 An elbow dislocation can be reduced by applying traction to the forearm while simultaneously applying a force on the proximal forearm that is aimed away from the humerus.


Treatment—Elbow Dislocations

The dislocation should be reduced as soon as possible to relieve pain and improve circulation. Conscious sedation helps to relax the muscles adequately for an atraumatic reduction. An easy method for reduction includes placing the child prone with the elbow flexed over the edge of the bed so that the forearm hangs vertically downward. When the child relaxes, a little pressure over the olecranon with correction of any sideways displacement usually reduces the elbow (Fig. 9-14).

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Nov 17, 2018 | Posted by in CARDIOLOGY | Comments Off on Elbow—Proximal Radius and Ulna
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