Trauma About the Elbow I: Overview, Supracondylar and Transphyseal Fractures

David L. Skaggs, MD, MMM

Martin J. Herman, MD¹

Steven Frick, MD¹

¹Gurus:

Beware! About 50% of radiograph interpretations of elbow fractures in children by emergency department physicians are incorrect.¹ Don’t trust the phone call; insist on seeing the X-ray. (From Shrader MW, Campbell MD, Jacofsky DJ. Accuracy of emergency room physicians’ interpretation of elbow fractures in children. Orthopedics. 2008;31(12).)

Figure 6-1 Secondary ossification centers of the elbow, with range of ages of appearance.

Elbow fractures in children present the practicing orthopaedist with many opportunities to get in trouble. A thorough understanding of the anatomy and development of the immature elbow helps one stay out of trouble.

Anatomy and Imaging

The secondary centers of ossification of the bones about the elbow appear in a relatively predictable order, which may serve as landmarks to define the anatomy of the largely cartilaginous elbow during early childhood (Fig. 6-1). Easily remembered mnemonics aid in remembering the order of ossification; however, in our age of political correctness, the most memorable ones may only be passed on verbally to trusted confidents. As a fracture line in pediatric elbows may travel through unossified cartilage, one often must rely on the relationship between the ossification centers and visible bone to define the injury on radiographs. The radial head, the trochlea, and the olecranon may appear as multiple ossification centers, which may be mistaken for a fracture.

To stay out of trouble, get into the habit of establishing the four following anatomic relationships in every radiograph of a child’s elbow:

The anterior humeral line intersects the capitellum. If the center of the capitellum is posterior to this line, an extension-type supracondylar fracture, or a transphyseal fracture, is likely seen more commonly in the very young. If the capitellum is anterior to the line, the less common flexion-type supracondylar fracture or transphyseal fracture is likely (Fig. 6-2).² One must be certain that the X-ray is a true lateral view of the distal humerus because any rotation will make the capitellum appear posterior.

Figure 6-2 In the normal elbow, a line drawn down the anterior humeral line will be in the middle third of the capitellum in children of age 5 years and older. In children younger than 5 years, the line will always touch the capitellum in a normal elbow, but it may not be in the middle third.² (Reprinted with permission from Ryan DD, Lightdale-Miric NR, Joiner ER, et al. Variability of the anterior humeral line in normal pediatric elbows. J Pediatr Orthop. 2016;36(2):e14-e16.)

The radius usually points to the capitellum in all views (Figs. 6-3 and 6-4). If it doesn’t, a lateral condyle fracture, a radial neck fracture, a Monteggia fracture-dislocation or equivalent lesion, or an elbow dislocation should be considered. While traditional teaching has been that a line drawn along the radial shaft always points to the capitellum, in reality this line misses the ossific nucleus in about one in seven normal children’s elbow X-rays.³

Figure 6-3 Relationship between the radius and capitellum, and the ulna and humerus, in normal and injured elbows, as visualized on an AP radiograph.
The humeral capitellar (Baumann) angle should be in valgus (95% of normal elbows have an angle of at least 10°) (Fig. 6-5). Baumann angle is a relatively sensitive indicator of varus angulation of the distal humerus and is primarily useful in assessing angulation or reduction in supracondylar and transphyseal fractures. Angulation of the humerus to the X-ray cassette or the X-ray beam to the humerus in the sagittal plane can lead to significant measurement errors of this angle, so if there is a question, repeat the X-ray with a true AP of the distal humerus.
In radiographs of a normal elbow, the long axis of the ulna should be parallel and slightly medial to the long axis of the humerus on a true AP view (see Fig. 6-3). If not, and the radial head and capitellum remain in correct alignment, a transphyseal injury or displaced supracondylar fracture should be considered. If the radius is no longer pointing to the capitellum, a lateral condyle fracture and an elbow dislocation must be considered.

Figure 6-4 The radius usually points to the capitellum in all radiographic views.

Occult fractures about a child’s elbow are easy to miss. A lateral radiograph of a normal elbow flexed at 90° may show a small anterior fat pad bulging from the shallow coronoid fossa; this is a normal finding and of no clinical significance. Do not waste brain power thinking or talking about anterior fat pads. In contrast, if an elevated posterior fat pad is visible, but no fracture is appreciated on initial radiographs, an occult fracture is likely present, and the child’s arm should be protected on the assumption that it is fractured.⁴

Growth and Remodeling

The distal humerus physis provides 20% of growth and the proximal 80%. As there is very little growth about the elbow, there is very little remodeling potential, even in the plane of motion. Have a low threshold for surgery on elbow fractures; if in doubt, your default should be to fix elbow fractures anatomically.

In contrast, because there is lots of growth about the proximal humerus and distal radius, we can predict remodeling in children who have years of remaining growth in fractures of the distal radius and proximal humerus. It is thought provoking that the opposite pattern is true of the lower extremity, with the most active growth about the distal femur, which is the most common site of bone tumors. Why are we designed this way?

Figure 6-5 Baumann angle is variable, but is usually at least 10°.

Routine use of comparison radiographs of the uninjured elbow have generally not proved useful in improving diagnostic accuracy by orthopaedic surgeons. However, if doubt remains, comparison views may be helpful in individual cases.
An arthrogram and/or live fluoroscopic imaging, or even MRI, will sometimes help to establish a diagnosis when plain radiographs are inconclusive. For example, prior to ossification of the trochlea and medial epicondyle, a lateral condyle fracture may appear identical to Salter II fracture on a plain AP radiographs (Fig. 6-6). These particular two fractures may at times be clinically differentiated by the location of maximal swelling, which is on the side where the periosteum is torn. The periosteum is torn opposite the Thurston Holland fragment in a Salter II fracture (medial) or on the lateral side of a lateral condyle fracture.

Figure 6-6 A Salter II fracture of the distal humerus may be mistaken for a lateral condyle fracture prior to the ossification of the trochlea and medial epicondyle. Lateral elbow radiograph of a 4-year-old boy who fell down the stairs. Preservation of the anatomic relationship of the radius to capitellum in all views and medial translation of the capitellum on the intraoperative imaging help make this diagnosis. (Used with permission of the Children’s Orthopaedic Center, Los Angeles.)

Figure 6-7 Avascular necrosis of the trochlea following posterior open reduction of a supracondylar humerus fracture. Patient has severely limited motion and pain. At this point, there is no good treatment option. (Used with permission of the Children’s Orthopaedic Center, Los Angeles.)

While collateral circulation about the elbow is generally rich, the capitellum and the lateral portion of the trochlea rely on end arteries entering posteriorly. Avoid the potentially catastrophic iatrogenic complication of avascular necrosis of the trochlea by avoiding posterior dissection of the distal humerus (Fig. 6-7).

Physical Examination

The two most important aspects of the physical examination are the neurovascular and soft tissue assessments (Fig. 6-8). The neurologic examination of a young child with an injured elbow is difficult yet essential, as the rate of neurological injury or vascular compromise is around 15% for displaced supracondylar fractures (Fig. 6-9). A thorough preoperative evaluation helps avoid the uncomfortable and dangerous situation of finding vascular compromise or a neurologic deficit postreduction without knowing the prereduction status. It is rarely necessary, but if sensation cannot be established by standard techniques, soaking a child’s hand in a wet washcloth will cause wrinkling in areas that have sensory nerves intact, while the skin with complete loss of afferent innervation will remain smooth.⁵

Figure 6-8 A: Skin puckering and antecubital ecchymosis are both red flags that timely surgery is required. B: Skin puckering signifies the distal humerus has torn through the brachialis, and almost tore through the skin, but is stuck in the dermis (arrow).

Figure 6-9 Motor nerve examination of the hand. A: Thumb up for radial nerve. B: Okay sign for median nerve. Confirm distal interphalangeal (DIP) flexion of index finger (red arrow) and IP flexion of thumb (white arrow). C: Crossing fingers for ulnar nerve. D: Preoperative assessment in a scared injured child can be challenging. However, even young children will usually pinch an examiner’s finger, allowing the examiner to palpate contraction of the first dorsal interosseous muscle (arrow) and confirm ulnar motor function. (Used with permission of the Children’s Orthopaedic Center, Los Angeles.)

Supracondylar Fractures

Supracondylar humerus fractures are the most common fracture in children requiring surgery. Although common, these fractures are notorious for complications and litigation.

TIMING

Often, reduction and pinning of a supracondylar fracture can safely wait until the morning. Studies report that mean delays of 8 to 21 hours in the treatment of supracondylar humerus fractures do not increase the risk of complications or need for an open reduction. These studies must be interpreted with a great deal of caution, as they are retrospective. One interpretation of these studies is that orthopaedic surgeons’ clinical judgment in determining which fractures needed urgent treatment was correct, and we should therefore continue to have a high vigilance for fractures at risk. Most type II and III fractures without undue swelling, skin puckering from the proximal fragment, significant vascular impairment, or signs of compartment syndrome do not require urgent surgery. Children awaiting surgery may have their arms splinted in 20° to 45° of elbow flexion, elevated, and checked every hour or two by someone capable of recognizing signs of trouble.

One of the best ways to stay out of trouble with these potentially problematic fractures is with a timely and careful evaluation.

Is a Supracondylar Fracture Emergent or Urgent?

EMERGENCY
	Cancel elective cases and get this patient to the operating room as soon as possible.
	Pulseless, poorly perfused: Hand is white and cool. Initial treatment of gentle traction and elbow flexion to 20° to 40° may restore pulse and perfusion. Do not waste time with an arteriogram; you know where the problem is.
URGENT
	Get this patient to the operating room that night or before the elective schedule starts.
	Pulseless, well perfused: Hand is pink and warm. Initial treatment of gentle traction and elbow flexion to 20° to 40° may restore pulse. Skin puckering Antecubital ecchymosis. Excessive swelling Ipsilateral forearm fracture: higher energy injury. Sensory nerve damage can mask pain of compartment syndrome; median nerve injury is particularly worrisome and may be considered an emergency. Out of proportion anxiety, anxiousness, or need for increasing pain medication raises the suspicion of a developing compartment syndrome and is particularly worrisome after a fracture is reduced.

Figure 6-10 Gentle traction flexion can help improve circulation and take pressure off soft tissues at risk (arrow). (Used with permission of the Children’s Orthopaedic Center, Los Angeles.)

VASCULAR COMPROMISE

Up to 20% of displaced supracondylar fractures present with an absent pulse. To clarify your thinking, consider three clinical scenarios:

Hand well-perfused (pink and warm), radial pulse present
Hand well-perfused (pink and warm), radial pulse absent
Hand poorly perfused (white and cool), radial pulse absent

A child with a poorly perfused, pulseless hand requires emergent treatment. Vascular compromise is often positional, with the proximal fragment causing occlusion the brachial artery (Figs. 6-10 and 6-11). Gentle traction and placement of the elbow in 20° to 40° of flexion should not be delayed. Most frequently a child with a poorly perfused, pulseless hand, whose arm was splinted in full elbow extension will have significant improvement in vascular perfusion with this maneuver. Note that this maneuver is not an attempt to anatomically reduce the fracture, as iatrogenic injury to neurovascular structures is possible. Arteriograms generally have no role in preoperative evaluation of the pulseless supracondylar fracture, as they delay treatment and rarely contribute useful information.

Figure 6-11 An example of what not to do. This 10-year-old with a pulseless, poorly perfused hand presented to a community hospital with the elbow splinted in full extension. An angiogram was performed in this position, which did not provide any useful information, and delayed the patient’s care without benefit. We know the arterial flow is stopped over the sharp bone fragment; we don’t need a study to prove that. What should have been done? Gentle traction and flexion of the elbow should have been done when the patient was first seen. When that maneuver was done many hours later, the pulse and perfusion immediately returned. Keeping the child’s elbow in full extension prevented the pulse and perfusion from returning to normal and increased the risk of a compartment syndrome. (Used with permission of the Children’s Orthopaedic Center, Los Angeles.)

Following a closed reduction of the fracture with a poorly perfused, pulseless hand, perfusion usually returns. If the hand remains poorly perfused and pulseless, operative exploration of the brachial artery is indicated. An anterior approach is best when the purpose of the approach is for arterial exploration. The secret to the anterior approach is the lacertus fibrosus (Fig. 6-12). (Fully extend your own
elbow and use your other hand to feel the lacertus fibrosus just medial to the bicep tendon in the antecubital fossa; it has a sharp fascial edge.) After making a transverse skin incision, place a clamp just under the lacertus fibrosus, cut it, and the brachial artery and nerve lie just medial to the biceps tendon in a normal elbow. If they are not there, dissect proximally until you find them. Many times the brachial artery itself is not trapped in the fracture site, but soft tissue adjacent to the artery is trapped, tethering the artery just enough to stop flow (Fig. 6-13). If the hand is still poorly perfused after exploration and removal of an entrapped or tethered artery from fracture site, a general or vascular surgical consult is wise.

Only gold members can continue reading. Log In or Register to continue