Supracondylar Humerus Fracture Case File

Supracondylar Humerus Fracture Case File

Eugene C. Toy, MD, Andrew J. Rosenbaum, MD, Timothy T. Roberts, MD, Joshua S. Dines, MD

CASE 15

A 6-year-old female presents to the emergency department complaining of left arm pain after falling from the monkey bars. She says she lost her grip and fell directly onto an outstretched hand. She has difficulty flexing her forearm. Her past medical and surgical histories are unremarkable. On examination of her left elbow, there is a “dimpling” of the skin in the antecubital fossa, with mild swelling around the elbow. She will not allow any range of elbow motion secondary to pain. With encouragement, the patient can extend her wrist and fingers and can spread her fingers apart. She has difficulty, however, flexing her thumb interphalangeal (IP) joint and flexing her index and middle fingers at the distal interphalangeal (DIP) joint. Sensation is intact throughout her left arm. Radial pulses are 2+. Anteroposterior (AP) and lateral plain films of the elbow are obtained ( Figure 15–1 ).

Figure 15–1. AP and lateral radiographs of a skeletally immature elbow. (Reproduced, with permission,

from Tintinalli J, et al. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 7th ed.

New York, NY: McGraw-Hill; 2010:Fig. 267-9.)

► What is the most likely diagnosis?

► Why are children most prone to this type of injury?

► What additional radiographs, if any, do you wish to order?

► What aspects of this child’s exam are concerning?

ANSWER TO CASE 10:

Supracondylar Humerus Fracture                              

Summary: This is a 6-year-old healthy girl with left elbow pain after falling 5 feet from the monkey bars. There is dimpling in the antecubital fossa and mild swelling about the elbow. She has a motor deficit in her ipsilateral flexor pollicis longus (FPL) and flexor digitorum profundus (FDP) of the index and middle fingers.

• Most likely diagnosis: Extension-type supracondylar fracture.
• Why children are most prone to this injury: Between 5 to 8 years of age, pediatric humeri undergo remodeling in which the AP diameter of the distal humerus becomes relatively thin. With forced extension, a taut, thick anterior elbow joint capsule resists stretching as the olecranon engages the olecranon fossa. This places great stress on the supracondylar region, potentially resulting in extension-type fracture.
• Appropriate imaging: AP and lateral views of the elbow are essential. Additional imaging of the entire extremity is indicated for pediatric patients with symptoms that cannot be entirely localized to the elbow.
• Physical exam findings: This patient has obvious palsies for the FPL and the FDP of the index and middle fingers, which, in addition to the pronator quadratus, are the muscles typically innervated by the anterior interosseous nerve (AIN), a branch of the median nerve. The AIN is the most commonly affected nerve with extension-type supracondylar fractures.

ANALYSIS

Objectives

1. Recognize the clinical presentation of supracondylar fractures.
2. Understand the potential complications of supracondylar injuries.
3. Understand the treatment options for supracondylar fractures, their indications, and their potential complications.

Considerations

This patient has suffered an isolated, 100% displaced, closed extension-type supracondylar fracture. Priorities include adequate initial pain control, careful neurologic exam, and prompt immobilization. Neurologic exams should always be carefully performed and documented both before and after any form of manipulation. With 100% displaced fractures such as with this patient, it is highly likely that closed reduction with percutaneous pinning or open reduction with fixation will be required to stabilize the fracture. For this reason, steps to prepare the patient for the operating room should begin as soon as the diagnosis is made. Obtain an efficient but thorough medical history; be sure to inquire about the patient’s last meal or fluid intake and to alert the OR of the potential case.

    Additionally, the presence of an AIN palsy complicates treatment. Neurologic deficit may be seen in up to 10% to 20% of closed supracondylar fractures, yet the great majority of these injuries resolve spontaneously without operative nerve exploration. Although controversial, attempts may be made to close reduce this fracture in the operating room with possible percutaneous pin fixation. If closed reduction cannot be achieved, open reduction must be performed; at this point, exploration of the nerve may be indicated.

APPROACH TO:

Supracondylar Humerus Fracture                                       

DEFINITIONS

ANTERIOR HUMERAL LINE: A radiographic line drawn along the anterior humerus on lateral radiographs of the elbow. In normal elbows, this should intersect the middle third of the capitellar ossification center.

POSTERIOR FAT PAD SIGN: A radiographic lucency located immediately posterior to the elbow on lateral elbow radiographs when a joint effusion is present. Normally, this small pad of posterior fat is radiographically invisible because it is hidden within the olecranon fossa; however, with elbow effusions, the distended joint brings the fat pad into view. In the setting of trauma, a posterior fat pad sign is up to 70% sensitive for an intracapsular fracture.

CLINICAL APPROACH

Epidemiology

Supracondylar fractures are the most common pediatric elbow fractures, accounting for approximately 55% to 75% of all pediatric elbow fractures. These injuries occur most frequently in the nondominant hand of children between 5 and 10 years of age. There is a slight male predominance. Supracondylar fractures may be either extension type or flexion type, depending on the mechanism of injury. Extension-type injuries are by far the most common, representing up to 98% of all cases.

Mechanism of Injury and Relevant Anatomy

The supracondylar region is located directly above the articular condyles of the distal humerus and consists of an area of cancellous bone encased within a thin cortex. This region is especially susceptible to injury, as significant remodeling occurs roughly between the ages of 5 to 8 years of age. A thick anterior joint capsule resists stretch when the elbow is hyperextended. As the olecranon engages the olecranon fossa, significant stress is placed on the relatively thin supracondylar region, resulting in potential extension-type fracture. Extension-type supracondylar fractures result most frequently from a fall on an extended forearm, which may result posterior displaced or posterior angulation (ie, apex anterior) of the distal fragment. A direct fall on the posterior region of a flexed elbow is the most common mechanism for flexion-type supracondylar fractures.

History and Physical Exam

The physician should suspect a fracture in any child who exhibits pain or reluctance to move the affected elbow. Close inspection should evaluate for open fracture. In the setting of local laceration, when one is unsure if the joint is violated, the elbow may be injected with normal saline and observed for extravasation to rule out an open joint injury. A complete neurovascular exam should be obtained, evaluating pulses and capillary refill distally with comparison to the unaffected side. Next, sensory distributions of the radial nerve (first dorsal webspace), medial nerve (palmar side of index finger), ulnar nerve (palmar side of fifth digit), and musculocutaneous nerve (lateral aspect of forearm) should be evaluated, as well as motor evaluation of the median, AIN, radial, and ulna nerves. Neurovascular exams must be repeated and carefully documented after reduction or manipulations of any kind.

Radiographic Evaluation

Radiographs of the pediatric elbow are among the most complex and difficult-tointerpret images in all of orthopaedics. At 5 to 10 years of age, roughly the age at which children are most prone to supracondylar fractures, there are six immature ossification centers that eventually fuse to form the mature elbow. The order of ossification for the six ossification centers may be memorized by the acronym “CRMTOL”—capitellum, radial head, medial epicondyle, trochlea, olecranon, and lateral epicondyle. Conveniently, these begin to ossify at approximately 2, 4, 6, 8, 10, and 12 years of age, respectively.

    Radiographic evaluation of the entire affected extremity is recommended when symptoms cannot be clearly localized to a single, specific point. As stated, AP and lateral views of the elbow are essential. When obtaining lateral films of the elbow, external rotation must be avoided, as this can displace the fracture.

    Classically, supracondylar fracture radiographs will have a positive posterior fat pad sign, indicative of joint effusion from a fracture. The sensitivity of the posterior fat pad sign is > 70% in the setting of trauma without visible fractures lines. Anterior and superior fat pad signs are less sensitive. Additional radiographic assessment should include confirmation that the radial head aligns with the capitellum in all views. Finally, the anterior humeral line should bisect the middle third of the capitellum; in displaced extension-type injuries, the capitellum can fall posterior to the anterior humeral line.

CLASSIFICATIONS AND TREATMENT

Extension-type supracondylar fractures are classified by the Gartland classification, which is based primarily on the degree of displacement.

• Type I fractures: nondisplaced
• Type II fractures: displaced with minimal angulation/rotation, posterior cortex is intact
• Type III fractures: complete displacement

    The majority of supracondylar fractures that are neither open nor complicated by neurovascular injury are treated with careful reduction followed by long-arm cast or splint immobilization. Nondisplaced, or type I fractures, are treated with a long-arm cast with the elbow flexed between 60 and 90 degrees for a minimum of 2 to 3 weeks.

Reduction

Type II and Type III fractures require careful reduction, which may be performed by hyperextending at the elbow with simultaneous traction, followed by flexion at the elbow while simultaneously applying posterior force to the reduced fragment to prevent it from slipping. Long-arm cast immobilization should follow. Both type II and III fractures that are unstable on reduction may benefit from percutaneous pinning, which should be performed under anesthesia in the operating room. Type III fractures may not always be reducible by closed methods, and therefore, open reduction and pinning or internal fixation may be necessary to achieve stabilization.

Complications

Neurovascular injury can have an incidence rate as high as 7% to 10%, typically secondary to excessive traction during injury or nerve/vessel entrapment at the fracture site. Fortunately, the majority of nerve injuries are neurapraxias—self-limited, physiologic (not structural) nerve dysfunctions that typically resolve spontaneously. With extension-type injuries, the AIN is the most commonly affected nerve. With flexion-type injuries, conversely, the ulnar nerve is the most commonly affected nerve.

    The ulnar nerve is also especially prone to iatrogenic injury due to its prominent, superficial location over the lateral epicondyle. During cross-pinning fixation for type II and type III injuries, great care must be taken to avoid trauma to the nerve when placing medial-to-lateral pins. For this reason, many surgeons simply avoid placing medial-to-lateral pins and instead achieve fixation with 2 or more lateral-tomedial percutaneous pins in parallel. Although biomechanical studies have demonstrated that cross-pinning techniques achieve stronger fixation than parallel pins, the clinical outcomes are essentially equivalent between the techniques.

    Although rare (< 1% in isolated supracondylar injuries), it is important to evaluate for developing compartment syndromes. Concomitant vascular injury is uncommon with supracondylar fractures, occurring in fewer than 20% of displaced fractures—or approximately 0.5% of all cases. Typically, the brachial artery is impinged or lacerated at the fracture site, or it can become compressed secondary to swelling in the antecubital fossa. If pulses are absent on examination, but the hand is warm to touch with brisk capillary refill, the arm may be closely monitored. If the patient’s hand is cool to touch with markedly pale digits compared with the unaffected side, emergency compartment release and/or angiographic studies may be indicated.

    Finally, cubitus varus, sometimes referred to as a “gunstock deformity,” may result from inadequately reduced supracondylar fractures that heal with a malunion. This is typically a cosmetic, not functional, complication, and its incidence has been dramatically reduced with the widespread use of percutaneous pinning (2% with residual deformity) versus casting alone (8% with residual deformity).

COMPREHENSION QUESTIONS

15.1 A 10-year-old girl reports right elbow pain after a fall while running from a school bully. She has no other injuries and refuses to move the elbow out of fear of pain. Radiographs are notable for a positive fat pad sign, but show no obvious fracture line. Contralateral images of the left, unaffected elbow are obtained for comparison. Which of the following elbow apophyses is the last to appear on elbow radiographs?

A. Trochlea

B. Lateral epicondyle

C. Medial epicondyle

D. Radial head

E. Olecranon

15.2 An 8-year-old boy falls from the playground slide on a flexed left elbow and suffers a flexion type, fully displaced closed flexion-type supracondylar fracture. He complains of some finger numbness in the emergency department, but will not let anybody close enough to examine his arm. Which of the following is most likely injured in this fracture?

A. Brachial artery

B. Anterior interosseous nerve

C. Radial nerve

D. Ulnar nerve

E. Radial artery

15.3 A 5-year-old boy falls from a highchair during a rowdy game of “Go Fish” and falls onto an outstretched right hand. He presents to the emergency department with complaints that he can’t move his arm. X-rays reveal a Gartland type III extension-type supracondylar fracture. His fingers are warm and well perfused, but no radial pulse is palpable. On careful examination, with which of the following motions is he most likely to have difficulty?

A. Wrist extension

B. “Thumbs up”

C. “A-okay” sign

D. Thumb-small finger opposition

E. Fanning out his fingers

ANSWERS

15.1 B. The lateral epicondyle should be the last apophysis to ossify in normal skeletal development. Generally, the order and age for elbow apophyseal ossification is capitellum, radial head, medial epicondyle, trochlea, olecranon, and lateral epicondyle, which ossify at approximately 2, 4, 6, 8, 10, and 12 years of age, respectively.

15.2 D. Although the anterior interosseous nerve is most commonly injured in extension-type supracondylar fractures (by far the most common type of supracondylar fracture), the ulnar nerve is more commonly injured in flexion -type supracondylar fractures. The brachial artery is potentially injured, albeit rarely, with flexion-type injuries. The radial artery does not branch until the brachial artery trifurcation, which occurs distal to the elbow. Radial nerve injury is the second most common form of nerve injury in extension-type fractures.

15.3 C. The “A-okay” sign, made by flexing the thumb and index finger to make a ring, tests thumb IP flexion and index finger DIP flexion, 2 tasks specific to the AIN. The AIN is most commonly injured in extension-type supracondylar fractures. “Thumbs up” and wrist extension are functions of the radial nerve— the second most commonly injured nerve with extension-type injuries. Finger fanning is a function of the intrinsic finger abductors of the ulnar nerve. Thumb and small finger opposition relies mostly on the thenar eminence (pollicis opponens), which is innervated by the recurrent median nerve.

    CLINICAL PEARLS    

► There is a seasonal distribution of supracondylar fractures in children, with the great majority occurring during summer-time play. ► X-rays of the pediatric elbow are complex and often difficult to interpret due to the variability of ossification centers. Images of the contralateral, normal elbow are often helpful for comparison. ► The presence of a posterior fat pad sign on lateral x-ray is helpful in determining the presence of a fracture or intraarticular pathology when no fracture line is obvious.

REFERENCES

Beaty JH, Kasser JR, eds. Supracondylar fractures of the distal humerus. In: Rockwood and Wilkins’ Fractures in Children. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2010:487-532. 

Egol KE, Koval KJ, Zukerman JD, eds. Pediatric elbow. Handbook of Fractures . 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2010:598-644.

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