Closed Reduction and Percutaneous Pinning of Supracondylar Fractures of the Humerus
Closed Reduction and Percutaneous Pinning of Supracondylar Fractures of the Humerus
DEFINITION
Supracondylar fractures of the humerus are common injuries in children. As many as 67% of children hospitalized with elbow injuries have supracondylar fractures; supracondylar fractures of the humerus represent 3% to 17% of all childhood fractures.7,10,11 The annual incidence of supracondylar fractures
has been estimated at 177.3 per 100,000.9 The peak age at fracture is 5 to 7 years.
The cause of injury is most commonly trauma to the elbow, most often resulting from a fall from height (70%) or related to sports activities.
Nearly all (98%) supracondylar fractures of the humerus are of the extension type.1 Flexion-type injuries also occur.
Open injuries occur in 1% of cases. Concurrent fractures, most commonly involving the distal radius, scaphoid, and proximal humerus, occur in 1% of cases. Associated neurovascular injuries can occur, with
nerve injury existing in 11% of cases and vascular insufficiency present in up to 20% of cases.1,2,10 Anterior interosseous nerve injury is the most common nerve injury associated with extension-type supracondylar fractures of the humerus.
ANATOMY
The periosteum most commonly fails anteriorly with extension-type supracondylar fractures of the humerus.
With posteromedial displacement, the periosteum also fails laterally.
Therefore, with posteromedially displaced fractures, forearm pronation can aid in the reduction (FIG 1).
With posterolateral displacement, the periosteum also fails medially.
Forearm supination usually aids in the reduction of these posterolaterally displaced fractures.
The direction of displacement has implications for which neurovascular structures are at risk from the penetrating injury of the proximal metaphyseal fragment (FIG 2).
Medial displacement of the distal fragment places the radial nerve at risk.
Lateral displacement of the distal fragment places the median nerve and brachial artery at risk.
The ulnar nerve courses through the cubital tunnel posterior to the medial epicondyle. It is at particular risk with flexion-type fractures or when a medial pin is placed for fracture fixation.
The ulnar nerve subluxates anteriorly as the elbow is flexed. Therefore, the elbow should be relatively extended if a medial pin is placed for fracture fixation.
PATHOGENESIS
Supracondylar fractures of the humerus generally occur as a result of a fall onto an outstretched hand with the elbow in full extension.
The distal humerus is very thin at the supracondylar region, a critical factor in producing a consistent injury pattern and failure in the supracondylar humeral region.
During a fall with the elbow in full extension, the olecranon in its fossa acts as a fulcrum.
The capsule, as it inserts distal to the olecranon fossa and proximal to the physis, transmits an extension force to this region, resulting in failure and fracture.
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FIG 1 • Reduction of a posteromedially displaced supracondylar fracture of the humerus. Pronation of the forearm closes the hinge and aids in reduction.
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FIG 2 • Relationship to neurovascular structures. The proximal metaphyseal spike penetrates laterally with posteromedially displaced fractures and places the radial nerve at risk. With posterolaterally displaced fractures, the spike penetrates medially and places the median nerve and brachial artery at risk.
With the elbow in full extension and the elbow becoming tightly interlocked, bending forces are concentrated in the distal humeral region.
Increased ligamentous laxity, leading to hyperextension of the elbow, may be a contributing factor to this injury pattern.
NATURAL HISTORY
The physis of the distal humerus contributes little to the overall growth of the humerus (20% of the humerus); therefore, the remodeling capacity of supracondylar fractures of the humerus is limited. Near-anatomic reduction of these fractures is important.
The majority of supracondylar fractures of the humerus (other than extension type I fractures) are unstable; therefore, stabilization in the form of cast immobilization or, preferably, operative fixation is usually necessary.
PATIENT HISTORY AND PHYSICAL FINDINGS
Evaluation of the child with an elbow injury must include an overall assessment to look for associated trauma (especially in the proximal humerus and distal radius regions) as well as associated neurovascular injury.
The physical examination may reveal swelling, tenderness, ecchymosis, and deformity. The pucker sign, which occurs as a result of the proximal fracture fragment spike penetrating through the brachialis and anterior fascia into the subcutaneous tissue, may be present.
Thorough neurologic examination of the involved extremity is critical. Physical examinations to perform include the following:
Assessing for potential associated injury to the ulnar nerve. Finger abduction and adduction (interossei) strength are tested. Sensation in the palmar little finger is tested.
Assessing for potential associated injury to the radial nerve. Finger, wrist, and thumb extension (extensor
digitorum communis, extensor indicis proprius, extensor carpi radialis longus and brevis, extensor carpi ulnaris, extensor pollicis longus) are tested. Sensation in the dorsal first web space is tested.
Assessing for potential associated injury to the median nerve. Thenar strength (abductor pollicis brevis, flexor pollicis brevis, opponens pollicis) is tested. Sensation in the palmar index finger is tested.
Assessing for potential associated injury to the anterior interosseous nerve. Index distal interphalangeal flexion (flexor digitorum profundus index) and thumb interphalangeal flexion (flexor pollicis longus) are tested.
Accurate vascular assessment of the involved extremity is also critical. Examinations to perform include the following:
Palpation of distal radial pulse
General evaluation of perfusion: capillary refill, skin temperature and color
The role of modalities like Doppler ultrasonography and pulse oximetry is still unclear. Preoperative angiography is not usually warranted.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Initial imaging studies should include plain radiographs of the elbow—anteroposterior (AP), lateral, and sometimes oblique views.
Comparison views of the contralateral elbow are sometimes helpful.
The fat pad sign, particularly posterior, represents an intraarticular effusion and can be associated with a supracondylar fracture of the humerus (53% of the time) (FIG 3A).10
On the AP view, the Baumann angle correlates with the carrying angle and should be 70 to 78 degrees or symmetric with the contralateral elbow (FIG 3B).
On the lateral view, the anterior humeral line (line drawn along the anterior aspect of the humerus) should intersect the capitellum (FIG 3C).
This line crosses the middle third of the capitellum in most healthy children older than 4 years. In children younger than 4 years, this line may cross the anterior one-third of the capitellum.1
The most commonly used classification system, the Gartland classification, is based on plain radiographic appearance:
Extension type I: nondisplaced
Extension type II: capitellum displaced posterior to anterior humeral line with variable amount of extension and angulation; posterior cortex of the humerus is intact
Extension type III: completely displaced with no cortex intact
A multidirectionally unstable type IV fracture has more recently been described. These fractures are unstable in both flexion and extension because of complete circumferential loss of a periosteal hinge.1,10 Flexion type
DIFFERENTIAL DIAGNOSIS
Fracture of elbow (other than involving the supracondylar humeral region)
Salter-Harris fractures involving the elbow Nursemaid's elbow
Infection
NONOPERATIVE MANAGEMENT
Recent clinical practice guidelines by the American Academy of Orthopaedic Surgeons (AAOS) recommend nonsurgical immobilization of the injured limb for nondisplaced fractures (type I) meeting the following
criteria4,9:
The anterior humeral line transects the capitellum on the lateral radiograph.
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FIG 3 • A. Posterior fat pad sign. The presence of a posterior fat pad sign suggests an intra-articular
effusion and can be associated with an occult supracondylar fracture of the humerus. B. The Baumann angle is variable but in general is greater than 10 degrees. C. On a lateral view of the elbow, the anterior humeral line should intersect the capitellum.
The Baumann angle is greater than 10 degrees or equal to the other side. The olecranon fossa and medial and lateral cortices are intact.
Nonoperative management consists of immobilization of the elbow in no more than 90 degrees of flexion in a splint or cast.
As the brachial artery becomes compressed with increasing flexion of the elbow, the clinician must ensure that the distal radial pulse is intact and that there is adequate perfusion distally.
SURGICAL MANAGEMENT
Clinical practice guidelines by the AAOS advocate closed reduction and percutaneous pin fixation for most displaced supracondylar fractures of the humerus.9
The two main options for percutaneous pin fixation are the lateral entry pin and crossed-pin techniques. Most fractures can be stabilized successfully by the lateral entry pin technique.5,9,12
Two pins are usually adequate for type II fractures; three pins are recommended for type III fractures.
Biomechanical studies have revealed comparable stability in the lateral entry and crossed-pin techniques.
An advantage of the lateral entry pin technique is the significantly lower risk of iatrogenic nerve injury. The ulnar nerve is at risk when pins are inserted medially (5% to 6% risk).
The crossed-pin technique may be indicated if persistent instability is noted intraoperatively after placement of three lateral entry pins.
Preoperative Planning
Displaced supracondylar fractures of the humerus (including Gartland type II and III) require reduction. Usually, reduction can be achieved by closed means. The preferred method for fixation is percutaneous pinning.
Indications for open reduction of supracondylar fractures of the humerus are limited but include open injuries, fractures irreducible by closed means, and fractures associated with persistent vascular compromise even after adequate closed reduction.
One may consider open reduction and early antecubital fossa exploration in the setting of displaced supracondylar fractures of the humerus with vascular compromise and median nerve injury—as higher risk
of nerve and/or vascular entrapment at the fracture site has been reported.6
All imaging studies are reviewed. A high index of suspicion for associated fractures, especially of the forearm, is important; if present, there is an increased risk of compartment syndrome.
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Complete preoperative neurologic and vascular examination is performed and documented.
The contralateral arm should be examined, and the carrying angle of the contralateral arm should be noted.
The timing of surgery remains controversial. Recent retrospective evidence suggests that a delay in treatment of some supracondylar fractures may be acceptable.1,3,8
Fractures with “red flags” usually require urgent treatment.
Significant swelling
Antecubital skin tenting, puckering, or ecchymosis
Neurologic or vascular compromise (except an isolated anterior interosseous nerve injury)
Concern for compartment syndrome (firm compartments, increasing analgesic requirements, increased anxiety, associated forearm fracture [“floating elbow”])
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FIG 4 • A. Positioning of patient. The injured elbow is positioned on a radiolucent arm board. In smaller children, the child's shoulder and head may also need to rest on the arm board to allow full views of the elbow and distal humerus. B. Positioning the fluoroscopy monitor on the opposite side of the bed allows the surgeon to see the images easily while operating.
Positioning
The patient is positioned supine on the operating room table.
The fractured elbow is placed on a radiolucent arm board (FIG 4A). The arm should be far enough onto the arm board to allow for complete visualization of the elbow and distal humerus. In smaller children, the child's shoulder and head may need to rest on the arm board as well.
The wide end of a fluoroscopy unit is sometimes used as a table.
In cases of severe instability of the fracture, use of the fluoroscopy unit as an arm board is suboptimal because reduction of the fracture is frequently lost with rotation of the arm, which is needed for AP and lateral views of the elbow.
The fluoroscopy monitor is placed opposite to the surgeon for ease of viewing (FIG 4B).
TECHNIQUES
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Closed Reduction
Traction is applied with the elbow in 20 to 30 degrees of flexion (TECH FIG 1A) to prevent tethering of
the neurovascular structures over the anteriorly displaced proximal fragment.
For severely displaced fractures, where the proximal fragment is entrapped in the brachialis muscle, the “milking maneuver” is performed (TECH FIG 1B).
The soft tissue overlying the fracture is manipulated in a proximal to distal direction. Once length is restored, the medial and lateral columns are realigned on the AP image.
Varus and valgus angular alignment is restored. Medial and lateral translation is also corrected.
For the majority of fractures (ie, extension type), the flexion reduction maneuver is performed next (TECH FIG 1C).
The elbow is gradually flexed while applying anteriorly directed pressure on the olecranon (and distal condyles of the humerus) with the thumbs.
The elbow is held in hyperflexion as the reduction is assessed by fluoroscopy. Reduction is adequate if the following criteria are fulfilled:
The anterior humeral line crosses the capitellum.
The Baumann angle is greater than 10 degrees or comparable to the contralateral side. Oblique views show intact medial and lateral columns.
The forearm is held in pronation for posteromedial fractures. The forearm is held in supination for posterolateral fractures.
For unstable fractures, the fluoroscopy machine instead of the arm is rotated to obtain lateral views of the elbow (TECH FIG 1D).
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TECH FIG 1 • A. Reduction. Traction is applied with the elbow flexed 20 to 30 degrees. Countertraction should be provided by the assistant with pressure applied to the axilla. B. If the fracture is difficult to reduce, the proximal fracture fragment may be interposed in the brachialis muscle. The milking maneuver is performed to free the fracture from the overlying soft tissue. C. The elbow is flexed while pushing anteriorly on the olecranon with the thumbs. D. For unstable fractures, the fluoroscopy unit instead of the arm is rotated to obtain lateral views of the elbow.
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Lateral Entry Pin Technique
Once satisfactory reduction is obtained, K-wires can be inserted percutaneously for fracture stabilization.
A 0.062-inch smooth K-wires are commonly used.
Smaller or larger sizes may be used depending on the size of the child.
The goals of the lateral entry pin technique are to maximally separate the pins at the fracture site and to engage both the medial and lateral columns (TECH FIG 2A-C).
The pins can be divergent or parallel.
Sufficient bone must be engaged in the proximal and distal fragments. Pins may cross the olecranon fossa.
As a general rule, two pins are adequate for type II fractures; three pins are recommended for type III fractures.
The K-wire is positioned against the lateral condyle without piercing the skin (TECH FIG 2D).
The starting point is assessed under AP fluoroscopic guidance. The K-wire is held freehand to allow maximum control.
Once a satisfactory starting point and trajectory are confirmed, the K-wire is pushed through the skin and into the cartilage.
The cartilage of the distal lateral condyle functions as a pincushion.
The starting point and trajectory are assessed by AP and lateral fluoroscopic guidance.
When satisfactory starting point and trajectory are confirmed, the pin is advanced with a drill until at least two cortices are engaged.
At this point, the reduction is again assessed.
The reduction must appear satisfactory on AP, lateral, and two oblique views. The elbow is rotated to allow for oblique views of the medial and lateral columns.
Additional pins are inserted (TECH FIG 2E-H).
The elbow is stressed under live fluoroscopy in both the AP and lateral planes.
Once satisfactory reduction and stability are confirmed, the vascular status is again assessed. Upon completion, the pins can be bent and cut approximately 1 to 2 cm off the skin.
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TECH FIG 2 • A-C. Lateral entry pin technique: optimal pin configuration. The pins are separated at the fracture site to engage the medial and lateral columns. A. Optimal pin configuration for two pins (AP view).
B. Optimal pin configuration for three pins (AP view). C. Optimal pin configuration (lateral view). D. The pin is held freehand. Once starting point and trajectory are confirmed under fluoroscopic guidance, the pin is pushed through the skin and into the cartilage. E,F. Assessment of coronal alignment on AP and lateral views. G. Externally and internally rotated oblique views are used to assess the medial and lateral columns.
H. Stress fracture. The elbow should be stressed under live fluoroscopy to confirm adequate stability.
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Crossed-Pin Technique
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If satisfactory stability cannot be achieved by lateral entry pins or if the surgeon is more comfortable with lateral and medial entry pins, the crossed-pin technique can be performed.
The lateral entry pins are inserted first: This will allow the elbow to be extended when placing the medial entry pins.
The ulnar nerve subluxates anteriorly with increasing flexion of the elbow; therefore, the ulnar nerve
may be at risk when medial entry pins are placed with the elbow in 90 degrees or more of flexion.
After insertion of the lateral entry pins, the elbow is extended to 20 to 30 degrees of flexion (TECH FIG 3A).
A small incision is made over the medial epicondyle.
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TECH FIG 3 • Crossed-pin technique. A. To minimize risk of iatrogenic injury to the ulnar nerve, the elbow is extended to 20 to 30 degrees of flexion before the pins are inserted medially. B. The starting point is on the medial epicondyle. C,D. The medial pin should engage the medial column and at least two cortices.
Blunt dissection is performed down to the level of the medial epicondyle. A pin is positioned on the medial epicondyle (TECH FIG 3B).
The starting position and trajectory are assessed under fluoroscopic guidance.
When a satisfactory starting point and trajectory are confirmed, the pin is advanced with a drill until at least two cortices are engaged (TECH FIG 3C,D). The medial column should be engaged.
Ideally, the pin should be separated from the other pins maximally at the fracture site.
The reduction and stability of the fracture are assessed just as with the lateral entry pin technique. The vascular status is similarly evaluated.
PEARLS AND PITFALLS
Clinical ▪ A thorough preoperative neurologic and vascular examination should be
examination performed and documented.
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The surgeon should look for red flags such as ecchymosis, excessive swelling, puckering of skin, and associated fractures, which may be indications for an urgent reduction.
Indications
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Nondisplaced (type I) fractures can be treated nonoperatively with splint or cast
immobilization.
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Fractures with medial comminution or impaction should be treated operatively to avoid cubitus varus.
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Displaced fractures require reduction (usually closed) and operative fixation (usually percutaneous pinning).
Reduction
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Traction is applied with the elbow in 20-30 degrees of flexion.
Lateral
entry pin placement
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Maximal pin separation at the fracture site to engage the medial and lateral
columns is the goal.
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For type II fractures, two pins are usually adequate; for type III fractures, additional fixation with a third pin is usually indicated.
Medial
entry pin placement
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Lateral entry pins are inserted first so that the elbow can be extended to 20-30
degrees of flexion, allowing for safer insertion of medial entry pins.
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POSTOPERATIVE CARE
The arm is immobilized, preferably in a cast (sometimes a splint), with the elbow in 45 to 60 degrees of flexion.
Flexing the elbow to 90 degrees, as is used for most other casting, is not recommended because it will increase the risk of compartment syndrome. Moreover, flexion to 90 degrees is not needed since the fracture reduction is stabilized by the pins, not the cast.
Sterile foam may be directly applied to the skin before cast application to allow for postoperative swelling.
The arm is immobilized for 3 to 4 weeks, with follow-up evaluations at 1 and 3 (or 4) weeks. Postoperative radiographs (AP and lateral views) are obtained.
Pins are usually discontinued at 3 to 4 weeks postoperatively.
Range-of-motion exercises are initiated shortly after pins and immobilization are discontinued.
Return to full activity typically occurs by 6 to 8 weeks postoperatively.
OUTCOMES
The AAOS has reported improved outcomes (radiographic, clinical, and functional) following closed reduction and percutaneous pin fixation of most displaced supracondylar fractures of the humerus (type 2, type 3, flexion).4,9
Multiple studies have reported on the efficacy and high safety profile of the lateral entry pin technique.4,5,9,12,13
No significant difference in loss of reduction between lateral entry and crossed-pin techniques No significant difference in radiographic outcome (Baumann angle, Baumann angle change) Significantly lower risk of iatrogenic nerve injury (ulnar) with lateral entry technique
Studies have suggested that treatment of some supracondylar fractures may be delayed without significant added risk in appropriately selected patients.1,3,8
COMPLICATIONS
Elbow stiffness Infection Vascular injury Neurologic injury Malunion Nonunion
Avascular necrosis Myositis ossificans
REFERENCES
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Franklin CC, Skaggs DL. Approach to the pediatric supracondylar humeral fracture with neurovascular compromise. Instr Course Lect 2013;62:429-433.
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Gupta N, Kay RM, Leitch K, et al. Effect of surgical delay on perioperative complications and need for open reduction in supracondylar humerus fractures in children. J Pediatr Orthop 2004;24(3): 245-248.
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Howard A, Mulpuri K, Abel MF, et al. The treatment of pediatric supracondylar humerus fractures. J Am Acad Orthop Surg 2012;20(5):320-327.
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Kocher MS, Kasser JR, Waters PM, et al. Lateral entry compared with medial and lateral entry pin fixation
for completely displaced supracondylar humeral fractures in children. A randomized clinical trial. J Bone Joint Surg Am 2007;89(4):706-712.
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Woratanarat P, Angsanuntsukh C, Rattanasiri S, et al. Meta-analysis of pinning in supracondylar fracture of the humerus in children. J Orthop Trauma 2012;26(1):48-53.