Supracondylar Humerus Fractures

Etiology

The distal humerus is composed of medial and lateral columns. The medial and lateral columns are composed of the trochlea and medial epicondyle medially and the capitellum and lateral epicondyle laterally. The distal humerus narrows proximally from metaphysis to diaphysis. The humerus also thins in its anteroposterior width as the medial and lateral columns merge at the proximal aspect of the olecranon fossa. This creates a point of relative weakness in the supracondylar region of the distal humerus.[6]

Epidemiology

The supracondylar region of the distal humerus is the most commonly fractured area around the elbow in children.[7] They most frequently occur in children aged 5 to 7 years. The median age is approximately six years, and the incidence gradually decreases with age.[8] Some studies describe an increased prevalence among males than females, while others describe a higher prevalence in females.[8][9][10] However,  a recent epidemiological study found no significant difference between the genders.[11] Extension-type fractures are much more common than flexion-type fractures and occur as a result of a fall on an outstretched hand.[12] 

Ligamentous laxity in the pediatric age group causes hyper-extension of the elbow and contributes to causing extension-type fractures.[11][13] Also, it has been reported that these fractures are more common on weekends and during summer.[8][11] Flexion-type fractures are more prevalent in older children. These injuries often occur in the non-dominant upper extremity.[14] The incidence of open supracondylar fractures is around 1%.[11]

Pathophysiology

The shape of the distal humerus is roughly triangular in the coronal plane, with the base composed of the lateral epicondyle, capitellum, trochlea, and medial epicondyle. In the axial plane, it is dumbbell shaped owing to the thin plate of the bone in the middle, at the site of the olecranon fossa and coronoid fossa. Most fractures occur when the child falls on an outstretched arm causing hyperextension of the elbow. The olecranon process engages the olecranon fossa producing an extensive force on the distal humerus.[15][16] The bone fractures at the weakest point, and the anterior humeral cortex fails in tension. The posterior cortex and periosteum may be intact. This is the mechanism of injury for extension-type fractures, which account for up to 95% of supracondylar fractures. Flexion-type fractures occur with a fall on a flexed elbow but are much less common.[12] 

The mechanism of injury and the resultant displacement of the fracture also guides the reduction maneuver performed. In posteromedial displacement of the distal fragment, the medial periosteum is intact. Due to this, the reduction is performed in pronation which tensions the medial periosteum and prevents varus malalignment. On the other hand, posterolateral displacement tends to rupture the medial periosteum, and the reduction is therefore performed in supination.[17]

History and Physical

History

There may be a history of a fall on an outstretched arm, causing an extension-type fracture or a fall on a flexed elbow. Although rare, a non-accidental injury must be excluded, accounting for <0.5% of the fractures.[18] The child or carer may give a history of pain, swelling, or deformity of the affected limb. Young children may be reluctant to use the affected limb.

Physical Examination

The affected limb must be thoroughly assessed for the integrity of the soft tissue envelope and the distal neurovascular status. Any other injuries must also be carefully evaluated and documented.

The arm may be swollen, bruised, and deformed. Any bleeding around the elbow may point towards an open fracture and needs to be assessed. The typical deformity for an "off-ended" Gartland III injury is an S-shaped deformity. There may be a "pucker sign" in the antecubital fossa, indicating that the proximal fragment may have button-holed through the brachialis muscle indenting the deep dermis.[19] This sign indicates a high-energy injury and should alert the attending clinician to the risk of the brachial artery or median nerve injury. These structures can get entrapped between the fracture fragments while performing reduction, and the surgeon should be careful.[16] These patients are also at risk of developing compartment syndrome.  

Careful assessment and documentation of the functions of the median, anterior interosseous, ulnar, and radial nerves are mandatory. Best practice includes documentation of the motor and sensory functions of each nerve. Neurovascular injuries have been reported to be as high as 49%. The vascular compromise has been reported in 10-20% of the displaced supracondylar humerus fractures. Similarly, traumatic neurapraxia has been documented in around 11% of fractures, with the anterior interosseous nerve most commonly involved in extension-type fractures and the ulnar nerve most frequently involved in flexion-type injuries.[16][20] 

Brachial artery injury can occur in up to 38% of displaced Gartland III fractures cases.[21] Examining the perfusion of the limb distal to the fracture is essential. Radial and ulnar pulses should be assessed. Note the temperature and color of the ipsilateral hand and measure the capillary refill time. The distinction must be made between the 'pulseless pink, perfused hand' and the 'pulseless, pale, cold hand.' There is good collateral circulation from the elbow in some children, and this accounts for the pulseless but perfused hand. Both cases require urgent management; however, the latter shows evidence of an ischaemic limb, which is a surgical emergency. The presence of neurological deficit and a pulseless hand is predictive of vascular compromise with entrapment of both artery and nerve within the fracture site.[22]

Similarly, adequate neurological evaluation is of paramount importance and should be repeated after every intervention. It is difficult to perform a thorough nerve examination in children; however, certain games like rock, paper, scissors, and ok can help in the motor assessment. The child is asked to make a fist (rock) that evaluates the median nerve, extend the fingers (paper) to assess the radial nerve, and abduct the fingers (scissors) that check the ulnar nerve motor function. Finally, asking them to make an ok sign evaluates the anterior interosseous nerve.[16]

Evaluation

Radiographic Evaluation

Plain radiographs of the elbow are required to make the diagnosis. Anteroposterior and lateral views are needed to confirm the type of fracture (extension vs. flexion-type), degree of displacement, malrotation, and comminution. The elbow is mostly cartilaginous in children. The first epiphyseal center to appear is that of the capitellum at one year of age.[23] Adequate knowledge of the ossification of the distal humerus with the age of appearance and fusion of the various epiphyseal centers, including the proximal radius and ulna, is needed to interpret elbow radiographs in children accurately.

Anteroposterior (AP) Radiographs

A transverse or short oblique fracture line may be seen in the supracondylar region of the distal humerus. These can be difficult to identify and may even be missed in nondisplaced fractures.

Baumann's Angle: This is also known as the humerocapitellar angle in the coronal plane. It is the angle between a line along the longitudinal axis of the humerus and a tangential line across the capitellar physis. Normal is 64-81 degrees from the longitudinal axis line. Increased Baumann's angle is suggestive of cubitus varus deformity.[24][25] Baumann's angle is a reliable measurement guide for coronal plane alignment.[26]

Radiocapitellar Line: A line drawn along the long axis of the radius should intersect the capitellum in all views. This is usually intact in supracondylar fractures unless there is an associated radial head/neck fracture.

Lateral Radiographs

Posterior Fat Pad Sign: In a flexed elbow, the posterior fat pad lies adjacent to the olecranon fossa. An intra-articular fracture from any bone within the elbow causes bleeding from the fracture site. The resultant hematoma/effusion causes the fat pad to lift away from the olecranon fossa. This creates a positive posterior fat pad sign. Several studies have reported on the utility of identifying the presence of a posterior fat pad sign in the identification of occult/nondisplaced intra-articular fractures of the elbow.[27]

Anterior Humeral Line: A longitudinal line drawn along the anterior humeral cortex on the lateral view must bisect the middle third of the capitellum. The line may intersect the anterior one-third of the capitellum in those younger than four years of age.[28] If the line is anterior to the capitellum, it indicates an extension-type fracture pattern.[29]

Angiography

Angiography is not recommended before the reduction in cases of vascular compromise.[30][31] The Pediatric Orthopedic Society of North America (POSNA) does not recommend arteriography before reduction as it delays treatment.

Gartland Classification of Supracondylar Fracture of Humerus

Supracondylar fractures in children have been classified according to Gartland.[32] Fractures are either extension or flexion-type injuries depending on the mechanism of injury and the direction of displacement of the distal fragment. Extension-type fractures are the most common, and the distal fragment is extended compared to the proximal fragment. Extension injuries were classified initially as nondisplaced, moderately displaced, and severely displaced.[32] Gartland's classification was modified by Wilkins and included a subdivision of type II injuries to include the presence or absence of a rotational deformity.[33] Leitch added the IV type of fracture to signify multiplanar instability with a completely torn periosteum. This subtype of the fracture is identified intra-operatively when complete instability of the fracture is present.[34]

The modified Gartland classification is as follows:

• Type I – Nondisplaced or minimally displaced (<2 mm) fractures
• Type IIA – Displaced fractures (>2 mm) with intact posterior hinge
• Type IIB – Displaced fracture with intact posterior hinge and malrotation
• Type III – Completely displaced fractures with disruption of the posterior periosteum
• Type IV - Completely displaced fractures with multidirectional instability[34]

Treatment / Management

All patients should be assessed according to Advanced Trauma Life Support (ATLS) principles. A non-accidental injury should be excluded from all pediatric injuries.

Non-Operative Management

Non-operative management is acceptable for nondisplaced Gartland I and minimally displaced Gartland IIA fractures. Management of Gartland II fractures has been controversial. Gartland II injuries can be managed non-operatively, provided that fracture alignment is satisfactory. Displacement and malunion can occur in the presence of medial column comminution. There is a risk of medial column collapse, leading to a cubitus varus deformity.[35] A recurvatum deformity secondary to malunion can occur if the anterior humeral line does not intersect the capitellum on lateral radiographs. These three factors: medial comminution, posterior displacement, and excess swelling, are contraindications to non-operative management of Gartland II fractures.(B2)

Non-operative management involves immobilization in a collar and cuff or an above-elbow cast with the elbow in 80 to 90 degrees of flexion for three to four weeks. Excess swelling can compromise the vascularity of the forearm and lead to compartment syndrome.[36] Above-elbow casts have been found to provide more effective pain relief than a collar and cuff for Gartland I fractures.[37] One study found that patients with Gartland II displaced fractures had satisfactory functional outcomes when managed in a cast, although some developed cubitus varus.[5] Excessive flexion should be avoided in patients with significant elbow swelling as it can cause compartment syndrome.(B2)

Traction has been used historically for displaced fractures.[38] It may be used in low-resource settings in low- and middle-income countries where there is limited access to equipment for surgical treatment.[39](A1)

Surgical Management

Surgical management is indicated for displaced Gartland II and Gartland III fractures. Urgent surgical management is indicated for patients with neurovascular compromise, compartment syndrome, and open fractures. Surgical management involves closed reduction and percutaneous pinning with K-wires for closed injuries. Open reduction may be required for failed closed reduction, irreducible fractures, and vascular exploration. Orthopedic surgeons managing these intricate fracture patterns with potential concomitant neurovascular injuries should ensure that they can handle the associated injuries and have a vascular surgeon on hand for assistance during the surgery.

Closed Reduction and Percutaneous Pinning

This is indicated for Gartland IIB and III fractures. It is also indicated for Gartland IIA fractures if an acceptable reduction is not obtained in a cast and if there are any contraindications to non-operative treatment (e.g., medial column comminution).

Closed Reduction

Closed reduction involves in-line traction with 'milking' of the soft tissues when a pucker sign is present. Traction pulls the fracture out to length, and 'milking' helps release the soft tissues. Traction should be applied with the elbow in slight flexion. This is followed by the correction of coronal plane displacement: medial/lateral translation and varus/valgus angulation of the distal fragment. Pronation with a valgus-directed force or supination with the addition of a varus force may be required, and these maneuvers also help correct rotational deformity. Pronation helps to correct posteromedial displacement (internal rotation) while tightening the medial periosteum, while supination can help correct posterolateral (external) rotation. The sagittal plane deformity is corrected by hyperflexion of the distal fragment in extension-type fractures. The extension may be required in flexion-type fractures. 

The joystick technique has been described as a method to reduce multi-directionally unstable fractures.[40][34](B2)

Percutaneous Pinning Technique

Lateral pins and crossed pins (medial and lateral) bicortical constructs can be used.

Lateral pin configurations are frequently used, and they reduce the risk of iatrogenic ulnar nerve injury. Two or three lateral pins may be used. Pins must be inserted in a parallel or divergent manner with maximal separation between them. The divergent pattern is reported to be more stable than the parallel configuration.[41] For lateral pins, a capitellar starting point also provides improved construct rigidity compared to a direct lateral entry point.[42] A trans olecranon fossa four-cortex purchase has been described as a technique for lateral pinning to increase construct rigidity.[43] Pin size has been shown to affect the stability of the fixation. 2 mm pins have been found to provide improved biomechanical strength compared to 1.6mm pins.[42](B2)

The use of crossed pins increases the risk of iatrogenic ulnar nerve injury; however, they improve the torsional rigidity of the construct compared to the use of two lateral pins.[20][44] A medial incision should be made of an adequate size that will allow the protection of the ulnar nerve before inserting a medial pin.[45] The insertion of percutaneous medial pins should be avoided due to the risk of nerve injury. A further way to reduce the risk of iatrogenic ulnar nerve injury is to extend the elbow while inserting the medial pin. This maneuver displaces the nerve more posteriorly.(A1)

Open Reduction and Percutaneous Pinning

Open reduction is necessary when reduction cannot be achieved by the closed method. In particular, soft tissue/neurovascular structures can become trapped in the fracture site preventing anatomical reduction. Open reduction may also be necessary for open fractures. Exploration of the brachial artery via an open approach is required in cases where perfusion is not established peri-operatively following reduction and fixation of the fracture. Open exploration of the brachial artery in the setting of an absent radial pulse but perfused hand following reduction and fixation remains controversial.

An anterior approach has been recommended for open reduction.[46][47] Alternative approaches include medial, lateral, and posterior approaches.[48]

Vascular Exploration

Urgent vascular exploration is indicated in patients with a pulseless, pale hand. This must be performed by a surgeon experienced in repairing small vessels or in conjunction with a vascular surgeon. An attempt at closed reduction and fixation of the fracture should be performed in the first instance to see if this restores perfusion to the limb.

The management of patients with a pink, perfused, but pulseless hand following reduction and fixation remains controversial. These patients need close observation following surgery. Non-operative management has been shown to yield acceptable results.[49][50][51] Some patients with a pulseless, perfused hand may go on to develop ischemia, and this patient cohort necessitates urgent vascular exploration.[51](B2)

Differential Diagnosis

A significant proportion of the distal humerus is cartilaginous in children. Although the ossification centers appear predictably around the elbow, there may be diagnostic uncertainty in very young children. Differential diagnoses include

• Radial head fractures
• Distal humeral medial or lateral condyle fractures
• Transphyseal fractures of the distal humerus are another differential diagnosis, and non-accidental injury should be excluded in such cases.
• A pulled elbow is usually indicated from the history, and radiographs are rarely performed in these cases.

Prognosis

The prognosis depends on the remodeling potential of the bone, patient, and injury-specific factors.

Remodeling Potential

Remodeling depends on the following factors:

1. The age of the patient and the amount of growth remaining
2. The distance of a fracture from the physis
3. Plane of deformity
4. Degree of displacement

The distal humerus physis provides 20% of the longitudinal growth of the humerus. As a result, the supracondylar region of the distal humerus does not have a significant ability to remodel in cases of malunion. At the elbow, the sagittal plane deformity has better remodeling potential than the coronal plane deformity. Younger patients have more growth remaining and thus have a higher remodeling potential but only for sagittal plane deformity. Coronal plane deformity does not remodel.

Patient Factors

Children younger than five years old have better remodeling potential than those older than five.[31] After age five, children have limited residual growth of the distal humerus. Obesity is an indicator of injury severity and worse outcomes.[52][53]

Injury-Specific Factors

• Grade of injury
• Adequacy of reduction and fixation
• Neurovascular status of the limb

Appropriate treatment on time improves the long-term prognosis of these injuries. The prognosis may be worse for higher-grade injuries; however, anatomical reduction, stable fixation, and appropriate care of the soft tissues (including neurovascular injuries and compartment syndrome) improve outcomes. Nondisplaced Gartland I fractures usually heal well without complication. Gartland II fractures with medial comminution can develop cubitus varus if this is not recognized, reduced, and stabilized. Gartland III and IV injuries are more likely to be associated with neurovascular injuries; however, timely, appropriate treatment can lead to excellent outcomes.[54]

Complications

1. Neurological Injury

• 11.3% incidence of traumatic neuropraxia.[20]
• Anterior Interosseous Nerve Palsy: This is the most commonly injured nerve in extension-type supracondylar fractures.
• Median Nerve Palsy: This can be traumatic or iatrogenic in origin. 
• Radial Nerve Palsy: This has been found to be more common in fractures with posteromedial displacement.[54]
• Ulnar Nerve Palsy: This is the most commonly injured nerve in flexion-type fractures.

2. Vascular Injury

• Brachial artery injury is more common in completely displaced Gartland III (and IV) injuries.[55]

3. Compartment Syndrome

• This can result in the forearm from impaired perfusion in the setting of brachial artery injury and inadequate collateral circulation.

3. Volkmann Ischaemic Contracture

• This is relatively rare.
• It can occur as a complication of forearm compartment syndrome and delayed treatment of arterial injury with resultant forearm ischemia.[55]

4. Malunion and Deformity

• Malunion can occur with resultant deformity in the sagittal, coronal and axial planes.
• Recurvatum Deformity:
  • The sagittal plane deformity is more likely to remodel in younger children because this is in the plane of movement of the elbow (flexion/extension).
  • This is the most common sagittal plane deformity.
• Cubitus Varus:
  • Coronal and axial plane deformity have minimal remodeling potential.
  • Comminution of the medial column can cause collapse, malunion, and varus deformity.
  • It may also occur because of a residual internal rotation deformity.[56]
• Cubitus Valgus:
  • This can occur due to inadequate reduction and malunion.
  • It can lead to tardy ulnar nerve palsy. 

5. Stiffness

• The range of movement rapidly improves within the first six weeks following surgery.
• The range can improve to 98% of normal within the first 12 months.[57]
• Stiffness is more commonly associated with open reduction procedures.[46]
• Long-term reduction in the range of movement is also associated with malunion.

6. Pin-site Infection

7. Pin-site Migration