Supracondylar humerus fractures are most often due to a fall from a height. It is usually the nondominant, outstretched arm (and therefore, typically the left arm since only 8% to 15% of the world’s population is lefthand dominant) that hits the ground first and hardest.1^,2 Fortunately, most supracondylar fractures are isolated injuries. Children with ligamentous laxity and hyperextension at the elbow have a higher predilection for a supracondylar rather than a forearm fracture with a fall.3 The peak age is 5 to 6 years, which is also a time when children have more ligamentous laxity and resultant elbow hyperextension.4^,5 The anatomic mechanism of injury is that the olecranon abuts the olecranon fossa, and the anterior capsule simultaneously provides anterior tension. This combination of traumatic forces propagates an extension fracture through the thin supracondylar bone of the distal humerus. Only about 1% of these injuries are open fractures, but near open fractures with entrapment of the brachialis muscle, periosteum, neurovascular structures, and skin and subcutaneous tissue in the fracture site are more common. On average, there is about an 8% risk of nerve injury. However, the more severely displaced the fracture, the higher the risk of neurovascular compromise. Displaced fractures have, on average, a 20% to 40% risk of neurovascular injury. Supracondylar fractures are the most common and riskiest fractures about the elbow in a child.

Floating elbow injuries with simultaneous supracondylar humerus and forearm fractures are an even higher energy trauma and, therefore, are at more risk for compartment syndrome. Metaphyseal-diaphyseal fractures are more often due to a direct blow and are harder to align by percutaneous pinning techniques. Nonaccidental trauma, including a difficult delivery at birth, can result in a distal humeral physeal separation. A high index of suspicion is necessary for acute diagnosis and treatment of transphyseal injuries, especially when the secondary centers of ossification have yet to appear. T-condylar humerus fractures are usually due to high-velocity sports injuries in the adolescent and require adult-type treatment for best results.

All displaced supracondylar, transphyseal, metaphysealdiaphyseal, and T-condylar fractures require reduction and stabilization (Figure 27-9). Almost all, if not all, of these injuries are treated with operative fixation, either percutaneous or open. The major differences in treatment have to do not with whether to perform surgery but rather when and how. Open fractures, pending compartment syndromes, and avascular limbs are emergencies. There is now sufficient evidence to know that overnight delay in surgery is acceptable as long as there is not vascular compromise, worsening peripheral neurologic status, and the wait is not too long (see Coach’s Corner).23^, 24^, 25^, 26^, 27^, 28^, 29 and 30

The nondisplaced, stable fracture will heal regardless of what immobilization is chosen. Sling, collar and cuff, posterior splints, and casts have all been used successfully. There is some limited evidence that the children are more comfortable in a posterior above-elbow splint or bivalved cast. Immobilization also protects against repeat injury that could lead to fracture displacement.32 It is important not to mistake the fracture with minimal medial comminution for a nondisplaced, stable fracture, as this “tweener type 1.5” fracture is the one that will drift and heal in varus and extension with limited immobilization.33

Type II and even some type III fractures have been treated successfully with closed reduction and cast, sling, splint, or collar and cuff immobilization.34^, 35^, 36^, 37^, 38^, 39^, 40^, 41 and 42 If closed reduction and immobilization are chosen, careful follow-up clinically and radiographically is necessary to prevent complications. Supracondylar, and especially transphyseal, fractures heal quickly, and there is limited time for repeat reduction. Successful second reduction or conversion to a CRPP or ORIF technique for an impending malunion has been reported on average at 6 days with a range from 2 to 19 days.43 For us, all displaced (type II and III) fractures are treated with operative reduction and pin stabilization.44^,45 The CRPP approach lessens the risk of malunion in an extended (<90 degrees) cast and neurovascular compromise in a flexed (>120 degrees) cast.46

The reduction technique is the same for closed reduction and immobilization or CRPP. With the patient under anesthesia, gentle longitudinal traction is applied with the arm in approximately 30 degrees of flexion until the soft tissues and bony fragments disengage. The closed reduction can be performed with one of the surgeon’s hands controlling the distal fragment and the other hand stabilizing the upper arm and proximal fragment or by the surgeon distracting with both hands on the forearm or distal fragment and the assistant holding the upper arm. If there is brachialis muscle entrapment by the metaphyseal
proximal fragment, the milking maneuver is performed from proximal to distal (Figure 27-10).47^,48 Once the fracture fragments are mobile, valgus-varus malalignment is corrected in 30 to 40 degrees of elbow flexion to prevent neurovascular entrapment. The surgeon’s thumb controls one side of the humerus, and the other digits control the other side of the humerus during correction of malalignment (Figure 27-11). Finally, the surgeon’s hands are rotated with the thumb over the olecranon apophysis and displaced distal fragment, and the rest of the hand is anterior on the humeral diaphysis to stabilize the proximal fragment (Figure 27-12). An alternative method is to have both of the surgeon’s thumbs on the olecranon and the fingers of both hands on the proximal humerus. The extended fragment is then flexed >120 degrees by holding the proximal fragment stable and bringing the olecranon
and distal fragment into anatomic position. To correct malrotation and provide periosteal tension band stability, forearm rotation is performed during flexion reduction. For most fractures, this is in pronation. For some posterolateral fractures, this is in supination. (In the more common posteromedially displaced fractures, the lateral periosteum is torn; therefore, additional stability is conferred by pronating the forearm, as this tensions the lateral muscles and soft tissues. Conversely, in posterolateral injuries, the medial periosteum is disrupted, and forearm supination will add stability by tightening the flexor-pronator mass and medial soft tissues.) Proper rotational positioning can be assessed under fluoroscopy. To maintain a stable closed reduction, >120 degrees of flexion is required, which is risky for neurovascular compromise. This is why now all these fractures are pinned.49^, 50 and 51 If there is a persistent bony block to flexion during reduction, then the fragments have not been disengaged. If there is a “mushy” or “rubbery” feeling, then there is soft tissue interposed, the most worrisome of which could involve the NVB. Confirmation of anatomic reduction is obtained with AP, lateral, and oblique radiographs of the distal humerus. Irreducible fractures, especially those with neurovascular entrapment, require open reduction. The vascularity to the hand is always assessed after closed reduction by feeling for a pulse and checking the color, capillary refill, and fullness of the digital pulps (Figure 27-13).

The techniques of CRPP vary in terms of body position (supine [preferred at most centers including ours] or
prone)52^, 53 and 54; divergent lateral entry or medial and lateral entry crossed pins; number of pins placed (two or three); use of arm support (fluoroscopy image intensifier or fluoroscopic arm board); and whether you move the arm through the shoulder (not the fracture site) or rotate the fluoroscopy to obtain a lateral image of the reduction and pinning.

Our method is to perform closed reduction under general anesthesia in the operating room in the supine position after sterile prepping and draping. The fluoroscopy image intensifier is used as the arm support. The forearm, elbow joint in full flexion, and humerus are rotated as a single, stable unit through the shoulder to obtain AP, oblique (optimal views of medial and lateral columns), and lateral fluoroscopic images. Young children have sufficient tension-free shoulder external rotation to 90 degrees or greater to do this safely without loss of fracture reduction. The lateral entry pins are placed obliquely from distal to proximal with one up the lateral column and one across the olecranon fossa (Figure 27-14). The proximal medial humeral cortex needs to be penetrated with each pin for sufficient stability. The medial cortical penetration can be felt by the operating surgeon, heard by the change in pitch of the drill by others in the room, and confirmed by fluoroscopy. The preferred pin size is 5/64″ for children >20 kg and 0.0625″ for children <20 kg. The fracture stability is tested manually with flexion-extension and rotation movements; brief continuous fluoroscopy can be used for confirmation.55^, 56 and 57 If the fracture is at all unstable or acceptable but not perfect, a third lateral pin or a medial pin is placed (Figure 27-15).58^, 59^, 60 and 61 Biomechanical analysis indicates crossed pins are more stable; clinical evidence
confirms this trend, but three divergent lateral pins suffice in most cases.62^, 63 and 64 Divergent lateral pins are more stable than parallel lateral pins.65

Although medial pins raise the concern of iatrogenic ulnar nerve injury,66^, 67 and 68 they can be placed safely through a small incision.69 Since ulnar nerve instability is common in this age group,70 the medial pin is placed with <90 degrees of elbow flexion to avoid impingement or injury. The ulnar nerve is identified and protected with a retractor. The pin entry site is more anterior on the medial epicondyle to avoid the posterior position of the ulnar nerve. The pin trajectory is more horizontal to prevent nerve compression.71 Oscillating technique with the drill is used to prevent soft tissue engagement by the wire that could compress or kink the nerve. Again, confirmation of desired pin placement, fracture alignment, and stability are obtained on the intraoperative fluoroscopic images. The final act when using a medial pin is to check the ulnar nerve, being certain there is no compression, impingement, or kinking of the nerve at rest and with full elbow movement. The wire is bent anterior to lessen the risk of problems.

Of note, flexion type and multiple-plane, unstable extension fractures can be much harder. To achieve anatomic alignment with CRPP, the fracture fragments often need to be held reduced in space by the surgeon or assistant while the other one gets the first stabilizing lateral entry pin in place. The position is usually with maximum distraction and flexion of 60 to 80 degrees while correcting the varus-valgus malalignment. In flexion-type injuries, axial loading of the forearm may assist in reduction, as the proximal radius and ulna push against the flexed distal humerus. The reduction and pinning are based on the AP plain images only. Be careful not to overirradiate your hands. Once the first pin is across, then the other pin(s) can be placed in the typical fashion noted above. On occasion, two pins are placed appropriately in the distal fragment and used to joystick the fracture reduction before being passed into the proximal fragment.72 There is a higher incidence of open reduction with flexion injuries. If the ulnar nerve is out preoperatively, decompression is appropriate at the time of open reduction.73

Transphyseal fractures are often markedly unstable. The children are often very young, and the diagnosis can be delayed due to the nonaccidental trauma etiology. If you are fortunate enough to make the diagnosis early, CRPP is indicated. In the very young, an intraoperative elbow arthrogram is often necessary to confirm the diagnosis, location of the epiphysis, and articular surface and to guide anatomic reduction (Figure 27-16). Since the periosteum can be disrupted all the way to the shoulder by the force of injury, pin stabilization with two to three lateral pins or crossed pins is mandatory. Placement of these pins is not easy in the small child with a maximally swollen elbow and limited views of the osseous and cartilaginous fracture fragments arthrofluoroscopically.

The metaphyseal-diaphyseal fractures have more obliquity to them and a tendency toward malangulation even after pinning.22 Some of these fractures need an intramedullary pin or more proximal pin placement to maintain varus-valgus alignment. The radial nerve becomes more at risk the more proximal you place your lateral pins.

If there is a floating elbow injury, pin both the supracondylar and forearm fractures to avoid the risk of a
compartment syndrome in a cast. The most common floating elbow combination in a child is distal radius and supracondylar fractures. The distal radius is pinned first (see Chapter 34

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