Tips and pitfalls of reduction and fixation in displaced supracondylar fractures in children

Modified pin leverage technique in closed reduction

Gartland type III and IV fractures are difficult to obtain and maintain reduction before and during the fixation with pinning. Especially in patients with severe swelling or at risk of developing compartment syndrome, a closed reduction can be challenging. Fractures with a flexion-type pattern are also more likely to need open reduction, especially when the ulnar nerve injury is associated. Ulnar nerve injury may give a clue for a higher energy injury with associated soft-tissue damage, which might make closed reduction more difficult.^[6] Pin leverage technique was reported to show an excellent result,^[2] when satisfactory closed reduction after general anesthesia could not be achieved after three attempts. Similarly, the Kapandji technique could be an alternative to achieve a successful sagittal alignment.^[3] In these techniques, a K-wire or a Steinmann pin is inserted cephalad to the posterior aspect of the distal humerus at the level of the fracture site. The inserted wire or pin is then levered to correct the posterior displacement of the distal fragment. To maintain the reduction, the inserted wire or pin may be driven across the anterior cortex of the humerus. As the pin penetrates the anterior cortex, there is a chance to lose the reduction. Therefore, authors do not advance the pin to purchase the anterior cortex and usually maintain the leverage effect with the flexion of the elbow. In most cases, closed anatomical reduction is commonly obtained with this maneuver.

Nevertheless, the posterior pin leverage may achieve a satisfactory alignment, malreduction still may occur at the coronal plane. It may show a considerable amount of medial/lateral translation or varus/valgus angulation. Direct manipulation may correct it, using a thumb and index finger on the medial/lateral condyles. However, in a swollen elbow or after repeated reduction trials, it is difficult to obtain the acceptable reduction. We also apply the pin leverage technique at the coronal plane, at the lateral aspect or medial aspect of the elbow. K-wire is introduced and advanced at the fracture site. Then, it is levered to correct the translation or angular deformity of the distal fragment. The coronal leverage procedure is usually performed after the sagittal leverage, but sometimes its sequence may be reversed [Figure 1].

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Figure 1:

Type III displaced fracture (a), a 2 mm K-wire was introduced at the posterior aspect of the fracture site (b). After inserting the first K-wire between the fragments, the alignment was achieved at the sagittal plane with the K-wire leverage (c). However, there is a moderate translation at the coronal view (d). Another K-wire was introduced at the medial side (e). Using leverage technique, an anatomical reduction was gained (f). Two lateral K-wires and one medial K-wire were inserted (g). A satisfactory healing was achieved without deformity (h).

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Maintenance of achieved reduction is also important before the internal fixation by K-wires. The surgeon’s thumb usually presses the distal fragment on the olecranon to maintain the reduction if the pin leverage technique is not used. However, the surgeon’s hand may block the image of the elbow or interfere with the procedure of K-wire fixation. Since the leverage wire is distant from the fracture site, it may facilitate the following fixation procedure.

Indications and techniques of open reduction

The soft-tissue interposition is one of the most common reasons for failed closed reductions in supracondylar humeral fractures in children. Several irreducible fractures are suggested to need open reduction for this injury. In cases with pucker sign on the anterior arm, the brachialis muscle may prevent the anatomical reduction. A milking maneuver can be attempted, which gently milks the brachialis muscle distally and anteriorly from the penetrated proximal fragment. However, the interposition of disrupted periosteum and brachialis may make the accurate closed reduction fail.

Failed closed reduction several times may necessitate an open reduction to reduce further soft-tissue injury. In posterolaterally displaced fractures, the median nerve and brachial artery are at risk over the sharp edge of the proximal fragment. Furthermore, these important structures can be entrapped at the fracture site during the closed reduction. Open reduction may be a reasonable option if vascular exploration is needed, in some instances with pink, pulseless fractures.^[7] Type-IV fractures also may need longer operative times and a higher frequency of open reduction, compared with type III fractures. Multidirectional instability is the leading cause of reduction difficulty, since both anterior and posterior periosteal hinges are lost in these fractures.^[8] Therefore, it is essential to identify these injuries preoperatively, which may allow better pre-operative planning of possible switches from closed reduction to open reduction.

Authors prefer to select the anterior approach, when the open reduction is performed in these situations. A small transverse incision is made over the cubital crease, which is sufficient to insert the thumb for reduction (thumb reduction technique).^[9] While traction is applied to the forearm, the pressure over the proximal fragment with the thumb can correct the coronal tilting, translation, and rotation [Figure 2]. Once a satisfactory reduction is achieved and maintained, K-wire fixation follows. The anterior approach has several advantages to free up intervening soft tissues, confirm the intactness of important structures, and even repair them when injured. Furthermore, it can minimize the scar, comparing to the longitudinal incision with medial or lateral approaches.^[10]

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Figure 2:

An 8-year-old boy suffered a completely displaced supracondylar fracture (a). A closed reduction could not achieve an acceptable reduction (b). A transverse incision was made over the anterior elbow crease (c). Thumb pressure was applied over the spike of the proximal fragment and the reduction was gained (d). Cross-pinning was performed (e). A successful healing was achieved (f) with a satisfactory function (g).

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In fractures with an intercondylar component, although it is not common, open reduction may be necessary to obtain the anatomical reduction of the articular fracture. While the anterior approach is a safe and commonly used method, it is difficult to visualize the articular fracture through this window. The posterior approach may be selected, as it can provide better visualization of the intra-articular fracture [Figure 3]. Through the triceps sparing approach, the fracture site is easily reached to perform the reduction. However, there are concerns regarding the potential disruption to the blood supply, resulting in osteonecrosis, with this approach. Furthermore, post-operative stiffness of the elbow may be increased by adding a posterior dissection to an injury with an existing traumatic anterior soft-tissue injury.^[5] Comparably, a recent report of open reduction using a posterior approach showed an excellent functional outcome with a high safety level.^[11]

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Figure 3:

A 9-year-old boy suffered a displaced supracondylar humeral fracture (a). An intra-articular fracture was clearly noted on the CT scan (b). Using the triceps sparing approach, the articular reduction was performed (c). Post-operative radiograph shows a satisfactory reduction by cross-pinning (d). A successful healing (e) was achieved with the functional recovery at 1 year after operation (f).

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When do we need medial pinning?

Fracture personality is known to contribute to reduction loss, with inherently less stable injuries such as Gartland type IV fractures, flexion-type fractures, or fractures with medial comminution.

When the medial column is comminuted, the fixation with lateral-entry pins only may lead to instability. In a biomechanical model simulated with medial column comminution, the torsional and varus bending stiffness were lower with lateral only entry pins, while a significant increase in stiffness was achieved by the addition of one medial pin.^[14] Close attention is needed when the fracture line is located at the medial column. To gain a firm purchase, the lateral pins are not enough and you need in these cases to add a medial pin in addition to one or two lateral pins depending on the degree of the comminution.

How to fix the medial pin safely?

The risk of iatrogenic ulnar nerve injury is inherent by the medial pin, when performing the crossed pinning. There have been several reports of ulnar nerve palsy after crossed pinning, reaching up to 11%.^[15] It may occur through direct wire penetration or laceration of nerve, or through narrowing of the cubital tunnel (the path of the ulnar nerve) [Figure 6]. Therefore, medial wire fixation must be carefully performed after identifying the medial epicondyle and securing the ulnar nerve.

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Figure 6:

Pre-operative anteroposterior radiograph of a 4-year-old boy with displaced supracondylar humeral fracture (a). Cross-pinning achieved an acceptable reduction. However, the medial pin was started at the inaccurate area, which seems distal to the unossified medial epicondyle (arrow) (b). Ulnar claw hand occurred in this patient (c).

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The position of the elbow is important during the medial pinning. In some children with anterior ulnar nerve instability, the ulnar nerve can subluxate anterior to the medial epicondyle during the elbow flexion. To minimize the ulnar nerve injury risk, semi-extension of the elbow joint (about 45° flexion) is recommended. To locate the medial epicondyle as an insertion point, the surgeon may palpate it by firmly pressing with the thumb. However, it is difficult to accurately locate it by superficial palpation, usually secondary to significant swelling in most displaced fractures. Fluoroscopic imaging may help to find it as the ossification of medial epicondyle may appear at 5–7 years. However, in younger patients, it is still difficult to locate the starting point of the medial pin.

When crossed pinning is performed, we prefer to make a small incision to insert the medial pin directly into the medial epicondyle safely.^[16] While comparing with the non-injured elbow, the location of the medial epicondyle is assumed under the fluoroscopic image. Then, a 1 cm incision is made directly over the medial epicondyle. The medial pin is placed and directed proximally and slightly anteriorly to firmly engage the lateral cortex [Figure 7]. This technique will reduce the risk of direct damage to the ulnar nerve, while a little possibility of neuropraxia still remains.

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Figure 7:

A 4-year-old boy sustained a type III supracondylar humeral fracture (a). After closed reduction, two lateral pins were inserted first (b). Then, a small incision was made over the medial epicondyle (c). An additional medial pin was inserted with the elbow at about 45° of flexion (d). Post-operative radiographs show a satisfactory reduction (e). A successful healing was achieved without loss of the reduction (f).

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