Supracondylar Fractures of the Humerus in Children

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Chapter 8 Supracondylar Fractures of the Humerus in Children

Alastair W. Murray, James Robb

Introduction

Supracondylar fractures of the distal humerus are a commonly encountered injury in children. The association with neurovascular compromise and the potential problems of accurately reducing a displaced fracture can make treatment difficult particularly for the unwary surgeon. While outcome can still be poor following this injury, changes in the management of these fractures over the last three decades have significantly reduced the risks and morbidity with which they were previously associated. Non-operative treatment of displaced fractures has been replaced by fracture stabilization with wires and it is this that has resulted in improved outcomes.^1,²

Background/aetiology

Ambulant children of any age are vulnerable to supracondylar humeral fractures but the peak incidence occurs between the ages of 5 and 7 years, with the left arm most commonly affected. Boys sustain the majority of fractures but the gender gap is narrowing, reflecting a change in childhood activity.³

The fracture is usually caused by a fall from height. Children under 3 years of age usually sustain the injury by falling from furniture, while older children sustain their fractures when falling from playground apparatus. It is very rare for this injury to be caused by physical abuse.

Coincidental injury to any of the three major peripheral nerves around the elbow can occur and has a reported incidence of up to 15%. It may be detected immediately following the injury or may not be noted until after the subsequent treatment.⁴ The anterior interosseous nerve appears to be the most susceptible to damage from the original injury and radial nerve dysfunction is slightly less common.⁵ The ulnar nerve is the most vulnerable to iatrogenic injury from medial wire fixation.

Associated ipsilateral fractures need to be excluded but are rare (5%).⁶ The vast majority of supracondylar fractures are closed (99%), with major vascular injury occurring in 3% or fewer children.⁷

Pathogenesis of injury

The ability to hyperextend the elbow joint is common in children owing to the normal, physiological ligament laxity of childhood.

Supracondylar humeral fractures most frequently result from forced hyperextension of the elbow (95%). A fall on the outstretched arm results in hyperextension of the elbow, with the olecranon acting as a fulcrum in its fossa. Tension in the anterior tissues then exaggerates the effect with further force resulting in fracture of the medial and lateral columns of the relatively thin supracondylar region of the humerus. Continued extension force results in the proximal humeral segment being forced distally and anteriorly, which is when buttonholing of the bicipital aponeurosis and damage to the anterior neurovascular structures can occur. This mechanism results in disruption of the anterior periosteum but the posterior periosteum usually remains intact. This aids treatment by facilitating reduction and adding stability to the correctly reduced fracture. Integrity of the medial or lateral periosteum will be suggested by the lateral or, more commonly, medially displaced fracture. The direction of displacement in the coronal plane is indicative of the soft tissue structures at risk. With a medially displaced fracture the radial nerve is at risk, while lateral displacement is more likely to entrap the median nerve and brachial artery.

The fracture line is usually transverse in the sagittal and coronal planes but a more oblique fracture line in either plane should alert the surgeon to the potential for greater difficulty in obtaining and maintaining a sound reduction.⁸

The far less common (5%) flexion type supracondylar fracture results from a fall onto the point of the olecranon with the elbow flexed. Completely displaced flexion fractures can be very challenging to reduce and are associated with a risk of ulnar nerve damage (Fig. 8.1).

Figure 8.1 Lateral radiograph of flexion type supracondylar fracture.

It is of interest to note that children who sustain a supracondylar fracture do not have a greater range of elbow hyperextension than those who sustain a fracture of the distal radius.⁹

Gartland ¹⁰ grouped extension type fractures into undisplaced, moderately and severely displaced in his original paper in 1959. This was subsequently modified by Wilkins⁴ into types I to III as follows:

• Type I – undisplaced (Fig. 8.2)

• Type II – displaced with posterior cortical hinge intact (Fig. 8.3)

• Type III – displaced with no cortical contact (Fig. 8.4)

Figure 8.2 Lateral radiograph of type I extension supracondylar fracture.

Figure 8.3 Lateral radiograph of type II extension supracondylar fracture with anterior humeral line superimposed.

Figure 8.4 Lateral radiograph of type III extension supracondylar fracture.

Type I fractures can also include minimally displaced fractures with some separation of the anterior cortex in the sagittal plane, but the anterior humeral line still passes through the capitellum. Any rotational deformity qualifies the fracture as a type III. Intra-articular extension of the fracture line can also be seen in some type III fractures.

Leitch et al ¹¹ proposed adding a type IV to describe the rarer but highly challenging severely displaced fracture with no intact periosteal hinge. The resulting multidirectional instability only becomes apparent under anaesthesia. From a practical point of view the introduction of this additional category does not influence the management, which is the same as for a type III injury.

Presentation, investigation and treatment options

Any child with pain and swelling around the elbow following a fall may have a supracondylar fracture. Where such an injury is suspected the child must be provided with adequate analgesia, which will often include parenteral opiates. This will allow the examiner to perform a more detailed examination and reassure the child and the parents. The injured limb must be examined both locally with respect to the elbow and generally for neurovascular status, soft tissue integrity and for evidence of skeletal tenderness that may indicate a coincidental fracture. Puckering of the skin or marked ecchymosis in the antecubital fossa is indicative of tethering of the underlying dermis by the fracture and threatens the soft tissues. After inspection of the soft tissues a plaster backslab should be applied to provide stability, reduce pain from fracture movement and facilitate the attainment of good-quality radiographs. The limb should be splinted in the position of maximal comfort, which is usually the position in which the child supports the limb. No attempt should be made to flex the elbow when applying the backslab as this will cause pain and may jeopardize the neurovascular structures. A more meaningful assessment of neurological function can often be obtained after application of the backslab. Movements of the thumb afford the opportunity to check the motor function of the median, ulnar and radial nerves. The anterior interosseous branch of the median nerve should be specifically assessed by asking the child to form the ‘OK’ sign. A good neurological assessment may not be possible in very young or distressed children but observation of gross movements of the digits should still be recorded.

The presence of a radial pulse is reassuring but its absence is not in itself an emergency if the hand is warm and has good capillary refill. A cool, mottled hand, however, indicates vascular compromise and mandates emergency reduction of the fracture in theatre. The presence of a Doppler signal in the radial artery should not be considered a reassurance in this situation. Preoperative angiography is not indicated as the site of any vascular compromise is highly likely to be at the fracture and this investigation will result in unnecessary delay.

If there is no actual or imminent soft tissue or neurovascular compromise then a moderate delay before reduction of a displaced supracondylar fracture is permissible (see later section on timing of reduction of type III fractures). In this situation the splinted limb should be rested on a pillow to provide some elevation, with regular reassessment until reduction can be performed. Increasing pain despite normal amounts of analgesia should alert the surgeon to the possibility of compartment syndrome or deteriorating limb perfusion.

Displaced supracondylar fractures can be seen readily on standard AP and lateral radiographs. Undisplaced fractures may be harder to see but the presence of a posterior fat pad sign is suggestive of the diagnosis. Any suspicion of coincident fractures indicates the need for radiographs of the whole forearm or upper limb (Fig. 8.5).

Figure 8.5 Radiograph showing ipsilateral supracondylar and distal radial fractures.

Care should be taken when interpreting films where the elbow is not centred or correctly oriented. Interpretation of coronal angulation or displacement of the distal humerus requires an adequately positioned AP film of the distal humerus and not of the flexed elbow. CT scanning is rarely indicated but can be of some use in planning treatment of complex intra-articular fractures, provided the clinical situation permits the time for the investigation.

Surgical techniques and rehabilitation

Type I fractures

These injuries are usually managed with a posterior splint or a collar and cuff sling. The elbow should be flexed to at least 90°, provided that swelling permits. Ballal et al ¹² found their patients were more comfortable in a plaster backslab and suggested that this was preferable to a simple sling. Whichever method is chosen, a follow-up radiograph at 5–7 days to ensure displacement has not occurred is recommended.

Type II fractures

Some controversy exists as to the indications for operative reduction and stabilization in this group. Extension of the fracture to a point where there is no intersection of the capitellum by the anterior humeral line would be considered by most to be an indication for reduction. Lesser degrees of extension may be remodelled by younger children but children beyond the age of 3–5 years have limited remodelling potential in the distal humerus. Some studies ¹³ have suggested that splintage in flexion of more than 90° is all that is required in most cases of reduced type II fractures. Maintenance of the elbow in a splint at more than 90° is difficult, however, because of swelling, and loss of reduction can occur in a significant proportion. The risk of neurovascular complications also increases with flexion of the injured elbow beyond 90°. For these reasons many now advocate stabilization with K-wires after reduction of type II fractures.¹⁴

Type III fractures

The good results obtained with closed reduction and percutaneous pinning has meant that the majority of surgeons prefer this option for type III fractures. Olecranon pin or straight-arm traction has compared poorly with percutaneous pinning because of the higher rates of malunion.¹⁵ Others have reported reasonable results from traction, but the prolonged inpatient stay makes this option less desirable.¹⁶

Timing of reduction of type III fractures

Loizou et al ¹⁷ identified five recent non-randomized retrospective studies¹⁸^–²² that considered the effects of delay on the treatment of type III fractures. From these papers Loizou et al analysed 396 patients (243 in the early treatment group and 153 in the delayed treatment group). The distinction between early and delayed treatment was 8 h in the reports of Iyengar et al,¹⁸ Carmichael et al¹⁹ and Walmsley et al²⁰, and 12 h in those of Gupta et al²¹ and Sibinski et al.²² Loizou et al found that the failure of closed reduction and conversion to open reduction was significantly higher in the delayed-treatment groups. They concluded that type III fractures should be treated within 12 h of injury. The Walmsley et al study originated from our department and the 8 h delay was defined from the patients’ arrival in the accident and emergency department. This time period was used because of the difficulty in identifying the timing of the injury. All fractures were either treated or supervised by a consultant, which was apparently not the case in the other papers considered by Loizou et al.

Authors’ preference for timing of reduction for type II and III fractures

Type II extension fractures are evaluated for medial comminution and reduced and pinned at the next convenient opportunity within 24 h of presentation. Type III fractures are reduced and pinned with an inpatient delay of less than 12 h. Open fractures, or a pale, pulseless hand are indications for urgent reduction and stabilization. We also reduce at the earliest opportunity fractures where there is severe swelling of the elbow or tenting of the skin from a bone end.

Closed reduction and fixation of displaced extension supracondylar fractures

The operating table should be positioned in such a way that the surgeon has plenty of room and the image intensifier can gain easy access (Fig. 8.6). Children older than 3 or 4 years usually have sufficiently long arms to allow positioning in a conventional way with their arm extended on an arm table. Sufficient room must be available around the arm table for the image intensifier to swing through 90° to provide AP and lateral views without moving the injured arm. Rotation of the arm to obtain a lateral view can result in displacement of a reduced fracture and should be avoided.