A supracondylar humerus fracture is a fracture of the distal humerus just above the elbow joint. The fracture is usually transverse or oblique and above the medial and lateral condyles and epicondyles. This fracture pattern is relatively rare in adults, but is the most common type of elbow fracture in children. In children, many of these fractures are non-displaced and can be treated with casting. Some are angulated or displaced and are best treated with surgery. In children, most of these fractures can be treated effectively with expectation for full recovery. Some of these injuries can be complicated by poor healing or by associated blood vessel or nerve injuries with serious complications.
Signs and symptoms A child will complain of pain and swelling over the elbow immediately post trauma with loss of function of affected upper limb. Late onset of pain (hours after injury) could be due to muscle ischaemia (reduced oxygen supply). This can lead to loss of muscle function. The fracture can disrupt the neurovascular status of the distal arm. Clinical parameters such as temperature of the limb extremities (warm or cold), capillary refilling time, oxygen saturation of the affected limb, presence of distal pulses (radial and ulnar pulses), assessment of peripheral nerves (radial, median, and ulnar nerves), and any wounds which would indicate open fracture. Doppler ultrasonography should be performed to ascertain blood flow of the affected limb if the distal pulses are not palpable. The anterior interosseous nerve is most often injured in postero-lateral displacement of the distal humerus as the proximal fragment is displaced antero-medially. This is evidenced by the weakness of the hand with a weak "OK" sign on physical examination; instead, a pincer grasp is performed. The radial nerve would be injured if the distal humerus is displaced postero-medially as the proximal fragment will be displaced antero-laterally. The ulnar nerve is most commonly injured in the flexion type of injury because it crosses the elbow below the medial epicondyle of the humerus. A puckered, dimple, or an ecchymosis of the skin just anterior to the distal humerus is a sign of difficult reduction because the proximal fragment may have already penetrated the brachialis muscle and the subcutaneous layer of the skin.
Complications
Volkmann's contracture
Swelling and vascular injury following the fracture can lead to the development of compartment syndrome which leads to long-term complication of Volkmann's contracture (fixed flexion of the elbow, pronation of the forearm, flexion at the wrist, and joint extension of the metacarpophalangeal joint ). Therefore, early surgical reduction is indicated to prevent this type of complication.
Malunion The distal humerus physis grows slowly (only contributes 20% of the longitudinal growth of the humerus). Errors in correction are common and may result in osteonecrosis, malunion and nonunion. Malunion can result in cubitus varus deformity.
Mechanism Extension type of supracondylar humerus fractures typically result from a fall on to an outstretched hand, usually leading to a forced hyperextension of the elbow. The olecranon acts as a fulcrum which focuses the stress on distal humerus (supracondylar area), predisposing the distal humerus to fracture. The supracondylar area undergoes remodeling at the age of 6 to 7, making this area thin and prone to fractures. Important arteries and nerves (median nerve, radial nerve, brachial artery, and ulnar nerve) are located at the supracondylar area and can give rise to complications if these structures are injured. Most vulnerable structure to get damaged is median nerve. Meanwhile, the flexion-type of supracondylar humerus fracture is less common. It occurs by falling on the point of the elbow, or falling with the arm twisted behind the back. This causes anterior dislocation of the proximal fragment of the humerus.
Diagnosis A supracondylar humerus fracture is diagnosed by X-ray and the injured limb will be examined to assess the surrounding soft tissue, neurovascular status, and to identify any other injuries to the affected area. Pain, swelling, and deformity near the elbow or arm area is common and a bleed near the fracture may result in an effusion in the elbow joint. With severe displacement, there may be an anterior dimple from the proximal bone end trapped within the biceps muscle. The skin is usually intact. If there is a laceration that communicates with the fracture site, it is an open fracture, which increases infection risk. For fractures with significant displacement, the bone end can be trapped within the biceps muscle with resulting tension producing an indentation to the skin, which is called a "pucker sign".
Vascular system examination The vascular status must be assessed, including the warmth and perfusion of the hand, the time for capillary refill, and the presence of a palpable radial pulse. Limb vascular status is categorized as "normal," "pulseless with a (warm, pink) perfused hand," or "pulseless–pale (nonperfused)" (see "neurovascular complications" below).
Sensory and motor nerve examination The neurologic status must be assessed including the sensory and motor function of the radial, ulnar, and median nerves (see "neurovascular complications" below). Neurologic deficits are found in 10-20% of patients. The most commonly injured nerve is the median nerve (specifically, the anterior interosseous portion of the median nerve). Injuries to the ulnar and radial nerves are less common.
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