Reduction of Radial Head Subluxation

Radial head subluxation, also known as pulled elbow or nursemaid’s elbow, is one of the most common upper-extremity injuries in infants and young children who present to the emergency department (ED). Reduction of the subluxated radial head is easily performed in the ED, and complications are rare.

Subluxation of the radial head is a minor soft-tissue injury that has a peak incidence in children aged 2-3 years and generally affects children younger than 6 years.[1] Although occurrence outside this population is uncommon, radial head subluxation does occur in patients younger than 6 months, as well as in older children and even adults.[2]

Subluxation of the radial head typically results from a quick pull on a child’s arm (see the image below).[3] Often, this occurs when a child is holding hands with a caregiver who lifts the child by the arm or tries to prevent a fall. Parents therefore may provide a history of a fall preceding the injury. Frequently, however, caregivers are unsure what caused the injury because the causative mechanical force can be minor or even trivial.[4] Rarely, underlying musculoskeletal abnormalities may precipitate a subluxation.[5]

Joint reduction is indicated for diagnosed radial head subluxation. The diagnosis is mostly supported by the finding of a child holding the elbow slightly flexed and pronated, with a lack of ecchymosis, significant tenderness, or edema in the affected joint. Whenever an injured child presents for care, the physician must consider possible abuse, though this specific injury occurs via a very low force mechanism that is not in itself suggestive of abusive behavior.

A diagnosis other than radial head subluxation should be sought if the history includes trauma to the arm, swelling, significant tenderness, deformity, or ecchymosis to the patient’s elbow (see the image below).

Furthermore, older children and adults should undergo radiography to evaluate for fracture. In particular, an associated ulnar fracture known as the Monteggia fracture-dislocation should be considered in these older individuals. This injury is diagnosed by means of plain radiography and must be treated with surgical reduction.

Patients with known congenital lesions or neurologic deficits require a more detailed evaluation.

Anatomy

In maturity, the annular ligament encircles and supplies stability to the radial head (see the image below). In children, this ligament is not completely fused and thus is generally weak. Accordingly, when longitudinal axial traction is placed on a child’s extended pronated arm, the radial head may slip or tear through the weak annular ligament into the radiocapitellar articulation.[6] This results in entrapment of the annular ligament and subluxation (or partial dislocation) of the radial head.

The left arm is more commonly involved, presumably because most caretakers are right-handed. Cases in which both elbows are subluxed at the same time have been reported.[7] Girls tend to be affected more often than boys are. Patients with prior radial head fractures are at risk for progressive radial head subluxation.[8]

As many as 27% of patients with radial head subluxation who are treated with joint reduction experience recurrence. Specialists may recommend temporary immobilization or bracing. Fractures are a rare complication of reduction. Infrequently, operative repair is required for subluxations. In rare cases, subluxation may lead to osteochondritis dissecans of the radial head.[9]

Recurrence of radial head subluxation may be avoided by instructing parents and caregivers not to pull children by their arms. Some practitioners advocate teaching parents or caregivers how to reduce a subluxated radial head so that they can provide appropriate management in the event of a recurrence. Cases in which the subluxation was diagnosed and treated over the telephone have been reported.[10]

Children are often brought for evaluation because they are not using the affected arm. Because these children often support the affected hand or wrist, caregivers may suspect wrist injury. An examination quickly rules out injury to these areas.

A child with a radial head subluxation usually is not in any distress. The affected arm is held semiflexed, adducted, and pronated (see the image below).[11] The lateral elbow may be mildly tender, and attempts to pronate or supinate the arm may cause pain. All other range of motion is often permitted.

No significant edema or effusion should be found on clinical examination. If focal swelling or other areas of tenderness are present, radiographs should be performed. The examiner should keep in mind that fractures, especially supracondylar ones, can be mistaken for simple subluxations.[12]

As a rule, if there is no history of significant trauma and if no deformity or local tenderness (other than that at the radial head) is noted, radiographs are not necessary.[13] When radiography is performed, the radiographs of the subluxated radial head are typically normal; however, they can sometimes demonstrate subtle discontinuity of the radius and capitellum along a straight line.[14] The positioning required to take proper radiographs often reduces the radial head into place.

Ultrasonography can also be used to demonstrate displacement of the cartilaginous radial head away from the capitellum.[15] Arthrography is useful for detecting occult subluxations in children with other operative injuries of the elbow.[16]

As with any injury, neurologic and vascular status should be documented both before and after manipulation.

Anesthesia

Reduction of a radial head subluxation is generally a quick and easy procedure that requires no anesthesia. Acetaminophen or ibuprofen may be given to a child for pain relief. In special situations, procedural sedation may be used; however, in routine reductions, the risks of sedation usually outweigh the benefits.

Positioning

During radial head reduction, the patient stands or sits on the caregiver’s lap for comfort and support. The physician faces the patient and sits or kneels to be at the same eye level.

Radial head subluxation is managed by means of manual reduction. Either of the following two reduction methods may be used:

• Supination-flexion technique
• Hyperpronation/forced pronation technique

If one technique fails initially, the other may be attempted.

A 2012 Cochrane review evaluated the literature available for comparison of the two techniques.[17] The reviewers found only four trials, with a total of 379 participants; overall, the methodologic quality was low. Limited evidence from these trials suggested that the hyperpronation method was more effective and less painful.

The supination-flexion technique (see the image below) is the classic method of reducing a subluxated radial head. It has a success rate of 80-92%.

The procedure begins with the patient’s arm in pronation and elbow in 90° of flexion, with pressure applied over the patient’s radial head (see the images below).

Next, the wrist is firmly supinated, with pressure maintained on the radial head (see the images below).

The patient’s elbow is then completely flexed (see the images and videos below). A click is often felt over the radial head (or heard) when the arm has reached full flexion. A palpable or audible click is associated with a high probability of successful reduction.

Although the hyperpronation technique (also known as the forced pronation technique) was first described in 1886 by Hutchinson, it has only comparatively recently begun to emerge as a potentially superior means of reduction.

First, the patient’s elbow is held in 90° of flexion. (Some practitioners prefer to have the elbow extended for this technique.) Next, the wrist is firmly hyperpronated (see the image and videos below). As with the supination-flexion technique, a palpable or audible click is associated with a high probability of successful reduction.

In a few studies, the hyperpronation technique resulted in fewer failures than supination.[1] It has been suggested that hyperpronation may also be less painful; accordingly, some have advocated hyperpronation as the first-line reduction maneuver.[17, 18, 19]

Using a combination of the two techniques (hyperpronation followed by supination) to ensure reduction has been proposed. Such a combined approach would allow simultaneous assessment the return of proper range of motion.

Once the radial head has been reduced, the child’s pain and apprehension often immediately resolve. The practitioner should leave the patient’s bedside immediately after the procedure and return to reevaluate in 10 minutes. Most children begin to use the affected arm immediately, though some may take as long as 30 minutes to start doing so (see the image below).[20] The time from reduction to normal arm use is increased in younger patients and those whose subluxations have been present for more than 12 hours.

If the first attempt at reduction proves unsuccessful, further attempts can be made (~15 minutes apart); however, alternative diagnoses should be considered after multiple failed attempts. If the child does not begin using the arm normally after such attempts, a radiograph should be obtained to look for fractures or other complications.[21] When multiple reduction attempts prove unsuccessful, a sling or posterior long arm splint may be applied for comfort, and the child can be referred to an orthopedist.

Although a 24-hour sling may be placed on the elbow for comfort, this measure is not necessary for most patients. Occasionally, symptoms may last for several days, and a sling may be worn for longer.

Ultrasonography can be used to evaluate subluxations and determine the success of reduction. Furthermore, it can be used to confirm the healing of the annular ligament after treatment in complex cases.[22]

The goal of pharmacotherapy is to treat the pain associated with the procedure.

Class Summary

Pain control is essential to quality patient care. It ensures patient comfort, promotes pulmonary toilet, and aids physical therapy regimens. Many analgesics have sedating properties that benefit patients who experience pain.

Acetaminophen (Tylenol, FeverAll, Aspirin Free Anacin)

Acetaminophen is the drug of choice (DOC) for pain in patients with documented hypersensitivity to aspirin or NSAIDs, who have upper GI disease, or who are taking oral anticoagulants.

Class Summary

NSAIDs have analgesic, anti-inflammatory, and antipyretic activities. Their mechanism of action is not known, but they may inhibit cyclooxygenase (COX) activity and prostaglandin synthesis. Other mechanisms may exist as well, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell membrane functions.

Ibuprofen (Motrin, Advil)

Ibuprofen is the DOC for patients with mild to moderate pain. It inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.