Radial Head Subluxation Joint Reduction 

Radial head subluxation, also known as nursemaid's elbow, is the most common upper extremity injury in infants and young children who present to the emergency department (ED). Reduction of the radial head is easily performed in the ED with few complications.

Subluxation of the radial head is a minor injury with a peak incidence in children aged 2-3 years. Radial head subluxation does occur in patients younger than 6 months as well as in older children. Cases in adults have been reported.^[1]

Mechanism

Subluxation of the radial head typically results from a quick pull on a child's arm.^[2] 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. However, half the time caregivers are unsure what caused the injury because the mechanical force can be trivial.^[3]

See the image below.

The annular ligament encircles and supplies stability to the radial head. In children, this ligament is not completely fused and is therefore generally weak. When longitudinal axial traction is placed on an extended pronated arm, the radial head may therefore slip through the weak annular ligament into the radiocapitellar articulation. This results in entrapment of the annular ligament and a 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.^[4] Girls tend to be affected more often than boys.

See the image below.

Physical Examination

Children are often brought for evaluation because they are not using the affected arm. The caregivers may suspect wrist injury as the child often supports the affected hand or wrist. An examination quickly rules out injury to these areas. The child with a radial head subluxation is usually in no distress. The affected arm is held semi flexed, adducted, and pronated.^[5] The lateral elbow may have mild tenderness, and attempts to pronate or supinate the arm 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. Be aware that fractures, especially supracondylar, can be mistaken for simple subluxations.^[6]

See the image below.

Imaging

Radiographs are usually not typically necessary, provided no history of significant trauma and no deformity or local tenderness (apart from at the radial head) are noted.^[7] The positioning required to take proper radiographs often reduces the radial head into place. Radiographs of the subluxed radial head are typically normal; however, they can sometimes demonstrate subtle discontinuity of the radius and capitellum along a straight line.^[8]

Sonography can also be used to demonstrate displacement of the cartilaginous radial head away from the capitellum.^[9]

The diagnosis is mostly supported by a child holding the elbow slightly flexed and pronated and a lack of ecchymosis, significant tenderness, or edema to the affected joint.

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. Further, older children and adults should have radiography performed to evaluate for fracture.

See the image below.

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

• Reduction of a subluxed radial head 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, the risks usually outweigh the benefits in routine reductions.

No equipment is necessary for this joint reduction.

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

Two methods are popular for reducing a subluxed radial head: the supination-flexion technique and the hyperpronation technique.^[10]

A 2009 Cochrane review evaluated the literature available for the comparison of these two techniques. Only three trials with 313 participants were found. Overall, the methadologic quality was low. Limited evidence from these trials supported the pronation method as the most effective and least painful.

With either technique, a palpable or audible click is associated with a high probability of successful reduction. Once the radial head is 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. The child usually begins to use the arm immediately, although some children may take as long as 30 minutes to use the affected arm.^[11] If the first attempt is unsuccessful, further attempts can be made; however, alternative diagnoses should be considered after 4 failed attempts.

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. A 24-hour sling may be placed on the elbow for comfort; however, this is not necessary for most patients. Occasionally, symptoms may last for several days and a sling may be worn for longer. Recurrence of such an injury may be avoided by instructing parents and caregivers not to pull children by their arms.

Supination technique

• This is the classic method of reduction.
• Begin with the arm in pronation and the elbow in 90 º of flexion.
• Place pressure over the patient's radial head. See the images below.For the supination technique, begin with the elbow flexed.Hold the elbow in 90 degrees of flexion with pressure on the radial head.
• Next, firmly supinate the wrist, keeping pressure on the radial head. See the images below.Supinate the wrist with the elbow still in 90 degrees of flexion. While supinating, keep pressure on the radial head.
• Then, flex the elbow completely. A click is often felt over the radial head when the arm has reached full supination. See the images below. Once supinated, fully flex the elbow. With one hand supinating the wrist, the other thumb feels a click as the radial head falls into place on full flexion. To perform the supination technique, begin with supination, then fully flex at the elbow.

  Supination technique, side view.

  Supination technique, front view.
• This technique has an 80-92% success rate.

Hyperpronation technique

• Also known as the forced pronation technique, this newer method is emerging as a potentially superior means of reduction.
• Hold the patient's elbow in 90 º of flexion. (Note that some practitioners prefer to have the elbow extended for this technique). Next, firmly hyperpronate the wrist. See the images below.

  Hyperpronation technique, side view.

  Hyperpronation technique, front view.
• In a few studies, the hyperpronation technique resulted in fewer failures than supination.^[12] Pronation has also been suggested to be less painful; therefore, some advocated hyperpronation as the first-line reduction maneuver.^{[13, 14, 15]}

A combination of both techniques (hyperpronation followed by supination) to ensure reduction has been suggested. Further, using both methods you can simultaneously assess the return of proper range of motion.

• Some practitioners advocate teaching the parents or caregivers how to reduce a subluxed radial head in case of recurrences. Cases in which the subluxation was diagnosed and treated over the telephone have been reported.^[16]
• As with any injury, document the neurologic and vascular status before and after manipulation.
• Although a nursemaid's elbow may occur in older children and rarely in adults, consider an associated ulnar fracture known as the Monteggia fracture-dislocation in this age group. This injury is diagnosed by plain radiographs and requires surgical reduction.

• If the above reduction techniques do not result in normal function within 30 minutes, consider an alternative diagnosis.
• About 2-4 reduction attempts may be made 15 minutes apart. 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.^[17]
• If one technique fails initially, the other may be attempted.
• If 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.
• As many as 27% of patients experience recurrence. Specialists may recommend temporary immobilization or bracing.
• Ultrasonography can be used to evaluate subluxations and reduction success. Further, it can be used to conform healing of the annular ligament after treatment in complex cases.^[18]
• Fractures are a rare complication of reduction.
• Rarely, operative repair is required for subluxations.

Upon presentation of any injured child, the physician must consider possible abuse, especially in cases of recurrent subluxation.