Nursemaid's elbow

Nursemaid's elbow or Babysitter's elbow is a dislocation of the elbow joint caused by a sudden pull on the extended pronated arm, such as by an adult tugging on an uncooperative child. The technical term for the injury is radial head subluxation.

Overview

In radial head subluxation, there is little complaint of pain, and the patient generally reports pain in the distal forearm. Radial head subluxation is a common pediatric presentation generally occurring between the ages of 1 and 3 years. The mean age of presentation is just older than 2 years. The pathologic lesion is generally a tear in the attachment of the annular ligament to the periosteum of the radial neck, with the detached portion becoming trapped between the head of the radius and the capitellum. The older child will usually point to the dorsal aspect of the distal forearm when asked where it hurts. This may mislead one to suspect a buckle fracture of the distal radius.

This injury has also been reported in infants younger than six months and in older children up to the preteen years. There is a slight predilection for this injury to occur in girls and in the left arm. The classic mechanism of injury is longitudinal traction on the arm with the wrist in pronation, as occurs when the child is lifted up by the wrist. There is no support for the common assumption that a relatively small head of the radius as compared to the neck of the radius predisposes the young to this injury.

Anatomy

The forearm contains two bones, the radius and the ulna. These bones are attached to each other both at the proximal, or elbow, end and also at the distal, or wrist end. Among other movements, the forearm is capable of pronation and supination, which is to say rotation about the long axis of the forearm. In this movement the ulna, which is connected to the humerus by a simple hinge-joint, remains stationary, while the radius rotates, carrying the wrist and hand with it. To allow this rotation, the proximal (elbow) end of the radius is held in proximity to the ulna by a ligament known as the annular ligament. This is a circular ligamentous structure within which the radius is free, with constraints existing elsewhere in the forearm, to rotate.The proximal end of the radius in young children is conical, with the wider end of the cone nearest the elbow. With the passage of time the shape of this bone changes, becoming more cylindrical but with the proximal end being widened.

If the forearm of a young child is pulled, by a parent or caregiver, it is possible for this traction to pull the radius into the annular ligament with enough force to cause it to be jammed therein. This causes significant pain, partial limitation of flexion/extension of the elbow and total loss of pronation/supination in the affected arm. The situation cannot arise in adults, or in older children, because the changing shape of the radius associated with growth prevents it.

Signs and symptoms

Radial head subluxation:

• The child stops using the arm, which is held flexed and pronated.
• Minimal swelling.
• All movements are permitted except supination.
• Caused by longitudinal traction with the wrist in pronation, although in a series only 51% of patients were reported to have this mechanism, with 22% reporting falls, and patients less than 6 months of age noted to have the injury after rolling over in bed.

Treatment

Parents should not attempt these maneuvers at home unless advised by a physician. The condition can be treated by a primary care practitioner, or specialist at your local Children's Hospital. To resolve the problem, the affected arm must be held by the attending physician with one hand/finger on the radial head and the other grasping the hand. While applying compression between these two hands, the forearm of the patient is gently supinated and the arm flexed. The physician will usually feel a "click" if the maneuver is done properly, the child will feel momentary pain, and usually within 5 minutes, the forearm will thereafter function well and painlessly.

Flexion and supination

Subluxation of the radial head in children:

Therapeutic goal is reduction. No premedication is required.

X-rays are generally not obtained in a patient with a nontender arm (positioning the child for X-rays may result in reduction). Indication for X-rays: child not using arm 30 min after a reduction; external signs of trauma such as swelling, abrasions, or ecchymosis.

Inform child and caregiver that the reduction may be uncomfortable, but the discomfort will end quickly after reduction.

Perform reduction by firm supination of the forearm with the other hand supporting the elbow in 90º of flexion, feeling and listening for the 'click' as full supination is achieved (although 'click' signifies reduction, absence of a 'click' is noted in successful reductions.)

The child can be expected to resume use of the arm promptly after reduction (within 30 minutes).

If the elbow does not reduce, consider the following diagnoses: fractures, joint infection, tumors, or osteomyelitis. Assure and document that the child has full, unrestricted, painless use of the arm after reduction.

Some recommend that the arm remains in a sling for one week. Caregivers are cautioned against repeated traction injury to the elbow. Recurrent subluxation may result in need for surgery if the patient does not outgrow condition.

Hyperpronation

A strategy of pronation was found by one study to be more successful than the above technique.[1]

External links

• University of Chicago
• University of Utah (broken link)
• FPNotebook
• MedlinePlus (U.S. National Library of Medicine