Nursemaid's Knee: Understanding, Symptoms, Treatment, and Prevention

What is Nursemaid's Knee?

Nursemaid's knee, clinically known as radial head subluxation, is a common pediatric injury where the radius bone partially slips out of its normal position at the elbow joint, often caused by a sudden pull on the child's arm.

Understanding Nursemaid's Knee

Nursemaid's knee is an injury to the elbow, specifically involving the radial head and the annular ligament. While the name suggests a knee injury, it exclusively refers to the elbow. This condition is most prevalent in children between 1 and 4 years of age, though it can occur from infancy up to about 6 or 7 years. It is rare in older children because their ligaments and bones are more developed and stronger, making them less susceptible to this type of dislocation.

The elbow joint is formed by three bones: the humerus (upper arm bone), the ulna, and the radius (forearm bones). The radial head, the top part of the radius, is held in place against the ulna by a ring-like ligament called the annular ligament. In young children, this ligament is looser and not yet fully developed, making it easier for the radial head to slip through it when sudden traction is applied to the arm.

The Mechanism of Injury

Nursemaid's knee typically occurs due to a sudden, strong pull on a child's hand or forearm. Common scenarios include:

• Lifting a child by one arm: Often happens when an adult lifts a child onto a curb, into a stroller, or just to pick them up quickly.
• Swinging a child by their hands or arms: Playful activities like swinging a child around by their arms can exert significant traction.
• Catching a child by the hand: If a child is about to fall, an adult might instinctively grab their hand, causing a sudden pull.
• Pulling a child by the arm: For example, pulling a reluctant child along.

The force of the pull causes the radial head to slip partially out of the annular ligament, becoming trapped. This partial dislocation (subluxation) is painful and prevents the child from using their arm normally.

Recognizing the Signs and Symptoms

The onset of symptoms is usually sudden and immediately follows the traumatic pull. Parents or caregivers will typically observe:

• Sudden pain: The child will often cry out in pain immediately after the injury.
• Refusal to use the arm: The most hallmark sign is the child's reluctance or complete refusal to move the affected arm. They will often hold it still, close to their body, with the elbow slightly bent and the forearm turned inward (pronated).
• No visible deformity or swelling: Unlike a fracture, there is usually no bruising, swelling, or obvious deformity around the elbow joint.
• Distress: The child may be visibly upset or distressed due to the pain and inability to use their arm.
• Pain on movement: Any attempt to move the arm, especially rotating the forearm, will cause pain.

It's important to note that the child may continue to move their shoulder and wrist freely, as these joints are not affected.

Diagnosis

Diagnosis of Nursemaid's knee is primarily clinical, meaning it's based on a detailed history of the injury and a physical examination by a healthcare professional.

• History: The doctor will ask about the specific incident that led to the child's arm pain (e.g., "Did you pull your child's arm?").
• Physical Examination: The doctor will carefully observe how the child holds their arm and gently palpate the elbow area. They will confirm the absence of swelling or deformity.

X-rays are typically not necessary for diagnosing Nursemaid's knee. In fact, an X-ray would appear normal as it doesn't show ligaments or the subtle subluxation of the radial head. X-rays may be ordered only if there's suspicion of another injury, such as a fracture, or if the mechanism of injury is unclear.

Treatment: Reduction Procedure

The treatment for Nursemaid's knee is a simple and highly effective procedure called reduction, performed by a trained healthcare professional (doctor, physician assistant, or nurse practitioner). The goal is to gently maneuver the radial head back into its correct position within the annular ligament.

There are two common reduction techniques:

1. Supination-Flexion Method:

   • The healthcare provider holds the child's wrist and applies gentle pressure to the radial head with their thumb.
   • The forearm is then fully supinated (turned palm up).
   • While maintaining supination, the elbow is fully flexed (bent).
   • A subtle "click" or "pop" may be felt or heard as the radial head slips back into place.

2. Hyperpronation Method:

   • The healthcare provider holds the child's wrist and applies gentle pressure to the radial head.
   • The forearm is rapidly and firmly hyperpronated (turned palm down as far as possible).
   • This method is often considered faster and equally effective, sometimes preferred for its quick results.

After a successful reduction, the child typically experiences immediate relief from pain and will often begin to use their arm normally within minutes. This rapid recovery is a hallmark of the condition and confirms the diagnosis and successful treatment. In some cases, if the child is still hesitant, offering a toy or snack can encourage them to use the arm. Pain medication is rarely needed after a successful reduction.

Prevention Strategies

Preventing Nursemaid's knee involves educating parents and caregivers about safe handling techniques for young children:

• Avoid lifting by the hands or wrists: Always lift young children by their torso, under their armpits, or by supporting their bottom.
• Do not swing children by their arms: This playful activity, while seemingly harmless, is a common cause of Nursemaid's knee.
• Be mindful when holding hands: If walking with a child, hold their hand gently and avoid sudden jerking or pulling. If they trip, try to support their torso rather than pulling on their arm.
• Educate other caregivers: Ensure babysitters, grandparents, and other individuals caring for your child are aware of these preventive measures.

When to Seek Medical Attention

If you suspect your child has Nursemaid's knee or any other arm injury, it's crucial to seek medical attention promptly.

• Immediate Consultation: If your child suddenly refuses to use an arm after a pull or a fall, it's important to have them evaluated by a healthcare professional.
• Persistent Symptoms: If a suspected reduction has been attempted (e.g., by a family member based on prior experience) but the child's arm remains painful or unused, medical evaluation is essential to confirm the diagnosis and ensure proper treatment.
• Unclear Mechanism: If you are unsure how the injury occurred or if there was direct trauma, medical evaluation is needed to rule out other, more serious injuries like fractures.

Nursemaid's knee is a common and easily treatable condition. With proper awareness and safe handling practices, many cases can be prevented, ensuring the well-being of young children.