Radial Head Dislocation and Subluxation (Nursemaid's Elbow)

Basics

Description

Subluxation more common in children. In both adults and children, typically associated with distracting force across elbow or trauma; dislocation more common in men subject to high-force injury
Dislocation of the radial head and fracture of ulna shaft is termed a Monteggia fracture.
Atraumatic radial head dislocation is usually due to congenital anomalies.
Categorized based on direction of dislocation: anterior, posterior, lateral

Epidemiology

Incidence

Isolated radial head dislocation is rare. Subluxation (annular ligament displacement) occurs in children between the ages of 6 months and 5 years—mean age of 2 years; slightly more common in girls (1,2)[A]

Prevalence

Subluxation has the highest incidence between 12 and 35 months. The left arm is more commonly involved (60%; distracting force applied by right arm–dominant adult to left arm of child). Obesity may be an associated factor (many affected children >75th percentile for weight). The recurrence rate is ~1% (3)[B].

Etiology and Pathophysiology

Isolated radial head dislocation is uncommon; most typically associated with complete elbow dislocation or elbow fractures in high-force traumatic injuries
In subluxation, axial traction allows the underdeveloped annular ligament to slip over the head of the radius and it becomes entrapped between the radius and capitulum. The annular ligament is typically not fully developed until the age of 5 years (2)[A].
Proximal ulnar malalignment combined with annular ligament tear affects elbow biomechanics leading to radial head subluxation (4).

Genetics
No genetic correlation to injury

Risk Factors

Cerebral palsy
Osteogenesis imperfecta
Osteochondroma
Fibrous dysplasia

Commonly Associated Conditions

Elbow dislocation
Elbow fracture
Obsessive-compulsive disorder (OCD) lesion seen in pediatrics

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