Radial head dislocation (congenital)

Congenital radial head dislocation is a an anomaly of the upper limb that can occur in isolation or be part of a wider syndrome such as ulnar dysplasia. The main differential is that of traumatic radial head dislocation - see submenu. It is the most common congenital elbow anomaly and in the majority of cases it is bilateral. A minority of cases are inherited in an autosomal dominant manner. Associations include:

• Apert's Syndrome
• Klinefelter's Syndrome
• Cornelia de Lange Syndrome
• Ehler's-Danlos Syndrome
• nail-patella syndrome

Clinically, there is often a delayed presentation as functional activities increase. Parents may notice the fullness of the radial head if it dislocates anteriorly in the elbow, a reduced range of extension or forearm pronation/supination. Usually, there is no history of trauma. It is rare for the patient to report pain or a 'popping' sensation during early childhood, but these may be common features later. Examination reveals a palpable radial head distal to the cubital fossa for anterior dislocations with associated reduced range of flexion. Posterior dislocations limit extension. Typically, there is a subtle reduction in pronation and supination. An older child presenting for the first time with congenital radial head dislocation may have little evidence of functional debility.

Investigations include:

• plain radiography:
  • radial head does not align with capitellum
  • dysplasia of radial head or capitellum
  • ulnar negative variance (short ulna)
• ultrasound: possible use in unossified infant with suspected dislocation

The direction of dislocation provides a means of classifying congenital radial head dislocation(1):

• posterior (47%)
• anterior (43%)
• lateral (10%)

For minor deformities, the management is largely supportive. Indications for surgery include pain, eg due to impingement of radial head and distal humerus, significant cosmetic deformity and functional impairment due to reduced range of motion. Surgery is delayed until skeletal maturity. Surgical options include:

• excision of the radial head:
  • good for pain, appearance and range of motion
  • complications include post-operative radioulnar synostosis and cubitus valgus deformity with growth
• shortening of proximal radius
• reconstruction of the annular ligament using triceps fascia; not particularly successful

Ref: (1) Almquist EE, Gorden LH, Blue AI. J Paediatr Orthop (1993); 13: 526-528.