Radial ray anomaly

Radial ray anomalies comprise of a large spectrum of upper limb anomalies which range from partial (radial hypoplasia) to a complete (radial aplasia) deficiency of the radius with or without accompanying deficiency of the thumb bones.



They can be associated with a number of associations which include:

Sub types

Radial ray anomalies can be classified into four main sub types depending the extent of severity:

  • type I: radius is slightly (>2 mm) short and the hand to bends sideways at the wrist (often associated with a hypoplastic thumb); proximal radius usually unaffected
  • type II: the radius bone is very short and the ulna curves sideways and supports the wrist poorly
  • type III: partial absence of radius 
  • type IV: complete absence of radius 

Radiographic features

Antenatal ultrasound

May show absent of hypoplasia of the radius (depending on type) with hand often in medial rotation

Plain film

Allows direct visualisation of anatomy but is usually performed postnatally.

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