Radial ray anomaly

Last revised by Abenezer Zinaye on 13 Oct 2021

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:


Radial ray anomalies can be classified into four main subtypes depending upon the extent of severity:

  • type I: radius is slightly (>2 mm) short and the hand 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 absence or hypoplasia of the radius (depending on type) with hand often in medial rotation

Plain radiograph

Allows direct visualization of anatomy but is usually performed postnatally.

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Cases and figures

  • Case 1
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  • Case 2: type IV with Holt-Oram syndrome
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  • Case 3: type IV with Fanconi anemia
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  • Case 4: type IV radial ray anomaly
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  • Case 5: type IV
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  • Case 6: bilateral radial ray anomaly
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