Skeletal abnormalities

Skeletal abnormalities in radial dysplasia depend on the severity of the anomaly. However, typical features include:

• humeral defects:
  • short humerus
  • hypoplastic:
    • coronoid
    • capitulum
    • medial condyle
  • reduced range of motion and stiffness at the elbow as a result of hypoplasia
• radius:
  • a spectrum from mild hypoplasia, typically of the distal radius, to complete absence
  • a fibrous anlage replacing the hypoplastic distal part of the radius; in terms of pathogenesis of subsequent deformity, this rigid band may worsen radial bowing by acting as a check rein on the radial side
• ulna:
  • often curved and progresses with growth
  • does not reach the size of the contralateral ulna with or without intervention
• carpal bone:
  • hypoplasia, absence or fusion
  • typically the scaphoid and trapezium
• metacarpal and phalangeal hypoplasia on the radial side of the hand
• thumb:
  • hypoplasia or absence
  • additional middle phalanx, particularly in cases associated with thalidomide exposure