What is amyoplasia (classic arthrogryposis)?

Updated: Jan 03, 2019
  • Author: Mithilesh K Lal, MD, MBBS, MRCP, FRCPCH, MRCPCH(UK); Chief Editor: Maria Descartes, MD  more...
  • Print
Answer

Disorders characterized mainly by limb involvement [12]

Amyoplasia (classic arthrogryposis) [7, 13]

This is characterized as follows:

  • The most common type of arthrogryposis seen in clinical practice and constitutes about one third of cases

  • The incidence is about 1 in 10,000 live births

  • Amyoplasia is a sporadic condition and has not been observed in siblings or offspring

  • The pathogenesis is thought to involve impaired blood circulation to the fetus early in pregnancy; hypotension and hypoxia damage the anterior horn cells, resulting in a lack or underdevelopment of muscle tissue, with fatty or connective tissue replacement

  • Symmetrical limb involvement is noted

  • The distinct positioning of the body includes internally rotated and adducted shoulders; fixed, extended elbows; pronated forearms; and flexed wrists and fingers

  • A severe talipes equinovarus deformity with either flexed or extended knees may be present

  • Hips may be flexed and externally rotated or extended and subluxated or dislocated

  • Characteristic midline facial hemangioma is often noted

  • Intelligence is normal

The natural history of untreated amyoplasia is largely undocumented and unknown. However, a study documented a 94% rate of survival for individuals with amyoplasia at 20 years. [4] Without treatment, the ambulatory and functional potential of afflicted individuals is poor.


Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!