- Amyoplasia
Amyoplasia is a generalized lack in the newborn of muscular development and growth, with contracture and deformity at most joints. It is the most common form of
arthrogryposis . [Citation |url=http://pediatrics.aappublications.org/cgi/content/abstract/97/2/225 |title=Amyoplasia, the Most Common Type of Arthrogryposis: The Potential for Good Outcome |authors=Jill M. Sells, Kenneth M. Jaffe, and Judith G. Hall |date=February 1996 |journal=PEDIATRICS |volume=97 |number=2 |pages=225-231 ]It is characterized by quadrimelic involvement and replacement of sketetal muscle by dense fibrous tissue and fat. Studies involving Amyolasia have revealed similar findings of the muscle tissue due to various causes including that seen in sacral agenesis and diseases of the anterior horn cell. So amyoplasia may not describe just one group of patients but may be an intermediate common pathway rather than the primary cause of the contractures.
Accounts for over 1/3 of the cases of arthrogryposis. Sporadic inheritance.
Characteristic appearance: Internally rotated shoulders, extended elbows, ulnar flexed wrists. More variable positioning of hips and knees. hips most often fixed and flexion and abduction. Half the hips are dislocated. Knees tend to be fixed in flexion. Equinovarus deformity of feet. most children have symmetrical limb involvement.
About 10% of children with amyoplasia have evidence of vascular compromise including bowel atresia, abdominal wall defects, gastroschisis.
No single factor is found consistently in prenatal histories of patients with amyoplasia.
Prognosis
Overall prognosis for these children with amyoplasia is good. Intensive therapies throughout developing years include PT, OT and multiple orthopedic procedures. Initial passive stretching to improve joint mobility. Most children require therapy for years. Almost 2/3 end up with ambulation. The older the child, the more likely the independent ambulation with or without braces or assistance.
Majority of children in school are in regular classes. Most read and write comparable to peers.
References
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