Arthrogryposis

Arthrogryposis or AMC (Artrogryposis Multiplex Congenita) is a syndrome of congenital malpositions in several limbs.

Rigidity and contractures can affect jaw, shoulder, elbow, knee, and ankle joints. The malpositioning is combined with more or less extensive muscular weakness.  The extent of the functional disability varies, from relatively slight to very serious disability. Treatment includes plaster casting or orthotics, physical therapy, and operations intended to produce as good a position and function as possible.  AMC can be caused by disease or injuries in the nervous system, the muscles or skeleton/joints, or by mechanical problems. About five children are born each year in Sweden with arthrogryposis, and there are about 350 people of various ages in the country with this disorder.
 
Source: Sällsynta Diagnoser (translated)