Cartilaginous abnormalities should be considered the cause of arthrogryposis multiplex congenita in neonates with any of the following characteristics: (1) long for gestational age, (2) abnormal earlobe shape (Figure 153.1 [A]), (3) hyperextensible and transparent skin (Figure 153.1 [B]), (4) blue sclera (Figure 153.2 [A]), and (5) craniosynostosis.
Figure 153.1.— Characteristic findings in patients with arthrogryposis due to cartilage problems. [A] dysplastic ears; [B] hyperelastic skin.
Intelligence is usually normal in patients with arthrogryposis multiplex congenita due to cartilaginous abnormalities. The mechanism that leads to arthrogryposis in patients with cartilaginous abnormalities is joint hyperelasticity combined with the normal restriction from movement imposed by intrauterine life. Arthrogryposis multiplex congenita improves with time. The most common entities that present arthrogryposis multiplex congenita due to cartilaginous abnormalities in the neonatal period are: (1) Beals syndrome, (2) Antley-Bixer syndrome, (3) diastrophic dysplasia, and (4) distal arthrogryposis.
Figure 153.2.— Beals syndrome: [A] large forehead and blue sclera; [B] long, arachnoid fingers.