A pivotal step in the management of arthrogryposis multiplex congenita is to determine its cause. The cause of the arthrogryposis multiplex congenita determines the prognosis and recurrence rate of the disease. There are many causes of arthrogryposis multiplex congenita in neonates. Smith’s book on recognizable patterns of human malformation lists arthrogryposis multiplex congenita as a feature of over 100 syndromes. The differential diagnosis among these syndromes is made by analyzing the distribution of the arthrogryposis, the presence of facial dysmorphism, and other associated findings.
Arthrogryposis multiplex congenita may involve the distal or the proximal joints. Involvement of the distal joints is more frequent than involvement of the proximal joints. Neonates with distal arthrogryposis often have a very typical hand position (Figure 152.1). This typical hand position is frequently present in trisomy 13 and 18 syndromes, Pena-Shokeir I and II syndromes, and Smith-Lemli-Opitz syndrome. Proximal arthrogryposis usually involves the shoulders, elbows, hips, and knees. Proximal arthrogryposis occurs in neonates with amyoplasia congenita.

Figure 152.1.— Trisomy 18 hand position. The middle finger is under the index finger and partially under the fourth finger. The thumb is totally or partially under the index finger.