Aetiology

The aetiology of arthrogryposis is unclear. There is thought to be a failure of differentiation of soft tissue and bony elements that is sporadic but due to a limitation of in utero fetal movements.

The reasons for a lack of in utero movements include:

• oligohydramnios or other causes of restricted space within the uterus
• primary nerve or muscle abnormalities; the neuropathic form is felt to be the most common type
• viral infection
• vascular insufficiency
• toxins eg chronic cyanide exposure

Consequently, skeletal muscle fibres can atrophy. Putatively, there is then a secondary imbalance of forces on specific joints leading to contractures.