Ainhum

Disease class: Bone resorption

Also known as

• Dactylolysis spontanea
  

This is a disease characterised by spontaneous auto-amputation of the fifth digit of the foot bilaterally. The process begins with the appearance of a groove, on the plantar, medial aspect of the proximal fifth digit. This groove progressively deepens and surrounds the digit until complete amputation occurs.

 

Etymology

• From the Yoruba word ayùn, (to saw, to file).

 

Aetiology

• Unknown.
• Vascular abnormalities may predispose to insufficient circulation, and an increased risk of ainhum.
• Absence of the plantar arch is associated with an increased risk of ainhum
• Walking barefoot is associated with an increased risk of ainhum.

 

Epidemiology

• Predominately seen in African populations. Historically described along the Gold Coast (Gulf of Guinea).

 

Pathophysiology

Grade	Pathological progress
I	groove
II	floor of the groove is ulcerated
III	bone involvement
IV	autoamputation has occurred

 

Management

Grade I-II lesions

• Injection of corticosteroids.
• Excision of the groove, followed by z-plasty can reduce pain and probability of amputation.

Grade III lesions

• Disarticulation of the metatarsophalangeal joint.