Ainhum Clinical Presentation

Updated: May 02, 2017
  • Author: Jeannette Rachel Jakus, MD, MBA; Chief Editor: Dirk M Elston, MD  more...
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Presentation

History

Criteria for diagnosis involves three conditions: soft tissue constriction, bulbous enlargement of the toes, and thinning or lysis of phalangeal bones. As the condition progresses, confirmation can be made via radiographic imaging.

The four stages of ainhum are as follows:

  • Grade I involving a groove with no swelling visible and no bone involvement

  • Grade II is a bulbous enlargement of the digit distally, resulting in external rotation

  • Grade III consists of osseous involvement

  • Grade IV is the development of autoamputation

 

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Physical Examination

The clinical presentation depends on the stage to which the ainhum has progressed. The initial sign of a painful fissure under a toe may not be defining, but the progressive constriction at the base of the toe with distal edema is diagnostic of ainhum. The toe may become rotated, clawed, and dorsiflexed at the metatarsophalangeal joint. Ultimately, before the toe is shed, it may be attached by an increasingly slender thread of fibrous tissue.

The clinical, histologic, and radiographic appearances in pseudoainhum are similar or identical to true ainhum.

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Causes

In 1952, Wells and Robinson [8] proposed 4 distinct sources of annular constrictions of the digits. The sources include (1) annular scarring from frostbite, burns, or trauma, (2) true ainhum, (3) constricting bands that simulate ainhum, and (4) congenital bands.

The exact etiology of true ainhum is unclear. Race and climate apparently are predisposing factors. Ainhum also may have a genetic component, since ainhum has been reported to occur within families. Infection and walking barefoot in childhood are linked to ainhum but probably are not major factors in its development. Abnormal scarring does not appear to be a cause; ainhum and keloid formation rarely occur in the same individual.

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Complications

Secondary infections may complicate ainhum. If more than just the two fifth toes are affected in ainhum or pseudoainhum, the individual's balance may be affected when walking. Dermatophytosis complex may be a complication.

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