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Ainhum



  • General considerations
    • Rare disorder in the US but relatively common amongst black Africans
    • Autoamputation (dactylolysis) of a digit, usually the fifth toe
    • Frequently bilateral (60%)
    • Caused by a constricting fibrous band or groove
    • Affects predominantly black males in tropical areas
      • Has a familial association
      • May be associated with running barefoot
    • Rare before the age of 30 or after 50
      • Infants may have the hair-thread tourniquet syndrome in which fibers of hair or thread become tightly wrapped around an appendage of an infant
    • May be triggered by trauma
  • Pseudoainhum has similar findings but arises secondary to another condition
    • Scleroderma and leprosy are amongst the causes
    • Band is made of collagen rather than fibrous tissue
    • No racial predilection
  • Clinical findings
    • The process described below may take as long as 10 years
    • A narrow fissure or groove develops on 5th toe, usually on a medial plantar fold
    • The fissure deepens and is associated with pain, but usually not sever pain
    • The toe distal to the band becomes globular in shape
    • Then, the bone separates at the joint
      • This is frequently the most painful phase
    • Lastly, there is amputation of the toe at the site of the fissure
  • Imaging findings
    • Conventional radiographs are diagnostic
    • A lucent band may be seen at the site of the constricting fissure
    • Osteolysis involves the middle and distal phalanges
      • They characteristically taper
    • Bone fractures and toe autoamputates
  • Treatment
    • There is no medical treatment which can halt the progression in Ainhum
    • Steroid injections and salicylic acid ointment may reduce pain
    • Surgery may release the constricting band

Aimhum

Ainhum. Three views of the little toe demonstrate a characteristic constricting soft tissue band (white arrows) that is associated with tapering and destruction of the middles and distal phalanges of the little toe (black arrows).
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Ainhum  eMedicine  Selden, S