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Symphalangism refers to ankylosis of the interphalangeal joints (i.e. fusion of the phalanges) in either the toes or the fingers. Less commonly, the metacarpophalangeal joints may be affected.

One study reports symphalangism of the fifth toe in ~55% (range 40-75%) of the population. It less commonly affects the fourth (~5%) and third toes (~1%) in descending incidence 1.

Stiffness, lack of volar skin fold and reduced range of motion may be present 4. More often, it is an incidental finding on radiographs.

Most commonly seen as an isolated anatomical variant as a fusion of the middle and distal phalanges in the 5th toe 1.

Symphalangism may also be associated with many conditions including 3:

First named by Dr Howard Cushing in 1916 2.  

Anatomy: Lower limb

Anatomy: Lower limb

Article information

rID: 30912
Section: Anatomy
Synonyms or Alternate Spellings:

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Cases and figures

  • Case 1: third, fourth and fifth toe symphalangism
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  • Case 2: fifth toe symphalangism with fracture
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  • Case 3: 1st-4th PIP fusion
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  • Case 4: little toe symphalangism with fracture
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  • Case 5: little toe pedal biphalangism with fracture
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