Symphalangism

Last revised by Ashesh Ishwarlal Ranchod on 8 Dec 2024

Symphalangism refers to ankylosis or synostosis 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.

Symphalangism may also be associated with many conditions including 2:

Stiffness, lack of volar skin folds and reduced range of motion may be present 3. More often, it is an incidental finding on radiographs.

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

Symphalangism was first coined by American neurosurgeon Harvey Cushing in 1916 4.