Citation, DOI & article data
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 3:
Stiffness, lack of volar skin fold and reduced range of motion may be present 4. 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.
Historical and etymology
Symphalangism was coined by Howard Cushing in 1916 2.
- 1. Nakashima T, Hojo T, Suzuki K et-al. Symphalangism (two phalanges) in the digits of the Japanese foot. Ann. Anat. 1995;177 (3): 275-8. doi:10.1016/S0940-9602(11)80199-8 - Pubmed citation
- 2. AUSTIN FH. Symphalangism and related fusions of tarsal bones. Radiology. 1951;56 (6): 882-5. doi:10.1148/56.6.882 - Pubmed citation
- 3. Ortiz D. Reeder and Felson's gamuts in radiology. Praeger. ISBN:0313312168. Read it at Google Books - Find it at Amazon
- 4. Baek GH, Lee HJ. Classification and surgical treatment of symphalangism in interphalangeal joints of the hand. Clin Orthop Surg. 2012;4 (1): 58-65. doi:10.4055/cios.2012.4.1.58 - Free text at pubmed - Pubmed citation