Swan neck deformity
Encyclopedia
Swan neck deformity is a deformed position of the finger
, in which the joint closest to the fingertip is permanently bent toward the palm while the nearest joint to the palm is bent away from it (DIP
hyperflexion with PIP hyperextension). It is commonly caused by injury or inflammatory conditions like rheumatoid arthritis
or sometimes familial (congenital, like Ehlers-Danlos syndrome
).
, PIP, or even the MCP
joints. In all cases, there is a stretching of the volar plate at the PIP joint to allow hyperextension, plus some damage to the attachment of the extensor tendon to the base of the distal phalanx that produces a hyperflexed mallet finger
. Duck bill deformity is a similar condition affecting the thumb (which cannot have true swan neck deformity because it does not have enough joints).
Finger
A finger is a limb of the human body and a type of digit, an organ of manipulation and sensation found in the hands of humans and other primates....
, in which the joint closest to the fingertip is permanently bent toward the palm while the nearest joint to the palm is bent away from it (DIP
Distal interphalangeal joint
Distal interphalangeal joint can refer to:* Interphalangeal articulations of hand* Interphalangeal articulations of foot...
hyperflexion with PIP hyperextension). It is commonly caused by injury or inflammatory conditions like rheumatoid arthritis
Rheumatoid arthritis
Rheumatoid arthritis is a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks synovial joints. The process produces an inflammatory response of the synovium secondary to hyperplasia of synovial cells, excess synovial fluid, and the development...
or sometimes familial (congenital, like Ehlers-Danlos syndrome
Ehlers-Danlos syndrome
Ehlers–Danlos syndrome is a group of inherited connective tissue disorders, caused by a defect in the synthesis of collagen . The collagen in connective tissue helps tissues to resist deformation...
).
Pathophysiology
Swan neck deformity has many possible causes arising from the DIPDistal interphalangeal joint
Distal interphalangeal joint can refer to:* Interphalangeal articulations of hand* Interphalangeal articulations of foot...
, PIP, or even the MCP
Metacarpophalangeal joint
The metacarpophalangeal joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow cavities on the proximal ends of the first phalanges, with the exception of that of the thumb, which presents more of the characters of a ginglymoid joint...
joints. In all cases, there is a stretching of the volar plate at the PIP joint to allow hyperextension, plus some damage to the attachment of the extensor tendon to the base of the distal phalanx that produces a hyperflexed mallet finger
Mallet finger
In medicine, mallet finger, also baseball finger, dropped finger and extensor tendon injury, is an injury of the extensor digitorum tendon of the fingers at the distal interphalangeal joint...
. Duck bill deformity is a similar condition affecting the thumb (which cannot have true swan neck deformity because it does not have enough joints).
External links
- Swan neck deformity at Wheeless' Textbook of Orthopedics, a technical review of the condition
- Rheumatoid arthritis: Image showing deformities