Swan neck deformity is a deformed position of the

finger A finger is a limb of the body and a type of digit, an organ of manipulation and sensation found in the hands of most of the Tetrapods, so also with humans and other primates. Most land vertebrates have five fingers ( Pentadactyly). Chamber ...

, 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

flexion Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

with PIP

hyperextension Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

). It is commonly caused by injury, hypermobility or inflammatory conditions like

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are inv ...

or sometimes familial (congenital, like Ehlers–Danlos syndrome).

Pathophysiology

Swan neck

deformity A deformity, dysmorphism, or dysmorphic feature is a major abnormality of an organism that makes a part of the body appear or function differently than how it is supposed to. Causes Deformity can be caused by a variety of factors: *Arthritis an ...

has many of possible causes arising from the DIP, PIP, or even the MCP joints. In all cases, there is a stretching of the volar plate at the PIP joint to allow

, 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

is a similar condition affecting the thumb (which cannot have true swan neck deformity because it does not have enough joints).

Diagnosis

Diagnosis of swan neck deformity is mainly clinical. MRI of the hand may suggest volar plate attenuation of PIP and extensor tendon damage for DIP Genetic screening tests such as for CMT disease may also be indicated.

Treatment

Splinting for fingers. Passive stretching and clearing the

References

External links

Swan neck deformity
at Wheeless' Textbook of Orthopedics, a technical review of the condition

Fingers Skeletal disorders Ehlers–Danlos syndrome {{Musculoskeletal-stub