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Swan neck deformity Classification and external resources
Human hand bones (Joints visible but not labeled.)
ICD-10	M20.0
ICD-9	736.22
eMedicine	Orthoped/562

Swan neck deformity is a deformed position of the finger, in which the joint farthest from the knuckle is permanently bent toward the palm while the nearest joint is bent away from it (DIP hyperflexion with PIP hyperextension). It is commonly caused by injury or inflammatory conditions like rheumatoid arthritis.

Pathophysiology

Swan neck deformity has many 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 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).

References

External links

• Swan neck deformity at Wheeless' Textbook of Orthopedics, a technical review of the condition
• Rheumatoid arthritis: Image showing deformities

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