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Condition/Disorder Synonyms

  • Volar plate injury

  • Duck bill deformity

  • Recurvatum deformity

ICD-9-CM Code1

  • 736.22 Swan-neck deformity

ICD-10-CM Codes2

  • M20.03 Swan-neck deformity

  • M20.031 Swan-neck deformity of right finger(s)

  • M20.032 Swan-neck deformity of left finger(s)

  • M20.039 Swan-neck deformity of unspecified finger(s)

Preferred Practice Pattern3

Key Features


  • Injury or loosening of the volar plate (ligament connecting proximal and middle phalanx that prevents hyperextension of the PIP)

  • Hyperextension of the proximal interphalangeal joint (PIP) and flexion of the distal interphalangeal joint (DIP)

  • Duck bill deformity is the same issue in the thumb less one joint

Essentials of Diagnosis

  • Rheumatoid arthritis (RA)—most common cause of swan neck deformity

  • Chronic inflammation loosens the volar plate, making PIP susceptible to hyperextension

  • As a result, extensor tendon tightens causing DIP to pull into flexed position

  • Swan neck classification4

    • I: PIP joint flexible in all positions

    • II: PIP motion limited only by tenodesis effect

    • III: fixed PIP joint contracture, x-ray okay

    • IV: x-ray shows arthritic changes

General Considerations

  • Pain and swelling of the PIP

  • Can be managed surgically or non-surgically depending upon signs and symptom severity, response to conservative treatment, and orthopedic physician recommendations

  • Other causes include trauma, nerve injury such as cerebral palsy, Parkinson's disease, or stroke.


  • Adults

  • 50% of population with RA4

  • Associated with population with neurological disorders (cerebral palsy, Parkinson's disease, CVA)

Clinical Findings

Signs and Symptoms

  • Pain and swelling of the PIP joint

  • Laxity of the volar plate

  • Snapping and locking of the fingers

  • Hyperextension of the PIP and flexion of the DIP

Functional Implications

  • Difficulty and or pain with opening and closing hand in preparation for grasping or reaching

  • Difficulty and/or pain with grasping dishes, utensils, or drinking cups due to pain and weakness

  • Difficulty and/or pain with grasping and turning steering wheel

  • Difficulty and/or pain with turning doorknob

Possible Contributing Causes

  • Trauma

  • Rheumatoid arthritis, or other rheumatic or connective tissue disorders

  • Neurological disorders

  • Cerebral palsy

  • Parkinson's disease

  • Ehlers-Danlos syndrome

  • Untreated mallet finger

  • Overuse of the hand and fingers

Differential Diagnosis

  • Ganglion of tendon sheath

  • Dupuytren disease

  • Loose body in the MCP joint

  • Subluxation of the extensor digitorum communis

Means of Confirmation or Diagnosis


  • X-ray to rule out fracture.



  • NSAIDs

Medical ...

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