Swan neck deformity

• Volar plate injury
• Duck bill deformity
• Recurvatum deformity

• 736.22 Swan-neck deformity

• 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)

• 4D: Impaired joint mobility, motor function, muscle performance, and range of motion associated with connective tissue dysfunction

Description

• 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.

Demographics

• Adults
• 50% of population with RA4
• Associated with population with neurological disorders (cerebral palsy, Parkinson’s disease, CVA)

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

Imaging

• X-ray to rule out fracture.

Medication

• NSAIDs

Medical Procedures

• Surgical options possible after failed conservative care
• Soft tissue repair
• PIP arthroplasty (PIP replaced with metal implant)
• Interphalangeal arthrodesis

• Radiologist for imaging, x-ray to rule out other pathology
• Primary care to rule our rheumatic causes ...