Swan neck deformity is characterized by proximal interphalangeal (PIP) joint hyperextension and distal interphalangeal (DIP) joint flexion. There is also reciprocal flexion noted in the metacarpophalangeal (MCP) joint radial deviation at the wrist ulnar deviation of the digits, and often palmar subluxation of the proximal phalanges. This is a result of an imbalance of the extensor mechanism of the digit. A swan neck deformity can cause your finger joints to feel painful and swollen. Your PIP joint will bend back too far in hyperextension and your DIP joint will bend in towards the palm of your hand. Finger function can be affected when the deformity is not flexible.
Swan neck deformity is usually caused by weakness or tearing of the ligament in the middle joint. In some cases, the tendon is torn and weakened. Over time, it gets harder for your tendons to straighten the joint. This causes the joint to bend abnormally. Generally, the swan neck deformity finger can be treated non-surgically using specially designed splints that immobilize the finger and promote natural healing. In cases of fracture, complete bone healing may take 6-8 weeks, followed by physical therapy for strengthening.
Pathophysiology
- General
- Characterized by hyperextension of PIPJ and compensatory flexion of DIPJ
- Occurs as a result of an injury to the Volar Plate
- Subsequently, extension forces exceed flexion forces at the PIPJ
Causes
- Acute
- Trauma including direct below and subsequent Mallet Finger injury
- Flexor Digitorum Superficialis laceration
- Chronic
- Rheumatoid Arthritis
- Scleroderma
- Psoriatic Arthritis
- Systemic Lupus Erythematosus
- Rheumatoid Arthritis
- Female > Male [1]
Differential Diagnosis
- Fractures
- Phalanx Fractures (Hand)
- Metacarpal Fractures
- Boxer’s Fracture
- Rolando Fracture
- Bennett Fracture
- Dislocations
- Metacarpophalangeal Joint Dislocation
- Proximal Interphalangeal Joint Dislocation
- Distal Interphalangeal Joint Dislocation
- Carpometacarpal Joint Dislocation
- Tendinopathies
- Extensor Tendon Injuries (Hand)
- Central Slip Extensor Tendon Injury
- Flexor Tendon Injuries (Hand)
- Boutonniere Deformity
- Swan Neck Deformity
- Jersey Finger
- Mallet Finger
- Trigger Finger
- De Quervains Tenosynovitis
- Ligament Injuries
- Gamekeepers Thumb (UCL)
- Radial Collateral Ligament of the Thumb Injury (RCL)
- Volar Plate Avulsion Injury
- Neuropathies
- Wartenberg’s Syndrome
- Carpal Tunnel Syndrome
- Guyon Canal Syndrome
- Arthropathies
- Carpometacarpal Arthritis
- Finger Arthritis
- Rheumatoid Arthritis
- Nail Bed Injuries
- Nail Bed Lacerations
- Nail Bed Avulsions
- Subungual Hematoma
- Paronychia
- Felon
- Pediatric Considerations
- Proximal Phalanx Avulsion Fracture (Thumb)
- Middle and Distal Phalanx Avulsion Fracture
- Other
- Dupuytrens Contracture
Symptoms
- History
- The patient will report snapping, locking, stiffness, and difficulty bending the PIPJ
- Physical Exam: Physical Examination Hand
- Inspection of the affected digit should demonstrate extended PIPJ and flexed DIPJ
- Generally, these are non-mobile
Radiographs
- Standard Radiographs Hand
- Typically adequate to help support the diagnosis
- Findings
- Hyperextension of a proximal interphalangeal (PIP) joint
- Flexion of a distal interphalangeal (DIP) joint
Classification
Nalebuff Classification
- Type 1: PIP joint is flexible in all positions of the MCP joint.[3]
- Type 2: PIP joint flexion is limited in certain positions of the MCP joint.
- Type 3: PIP joint flexion is limited irrespective of the position of the MCP joint.
- Type 4: PIP joints are stiff and have a poor radiographic appearance
Treatment
Nonoperative
- Indications
- Vast majority
- Immobilization
- Double ring splint or extension block splint to help prevent hyperextension of PJPJ
- Progressive extension splinting
- Physical Therapy
- Hand therapy with passive stretching
Operative
- Indications
- Progression despite conservative management
- Technique
- FDS Tenondesis
