Hand Extensor Tendon Injury

Aka: Hand Extensor Tendon Injury, Extensor Tendon Laceration, Extensor Tendon Injury of Finger, Finger Extensor Tendon Repair, Primary Tenorrhaphy of Hand Extensor Tendon, Extensor Digitorum Tendon Rupture, Sagittal Band Rupture

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II. Epidemiology

  1. Hand Extensor Tendon Injury Incidence: 14 per 100,000 person-years
    1. Extensor tendon injuries are twice as common as flexor tendon injuries

III. Anatomy: Dorsal Hand Zones (Extensor Hand, odd numbered zones are over joints)

  1. Zone 1: DIP Joint and Distal Phalanx (or IP of thumb, including Fingernail)
  2. Zone 2: Middle Phalanx (or proximal phalanx of thumb)
  3. Zone 3: PIP Joint (or MCP of thumb)
  4. Zone 4: Proximal Phalanx (or Metacarpal of thumb)
  5. Zone 5: MCP Joint or Sagittal Band Rupture (or CMC of thumb)
  6. Zone 6: Metacarpals
  7. Zone 7: Wrist joint Carpal Bones
  8. Zone 8: Distal Forearm

IV. Causes

  1. Extensor Tendon Laceration (open wound)
    1. Consider Fight Bites with Lacerations over the MCP joint (zone 5)
  2. Extensor Digitorum Tendon Rupture
    1. Most commonly affects the index finger or thumb
    2. Forced extension of a flexed MCP joint, typically in Zone 5 (e.g. paddle sports)
    3. Fracture lacerates tendon
      1. Example: Distal Radius Fracture lacerates Extensor Pollicis Longus (EPL) of the thumb
    4. Attrition rupture
      1. Chronic fraying and tearing of tendon with overuse
      2. May occur with chronic inflammatory conditions (e.g. Rheumatoid Arthritis)

V. Signs

  1. Extensor Digitorum Tendon Rupture
    1. Reduced extension of the affected finger at MCP joint
  2. Extensor Tendon Lacerations
    1. Variable loss of active finger extension with Lacerations
    2. Inspect all Lacerations for Tendon Injury
    3. Metacarpal-phalangeal joint (MCP) Lacerations may be most difficult
      1. Tendon retracts most at this location
    4. Exploration may require Laceration extension
      1. Allows for tendon visualization

VI. Differential Diagnosis

  1. Extensor Tendon Injury at the DIP Joint
    1. Also known as Mallet Finger (or Drop Finger, Baseball Finger)
  2. Extensor Tendon Injury at the PIP Joint
    1. Associated with a Central Slip Extensor Tendon Injury and Boutonniere Deformity

VII. Imaging

  1. XRay Hand Indications
    1. Evaluate for Retained Foreign Body (Radiopaque Foreign Body)
    2. Concurrent Fractures
    3. Joint injury

VIII. Management: Repair of Extensor Tendon Laceration (open wound)

  1. Open Extensor Tendon Lacerations are amenable to Emergency department repair
    1. Contrast with flexor tendon injuries which are made more complicated by anatomy (e.g. tendon sheaths)
  2. Indications: Extensor tendon repair
    1. Full tendon Laceration
    2. Partial tendon Laceration over 33% of tendon
  3. Contraindications for emergency department extensor tendon repair
    1. Neurovascular injury
    2. Thumb injury
    3. Zone 7 or 8 injury (distal wrist)
    4. Significant wound contamination or tissue destruction
    5. Closed Tendon Injury
    6. Associated Fractures
  4. Laceration evaluation
    1. Extensive Wound Irrigation
    2. Evaluate for retained Skin Foreign Body
  5. Direct end to end repair of tendon
    1. Technique: Kessler Repair
      1. Wound Irrigation and exploration as above
      2. Extend fingers to best visualize tendon segments
      3. Consider proximal penrose drain or Blood Pressure cuff inflation
        1. May improve visualization if blood obscures surgical field
      4. Use braided non-Absorbable Suture (nylon) 4-0
      5. Proximal Tendon Segment
        1. Grasp proximal tendon end in forceps
        2. Suture enters medial (radial) tendon and exits on dorsal aspect tendon
        3. Suture loops behind tendon ventrally from medial to lateral
        4. Suture enters lateral (ulnar) tendon and exits on dorsal aspect of tendon
      6. Distal Tendon Segment
        1. Grasp distal tendon end in forceps
        2. Suture enters lateral (ulnar) tendon and exits on dorsal aspect of tendon
        3. Suture loops behind tendon ventrally from lateral to medial
        4. Suture enters medial (radial) tendon and exits on dorsal aspect tendon
        5. Tie the 2 Suture ends together
        6. Attempt to bury knot and cut the Suture ends close to the knot
      7. Perform Laceration Repair
    2. Disposition
      1. Splint wrist and finger in extension for 4 weeks
      2. Follow-up with hand surgery in 5-7 days
  6. Alternative: Deferred Repair
    1. Wound Irrigation and Laceration Repair
    2. Splint wrist and fingers in extension
    3. Urgent referral to hand surgery for definitive tendon repair

IX. References

  1. Warrington, David and Deaton (2020) Crit Dec Emerg Med 34(12): 15
  2. Grover (2026) Am Fam Physician 113(2): 185-7 [PubMed]

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