Hand

Extensor Tendon Injury at the DIP Joint

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Extensor Tendon Injury at the DIP Joint, DIP Extensor Tendon Avulsion, Mallet Finger, Mallet Fracture, Drop Finger, Baseball Finger

  • See Also
  1. Hand Fracture
  • Epidemiology
  1. Mallet Finger is the most common closed finger Tendon Injury
  • Mechanism
  1. Forced flexion of extended distal interphalangeal joint
    1. Ball strikes fingertip on catching a ball
  2. Trauma at DIP joint results:
    1. Avulsion of distal phalanx (Bony Mallet) as extensor tendon tears away bony insertion or
    2. Pure extensor tendon rupture (Tendinous Mallet)
      1. Tendon stretched, or partially or completely torn
  3. Images
    1. FingerExtensorTendonInjury.png
  • Symptoms
  1. Pain, Bruising and swelling at dorsal DIP joint
  • Signs
  1. DIP joint with flexion deformity at rest
    1. Intact flexor tendon unopposed by the ruptured extensor tendon
  2. Isolate the DIP joint to test active extension
    1. Variable loss of active finger DIP extension
    2. Confirm extension weakness due to extensor tendon
      1. Central slip at PIP joint can also extend DIP
  • Associated Conditions
  1. Volar subluxation of distal phalanx with bony mallet
  • Imaging
  • XRay of digit (esp. lateral)
  1. Assess for bony mallet at dorsal base of distal phalanx
    1. Type I: No avulsion fragment
    2. Type II: Small bony avulsion
    3. Type III: Avulsion with volar subluxation
  2. Post-reduction XRay to confirm proper alignment
  3. Repeat XRay every 2 weeks if bony mallet (DIP avulsion Fracture)
  1. General
    1. Splints are equally effective: Aluminum, Stack, Ring
    2. Splints are as effective as surgical repair
    3. May participate in sports with splinted DIP
  2. Technique
    1. May use prefabricated splint instead
    2. Measure and cut the splint to extend from fingertip to the middle phalanx
      1. Should only immobilize the DIP joint (not the PIP joint)
      2. Smooth sharp edges
    3. Mold the splint to keep the DIP joint in slight hyperextension (5-10 degrees)
    4. Splint may be applied to either the dorsal or volar surface (author prefers volar surface)
    5. Tape the splint in place
  3. Precautions
    1. See Orthopedic referral indications below
    2. Splint should not reduce range of motion of PIP
    3. Splinting must be continuous for entire period (DIP must remain in extension)
      1. Splinting time (6-8 weeks) restarts if the finger falls back into flexion
    4. Delayed presentation (e.g. month old injury) requires a longer period of Splinting
    5. Risk of skin necrosis with Splinting
      1. Avoid pressure to dorsum of DIP
      2. Avoid hyperextension of DIP joint
        1. Skin will blanch if DIP hyperextended
  4. Assessment
    1. Post-reduction XRay to confirm proper alignment
  5. Protocol
    1. First 6-8 weeks
      1. Splint finger in neutral extension for 6-8 weeks
      2. Splinting must be continuous without fail
        1. Twenty four hours per day
        2. Every day for 6-8 weeks
      3. Hold extension when changing splint
        1. Support distal phalanx against flat surface
        2. Ask for assistance when changing splint
        3. Allow skin to air for 10 minutes at splint change
          1. Reduces maceration at splint
      4. Restart 8 week Splinting period if finger flexes
    2. Next 3-6 weeks
      1. Splint finger in extension only at night
  • Management
  • Orthopedic Referral Indications (see prognosis below)
  1. Joint incongruent
  2. Inability to passively extend DIP joint
    1. Suggests bone or soft tissue entrapment
  3. Fracture involves >30% of joint space
  4. Fragment displaced >2mm
  5. Open Growth Plate
  6. Bony avulsion >1/3 of distal phalanx
  7. Volar subluxation of distal phalanx
  • Management
  • Follow up
  1. Re-examine every two weeks until healed
  2. XRay every two weeks if bony avulsion
  • Management
  • Anticipatory Guidance
  1. Warn that patient that outcome will not be perfect
  • Prognosis
  1. Outcomes are similar for conservative therapy versus surgical management (regardless of referral indications above)
    1. Kalainov (2005) J Hand Surg Am 30(3): 580-6 [PubMed]
  • Complications
  1. Chronic loss of full distal phalanx extension
  • References
  1. Brandenburg (1996) Consultant p.331-340
  2. Calmbach (1996) Lecture in Minneapolis
  3. Dvorak (1996) Lecture in Minneapolis
  4. Lillegard (1996) Lecture in Minneapolis
  5. Warrington (2023) Crit Dec Emerg Med 37(3): 22
  6. Childress (2022) Am Fam Physician 105(6): 631-9 [PubMed]
  7. Leggit (2006) Am Fam Physician 73(5):810-6 [PubMed]
  8. Simpson (2001) J Hand Surg 26:32-3 [PubMed]
  9. Wang (2001) Am Fam Physician 63(10):1961-66 [PubMed]