II. Pathophysiology

  1. Avulsion of the flexor digitorum profundis tendon
  2. Images
    1. FingerFlexorTendonInjury.png

III. Mechanism

  1. Ring finger most commonly affected (75% of cases)
    1. Protrudes further than other fingers on grasping
  2. Forced hyperextension of an actively flexed DIP joint
    1. Results in avulsion Fracture at the bony insertion (on distal phalanx) of the flexor digitorum profundus tendon
  3. Example
    1. Football player grabs a player's jersey on tackle
    2. Lifting latch on car door

IV. Symptoms

  1. Pain and swelling at volar aspect of DIP
  2. Localized tenderness and fullness if tendon retraction
  3. Affected finger more extended at DIP when hand at rest
  4. Inability to flex at affected DIP joint

V. Signs

  1. Do not passively force finger into extension
    1. Avulsed tendon retracts with avascular risk
  2. Assess Profundus
    1. Hold proximal interphalangeal joint (PIP)
    2. Test active flexion of distal Interphalangeal joint
    3. Avulsion results in inability to flex at DIP
    4. FDP Tendon may retract to the palm
  3. Assess for flexor digitorum superficialis rupture
    1. Hold all fingers except affected finger in extension
    2. Test proximal interphalangeal joint (PIP) flexion

VI. Imaging: XRay digit (AP, Lateral, Oblique)

  1. Assess for bony avulsion of volar distal phalanx

VII. Management

  1. Early surgical repair in all cases
  2. Temporize by Splinting finger in current position
    1. PIP and DIP joints in slight flexion
  3. Hand surgeon or orthopedics referral
    1. Best recovery if repaired within 7-10 days of injury
  4. Post-Operative Management
    1. No sports participation until fully recovered
    2. Hand therapy during recovery period
    3. Expect recovery over 6 to 12 weeks

VIII. Complications

  1. Fibrosis and scarring of tendon sheath
    1. Flexor digitorum profundus contracture with flexion deformity
    2. Associated with delayed surgical repair

IX. 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. Childress (2022) Am Fam Physician 105(6): 631-9 [PubMed]
  6. Wang (2001) Am Fam Physician 63(10):1961-66 [PubMed]

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