Extensor Tendon Injuries

An extensor tendon injury is a damage to the tissues on the back of the hand and fingers. It can make it hard for you to extend your wrist, open your hand, or straighten your fingers. The inability to perform these functions can severely limit hand and upper extremity function. Activity that requires repetitive motion of the forearm such as painting, typing, weaving, gardening, lifting heavy objects, and sports. Overuse of the forearm muscles. Direct trauma as a fall, work injury, or motor vehicle accident. The extensor carpi radialis brevis (ECRB) and longus, extensor digitorum, extensor digiti minimi, and extensor carpi ulnaris come together to form the common extensor tendon. The extensor carpi radialis brevis is almost always the primary tendon involved.

Other Names

  • Extensor tendinopathy

Causes

  • Generally a loss of ability to extend the affected digit, hand, and/or wrist
  • Superficial, susceptible to injury
  • The most common finger is the pointer/ index finger
  • Potential mechanisms are sharp object direct lacerations, burns, blunt trauma, bites, crush injuries, avulsions and deep abrasions
  • Can affect MCPJ and/or PIPJ or DIPJ of hand
  • Zone 1: Traumatic flexion of DIPJ
  • Zone 2: Dorsal laceration or crush injury
  • Zone 5: Fight bite
  • 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
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Symptoms 

  • Inability to straighten the fingers or extend the wrist.
  • Pain and swelling in the fingertip.
  • Recent trauma or laceration to the hand.
  • Drooping of the end joint of the finger.

Diagnosis

  • General: Physical Examination Hand
  • Universally present with inability to extend at some point on the dorsal finger, hand, or wrist
  • Inspect for etiology (laceration, crush trauma, overuse, etc)
  • Zone 1: Loss of extensor mechanism at DIPJ (digits 2-4), IJP (thumb)
  • Zone 3: Elson’s Test can help confirm a diagnosis
  • Standard Radiographs Hand
  • Consider ultrasound
  • MRI in complex injuries

Classification

  • Zone 1: DIPJ
    • Injury to terminal extensor tendon distal to or at the DIPJ (digits 2-4) or IPJ (thumb) involving EPL
    • Sequelae: Mallet Finger
  • Zone 2: Middle Phalanx
    • Injury of tendon over middle phalanx (digits 2-4), or proximal phalanx thumb
  • Zone 3: PIPJ
    • Injury over the PIPJ of digit 2-4 leading to Central Slip Injury or MCPJ of thumb involving EPL, EPB
    • Sequelae: Boutonniere Deformity
  • Zone 4: Proximal Phalanx
    • Injury over the proximal phalanx (digits 2-4) or metacarpal of thumb (EPL, EPB)
  • Zone 5: MCPJ
    • Injury over MCPJ of digit (2-4) or CMCJ of thumb (EPL, EPB)
    • Sequelae: Fight Bite, Sagittal band rupture
  • Zone 6: Metacarpals
    • Injury over the metacarpal
    • Sequelae: Increased risk of neurovascular injury
  • Zone 7: Wrist
    • Injury at wrist joint
    • Surgical injury requiring repair of the extensor retinaculum
  • Zone 8: Distal third of the forearm
    • Disruption at the distal forearm
  • Zone 9: Muscle belly rather than tendon injury
    • Sequelae: High risk of neurologic injury, requires surgery

Treatment

Nonoperative

  • Depends on the zone of injury
  • Immobilization if <50% of tendon cut and extensor tendon remains intact
  • DJ extension splint
    • Zone 1 (mallet finger)
  • PIPJ extension splint
    • Zone 3 (central slip if simple)
  • MCPJ extension splint
    • Zone v (closed, uncomplicated sagittal band rupture)
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Operative

  • Incision & drainage: Open fracture involving joint, fite bite
  • Repair: tendon laceration >50%
  • Fixation: volar avulsion fracture
  • Reconstruction: tendon repair not possible
  • Central slip reconstruction