EM@3AM: Finger Amputation

Author: Christopher J. Nelson, MD (EM Resident Physician, UTSW, Dallas, TX) // Reviewed by: Alex Koyfman, MD (@EMHighAK); Brit Long, MD (@long_brit)

Welcome to EM@3AM, an emDOCs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.

Answer: Finger Amputation

Background:

• An average of over 46,400 finger amputations occurred in the US from 1997 to 2016²
• Bimodal distribution – below the age of 5 year and over the age of 65 years²
• Doors and power saws are the most common mechanisms²
• Goals of treatment are to restore function, sensation, durability, and proper nail growth
• Improper treatment may lead to loss of function, pain, and poor cosmetic outcome³

Anatomy:

• The hand consists of phalanges, metacarpal bones, and carpal bones
• Each finger has a distal, middle, and proximal phalanges
• The thumb has distal and proximal phalanges
• Finger joints (distal to proximal):
  • Distal interphalangeal joints (DIP)
  • Proximal interphalangeal joints (PIP)
  • Metacarpophalangeal joints (MCP)
• Thumb joints
  • Interphalangeal joint
  • Metacarpophalangeal joint
  • Carpometacarpal joint
• Neurovascular components run on the lateral aspects of the digits
• Naming digits is less likely confused than numbering – Thumb, index, long, ring and pinky
  • Varying numbering systems can otherwise lead to miscommunication

History and Exam:

• Mechanism of injury
• Time of injury
• Other signs of injury (amputation may be a distracting injury to other injuries)
• Amputated digit cold vs. warm (important for reimplantation time)⁵
• Tetanus status
• Dominant hand
• History of blood thinners
• History of diabetes and smoking, which are predictors of poor wound healing⁷
• Examination of each digit’s sensation and strength
  • Isolating and examining extension/flexion of MCP, PIP, and DIP to assess flexor and extensor tendon involvement
• Careful examination of nailbed/subungual hematoma
  • Treatment of nailbed injuries important to avoid cosmetic and functional loss in fingertip injuries⁶

Differential:

• Finger amputation, fingertip amputation, finger laceration, nail/nailbed laceration, ring avulsion injury, crush injury

ED Evaluation:

• Hand and finger x-rays, including amputated part
• Consider preop labs
  • CBC, BMP, PT/INR, PTT
• Time of amputations to guide reimplantation viability
  • Time between amputation/loss of blood supply to the digit prior to surgery
    • 12 hours of warm ischemia⁵
      • Time without cooling of amputated digit
    • 24 hours of cold ischemia⁵
      • Cooling of the digit
        • Covered in saline-moistened gauze in a sealed bag on ice

Management:⁷

• Stabilize patient and perform primary and secondary survey
• Irrigate amputated part and injury site with saline and wrap in moist sterile gauze
  • Palpate for obvious foreign body
  • Place amputated part in bag; place this in water with crushed ice
    • Direct contact with ice can cause irreversible damage to cells⁷
  • Limit handling of amputation when possible
  • Administer cefazolin 2 grams or clindamycin for penicillin allergy^7,8
    • No difference in infection rates (antibiotics vs. none) if injury is a fingertip amputation with planned surgical management⁹
  • Tetanus prophylaxis
  • Analgesics – Local vs. systemic
    • Local
      • Digital blocks
        • Lidocaine 1% vs. Bupivacaine 0.5%
    • Systemic
      • May consider when multiple injuries or insufficient analgesic effect with digital blocks
      • Fentanyl, hydromorphone, or morphine
  • Early hand surgery consultation
  • General indications for replantation¹⁰
    • Thumb
    • Multiple digits
    • Single digit distal to the insertion of the flexor digitorum superficialis tendon
    • Pediatric amputations
  • General contraindications for reimplantation¹⁰
    • Severe crush/avulsion injuries
    • Single digit proximal to the insertion of the flexor digitorum superficialis tendon
    • Prolonged ischemic time
  • Reimplantation counseling
    • 80% viability after reimplantation¹⁰
    • ~50% motion compared to normal¹⁰
    • Requires prolonged physical therapy (PT)

Disposition:

• Admit for patients with infection or if patient will undergo reimplantation
• Discharge those with controlled bleeding and distal phalanx amputation

Pearls:

• History involves mechanism, cold/warm ischemic time, tetanus, hand dominance, medical issues
• Imaging should include amputated part
• Place amputated part in moist gauze, avoid direct ice contact
• Consider both systemic and local analgesics
• Early surgical consult
• Council patient on realistic outcomes, 80% viability, 50% motion and prolonged PT