Evaluating Hand Injuries in the ED

Authors: Anthony Rodriguez, MD (EM Resident Physician, Denver Health); Spencer Tomberg, MD (EM Attending Physician, Denver Health); and Matthew Folchert, MD (Orthopedic-Hand Attending Surgeon, Denver Health) // Reviewed by: Alex Koyfman, MD (@EMHighAK); Manny Singh, MD (@MPrizzleER); Brit Long, MD (@long_brit)

A 35-year-old right hand dominant male presents to your ED with a deep laceration to his left pinky finger that occurred while working as a chef. He reports he has numbness to the palmer aspect of his left pinky finger, and as part of your musculoskeletal exam you evaluate for neurovascular and tendon injury. Prior to performing a digital nerve block to repair the laceration, you should evaluate the following

Perfusion

• Check capillary refill (should be less than 2-3 seconds)
• Attach a pulse oximeter to the injured digit
  • Should be ≥ 90% with a good plethysmogram
• Use a doppler to evaluate the radial & ulnar digital arteries
  • If you obtain a signal on the pulp, then the digit is being perfused
  • Make sure to check DISTAL to the laceration

Flexor Tendons

• Flexor Digitorum Profundus (FDP)
  • Mechanism: flexes the distal interphalangeal joint (DIP)
  • Evaluation: hold the proximal interphalangeal joint (PIP) in extension while the patient attempts to flex the DIP joint
• Flexor Digitorum Superficialis (FDS)
  • Mechanism: flexes the proximal interphalangeal joints (PIP)
  • Evaluation: hold adjacent fingers in extension while the patient attempts to flex injured finger at the PIP joint

Extensor Tendons

• Mechanism: extends/straightens the DIP and PIP joint
• Evaluation: ask patient to straighten the digit out.
• These tendons have lateral bands and a central slip near the PIP joint
  • Central Slip Evaluation:
• Have patient bend at the PIP and provide resistant distal to the PIP joint
• Ask patient to hold extension at the digit
• Normal result: DIP joint should remain loose
  • This is known as the “Elson Test”
• Abnormal result: DIP joint would become rigid
  • This is due to the force being transferred to the lateral bands down into the DIP joint, instead of through the central slip

Nerves

• If available, can use two-point discriminator tool
  • Normal sensation should be detected between 4-6 mm
• Otherwise, use a bent paper clip and measure 4-6 mm between points
• Start by assessing a non-injured digit or opposite hand to have a control result
• Always ask patients to close their eyes
• Begin with widest measurement and move towards shorter measurement
• Provide support to the digit being tested
• Make sure to test IN-LINE (or vertical) to evaluate a single nerve’s dermatome
  • Testing across (or horizontal) the digit can pick up-cross innervation from the adjacent digital nerve