Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Hand Anatomy and Examination

Basics
Description
  • The hand is a unique organ that allows humans to work and to create.
  • The hand can be conveniently divided into the palmar (volar) and dorsal parts.
  • The volar portion of the hand contains the major digital nerves, the flexor tendons, and the muscles that allow finger movement.
  • The bony architecture is complex: The distal surface of the radius (the major portion of the wrist); 8 carpal bones; 5 metacarpals; 3 phalanges for each of the fingers; and a proximal and distal phalanx for the thumb.
Diagnosis
Signs and Symptoms
Physical Exam
  • General considerations:
    • Examination of the hand is extremely complex.
    • It is essential to understand the anatomy and biomechanics of the hand.
    • An examiner should have his or her own system of examining the key components of hand anatomy and function.
  • Vascular assessment:
    • Palpate the radial and ulnar arteries (Doppler examination as needed).
    • Examine the digital arteries using a Doppler technique.
    • Check the capillary refill in each finger (should be <2 sec).
    • Some hand surgeons examine individual digits by measuring the temperature of fingers and by placing a pulse oximeter to measure oxygen saturation.
    • Perform the Allen test to check the competence of the palmar arch:
      • Press firmly on radial and ulnar arteries and have the patient open and close the fingers actively several times.
      • Take pressure off 1 artery and observe for vascular refill in the digits within 15 seconds. (A slow or absent refill suggests vascular obstruction or an incomplete arch.)
  • Neurologic assessment:
    • Check the median nerve.
      • Examine the sensation on the volar tip of the thumb.
      • Perform a 2-point examination (normal: <5 mm).
      • Ask the patient to appose the thumb to the little finger to test the motor function of the median nerve.
    • Check ulnar nerve.
      • Examine the sensation on the volar tip of the little finger.
      • Ask the patient to cross the fingers (the motor branches of the ulnar nerve innervate the intrinsic muscles of the hand) to test the motor function of the ulnar nerve.
    • Check radial nerve.
      • The radial nerve has no motor branch in the hand.
      • The sensation of the radial nerve is tested on the dorsal aspect of the hand in the first web space.
  • Assessment of bones, tendons, and ligaments:
    • Each bone is palpated to rule out a fracture.
    • Swelling can be variable.
    • Check each joint for active and passive ROM:
      • IP thumb joint: Normal ROM, 0-80°
      • MCP thumb joint: Normal ROM, 0-50°
      • DIP and MCP finger joints: Normal ROM, 0-90°
      • PIP finger joints: Normal ROM, 0-100°
      • Wrist: Normal values, 80° of flexion and 70° of extension
Tests
  • Tinel sign:
    • Percussion over the median nerve at the wrist produces numbness, tingling, and pain in the thumb and index and middle fingers.
    • Test for CTS.
  • Phalen test:
    • Flexion of the wrist completely for 1 min produces numbness, tingling, and pain in the hand.
    • Test for CTS.
  • Aspiration of the wrist joint (2 approaches):
    • Dorsal approach: Insert a needle between the 3rd compartment (extensor pollicis longus) and the 4th compartment (extensor digitorum communis and extensor indicis proprius).
    • Palpate the Lister tubercle (bony prominence in distal radius) and introduce the needle just distal to it; flexing the wrist facilitates entry.
  • Finkelstein test:
    • Passive hyperflexion of thumb MCP and IP joints (thumb in fist) with ulnar deviation of wrist causes pain over abductor pollicis longus and extensor pollicis brevis.
    • Test for de Quervain tenosynovitis.
  • Grind test:
    • Hold the proximal phalanx and the MCP joint and forcefully push against the trapeziometacarpal joint.
    • Pain during this maneuver is consistent with arthritis in the trapeziometacarpal joint.
Imaging
AP, lateral, and oblique radiographs should be obtained as the 1st step in imaging.
 
Miscellaneous
FAQ
Q: What structures run through the carpal canal? What is released in carpal tunnel surgery?
A: The long finger flexors and the median nerve are contained in the carpal canal. The transverse carpal ligament, which forms the roof of the carpal tunnel, is released during carpal tunnel surgery.
 
Q: What ligament injury predisposes to a dorsal intercalated segment instability deformity and/or a wrist with a scapholunate dissociation advanced collapse pattern of arthritis?
A: The scapholunate ligament, when injured, causes a diastasis of the scaphoid and lunate, a resultant dorsal intercalated segment instability deformity, and likely a wrist with scapholunate dissociation advanced collapse.

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