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Introduction
  • Indications
    • decompression of median nerve
    • flexor tendon synovectomy
    • carpal tunnel tumor excision
    • carpal tunnel nerve and tendon repair
    • drainage of sepsis tracking up from the mid-palmar space
    • ORIF of fxs and dislocations of distal radius and carpus
      • especially volar lip intra-articular fxs
 
 
Preparation
  • Anesthesia
    • local (most common)
    • regional
  • Position
    • patient supine on table
    • supinate operative arm and place on armboard with palm facing up
  • Tourniquet
    • exsanguinate arm
 
Internervous Plane
  • Distal
    • no internervous plane
    • no muscles are transected
      • APB and palmaris brevis fibers that cross the midline can occassionally be dissected  
    • true anatomic dissection
      • major nerves identified, dissected out and preserved
      • plane of dissection between median nerve and FCR

 

 

 

 
Approach
  • Incision
    • landmark
      • thenar crease
    • make incision just ulnar to the thenar crease in hand and ulnar to palmaris longus in wrist
      • begin 4cm distal to flexion crease
      • make ulnar curve so you dont cross perpendicular to flexion crease
        • also helps protect palmar cutaneous branch
      • end 3 cm proximal to flexion crease

  • Superficial dissection
    • incise skin flaps
    • incise fat
    • section fibers of superficial palmar fascia in line with incision
    • retract curved flaps medially to expose insertion of PL into flexor retinaculum
    • retract PL tendon toward ulna to expose median nerve between PL and FCR
    • pass a blunt object between median nerve and flexor retinaculum.
    • incise entire length of retinaculum/transverse carpal ligament on ulnar side of nerve

  • Deep dissection
    • identify motor branch of median nerve (anterolateral side of median nerve as it emerges from carpal tunnel)
    • if require access to volar aspect of wrist joint
      • mobilize median nerve and retract radially (so you dont stretch motor branch)
      • mobilize and retract flexor tendons
      • incise base of carpal tunnel longitudinally

  • Extension
    • Indications
      • to further expose median nerve
    • Proximal
      • extend incision up middle of arm
      • incise deep fascia between PL and FCR
      • retract PL (ulnarly) and FCR (radially) to expose FDS
      • median nerve adheres to deep surface of FDS
   



Dangers
  • Palmar cutaneous branch of median nerve
    • arises 5 cm proximal to wrist joint
    • runs ulnar to FCR before crossing flexor retinaculum
    • greatest threat when you do not curve your incision ulnar
  • Motor branch of median nerve
    • significant anatomic variation
    • risk to nerve minimized if incision through retinaculum made ulnar to median nerve
  • Superficial palmar arch
    •  crosses palm at level of distal end of outstretched thumb
    • in danger if flexor retinaculum blindly cut (can go too far distally)
    • avoid injury if retinaculum cut under direct observation for its entire length
   
 

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