Tendon Injuries of the Thumb

- See:
      - Excursion, of Tendons
      - Thumb Deformities in Rheumatoid Arthritis
      - Thumb Soft Tissue Defects
      - Flexor Pollicis Longus
      - Extensor Pollicis Longus

- Tendon Sheath Anatomy:
    - A1 pulley: spans the MP joint, approximately 8 mm in width;
          - note that the FPB inserts just proximal to this pulley and the adductor pollicis inserts distal to the A1 pulley;      
    - oblique pulley: located over the mid aspect of the phalanx, approximately 10 mm in width;
          - note that the adductor pollicis partially inserts into the oblique pulley;
    - A2 pulley located at the most distal aspect of the proximal phalanx, and is 9 mm in width;
          - it may partially span the thumb IP joint;

- Zone 1 Flexor Tendon Injuries:
    - in thumb, zone 1 extends from tip of finger to just distal to IP joint;
          - contains, oblique and A2 pulleys;
          - of these, the oblique is more important, but either can be sacrificed if the other remains intact;
    - most tendon injuries of thumb occur at level of IP crease, which is near point of the FPL insertion;
    - exposure:
          - skin laceration needs to be extended both proximally and distally;
          - flexor tendon sheath is "Z" step cut so that edge of the resected sheath lies about 1 cm beyond excursion of thickened area of sutured tendon;
    - tendon retrieval:
          - first, note that FPL tendon lacerations often retract into the thenar area or wrist;
                 - unlike the fingers, the FPL often lacks a vinculum and does not have a lumbrical, and therefore the tendon is free to retract;
                 - when there is tendon retraction, the tendon must be retrieved at the wrist;
          - second, note that the FPL tendon sheath is narrow in the thenar region, and therefore, passage of the tendon thru the sheath can be frustrating;
                 - it is important to avoid "scuffing" of the tendon edge as it is pulled thru the tunnel;
          - pass a curved tendon grasper retrograde through the FPL tendon, and insert a core grasping suture into the free edge of the tendon;
                - the tendon grasper is then used to pull the suture back thru the tunnel;
    - delayed reconstruction: FPL Advancement and Pull Thru

- Zone 2 Flexor Tendon Injuries:
    - over thenar eminence, injuries to FPL tendon are likely to occur in conjunction w/ injuries to thenar muscles & recurrent branch of median nerve;

- Tendon Transfers:
    - the following  musculotendinous units have adequate exursion (muscle amplitude), but lack tension strength based on cross sectional area: EPL, EIP, PL;
          - muscles that replace strength and excursion are the following
          - FDS to the long and ring fingers, ECU, and ECRL

Restoration of flexor pollicis longus function by flexor digitorum  superficialis transfer.

Flexor superficialis tendon transfers to the thumb--an alternative to the free tendon graft for treatment of chronic injuries within the digital sheath.

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Friday, December 21, 2012 2:35 pm