Zone 1 Flexor Injuries


- See:
      - FDP Avulsion
      - FDP Lacerations
      - tendon pull thru technique

       

- Anatomy:
      - in zone 1, FDP has emerged from between & beneath decussating FDS and travels to its insertion in the distal phalanx;
      - zone 1 contains: A4, C3, and A5 pulley;
             - A4 pulley must be preserved, otherwise the majority of active PIP flexion will be lost;

- Injury Pattern:
      - most injuries are due to lacerations, but traumatic rupture from phalangeal attachment may occur; (see: FDP avulsion:)

- Exam:
    - when FDP is divided in zone 1, there is loss of active flexion of distal phalanx, as well as a hyperextension instability of distal IP joint;
           - this results in instability, esp when these injuries are in index & middle figners, because w/ unstable pinch, pts tend to drop things easily;
    - if tendon has retracted into the proximal finger or palm after rupture or laceration, pt will be unable to actively move distal phalanx;
           - dx is made by asking him to flex distal phalanx & watching level of ability to flex digit;
    - if proximal end of flexor profundus becomes caught at the level of sublimis chiasm, it may affect the range of activemovement at PIP joint;
           - in this area repair may be delayed upto 3 weeks;
           - if tendon is held by vinculum, some active flexion may be possible;
           - if tendon has retracted into the palm, it is difficult to reattach stump if injury is beyond 10 days old;

- Treatment Options for Zone 1 Lacerations:
    - treatment may consist of direct repair or tendon advancement;
    - for tendon lacerations w/in 1 cm of insertion, profundus tendon can be advanced and attached to the distal phalanx;
    - for clean, fresh, sharp lacerations more than 1.5 cm away from the insertion, primary tenorrhaphy is the treatment of choice;

- Surgical Technique:
    - wound edges are extended, debrided, and irrigated;
    - proximal tendon edge of tendon is identified;
         - typically the proximal tendon edge can be found just proximal to the PIP joint and is restrained by the viniculum;
         - it may be necessary to open either the C2 or C1 pulleys for tendon retrieval;
    - distal tendon edge
         - if digit was flexed at time of injury, then distal tendon stump will be short;
         - determine how far the laceration is to the insertion of the tendon;
    - tendon exposure and opposition:
         - w/ an especially short distal tendon stump, open the C3-A5 sheath;
         - through the appropriate proximal window (C2 or C1), a core suture is placed;
         - this core suture is then passed underneath the A4 pulley, and subsequently the proximal tendon stump is passed proximally;
                - the tendon is temporarily anchored by passing a 25 gauge needle thru the annular pulley;
    - tendon repair:
         - if laceration is more than 1 cm from insertion, perform primary repair using standard repair techniques;
    - tendon advancement:
         - see tendon pull thru technique

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Tenodesis for Restoration of Distal Interphalangeal Joint Flexion in Unrepairable Flexor Digitorum Profundus Injuries



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

Last updated by Data Trace Staff on Thursday, January 2, 2014 10:21 am