Flexor tendon repair

Zone I

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  When the flexor profundus tendon has been injured in zone I at or near its insertion, approach the distal end of the finger by extending the laceration with an oblique incision into the central portion of the pulp or through a midradial or midulnar incision.

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  Avoid injury to the terminal branches of the digital nerve and avoid devascularizing any skin flaps that are elevated. Usually, the insertion of the flexor profundus is easily seen. At times, the proximal stump of the tendon will have retracted very minimally.

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  Extend the incision proximally using a volar zigzag (Bruner), midradial, midulnar, or midline oblique incision. Avoid injury to the neurovascular bundles.

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  Elevate the skin flap. The neurovascular bundle is generally allowed to remain in place while the elevated skin envelope is retracted to the opposite side.

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  Expose the fibroosseous flexor sheath. If the proximal end of the tendon can be seen, attempt to deliver it into the wound by grasping it with a small forceps such as an Adson or a finer tissue forceps. If the tendon has retracted more proximally, extend the incision as needed in a midradial or a midulnar incision or by extending the skin incision in a volar zigzag or midline oblique incision, avoiding injury to the neurovascular bundle ( Fig. 36.3 ).

  

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  Open the thin cruciform portion of the sheath to assist in delivering the tendon. Open the sheath by an L-shaped incision or with a trapdoor with a Z-plasty arrangement to allow easier closure if needed.

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  If the tendon has retracted, place a grasping suture in its end using one of the techniques previously described. When exposing the flexor sheath over the middle phalanx, the A4 pulley may be preserved if it does not interfere with the repair or with tendon gliding. It has been found that 1.5 to 2 cm of release of the flexor sheath will not cause bowstringing as long as the remainder of the pulley system is intact. The A4 pulley may be released entirely if necessary.

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  Repair of the terminal tendon may be performed by a variety of methods. If enough distal tendon remains near its insertion, perform a standard flexor tendon repair with four to eight core strands and a supplemental epitendinous suture. Sutures commonly used include 4-0 FiberWire, looped 4-0 Supramid, and 5-0 or 6-0 Prolene for an epitendinous stitch.

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  If the tendon injury is very distal with only a small remaining stump, repair the proximal end with a suture anchor in the distal phalanx or with a pull-out suture tied over a padded button on the dorsum of the distal phalanx. For more secure fixation, combine anchor fixation with a pull-out suture. We often use Arthrex Nano Corkscrew anchors with 3-0 FiberWire (Arthrex, Naples, FL).

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  After ascertaining satisfactory rotation and attachment of the tendon, close the wound with fine 4-0 or 5-0 monofilament nylon sutures.