Staged Digital Flexor Tendon Reconstruction



Staged Digital Flexor Tendon Reconstruction


Sebastian C. Peers

Kevin J. Malone





ANATOMY



  • Flexor tendons can be divided into five zones (FIG 1A).


  • Bunnell originally described the region between the A1 pulley and the FDS insertion, zone II, as “no man’s land” because the initial results after attempted primary tendon repair were so poor he felt that no one should attempt this procedure.


  • In the limited confines of zone II, the two flexor tendons function together and rely on the digital sheath and its frictionless synovial interface for gliding and proper function.


  • Another complicating anatomic characteristic of zone II is the chiasm of Camper. Here, FDP passes through the slips of FDS, creating another potential region for adhesions (FIG 1B).






FIG 1A. The five flexor tendon zones of injury. B. The decussation of the flexor digitorum sublimus produces the chiasm of Camper. Both the flexor digitorum sublimus and FDP receive their blood supply via the vinculum longus and brevis.


PATHOGENESIS



  • Zone II has the highest probability of developing adhesions and the poorest prognosis after repair.


  • Violation of the sheath, the lining, or the blood supply to the tendons by trauma or infection may lead to dense scar and adhesion formation and can compromise the results after either a primary repair or an attempt at single-stage reconstruction with a tendon graft.1


NATURAL HISTORY



  • Flexor tendon injuries that are not reconstructed can progress to a stiff and sometimes painful digit.


  • If both tendons are not functional, no active proximal interphalangeal (PIP) or distal interphalangeal (DIP) motion will be possible, but if only the FDP tendon is disrupted, active PIP flexion will be present.


  • If a digit with incompetent flexor tendons is subjected to repeated extension stress, as in pinch, the volar supporting structures will become lax over time, leading to hyperextension and an unstable joint.



PATIENT HISTORY AND PHYSICAL FINDINGS



  • The examiner should elicit information about the initial injury, such as when it occurred and if there were associated injuries (fractures, laceration of digital nerves or vessels).


  • The examiner should determine when the patient first noticed a decrease in the function of the digit (if flexor tendon repair has already been attempted).


  • Staged flexor tendon reconstruction is contraindicated in the setting of an active infection, and for that reason, an infection history must be sought.



    • If an infection is identified, it should be treated aggressively with antibiotics and débridement to minimize the destruction of the flexor tendon sheath from the inflammatory process.


  • Tests for tendon function include the following:



    • Finger cascade: Loss of the normal cascade suggests disruption or loss of function of the flexor tendons.


    • FDP examination: Loss of active DIP flexion suggests disruption or loss of FDP function.


    • FDS examination: Loss of active PIP flexion suggests disruption or loss of FDS function.


    • Tenodesis effect: Loss of the tenodesis effect suggests disruption of the flexor tendons.


  • It is also important to assess the vascular supply and the digital sensation to determine if there is a concomitant injury to the digital neurovascular structures.


  • Both active and passive range of motion must be recorded for the metacarpophalangeal (MP), PIP, and DIP joints.



    • If contractures are present, as evidenced by decreased passive joint motion, intensive therapy should be initiated before proceeding with staged flexor tendon reconstruction.


IMAGING AND OTHER DIAGNOSTIC STUDIES



  • Radiographs should be obtained to rule out fractures or other associated injuries to the hand and digits.


  • Ultrasound or magnetic resonance imaging (MRI) can be used to help localize the site of tendon rupture and position of the proximal stump if not clear by clinical examination.




NONOPERATIVE MANAGEMENT



  • There is no acceptable nonoperative management for combined FDS and FDP tendon lacerations. Alternatives to staged flexor tendon reconstruction include arthrodesis and amputation.


  • Isolated chronic disruption of the FDP tendon with an intact FDS tendon is best treated nonoperatively. Attempts at reconstruction of the FDP tendon risk function of the FDS tendon.


  • Buddy taping or trapping of the injured finger by an adjacent figure during finger flexion may allow concealment of the functional deficit between stage 1 and stage 2 or in the patient who is not a candidate for staged tendon reconstruction.


SURGICAL MANAGEMENT



  • Indications for two-stage flexor tendon reconstruction include the following:



    • Loss of FDP and FDS


    • Protective sensation


    • Nearly full passive range of motion


    • Good-quality skin in the region of zone II


    • A cooperative patient willing to participate fully in rehabilitation


  • The patient will need to have access to a good hand therapist before and after each of the stages of this complex reconstructive process.


Preoperative Planning



  • For the second stage of the procedure, a tendon must be harvested to use for the reconstruction. Often, a palmaris longus graft is used. If the patient does not have a palmaris longus, then a long toe extensor or plantaris tendon can be used. In this situation, the lower extremity must also be prepared out into the surgical field.


  • As an alternative to a traditional free tendon graft, the proximal end of the lacerated FDS may be used as graft. Paneva-Holevich7 first described this technique in 1965. It has since been refined and is described as the modified Paneva-Holevich technique6 in this chapter. If this technique is selected, the proximal tendon stumps of FDS and FDP are sutured together in the shape of a “loop” during the first stage.


Positioning



  • For both stages of the procedure, the patient is placed supine on the operating table with the arm abducted on a hand table. A nonsterile tourniquet is placed around the upper arm for hemostasis.


Approach



  • Stage 1: A volar Brunner incision is made over the flexor tendon sheath and extended proximally into the palm. A second incision is made in the distal forearm to ensure placement of the rod within the carpal tunnel.


  • Stage 2: A limited Brunner incision is made at the level of the distal junction of the repair. A separate incision is made at the level of the proximal junction of the repair. This can be the same incision in the distal forearm as in stage 1 if the tendon graft is long enough. Alternatively, the proximal junction will be in the palm with shorter tendon grafts. A third incision or set of incisions will be made for the tendon harvest. If the modified Paneva-Holevich technique is used, a third incision at the musculotendinous junction of the FDS tendon is used.



Jul 22, 2016 | Posted by in ORTHOPEDIC | Comments Off on Staged Digital Flexor Tendon Reconstruction
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