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Flexor Tendon Reconstruction: Proximal Tendon Anchorage

- Discussion:
    - it is essenital to accurately determine the optimal tension to be applied to the motor unit;
    - use the relaxed natural cascade of the fingers to assist in determining the optimal tension;
    - most often the tendon graft is sutured to the proximal FDP in the mid palm, distal to the origin of the lumbrical;
    - consider using a Pulvertaft weave to join the tendons; (see tendon repair)
           - have fine misquito hemostat ready for this stage;

- Technique:
    - apply traction and test excursion and motion of IP joints are tested;
    - mid-palmar anastomosis:
          - indicated when the palm is free of substantial injury and scar and the proximal end of the profundus tendon remains in the palm;
          - advantages: palmaris longus is usually long enough (no need to additional graft harvest);
          - proximal tenorrhaphy is performed in the palm with a Pulvertaft weave technique with 4-0 Mersilene, keeping the lumbrical muscle free of the tenorrhaphy;
          - end to end or "button hole" suture is performed in palm proximal to origin of the lumbricals;
          - if proximal graft is placed distal to the origin of the lumbricals and if graft is placed slightly loose, the finger may develop a lumbrical plus deformity (where as overtightening can cause quadriga);
          - tendon graft is then sutured to the muscle belly, w/ muscle belly at half resting length & w/ wrist in neutral position;
          - alternatively, avoid the occurance of a lumbrical plus finger by dividing the lumbrical either in the palm or more distally at the radial band;
    - proximal (forearm) anastomosis:
          - indicated when the palm is heavily scarred and/or the proximal end of the profundus tendon is retracted proximal to the palm;
          - disadvantages:
                 - typically the palmaris longus is not long enough and surgeon may have to use plantaris or toe extensor for extra length;

- Complications:
    - tendon shortening:
            - in primary repair, musculotendinous unit can compensate for shortening as much as 1 cm;
    - excissive tendon lengthening:
            - a common complication is to leave the tendon too long;
            - this produces a lumbrical plus finger;
            - lumbrical plus finger can also be seen in unrepaired lacerations of flexor profundus and amputation of the distal phalanx;
            - this is manifested by intrinsic plus attitude in involved finger on attempted flexion w/ MP flexion there will be IP extension (Paradoxical Extension);
            - if several weeks have passed before this condition is noted, the radial lateral band may become adherent to the adjacent tissues;
                   - in this case, revision of the tendon repair will not correct the adherence of the lateral band;
                   - the adherent lateral band must be released in order to restore PIP flexion

Staged flexor tendon reconstruction fingertip to palm.