Operative techniques

Ideally, two teams are mobilized. One team addresses the amputated part and the other team addresses the distal stump. A decision is made regarding orientation of incisions on the stump and the amputated part. While the patient is being prepared for surgery, the amputated part is debrided and cleansed. Vessels and nerves are tagged. Locking sutures are placed in tendons and bone is prepared for fixation (see Fig. 1). This dissection should be performed with the assistance of x3.5 loupe magnification at a minimum. If the amputated part is considered to be favorable for replantation, the replantation effort continues. If not, the timing for revision amputation is less urgent and the operative staff is appropriately informed.

After anesthesia has been induced, and appropriate vascular access and monitoring has been established, one lower extremity and the injured extremity are isolated in the operative field. The lower extremity serves as a potential donor site for vessels and nerve and skin grafts. The second team reciprocates the identification and tagging of structures on the distal stump. Debridement is the single most important step in reconstructions for two reasons. First, a thorough debridement performed by the most senior member of the team determines if the replantation effort is feasible. Second, if the replantation effort is deemed to be worthwhile, then the debridement will determine what donor tissues may be necessary and what modifications will be needed. Both teams coordinate the bone shortening, essential to minimizing tension on the reattached structures. With sharply cut tidy amputations, the amount of shortening is routinely 2.5 to 3.5 cm, and with crush avulsion injuries, even greater amounts of shortening are required.

Preliminary fixation with Kirschner wires, small plates, or simple external fixators is undertaken while definitive fixation is determined by the urgency for revascularization. Reestablishment of arterial inflow becomes the principal concern as muscle death proceeds inexorably. Reestablishment of arterial inflow is performed straightaway in those cases with ischemic times greater than 6 hours, whereas in cases with ischemic times less than 6 hours definitive rigid internal fixation is performed before proceeding to revascularization.

Angiocatheters, ventriculoperitoneal shunts, or Sundt's carotid shunts can be used to cannulate the ends of the transected arteries as a temporizing conduit to reroute oxygenated blood to the muscles of the distal forearm and the hand. This minimizes the time of ischemia and also serves to flush out toxins that have accumulated in the amputated part.

With shunts in place, attention is then directed toward meticulous debridement followed by definitive bony fixation. Skin is cut back to bleeding edges. Similarly, muscles are debrided until bleeding is encountered in the stump. If the viability of muscle cannot be determined because of broad crush injury, the replantation effort is ill advised. In the amputated part, muscle attached to tendon alone is removed. Nerve ends are cut back to identifiable fascicles. Vessels are cut back until the intima is free of injury, adherent to the muscu-laris, and clots can be easily removed from the lumen. The venae commitantes of wrist-proximal amputations, although flimsy, are usually 2 to 3 mm in diameter and should be identified for later repair. This is especially necessary when the dorsal skin has been subjected to extensive crush. These venae commitantes may represent the only reliable venous outflow. The amputated part is flushed with a dilute solution of heparin delivered through one of the arteries using a small-bore catheter. Copious and frequent irrigation of the exposed tissues is repeated throughout the debridement and the remainder of the procedure. We rarely use jet lavage irrigation, choosing instead to use 3-L bags of normal saline elevated to 6 feet and delivered through wide-bore "cysto" tubing. Paraphrasing their combined thoughts, Godina [10] and Rockwell and Lister [11] emphatically state that ''upon completion of a single aggressive de-bridement the wound should resemble that created for tumor resection.'' If this axiom cannot be met, then the replantation effort should be aborted. If the debridement leads to large open wounds, but a potentially functional limb, then consideration should be given to early if not immediate free-tissue transfer.

Fig. 4. Illustrations of radiocarpal (A), forearm (B), and arm-level amputations (C) stabilized with the appropriate length plates and screws. We prefer rigid internal fixation to other methods of fixation for this level of injury.

Temporary fixation is converted to rigid internal fixation with plates and screws in deference to external fixation, K-wires, Steinmann pins, or tension bands [12]. We prefer wrist fusion plates for radiocarpal level amputations, 3.5-mm dynamic compression plates for forearm level amputations, and 4.5-mm dynamic compression plates for arm-level amputations (Figs. 4 and 5A, B).

The sequence of repair from this point on is from deep to superficial (Fig. 5C). Motor units are repaired with braided nonabsorbable sutures, using a locking four-strand technique. The profundus tendons of the fingers are tenodesed and repaired to the profundus muscle belly of the middle ring and small finger. The profundus to the index may be added to these or used to power the flexor pollicus longus (FPL) tendon in cases where the FPL muscle belly has been avulsed from the radius. Flexor digitorum superficialis tendons are repaired to their respective muscle bellies as are the wrist flexor tendons. The extensor tendons to the fingers are tenodesed and sutured to proximal muscle bellies as is the extensor pollicus longus. If no motors are available, the tendons are left in the floor of the wound with the anticipation of later reconstruction using an innervated free muscle transfer.

In those cases where a temporary shunt was not used, the operative microscope is now introduced into the field and final vessel preparation is performed. If vessel grafts are deemed necessary they are harvested at this time. Shunts, when used, are now removed and definitive anastomoses performed. In major wrist-proximal replantations arterial reconstruction should precede venous repair. The arterial repair is released and the accumulated lactic acid and toxins are flushed out through the transected veins. The exact time that an amputated part needs to be flushed is unknown but, from our experience, the time required to set up and perform tendon repairs and complete the venous repair is adequate. Whenever possible the radial and ulnar arteries are repaired as well as their venae commitantes. If the venae commitantes repair was successful, then the median and ulnar nerve repairs are completed. If the venae commitantes repair was not successful, then dorsal veins are anastomosed before the median and ulnar nerves are repaired. There is one exception to this sequence and that is in the case of radiocarpal-level amputations, in which the ulnar nerve will be found deep to the ulnar artery in Guyon's canal and repair of the nerve should precede repair of the artery.

After arterial inflow has been reestablished, swelling of the hand and forearm should remind the surgeon that fasciotomies of the hand, forearm, and possibly the arm may be required. We perform hand and forearm fasciotomies straightaway in those patients with ischemia times greater than 8 hours and all arm-level replantations. The forearm fasciotomies include release of the superficial and deep volar compartments and the dorsal compartment. The hand fasciotomies include release of the hypothenar, thenar, and interossei muscles as well as the carpal tunnel.

Wounds are closed loosely with transposition flaps and skin grafts. If the outcome of the replantation is questionable, allograft skin is used. If the limb survives, the allograft is replaced with autograft after 5 days.

To prevent a first web space contracture, a two-pin fixator bridges the first web (Fig. 5D). This fixator is removed 4 weeks later. The extremity is immobilized with the elbow flexed at 90 degrees, the forearm in neutral, and the wrist in slight extension. The fingers are blocked in slight flexion at the metacarpophalangeal joints and the interphalangeal joints are immobilized in extension. Soft dressings are applied loosely and the extremity immobilized with volar and dorsal splints.

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