4. repair flexor and extensor tendons;
5. anastomose arteries;
6. repair veins;
7. anastomose veins; and
Dissection of the amputated part can proceed ahead of the amputation stump. When this is possible, it is useful to perform as much of the surgery as possible with debridement, tagging of the vessels, bone shortening, placement of tendon sutures, and placement of skeletal fixation while the patient is readied for surgery. A second surgical team can begin dissection of the amputation stump in a similar manner to speed the process.
In the digits, incisions are made longitudinally just dorsal to the midlateral lines. This allows reflection of dorsal and volar flaps to identify all structures. For more proximal injuries incisions provide exposure, but the surgeon must not close these incisions upon completion of the replantation. Thus, incisions are directed away from areas where anastomoses are planned. The initial dissection of the proximal stump is generally performed under tourniquet control to allow the surgeon to accomplish the initial surgical steps faster than can be accomplished in a bloody field.
Bone shortening is accomplished to allow resection of the zone of injury so that the injured structures can be repaired primarily when possible. Bone shortening provides for better skin closure without tension. The amount of bone resection depends on the level of injury. In the digit, it is usually necessary to resect 0.5-1.0 cm of bone. Amputations of the forearm or arm require at least 2-4 cm of bone resection. For phalanges and metacarpals, I prefer using 2 Kirschner wires for fixation. When the proximal stump is grossly contaminated and additional procedures are required before replantation, more rigid fixation devices such as plates and screws are more time-consuming and less amenable to reapplication if additional bone shortening is required after initial hardware placement. Amputation through an interphalangeal joint is generally fixed by fusing the joint in a functional position. For amputations through the carpus, I prefer a proximal row carpectomy stabilized by Kirschner wires. In the forearm and arm, I prefer plate fixation.
The tendon sutures can be placed separately in advance and tied after bone fixation is completed. I prefer to use 3-0 braided polyester with an extra grasping loop to provide a stronger repair, permitting institution of early range of motion in the postoperative period67 (Fig. 4.8). If the tendon stock is of poor quality, then repair of only one flexor tendon may be preferable; however, repair of all tendons is accomplished whenever possible.
The operating microscope is used to repair arteries, nerves, and veins. Arterial repair is performed after deflation of the pneumatic tourniquet. The damaged ends of the artery are resected back until normal vessel is identified. If segmental damage has occurred, then an interpositional vein graft may be required. Potential donor vessels for grafting include volar or dorsal veins about the wrist, the dorsum of the foot, material from nonreplantable parts, and for larger vessel repairs, the saphenous vein.
Good blood flow should be confirmed from the proximal vessel. If inadequate arterial flow is evident, then several problems may be present and each potential cause should be evaluated. Retracted skin flaps may kink the proximal vessels. A proximal blood clot may block the artery; this can be dislodged by dilation and irrigation or even a small catheter. The vessel may be in spasm. For spasm, local dilating agents such as papaverin, 20% lidocaine, or application of a more proximal sympathetic block can be used to alleviate the spasm. I prefer to inject bupivicaine 0.5% into the wrist to block the median and/or ulnar nerves for digital replants. The patient may require hydration and elevation of the blood pressure.
After preparation of the arterial ends, they are irrigated with a dilute heparin solution to prevent adherence of platelets and clotting factors. Vascular repair is then accomplished with interrupted nylon sutures. For distal digital repair, 10-0 Nylon monofilament suture is typically appropriate. Proximal digital repairs usually require 9-0 suture. For amputations at the level of the wrist and proximal, 8-0 suture generally is appropriate. While a minimum of one artery and one vein repair are required for each replant, it is preferable to perform two arterial and three-to-four venous repairs to increase the chances of survival.54-56 For multiple digital injuries, it may be beneficial to repair one artery in each digit, then repair a vein for each digit to restore circulation before completing the secondary repairs of the other vessels and nerves.
Unique circumstances for each trauma may limit the ability to perform a direct repair of the injured vessels. Arteries can be mobilized and transferred across the digit when a proximal vessel on one side of a digit is of good quality and the distal vessel is of good quality on the other side.
Before initiating the first arterial anastomosis, a bolus of 3000-5000 units of intravenous heparin is administered to prevent clotting at the anastomosis site. A running infusion of 1000 units per hour is then initiated and adjusted throughout the case depending on the patient's degree of bleeding. Heparinization is discontinued at least temporarily if the bleeding is excessive. After the initial assessment of the adequacy of the blood flow through the proximal arteries, the pneumatic tourniquet may be inflated for subsequent vessel repairs when hemorrhage is obscuring the operative field.
Venous repair is usually the most technically challenging part of replantation. An attempt is made to repair two veins for each arterial repair, although this is not always possible. The most common error with vein repair is performing the anastomosis under too much tension. This generally can be avoided with skeletal shortening, but an interpositional vein graft can be used if the veins cannot be mobilized sufficiently to have a tension-free anastomosis. In the digits, the dorsal veins are located in the subdermal plexus. In the amputated part, the collapsed veins may be difficult to locate. After arterial repair with engorgement, their location should be more readily apparent. Some surgeons prefer to perform venous repairs before arterial repairs, finding there is less blood loss and venous repair is easier in a bloodless field. With use of a pneumatic tourniquet during venous repair, this problem can be averted.
The literature describes several techniques that can be used when dorsal venous repair cannot be accomplished readily. These techniques include repair of small and thin-walled volar veins, anastomosis of one distal digital artery to a proximal vein, removal of the nail plate and application of heparin pledges to allow bleeding out of the nail bed, use of leeches, and periodic massage of the digit to enhance venous outflow.57-59 I rarely rely on these methods, because I find them unreliable.
Primary nerve repair is usually accomplished without difficulty with sufficient bone shortening. Three or 4 stitches of 8-0 or 9-0 Nylon suture provide adequate repair of digital nerves, but more sutures are required to repair major proximal nerves. Nerve grafts are used when direct repair cannot be accomplished. Donor nerve graft can be taken from nonreplantable digits, the medial antebrachial cutaneous nerve distal to the elbow, the posterior interosseous nerve above the wrist, or the saphen-ous nerve. While nerve repair is one of the simpler steps in replantation, the long-term function of the replant is largely dependent on nerve recovery.
Skin coverage is the final step in replantation. At this point, care must be taken to ensure that wound closure is without tension in order to avoid constriction of the delicate vascular repairs. Routinely, the midlateral incisions on the digits are not closed. Fasciotomies are indicated for proximal major limb replantations. Local rotation flaps are used to cover anastomoses with viable skin when required. Skin grafting is typically deferred to a second procedure 3-5 days after the initial replantation in cases of soft tissue loss.
Before applying the dressings, I routinely place an indwelling catheter percuta-neously adjacent to the median nerve to provide continuous infusion of 0.5% bupivicaine, which creates a sympathetic block limiting vasospasm postoperatively66 (Fig. 4.9). At the completion of the operation, the hand is dressed in layers with nonadherent petrolatum-impregnated gauze, followed by dry gauze and a plaster splint. Care is taken to avoid any constriction of the replantation by the dressing.
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