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REPLANTATION


REPLANTATION
Replantation is defined as the reattachment of a completely severed part. The first successful replantation of an above-elbow amputation was reported in 1962 by Malt and McLehman. In 1965, Komatsu and Tamai reported the successful replantation of a thumb. The development of this type of microsurgery has been greatly aided by advances in optical instrumentation and especially in the manufacture of needles and sutures fine enough to repair vessels 1 mm in diameter or less. Replantation is not suitable or possible for all patients with amputations. Great care must be given to the assessment of patients and their requirements. The surgical technique is exacting and the postoperative care prolonged and difficult. However, with an experienced team and a well-informed and motivated patient, the procedure can produce good functional and cosmetic results.

Amputations and replantations are categorized as major or minor. A major amputation involves muscle and is treated differently from a minor amputation, which involves tendons but no muscle. Because both types of amputation require great expertise and special surgical techniques, patients with amputations should be referred to centers where such resources are available.

REPLANTATION

Indications
The decision to undertake replantation of a severed part is influenced by many factors, especially the level and mechanism of the amputation and, equally important, the needs and desires of the patient. There are no hard-and-fast rules to help in this decision. The patient and the family must be fully informed about the possible outcomes and consequences of replantation in terms of hospitalization, postoperative care, and hand therapy.
In a child, replantation of any amputation should probably be attempted. In adults, replantation is indicated for amputation of the thumb, multiple digits, hand, distal forearm, or single digit distal to the insertion of the flexor digitorum superficialis tendon. Replantation should be considered whenever the amputated part is crucial to hand function or when good functional restoration of the part can be expected.


Contraindications
The only absolute contraindication to replantation is a health condition, either a preexisting illness or associated injuries, that precludes a prolonged surgical procedure. Treatment of other severe injuries, which often accompany a major amputation, obviously takes priority over the replantation effort. Relative contraindications are numerous and can be either patient related or injury related.
Systemic Illness
Diabetes, renal failure in a patient treated with dialysis, generalized vascular disorders of the upper limb, and advanced connective tissue disease all reduce the likelihood of a successful outcome because of associated microvascular damage and possible vessel thrombosis.
Multiple Level Injuries
Replantation is rarely successful when there is wide- spread vascular damage due to multiple level injuries. If the injury is both above and below the elbow, however, every attempt should be made to save the elbow because the presence of the joint improves the function of a prosthesis.
Extreme Contamination
Replantation is contraindicated when both the stump and the amputated part have been inoculated with soil bacteria (particularly with Clostridium species). This degree of contamination is common in some farm injuries and in war injuries.
Age
The patient’s age alone is not a contraindication to replantation, but it must be taken into account. Although the tiny size of infants’ vessels reduces the chance that the replanted part will survive, the function gained by a successful replantation is often quite good. In elderly persons, useful or functional recovery is not a realistic expectation. Even in patients with mild degenerative joint disease, postoperative edema and the required postoperative splinting lead to stiffness in the whole hand. Therefore, replantation in an elderly patient must be carefully considered.
Amputation of Single Digit
Replantation of a finger amputated proximal to the insertion of the flexor digitorum superficialis tendon on the middle phalanx may be contraindicated because motion is limited by the severe scarring and tendon adhesions that develop after replantation. The index finger is not an essential finger; if the return of function or sensation after replantation is poor, the patient may prefer to use the normal adjacent middle finger for tasks usually accomplished with the index finger. A stiff little finger does not flex well in power grip, often catching in clothing. The benefits of replantation of either of these digits must therefore be carefully assessed.
Avulsion
The likelihood of successful replantation of digits or limbs torn from the body is poor because of the extent of injury and the amount of dissection needed to escape the zone of injury. A red line on the skin overlying the neurovascular bundle of a digit suggests an extensive avulsion of these structures and a poor chance of recovery. Ring avulsions are the most difficult avulsion injuries to replant. Even major vessel repair may not revascularize the devascularized flexor tendons and proximal interphalangeal joint; and although the finger may be successfully replanted, it often becomes stiff and atrophic. A revision amputation may be a better treatment choice, especially in the older patient.
Prolonged Ischemia
Either warm (32°C) or cold (5° to 10°C) ischemia seriously reduces the likelihood of a successful replantation. Unfortunately, studies have not yet shown what duration of warm or cold ischemia is critical. Most amputated parts sustain some warm ischemia until medical help arrives. Once the replantation procedure begins, the part goes through a second period of warm ischemia until vascular continuity is restored. Cooling (cold ischemia) to about 10°C clearly helps to preserve the amputated part. Given adequate cooling, major replantations have been successfully performed 8 to 16 hours after amputation and minor replantations have been successful even after 18 to 30 hours.


Preoperative Management
Treatment at the scene of the accident and at first medical contact strongly affects the outcome of later replantation. Improper handling of the amputated part or stump can seriously compromise the final result. The initial assessment of the patient’s status must exclude any life-threatening injuries, particularly if a major amputation is involved. The patient must be hemodynamically stable before either transportation or replantation is attempted.
Once the patient’s safety is ensured, the stump is cleaned of gross contamination and protected with a sterile compression bandage. Bleeding after amputation is rarely a problem because fully transected vessels usually contract. If bleeding persists, however, it should never be stopped with the blind application of a hemostat, because this may further damage the neurovascular structures. Elevation of the stump usually stops the bleeding. A tourniquet should not be used because unregulated pressure increases the risk of ischemia and vascular damage.
The severed part is cleaned of any gross contamination and foreign material and cooled to reduce its metabolic rate. A severed digit should be wrapped in moist gauze and placed in a watertight plastic bag, which is then immersed in ice water. The amputated part must not be allowed to come into direct contact with any ice, and dry ice should never be used. Properly cooled, a digit can be successfully replanted within 30 hours of amputation.
With a major amputation, preparation of the severed part is even more important. The amputated part is cleaned of all gross contamination, wrapped in a moist towel, and placed in a plastic bag. The part should be rapidly cooled to 10°C by immersing the plastic bag in ice water for 20 to 60 minutes. The part is then placed in an insulated container (but not in contact with the ice) and maintained at 10°C. Thus prepared, the amputated part is clearly labeled and rapidly transported to the replantation center.
Cold ischemia can preserve muscle up to 8 to 12 hours, after which irreversible changes may occur. Warm ischemia, which results from improper cooling, can lead to irreversible changes in as little as 4 to 6 hours, thus preventing successful replantation. Several attempts have been made to reduce ischemia time by perfusing the amputated limb with various substances such as oxygenated fluorocarbon solutions. At present, the most reliable fluid appears to be autologous arterial blood mixed with heparin. Perfusion plus cooling may make major replantations possible as much as 12 to 16 hours after injury.
In the emergency department, tetanus prophylaxis and a broad-spectrum antibiotic are administered as soon as possible. A complete history is obtained and a physical examination performed. Treatment options are thoroughly discussed with the patient and family. The decision to replant or to revise the amputation is based on the patient’s wishes, age, health, and occupation; the type and level of the amputation; ischemia time; associated injuries; and the surgeon’s experience.


Technique For Minor Replantation
Repair of Bone and Tendon
Ideally, every replantation center should have two surgical teams available at all times. Once the decision to undertake replantation is made, the severed part is taken to the operating room. While one team prepares the patient for surgery, the other team thoroughly debrides the amputated part, viewing it under magnification. All devitalized and heavily contaminated tissue is excised, including frayed tendon ends, comminuted bone fragments, but only a small margin of skin, because coverage is important and skin is more resilient than deeper tissues. Frayed tendon ends are excised because the damage to the exposed tendon surfaces greatly increases the risk that adhesions will subsequently form and restrict motion.
Bone is trimmed to (1) remove avascular bone that could initiate the development of osteomyelitis; (2) provide flat, congruent surfaces for stable bone fixation; and (3) provide the necessary skeletal shortening to facilitate tension-free vessel anastomoses and nerve coaptations after debridement. At the digital or metacarpal level, the bone may be shortened about 1 cm. In the arm or forearm, the amount of bone shortening may be as much as 2 to 4 cm.
A severed part can be handled more easily while it is detached from the body. An interosseous wire or a Kirschner wire can be placed in the bone of the amputated part to facilitate later fixation. A tendon suture of the Kirchmayr type (modified Kessler) can also be inserted at this time. The distal arteries, veins, and nerves are identified and tagged with fine sutures. Skin incisions are usually needed to expose these structures. The volar aspect of the finger is usually opened with a Brunner zigzag incision. A straight midline incision is made on the dorsal aspect. Only full-thickness skin flaps are reflected; the subcutaneous tissue and veins are left intact for later dissection under microscopic visualization.
While the amputated part is being prepared, the patient is transferred to the operating room and regional anesthesia is administered (preferably an axillary block). Regional anesthesia provides some sympathetic blockade and vasodilation as well as pain relief. The arm is cleaned with antiseptics, draped, and exsanguinated. The surgeon thoroughly debrides the stump, shortening the bone and tendon to permit easier anastomosis of vessels and coaptation of nerves. Use of a tourniquet facilitates the debridement. Once corresponding structures in the stump and the amputated part have been identified, replantation is begun. Because stability is essential for the vascular reconstruction, bone fixation is carried out first.
The technique of bone fixation should be appropriate for the type and level of amputation and provide stable fixation for early mobilization. Fixation devices include interosseous wires, Kirschner wires, and compression plates and should minimize further soft tissue disruption.
Replantation at the phalangeal level can be secured with interosseous wires with or without the added stability of a Kirschner wire; some surgeons prefer to use crossed Kirschner wires. Replantations at the joint level require a removable fixation device if the joint is to be preserved; otherwise, any standard technique for arthrodesis of small joints is suitable. At the metacarpal or more proximal level, a compression plate is preferred. If contamination is significant, however, an external fixator should be used to reduce the risk of infection. If possible, the periosteum is repaired to help bone healing and minimize adhesions to the flexor and extensor tendons. Kirchmayr (Kessler) sutures are used to repair flexor tendons, and interrupted figure-of-eight sutures are used for extensor tendons.
Repair of Blood Vessels and Nerves
After repair of bone and tendon, microvascular clamps are applied to the prepared arteries and veins, the tourniquet is released, and the blood flow is noted. This is the only way to assess arterial inflow. If arterial bleeding from the stump is not pulsatile after the arterial clamp is released, further resection of the artery is required to bypass the zone of injury. The distal artery and vein must be resected to remove all damaged tissue. Vein grafts are inserted to bridge the gap produced by the resection if the vessels cannot be anastomosed without tension. When used for repairing arteries, vein grafts are reversed so that valves do not impede the flow of blood. Repairing rather than resecting injured and compromised vessels to avoid use of vein grafts almost always ends in failure because thrombosis occurs almost immediately in these injured vessels.
The surgeon’s preference dictates whether repair of the arterial or the venous system is performed first. Generally, the arteries are repaired first to reduce ischemia time and to allow the surgeon to assess the adequacy of the venous debridement and determine which veins are best suited for repair. Ideally, both arteries and at least three veins are repaired in each digit.
Once the finger is revascularized, the nerves are repaired in standard fashion. Tendons are then repaired by tying the two core stitches in each end, adding a second core stitch and then an epitendinous repair. Then the skin is loosely approximated to avoid constriction of the vasculature when postoperative edema develops. Skin grafts or flap coverage should be used if primary closure is not possible and typically done secondarily within the initial hospital stay. For example, the lateral forearm rotation flap or free flow-through flap (see Plate 4-65) can be used to cover skin defects to the thumb after replantation. Use of normal skin and subcutaneous tissues from an uninjured zone brings excellent vascularity to the compromised digit.
Replantation of multiple digits is carried out in a similar sequence. One finger is completed at a time, while the other fingers are kept cold. However, nerve and tendon repair is often delayed until all digits are replanted and successfully perfused. If all the fingers are replanted together (i.e., bone fixation completed, then all tendons sutured, then blood vessels and nerves repaired), the prolonged duration of warm ischemia under the microscope lights may compromise the final result.
Postoperative Dressing
After replantation of fingers, a bulky dressing is applied to splint and protect the finger and hand in a position that enhances mobility, taking into account the delicate nature of the surgical repairs. The elbow should be flexed and the fingers pointing to the ceiling for edema control. The ideal position for postoperative immobilization is with the metacarpophalangeal joints in 70 degrees of flexion, with interphalangeal joints in neutral position, and with the thumb in maximal volar abduction. If this position is not possible, the alternative position used should come as close as possible to the ideal yet not stress or compress the vascular repairs. The dressing should be applied to allow easy visual inspection and temperature monitoring of the finger yet guard against excessive manipulation of the finger itself.


Secondary Reconstruction
One-stage reconstruction (primary repair or grafting of all divided structures) is the preferred treatment because it avoids scarring from additional surgical procedures and because the patient can concentrate on rehabilitation after surgery. However, some procedures cannot be effectively completed at the time of replantation. Rarely, a replanted part is stiff, painful, useless, and ugly, and the patient may benefit from reamputation. Secondary reconstruction is much more common after major replantations than after minor replantations. The most common secondary procedures are bone grafting to treat a nonunion, soft tissue surgery to correct scar deformity at the amputation site, tenolysis to restore motion, and nerve grafting to improve sensation. Most often, however, patients require muscle and tendon transfers to restore function after poor recovery after nerve repair.
A toe-to-hand transfer is recommended when an additional digit would significantly improve hand function (see Plate 4-66). Because the transplanted toe never functions as well as the original finger, patients must first appreciate the deficit created by the missing finger before they can accept the reconstructed digit.


Results
Results of replantation must be interpreted with great care and compared not with normal function but with function with the best prostheses. Replantations often survive, but the more important outcome subsequent hand and limb function is not well reported. For example, the person who cannot return to work because a replanted finger is stiff and painful has a much greater disability than someone who has a well-performed revision amputation and can return to work 4 weeks after surgery.
Generally, functional recovery is determined by nerve regeneration, which tends to be better in patients younger than 35 years of age with more distal amputation sites. However, good recovery is often seen in young patients with more proximal amputations.
Regarding nerve regeneration, different parts of the hand have different functional requirements. For example, the thumb and index finger require good sensation and stability, whereas the three ulnar digits require motion for power grip and are less involved in sensation. A comparison of functional assessments of replantations is difficult because patients’ needs with respect to mobility and stability vary. However, most patients are satisfied with the replanted part and report that they would choose the procedure again.