Microsurgery

Results

Overall survival rates reported by U.S. and foreign surgeons vary from slightly better than 50% to 92% for replanted and revascularized parts. The success rate of digital replantations at two U.S. academic Level 1 trauma centers recently was reported as 57% (69 of 135 digits).

Major limb replantations have a reported survival rate of nearly 40% to 80% and better. Results of replantation of above-elbow amputations are mixed compared with those of below-elbow replantations. There is some variation in reported results, with limb survival ranging from 61% to 88% in above-elbow replantations and 36% to 90% for below-elbow replantations.

Success of digital and limb replantations cannot be measured by survival alone. In the final analysis, success is measured better by the extent of return of useful function. Although it is of some value to compare the replanted part with the normal uninjured part, it is more meaningful to compare the replanted part with amputation or prosthetic function at the level in question. Insofar as function was concerned in one study, good or excellent outcomes were achieved in 36% to 50% of replanted limbs compared with prosthetic limbs in which no good results were obtained. Others have suggested that similar functional results between the two can be expected. Most authors use different grading systems based on factors such as ability to return to work, return of muscle function, range of motion, sensibility, ability to perform activities of daily living, and patient satisfaction. Chen et al. developed criteria for the evaluation of function that are ideal for assessing multisystem injury and are general enough to allow comparison of results within complex injury groups ( Table 63.1 ). Several studies have reported successful return of function after replantation in 62% to 78% of patients. Jones, Schenck, and Chesney used a scoring system to evaluate patients who had undergone replantation compared with a group of patients who had amputations at similar levels. In their small group of patients, they found grip strength to be better in patients who had replanted thumbs or replanted multiple digits than in patients with amputations. Grip strength in patients with single-digit replantation was not significantly different, however, from patients with amputations. Patients with replanted multiple digits had a small functional advantage over patients with amputations. Their study also reinforced the concept that amputated thumbs should be replanted if possible, although the type of amputa tion is a significant factor in the survival of replanted digits. Only 12% of replanted digits survived in crushing or avulsion amputations in one study, and the survival rate was significantly better if the injury occurred proximal to the metacarpophalangeal joint. In minimally damaged amputations, only the time between injury and surgery was significantly related to survival. Most patients who have had parts replanted are satisfied with the reattached part and would undergo replantation again; however, some were dissatisfied because of emotional stress, financial loss, and number of subsequent surgeries required.

Although most workers are able to return to some form of work, our experience suggests that the more proximal the injury, the less likely it is that the patient will be able to return to former employment in a reasonable time.

Cold intolerance is experienced by almost all replantation patients; however, it usually is not incapacitating. It may take 2 years or more to improve if at all, and patients may perceive moderate improvements because of change in habits. Most patients regain protective sensibility, but two-point discrimination, especially in more proximal injuries, is rarely less than 10 mm. Fine tactile discrimination rarely returns. Most patients have some residual limitation of movement, especially if a joint has been injured and if the flexor tendon injury in the hand lies between the metacarpophalangeal and proximal interphalangeal joints.

Functional results after major limb replantations vary with the age of the patient, the level of the injury, and the mechanism of injury. Generally, the more distal the injury, the sharper the injuring mechanism, and the younger the patient, the better the outlook (96% excellent results in children). This seems to be largely the result of the dependence on nerve regeneration for return of sensibility and motor function. The results of replantations are poorer if the amputation is above the elbow, if the elbow joint is involved, or if the injury is through the muscular portion of the proximal forearm. Transmetacarpal amputations carry a poor prognosis for replantation because of injury to the intrinsics. Functional outcomes at a mean of 4 years (range, 1 to 7 years) after replantations of radiocarpal amputations in six patients were reported by Patel et al. Total active motion of the hand was 38% (range, 26% to 59%) and grip strength was 9% (range, 0% to 18%) as compared with the contralateral extremity. Tip and key pinch were not achieved. Mean two-point discrimination was 10.6 mm (range, 8 to 12 mm). All outcome scores, including the Disabilities of Arm, Shoulder, and Hand score, showed moderate disability (mean, 76; range, 45 to 82).

Despite the guarded outlook regarding more proximal amputations, some patients achieve useful function that is significantly better than that obtained with a prosthesis.

Replantation team

Replantation of amputated upper extremity parts should be done by surgeons who are trained in surgery of the hand and upper extremity. In addition, digital replantation requiring the use of the operating microscope should be done by surgeons who have exhibited the ability to perform reliable microvascular anastomoses with a predictable patency rate of 90% or better.

Although replantation can be done by one surgeon with highly trained and motivated assistants, it is more desirable to use rotating teams of surgeons. During the microvascular portions of the procedure, at least one of the scrubbed surgeons should be proficient at microvascular and microneural repairs. The replantation surgeons should be available on a rotating basis 24 hours a day except in unavoidable circumstances. Assistants who are familiar with the sequence of events, instruments, and other equipment required for replantation procedures should be available. Finally, it is important that the hospital be able to support such an undertaking with surgical suites and an intensive care unit available around the clock and with nursing and anesthesia personnel to provide the essential care before, during, and after the procedure.

General considerations

The function anticipated after replantation must be better than that with a prosthesis or an amputation, and the difference must be worth the risk, time, and expense. The potential for the replanted part to regain useful motion and sensibility must be assessed carefully before committing the patient to a long and difficult course of rehabilitation. The following factors generally are evaluated for replantation of an amputated part:

• ▪

  Age of patient

• ▪

  Severity of injury

• ▪

  Level of amputation

• ▪

  Part amputated

• ▪

  Interval between amputation and time of replantation (especially warm ischemia time)

• ▪

  Multiple or bilateral amputations

• ▪

  Segmental injuries to the amputated part

• ▪

  Patient’s general condition, including other major injuries or diseases

• ▪

  Rehabilitation potential of patient (occupation and intelligence)

• ▪

  Economic factors

These considerations are expanded on in the discussions of indications and contraindications that follow.

Indications and contraindications

Because the final decision regarding replantation rests with the patient and the surgeon, there are no absolute indications for replantation of an amputated part. The following discussion reflects our present practice combined with the published recommendations of the previously noted authors. The factors discussed should be taken as relative guides based on current knowledge and experience.

Level of injury and part amputated

Replantation near the shoulder generally carries a poor prognosis regarding hand function because of unpredictable nerve regeneration, muscle atrophy, and joint stiffness. Amputations through the humerus, elbow, and proximal forearm have the potential for successful replantation and useful function, especially in a young, healthy patient, and especially if the injury is clean and sharp. The patient should be young enough and motivated enough to be able to await nerve regeneration sufficient for return of function. Replantation more distally, whether through the distal forearm, wrist, metacarpals, or digits, also should be seriously considered because generally the potential for sensory and motor return is good ( Fig. 63.6 ). Replantation just above the elbow, through the elbow joint, or in the proximal forearm has a guarded prognosis in older patients because of questionable nerve regeneration, limitation of elbow motion, and persistence of intrinsic muscle atrophy. Replantation for salvage of the elbow for later below-elbow prosthetic fitting may be feasible in selected patients.

Thumb amputations at almost any level should be considered for replantation despite nerve and tendon avulsion and joint involvement ( Fig. 63.7 ). If the thumb can be revascularized, sensibility can be restored with nerve grafts or a neurovascular island pedicle transfer if needed, and motion can be achieved with tendon grafts or transfers. Replantation may not be successful after amputations caused by roping injuries with crush and avulsion components. Replantation of single and multiple digits distal to the flexor digitorum sublimis insertion should be expected to achieve satisfactory function ( Fig. 63.8 ), but amputations at a more proximal level, especially through the proximal interphalangeal joint, usually result in poor function. They are usually stiff and tend to impair the overall function of the remaining digits by getting in the way. The amputated thumb is the exception to this generalization. Although many patients do well without replantation of single-digit amputations, such a replantation may be worthwhile for some musicians, individuals with other special occupations, some children, and for other aesthetic or social reasons. Replantation of a single digit also may be helpful if the remaining attached digits are severely damaged, especially with tendon and nerve injury over the proximal phalanx. If multiple digits have been amputated, replantation of at least two digits in the long and ring positions provides a good combination of digits to use with the thumb for pinch and for power grip. Occasionally, amputations through the distal phalanx may best be treated by replantation, and success with fingertip replantation has been reported. Hattori et al. believe that amputation proximal to the lunula is a relative indication for replantation. Except in some centers, these distal replantations are not performed because of the degree of difficulty in identifying and anastomosing suitable vessels, longer surgery time, longer time off from work, and higher costs. Indications for fingertip replantation remain controversial.

In bilateral amputations, replantation on each side should provide better function than bilateral prostheses. If replantation is not suitable or possible because of extensive injuries on one side, the best side should be selected, and at times parts from one side may be attached to the opposite, more suitable stump. Although amputations through the joints impair the movement of those joints, a satisfactory limb can result through arthrodesis, excisional or fascial arthroplasty, or, in ideal circumstances, silicone implant arthroplasty.

Management and transportation of patient and part

At the scene of the injury and in the outlying hospital, the patient’s condition is of utmost importance. Major injuries other than the amputated part should take precedence, and the patient’s condition should be stabilized. Major stump bleeding should be controlled with pressure. No attempt should be made to clamp or ligate vessels. A pressure dressing should be applied for transporting the patient to an institution with replantation capabilities. If bleeding is persistent, the temporary use of a pneumatic tourniquet or blood pressure cuff is helpful. Elastic tourniquets should not be applied; they may be covered later with bandages and forgotten.

As noted, cooling of the amputated part to about 4°C is important to prolong the viability of the part. After the part has been found, it can be rinsed gently with sterile saline, lactated Ringer, or other physiologic solutions so that excess contamination is removed. The part should be treated in one of two ways: (1) it can be wrapped with sterile gauze or other clean material, soaked in sterile lactated Ringer or saline, and placed in a plastic bag, which is then sealed, or (2) it can be immersed in a plastic bag containing a physiologic solution such as lactated Ringer or saline. The bag is placed on ice in an insulated container so that the part is not touching the ice to avoid freezing of the part. Dry ice should not be used; neither should the part be warmed. Nonphysiologic solutions such as alcohol and formaldehyde should not be used on the amputated part.

No attempt should be made to clamp, dissect, ligate, or cannulate vessels on the amputated part because this further damages vessels that may be essential to revascularization of the part. If the part has been incompletely severed, it should be handled gently. Care should be taken to correct any kinking of the soft tissues or rotation that might compromise marginal arterial or venous flow. Sterile bandages moistened with a physiologic solution should be applied to the limb and the injured part and an ice pack applied to the latter. The limb should be supported with padded splints and a nonconstricting wrapping for the trip to the hospital.

When the patient is stable with an intravenous infusion in place, the patient along with the part can be transported. Although air transportation may be preferable for patients traveling great distances, especially in limb amputations, ground transportation is suitable if the patient can reach the replantation team in 2 to 3 hours and if the amputated parts are digits that have been appropriately cooled. The receiving institution and replantation team should be contacted and alerted that the patient is being sent.

Finally, it is preferable for the patient and family to understand that the patient is being referred to another hospital and other surgeons who have the capability to reattach parts and who will evaluate the particular situation and make appropriate recommendations regarding treatment. This understanding helps to minimize unrealistic expectations of patients, family, and friends, who usually are quite distraught. In a 2010 report from one tertiary replant center, 65% of patients transported by air for possible replantation did not have replantation, with injury characteristic being the main contraindication. Delaying digital replantation overnight so that a suitable operating room and rested replantation team are available is an acceptable practice and may be beneficial as long as the amputated part is properly preserved.

Preoperative preparation

Some aspects of preoperative, intraoperative, and postoperative management vary slightly among institutions; however, general agreement has been reached on many of the basic principles regarding replantation. Having two teams to deal with replantation candidates from the time of their arrival in the emergency department is most helpful. While one team evaluates and prepares the patient, the other team assesses the amputated part.

Patient assessment and preparation should include (1) a history of the injury and medical history, including serious illnesses or previous injuries to the amputated part; (2) physical examination, especially to exclude injuries to other major organ systems; and (3) stabilization and resuscitation of the patient with the institution of an intravenous infusion, appropriate antibiotics, and tetanus prophylaxis. Blood typing and crossmatching are done, and transfusions are given if needed. An indwelling urinary catheter may be inserted in the emergency department or in the surgical suite. Radiographs of the amputated part, the amputation stump, the chest, and other areas as indicated should be obtained in the emergency department. The patient and family are advised of the nature of the injury, the uncertainties regarding survival of the part and return of function, the possible duration of the replantation operation, the possibility of repeated operations, and the likelihood that the replanted part will never be normal.

Order of repair

After all structures have been thoroughly cleansed, debrided, and identified, repair is begun. As indicated in the discussion that follows, certain conditions or circumstances dictate a variation in the order of repair. The following is our usual order of repair of damaged structures. Discussions of digit, hand, and arm replantations are included.

• • 1.

    Shorten and internally fix bone.

  • 2.

    Repair extensor tendons.

  • 3.

    Repair flexor tendons (2 and 3 may be reversed, or flexor tendon repair may be delayed).

  • 4.

    Repair arteries.

  • 5.

    Repair nerves.

  • 6.

    Repair veins.

  • 7.

    Close or cover wound.

If time permits, we often repair the veins immediately after extensor tendon repair. This minimizes repositioning of the hand and allows for venous anastomosis in a bloodless field. It also may minimize venous congestion. Also, if time permits, it is easier to repair the nerve just before repairing the artery.

In distal thumb amputations, it may be easier to anastomose interpositional vein grafts to the terminal branch of the ulnar digital artery and largest vein before performing osteosynthesis. The proximal anastomoses can be performed dorsally and proximal to the area of injury.

Management of bones and joints

The periosteum is stripped minimally. Bone is shortened to permit tension-free vascular anastomoses and nerve repairs ( Fig. 63.10A ). Initial bone shortening reduces the size of the soft-tissue defect, allows maximal soft-tissue debridement, and changes crush injuries to guillotine injuries. If vein grafts are used, the need for bone shortening is minimized, but survival depends on the patency of the two anastomoses of the graft, rather than one. Additional time is required to harvest the vein and to perform the anastomoses. Vein grafting may be necessary, however, if the amputation has occurred near an undamaged joint.

Shortening of an amputated thumb should be kept to a minimum ( Fig. 63.10B ). We have found that shortening of a digit much more than 1 to 1.5 cm at times impairs the function of the digit. Amputations damaging digital joints usually are treated by primary arthrodesis ( Fig. 63.11C ), but joint motion can be preserved by the insertion of a Silastic implant. This method probably is best reserved as a primary procedure for amputations that are sharp and clean and when occupational requirements are best satisfied by having mobile joints.

Bone fixation in digits and metacarpals usually is achieved by using two parallel medullary axial Kirschner wires or a single axial Kirschner wire supplemented by an oblique Kirschner wire to control rotation ( Fig. 63.11A ; see Fig. 63.10C ). Wires should be placed to allow joint motion, if possible. Occasionally, when the amputation is near an undamaged joint, wire loops through drill holes are used ( Fig. 63.11B ). Care must be taken to maintain axial alignment and rotational control, especially when dealing with multiple digital amputations. We have not found it necessary to use plates and screws for digital or metacarpal fixation during replantation. This is an acceptable but often time-consuming technique. Periosteal suture with 4-0 or 5-0 absorbable suture may be done after bone fixation. Whitney et al. evaluated clinical results after use of single and crossed Kirschner wires and intraosseous wires with and without Kirschner wire support ( Fig. 63.11D ). Although initial results showed similar early angulation deformities in all groups, intraosseous wires were found to have the lowest nonunion and complication rates.

Management of the skeleton in more proximal amputations is more varied and requires more skill in the handling of medullary fixation devices, bone plates, and screws than in distal amputations. If the amputation level is through the carpus, shortening may be achieved and motion preserved by excision of carpal bones and temporary fixation with transarticular Steinmann pins. Amputations through the forearm and arm usually are shortened 2 to 5 cm to allow tension-free vessel anastomoses and nerve repairs.

For amputations through the forearm, generally accepted principles of internal fixation are applied; however, time constraints frequently dictate modifications. Distal radial metaphyseal amputations usually are fixed with Steinmann pins; plates and screws are used less often. We have also used intraosseous wiring occasionally with success. Amputations more proximally are fixed with plates and screws on both bones, intramedullary fixation with Rush rods or Steinmann pins in both bones, or combinations, such as a plate and screws for the radius and intramedullary fixation for the ulna. Medullary screws combined with wire loops are used for olecranon amputations. If the elbow joint is comminuted, an attempt is made to salvage sufficient bone to allow subsequent elbow arthroplasty. Amputations through the humerus are usually fixed with plates and screws; however, fracture configuration and time considerations may require interfragmentary Steinmann pins or intramedullary rods.

Transposition of digits

Because of extensive damage to amputated parts or to the amputation stump, anatomic restoration of digits is sometimes impossible. In these situations, a functioning part may be restored by moving digits from their original anatomic position to a more suitable position. In bilateral digital amputations, parts from one hand may be better replanted to the opposite hand. Priority should be given to restoration of the thumb position with provision for a digit in the index or long position for pinch. Consideration also should be given to providing long, ring, and little digits for cup restoration. When digital transposition is considered in bilateral amputations, the dominant hand is given priority if possible.

Tendon repair

During replantation, damaged structures are usually repaired in a serial fashion from the skeletal plane to more superficial planes. This may delay repair of vessels in the sequence so that deeper structures can be repaired without jeopardizing vascular anastomoses.

Vessel repair

Identifying the volar digital arteries is usually easier than finding suitable veins for anastomosis. The arteries lie just dorsal to the volar digital nerves. Although both digital arteries can usually be identified with ease, hypoplastic vessels on the radial side of the index finger and the radial side of the thumb have been common in our experience. In the thumb, the princeps pollicis artery can provide sufficient blood flow from the dorsum if no palmar arteries are suitable for repair.

Management of circulatory compromise after replantation

If the replanted part shows signs of inadequate circulation, prompt evaluation and management of the problem might allow salvage of a part that otherwise would be lost. Mechanical monitors of skin temperature, oxygen tension, hydrogen and fluorescein dilution, and other factors (see Monitoring Techniques after Microvascular Surgery later in this chapter) in many instances are sufficiently sensitive to detect significant changes in blood flow before clinically apparent ischemic changes develop. If the part is cool and has developed the pallor and loss of turgor consistent with arterial insufficiency, or if it is cyanotic, congested, and turgid consistent with venous obstruction, several measures can be helpful in relieving the problem before the patient is taken to the operating room for exploration.

The room should be comfortably warm, and the patient should have sufficient analgesic medication and be sufficiently sedated to minimize emotional distress. As noted previously, the part should be elevated well above the level of the heart to enhance venous drainage. Medical-grade leeches (Hirudo medicinalis) are effective in relieving venous congestion; however, they may be a source of infection and should not be used in the presence of nonviable tissue. If arterial insufficiency is suspected, placing the part in a dependent position may be beneficial. Splints and dressings are loosened or removed to ensure that nothing is causing direct pressure on the vessels and that nothing is constricting the limb. Using gentle digital pressure, the arteries are lightly “milked” from proximal to distal and the veins are “milked” from distal to proximal.

In distal injuries, if Silastic catheters have been left adjacent to the median or ulnar nerves, 4 to 5 mL of 0.25% bupivacaine is injected. Stellate ganglion sympathetic blocks and brachial plexus blocks also have been useful, especially in patients with troublesome vessel spasm. Although it is not part of our usual routine, many surgeons with extensive experience find it useful to administer heparin intravenously as a bolus of 3000 to 5000 U when attempting to salvage a failing replanted part.

If the replanted part does not respond to these measures, the surgeon must decide, based on knowledge of the injury and experience, whether returning to the operating room to explore the vessels is worthwhile. This decision should be made promptly when definite signs of impaired circulation are evident. Reoperation is more likely to be successful if done within 4 to 6 hours of the development of signs of ischemia.

Complications

Although circulatory compromise related to the vessel repairs is the most pressing complication after replantation, other complications that occur in the early postreplantation period include bleeding, skin necrosis, ischemia caused by muscle compartment swelling, and infection. Excessive bleeding may be from vessels that have not been cauterized, or it may be caused by anticoagulant therapy. Significant skin necrosis usually occurs after closure of skin that initially appears viable but later undergoes necrotic changes resulting from the magnitude of the injury sustained at the initial traumatic amputation. Additional debridement and secondary closure with local flaps or skin grafts may be required. Significant sepsis is rare after replantation and usually is managed satisfactorily with appropriate systemic antibiotics, wound debridement, and drainage as needed. Although ischemia may be caused by excessive muscle compartment pressure, this usually occurs in major limb replantations and can be treated with appropriate fasciotomies in the arm, forearm, and hand. These early complications may require wound inspection and dressing changes with the patient under anesthesia in the first week after replantation.

Later complications, such as nonunion and malunion of bones, tendon adherence, joint stiffness, and delay in return of nerve function, usually can be managed with the usual techniques appropriate to these problems. In nonunion and malunion, bone grafts and internal fixation may be required. Tendon adhesions with loss of excursion may require tenolysis and, in some situations, tendon grafting as one-stage or two-stage procedures. Stiff joints may require capsulotomy, or if sufficient damage has occurred, interposition arthroplasty may salvage motion in selected patients. If a primary neurorrhaphy fails to show return of function in a reasonable length of time, or if the nerves are not repaired as part of the original replantation, reexploration and repair or interpositional nerve grafting may be necessary. The nature and timing of specific reconstructive procedures depend on the individual patient’s problems and needs and the judgment and experience of the surgeon.

Rehabilitation

The specific rehabilitation program for each patient depends on many factors, especially the patient’s needs and motivation and the extent of injury to the part. Generally, no attempt is made to begin significant movement of bone, joint, or tendon for the first 3 weeks after replantation. Then, depending on the extent of injury, most replantation patients are treated in a manner similar to most patients with combined tendon, bone, and nerve injuries. After the first 3 weeks, most patients are encouraged to participate in a graduated program of active, active-assisted, and protected passive stretching and range-of-motion exercises supplemented by appropriate dynamic and static bracing and splinting.

Monitoring techniques after microvascular surgery

After microvascular procedures such as replantation and free composite tissue transfer, a reliable monitoring system should be established for the replanted or transferred tissue. Although the clinical determination of the color, capillary refill, temperature, and turgor is easily made, there is room for error because of the subjective nature of these factors, especially color and temperature. This, combined with the possibility that considerable ischemic injury may occur before clear clinical signs are present, has led to the development and use of a variety of mechanical monitoring devices and techniques, including ultrasonic and laser Doppler probes, plethysmography, skin temperature probes, transcutaneous oxygen tension measurements, hydrogen washout techniques, and skin fluorescence measurements.

The Doppler probe and plethysmographic techniques are reasonably accurate indicators of arterial flow; however, they are not as accurate when venous flow is to be assessed. Although the transcutaneous oxygen tension determination, the hydrogen washout method, and the skin fluorescence measurement all have been found to be useful and sensitive assays of changes in the microcirculation, the use of skin temperature monitoring probes is presently a simple and reliable adjunct to the clinical evaluations. With separate temperature probes attached to the revascularized tissue, adjacent normal tissue, and the dressing, relative and absolute changes in the temperature can be monitored constantly. A decrease in the temperature of the replanted digit to less than 30°C or a decrease of more than 2°C or 3°C less than the normal digit is considered a sign of circulatory compromise.

Transcutaneous oxygen measurements show changes in oxygen tension several hours before the onset of clinical signs of ischemia and before temperature changes occur. This and other techniques hold promise for the development of monitoring techniques with increasing sensitivity.

Special techniques

For distal fingertip amputations in which microvascular anastomosis is impossible, Brent described the “pocket technique.” This technique involves debriding and deepithelializing the amputated part, reattaching it as a composite graft, and burying it in a contralateral chest wall subcutaneous pocket for 3 weeks. It is then removed, and the viable tip skin is grafted. Lee et al. used this technique with an abdominal pocket. Muneuchi et al. reported poor results with this technique in seven fingers and did not recommend it for injuries at or proximal to the lunula. To avoid shoulder and elbow stiffness, Arata et al. modified this procedure by using the ipsilateral palm as the pocket site. In their 16 patients, complete survival was seen in 13, with the remaining three showing partial necrosis.

Indications and advantages

The traditional indications for pedicle flaps are similar to the indications for free flaps, and pedicle flaps may be preferred in young children, electrical burn patients, fingertip amputations, and preparation for toe-to-hand microvascular transfers.

Each case must be considered individually. Current indications for free flaps include, but are not limited to, the following:

• • 1.

    Secondary and, in some situations, primary coverage of extensive skin and soft-tissue loss with exposure of essential structures (e.g., blood vessel, nerve, tendon, bone, and joint)

  • 2.

    Coverage of a soft-tissue bed unsatisfactory for later reconstructive procedures (e.g., scar, chronic draining ulcers, and chronic osteomyelitis that prevent tendon grafts, tendon transfers, nerve repairs or nerve grafts, bone stabilization, and bone grafting)

  • 3.

    Replacement of unstable area scars after burns, irradiation, radical surgery for cancer, and scar contracture

  • 4.

    Coverage situations for which a suitable random or axial pattern flap is unavailable

  • 5.

    Coverage situations in which immobilization of the extremities for prolonged periods in awkward positions is undesirable or impossible

  • 6.

    Restoration of specific tissue to satisfy a functional need (e.g., sensation in the hand or the plantar surface of the foot, digital reconstruction in the hand, replacement of major skeletal muscle loss in the forearm, replacement for bone loss in the upper and lower extremities, replacement of lost or destroyed joints in the fingers, replacement of functioning epiphyses in the hand and forearm, and correction of congenital and developmental deformities including radial clubhand and congenital pseudarthrosis of the tibia)

The advantages free flaps seem to have over more traditional techniques include the following:

• 1.

  They usually are done as single-stage procedures.

• 2.

  The choice of a donor site usually is not as restrictive.

• 3.

  There usually is more versatility regarding the matching of the color, texture, thickness, and hair distribution of the donor area with the recipient area.

• 4.

  In many situations, the donor site can be closed primarily, without resorting to skin grafts.

• 5.

  Most donor sites are left with an acceptable appearance.

• 6.

  Well-vascularized tissue with a permanent blood supply can replace ischemic or avascular tissue.

• 7.

  When indicated, a vascularized bone graft, functioning joints, epiphyses, and skeletal muscle can be electively included in the composite graft used to reconstruct a limb.

• 8.

  Prolonged immobilization in awkward positions is not required, allowing the patient more freedom in daily activities.

• 9.

  Joints adjacent to the recipient area are mobilized earlier than after conventional techniques, preventing joint stiffness and contractures.

• 10.

  Hospital stays usually are shortened.

Contraindications and disadvantages

Although absolute contraindications to the use of free flaps are few, the surgeon should have reservations regarding their use in the following situations:

• 1.

  The surgeon has neither microsurgical training nor microsurgical experience.

• 2.

  Institutional support for a reconstructive microsurgical program is insufficient.

• 3.

  No suitable recipient vessels are available in the area requiring coverage or tissue reconstruction.

• 4.

  Previous trauma or irradiation to the recipient area may have damaged the vessels sufficiently to preclude their use.

• 5.

  If only one major artery to the foot or the hand is present, the use of it as the recipient vessel for a free flap may jeopardize the viability of the foot or hand, even though an end-to-side anastomosis is used.

• 6.

  Age alone may not constitute a contraindication; however, if major systemic illnesses create a major anesthetic risk for the patient, an alternative method of treatment should be considered.

• 7.

  If systemic illnesses, such as atherosclerosis, vasculitis, or other lesions, have caused damage to the vascular system, microvascular procedures, although not certain to fail, are more likely to fail than are those done when the vessels are not diseased.

• 8.

  If previous operative procedures have been done in the donor area, the donor vessels may have been damaged, precluding the use of that specific donor site.

• 9.

  Obesity makes dissection of vascular pedicles difficult or impossible. Bulky, obese flaps are awkward to manipulate and difficult to place without causing tension, torsion, or disruption of anastomoses. The fat at times causes obstruction of a clear view of the vascular pedicles, preventing the performance of satisfactory anastomoses.

The disadvantages of free tissue transfer include the following:

• 1.

  The initial operation usually is longer than are operations for conventional flaps. Free flap procedures take 4 to 10 hours, depending largely on the flap selected and the experience of the surgical team.

• 2.

  The operations may be difficult and tedious.

• 3.

  Two teams of surgeons usually are required.

• 4.

  If vascular thrombosis occurs, the risk of complete loss of the free flap is considerable.

• 5.

  Reportedly, the overall risk of free flap failure compared with conventional techniques is greater. A 10% to 30% failure rate for free flaps is cited by Sharzer et al. In addition, the reoperation rate after free flap transfers may be 25%.

• 6.

  Postoperative vascular complications, which usually occur in the first 24 hours, may be seen 10 days after the procedure.

Selection of free flaps

Numerous free flaps have been described. The selection of one specific flap over another is influenced by many factors. Specific tissue requirements at the recipient site are important: Is full-thickness coverage needed? Would a skin graft or conventional flap suffice? Is a free flap really needed? Is the need only for simple coverage? How thick and how large should the coverage be? Is skin sensibility, bone, joint, nerve, or functioning muscle needed? In general, free skin flaps are selected rather than free muscle flaps when dead space is minimal and skin and subcutaneous tissue must be matched to restore cutaneous sensibility.

The condition and availability of donor and recipient vessels are important considerations in the determination of which flap would be best in a given situation. Generally, the simplest procedure should be chosen that would fulfill the tissue requirements of a specific recipient area. The flap should be designed so that if it fails, a satisfactory salvage procedure is possible. In most situations, a major factor in flap selection is likely to be the experience of the individual surgeon using specific flaps.

Single-stage transfers of composite tissue grafts (free flaps) are discussed here as they apply to repair and reconstruction of traumatic, infectious, neoplastic, congenital, and developmental problems in the upper and lower limbs. The simplest procedures, including local and remote pedicle flaps, should be considered first. In circumstances precluding more traditional techniques, microsurgical procedures should be considered, and in some situations, priority should be given to the use of free flaps.

Preoperative requirements

Proficiency in microvascular techniques and familiarity with the vascular anatomy of the various free flaps acquired through cadaver dissection are necessary.

The candidate for a free flap must be evaluated before surgery. The patient should be healthy enough to tolerate a potentially lengthy procedure. Surgical debridement of all unhealthy tissue should be completed before free flap coverage, and the patient should have demonstrably normal donor and recipient vasculature out of the zone of injury. The adequacy of vessels can be estimated by clinical palpation of peripheral pulses, the Allen test in the hand, and the use of the ultrasonic Doppler probe. These methods are considered inadequate by some surgeons who favor preoperative angiography, especially in a traumatized extremity, to help assess the condition of the recipient vessels. However, preoperative angiography may cause damage to the recipient vasculature, and at times surgical exposure is the only way to assess the vessels. Venography may help determine the adequacy of the deep venous system if the superficial system is incompetent. Although it may be difficult to assess the vasculature with angiography, if there are any questions regarding the donor site, angiography may be helpful.

Before the operation, the patient is informed of the risks, hazards, and potential problems involved in such procedures. In addition, laboratory studies, including assessment of bleeding and clotting factors, and adequate blood replacement arrangements should be made.

General plan of procedure

Excessively cold temperatures are avoided in the operating room. The patient is placed on a heating and cooling blanket. Body temperature is monitored with rectal or esophageal probes. If the planned procedure is expected to last several hours, an indwelling urinary catheter is inserted. After the induction of the anesthetic, the patient is positioned appropriately to permit access to the recipient and the donor sites. Bony prominences and neurovascular structures are padded to avoid excessive pressure. The recipient defect is mapped by measuring it and drawing it out on the patient, and the mapped defect is superimposed on the donor area so that the donor area can be determined to fit when transferred. The general courses of the donor and recipient vessels are identified by palpation and with a Doppler probe, and the courses are marked with a skin marker. In the extremities, a pneumatic tourniquet is used to maintain a bloodless field during most of the dissection. After major structures have been identified, the tourniquet is intermittently inflated and deflated as needed.

Two teams usually are preferred for free tissue transfers, especially for larger transfers. One team prepares the recipient area by debriding scar and all necrotic tissue, including bone. All recipient vessels are exposed to determine that arterial and venous pedicles of appropriate lengths are available. If venous grafts seem to be needed, they should be harvested before the delivery of the donor tissue to minimize the ischemia time of the tissue. Care is taken in this dissection to avoid stripping the vessel clean because this may cause refractory vessel spasm, precluding the planned tissue transfer. In the extremities, if the circulation to the limb depends on a single artery, the decision must be made regarding the use of the artery through an end-to-end or an end-to-side anastomosis, or whether the artery should be used at all. If nerve or tendon repairs are planned, those structures are identified as well.

While one team is working on the recipient area, a second team dissects the donor area, usually using the identified course of the donor artery as the axis for the outlined flap of tissue. The approach to the free flap usually begins at the vascular pedicle. If suitable arteries and veins are identified, the dissection of the flap proceeds. If no satisfactory vessels are found on the first side of the body to be dissected, the opposite side may be explored if patient positioning and preoperative planning permit.

After the flap has been elevated, it is left attached to its vascular pedicle until the recipient site has been completely prepared and it is certain that the recipient vessels are capable of supplying sufficient circulation to the donor tissue through the pedicle to maintain its viability. When it is certain that preparation of the recipient area and the recipient vessels has been completed, and that the donor vascular pedicle is long enough, the pedicle is transected. The artery usually is clamped and transected first to allow time for venous drainage to occur. The veins are clamped next and transected. The flap is now ready for attachment to the recipient site. The donor team delivers the flap to the recipient team. While the flap is being attached to the recipient area, the donor team closes the donor-site wound. Although this usually can be done by direct approximation of the wound edges, at times split-thickness skin grafts may be required.

The recipient team loosely attaches the flap to the recipient site with sutures placed at widely spaced intervals around its periphery, sufficient to hold the flap in place to prevent shear on the vessels and disruption of anastomoses. The flap is positioned so that the vessel anastomoses can be done conveniently. Perfusion of the flap with various solutions usually is not required.

The sterilely draped operating microscope is brought into the surgical field, and attention is turned to dissecting the perivascular adventitia and soft tissue away from the vessels. This dissection is done gently to avoid undue trauma to the vessel walls. Microvascular anastomoses are carried out first on the artery and next on the veins. It sometimes is helpful to keep the microvascular clips on the artery until at least one venous anastomosis is completed so that the flap does not become congested by the arterial inflow while the veins are being sutured. Because of potential injury to the vessel wall, the clip should not be left attached too long.

Anastomoses should be done on as many vessels as are available and suitable. Two-vein anastomosis is preferred to one-vein anastomosis, but is not essential for flap survival.

At the time of the anastomoses, anticoagulation therapy may be started; heparin or low-molecular-weight dextran can be used. Patency is assessed by removing the vascular clips from the artery and the vein. If the flap is being perfused through the anastomoses, the patency test of the artery shows flow across the repair, and the emptying veins rapidly fill. A pink, warm flap, with rapid capillary refill and no demonstrable venous congestion is a good indicator of satisfactory perfusion in most situations. Other indicators of satisfactory flow include bleeding from the skin edges of the flap and rapid, bright red bleeding from small stab wounds made in the margins of the flap.

If flow into the flap is questionable, a Doppler probe can be used to detect flow, although this may not be reliable. Similarly, patients may be given intravenous fluorescein, and the flap can be assessed for fluorescent perfusion using an ultraviolet light. If arterial spasm occurs, it can be relieved at times by using topical papaverine or lidocaine. Stellate sympathetic ganglion blocks may be helpful if problems caused by vessel spasm continue in the upper extremity.

When satisfactory arterial and venous flow has been established, attention can be turned to additional reconstructive procedures, such as bone, tendon, or nerve grafts and tendon transfers, if circumstances permit. If the situation does not permit these more extensive procedures, they should be delayed until another time. The margins of the flap are next sutured in place. Ideally, the vessels should be covered by the skin of the transplanted flap or the local skin in the recipient area. Split-thickness skin grafts may be required to cover exposed areas not completely covered by the free flap. To allow easier inspection of the flap after surgery, we do not routinely cover free muscle transfers with a split-thickness skin graft during the initial procedure. Care is taken to avoid excessive tension so that the vessels are not occluded by the pressure of overlying skin or muscle. If needed, a small suction drain may be left beneath the flap well away from the vascular anastomoses to avoid their disruption on removal of the drain.

When the dressing is applied, whether in the upper or lower limb, care should be taken to avoid excessive pressure on the flap or constriction of the limb proximal to the flap. Our practice is to apply a wide-mesh petrolatum gauze to the wound edges and over skin grafts. This is covered with a loose bandage of gauze. Next, cotton cast padding is evenly applied to allow the application of a plaster splint to support the hand and wrist, or the foot and ankle, depending on the specific situation. Although the manner in which a patient awakens from the anesthetic is difficult to control predictably, every effort should be made to avoid violent straining, shivering, and flailing about, which sometimes accompany this stage of the procedure.

General postoperative care

Placing the patient in an intensive care unit should ensure regular monitoring of vital signs and the vascularity of the flap. If the patient has medical illnesses that require special monitoring techniques, the intensive care setting is probably the safest place. After an uncomplicated operation, if the nurses and house staff are familiar with administering this type of postoperative care, the patient may be cared for safely in a hospital room. The room is kept warm; excessive cooling is avoided to prevent cold-induced vasospasm. The room is kept quiet, and visitors are kept to a minimum to prevent emotional upsets that might lead to vasospasm. Cigarette smoking by the patient and visitors is prohibited to avoid nicotine-induced vasospasm. Cold drinks and those containing caffeine also are avoided.

Medications usually include antibiotics, sedatives, analgesics, and different combinations of anticoagulant medications. Anticoagulation routines vary, depending on the preference of the individual surgeon. In some patients, no significant anticoagulant medication is given. Some experienced surgeons use heparin routinely. Others use low-molecular-weight dextran, and our current practice is to give dextran, 500 mL, every 24 hours for at least 3 days. In addition, aspirin usually is added in doses of 300 mg twice daily.

The involved part usually is kept at the level of the heart or slightly elevated to avoid venous congestion. If the flap seems to be ischemic, the part can be lowered to improve arterial flow. If the flap becomes congested, the part is elevated well above the level of the heart to improve drainage. If the flap appears to be in jeopardy, a great deal of time should not be spent in carrying out these maneuvers because reexploration is likely to be required, and valuable time may be lost awaiting improvement.

The circulation of the flap can be monitored satisfactorily using a variety of techniques. Regardless of the techniques used, regular clinical evaluations by the surgical and nursing staff are essential.

Monitoring

Currently available monitoring techniques include ultrasound and laser Doppler scanning, digital plethysmography, radioisotope clearance assays, fluorescein perfusion monitoring, transcutaneous oxygen tension monitoring, and photoplethysmography. Continuous temperature monitoring is widely used and currently seems to be the simplest method for assessing temperature of replanted digits and vascularized free flaps. The use of three temperature probes is required. One is placed on the replanted digit or hand, a second is placed on an adjacent or an opposite digit, and a third is placed on the bandage for monitoring the ambient temperature. The normal digital temperature ranges from 30°C to 35°C. Replanted digits should have temperatures within 2°C to 3°C of the control digit. If the temperature of the replanted digit decreases to less than 30°C, thrombosis on the arterial or venous side is likely, and reexploration of the replanted part or free flap should be considered.

If sufficient clinical signs of ischemia accompany the indications of ischemia by any mechanical monitoring device, the patient should be returned to the surgical suite for exploration of the anastomoses. If the flap is pale without capillary refill or is cyanotic and congested, if bright red bleeding is absent when the flap is punctured with a No. 11 blade, or if a deep purple ooze occurs, the flap is in jeopardy, and reexploration is indicated.

If arterial thrombosis is identified, the arterial anastomosis and at least one venous anastomosis should be excised. This excision allows assessment of perfusion of the flap after the arterial anastomosis is repeated. If venous thrombosis is the problem, excising the venous anastomosis is helpful to allow free bleeding from the flap for several minutes to determine satisfactory flap perfusion and adequate back bleeding from the flap before repeating the venous repair. If vessel torsion or tension is found to have caused thrombosis over a segment of the vessel, interpositional vein grafting may be required to salvage the flap. The wounds are bandaged as noted previously, and the postoperative routine is resumed.

Mobilization of the part is resumed, commensurate with the part receiving the tissue transfer. If a simple soft-tissue cover has been provided, the parts can be mobilized as soon as wound healing and edema permit. If vascularized bone or functioning muscle has been transferred, mobilization depends on the requirements of these procedures. If a free muscle transfer has been performed, the patient routinely is returned to the operating room at 2 to 3 days for any necessary further debridement and split-thickness skin grafting of the flap. The specific routines used are discussed in the following sections covering the specific free tissue transfer procedures.

Free groin flap

The iliofemoral (groin) pedicle flap, popularized by McGregor and Jackson, has been applied extensively for repair and reconstruction in the upper extremity. Since the report in 1973 by Daniel and Taylor describing its successful use as a free flap, many surgeons have found it useful for coverage problems encountered in reconstruction of the head, neck, and trunk and in the upper and lower extremities. The free groin flap also has been beneficial for coverage of the exposed tibia and for problems in the foot, especially over the heel. In some situations requiring a bone graft, the underlying iliac crest may be included with the groin flap, using the superficial circumflex iliac artery or the deep circumflex iliac artery.

Advantages ascribed to the free groin flap include its potentially large size, its location in an area with sparse hair distribution, minimal donor-site morbidity, its multiple arterial and venous systems, the potential for incorporating bone with the overlying skin, and its proven applications as a traditional pedicle flap before the development of microvascular surgical techniques. Disadvantages include its potential excessive thickness in obese patients, problems with color matching, its usually short vascular pedicle, difficulty in dissection of the vessels, its lack of satisfactory innervation, and the likelihood that previous surgical procedures in the inguinal region might have damaged the essential vessels. Primarily because of its short and unpredictable vascular pedicle, the groin flap has lost some of its initial popularity as a free tissue transfer.

Vascular anatomy

The iliofemoral flap, as usually described, receives its principal arterial supply from the superficial circumflex iliac artery, branching from the femoral artery. Anatomic studies reveal variations in the arterial supply, with the superficial inferior epigastric artery contributing significantly at times ( Fig. 63.14 ). Taylor and Daniel found the origin of the superficial circumflex iliac and the superficial inferior epigastric arteries to have one of three patterns ( Fig. 63.15 ). In 48% of their specimens, there was a common origin of the superficial circumflex iliac and the superficial inferior epigastric arteries. In 35% there was a large superficial circumflex iliac artery and absent superficial inferior epigastric artery. Separate origins were found for both arteries in 17%. The arteries arose from vessels other than the femoral artery at times, and the relationships were symmetric in about one third of the specimens. The diameters of the vessels were 1.1 to 1.4 mm.

The superficial circumflex iliac artery passes from its origin superficial to the femoral nerve, remaining subfascial until it reaches the lateral border of the sartorius, where it passes through the deep fascia into the subcutaneous tissue, supplying the dermal-subdermal plexus lateral to the anterior superior iliac spine. The flap is drained through the relatively constant superficial inferior epigastric and the variable superficial circumflex iliac veins. These veins may enter the femoral vein separately, usually on its anterior surface. They also may be found to join at the saphenous bulb. The vascular axis of the superficial circumflex iliac artery begins about 5 cm inferior to the inguinal ligament and generally is oriented parallel to the inguinal ligament toward the anterior superior iliac spine and the inferior angle of the scapula.

When a groin flap is being designed, this general alignment should be kept in mind. If the iliac crest is to be included in the flap, it may be supplied sufficiently by the overlying skin and superficial circulation; however, Taylor, Townsend, and Corlett have shown the importance of the osseous circulation from the deep circumflex iliac vessels. The dissection of these vessels is accomplished through the inguinal region.

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