Indications and Surgical Techniques for Digit ...

Bulletin • Hospital for Joint Diseases

Volume 60, Numbers 3 & 4

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Indications and Surgical Techniques for Digit Replantation F. Thomas D. Kaplan MD and Keith B. Raskin MD

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icrovascular surgery has revolutionized the care of patients with partial and complete digital amputations. Modern microvascular techniques enable us to reattach severed limbs, digits, and fingertips. The groundwork for the reattachment of severed limbs and digits was laid over a hundred years ago. In 1887, Halsted began experiments on limb replantation.1 In 1906, Carrel and Guthrie described the first successful canine limb replantation, and Carrel outlined his techniques for vascular repair the following year.2,3 Despite these early successes, it was not until the 1960s that limb and digit replantation became widely accepted. During the 1950s, advances in the field of organ transplantation led to the development of small sutures and vascular repair techniques. This, combined with the invention of the operative microscope, set the stage for the field of microvascular surgery. In 1960, Jacobson and Suarez reported using the microscope to repair small cortical vessels.4 Two years later, Malt and McKhann reported the first successful replantation of a severed arm in a 12-year-old boy.5 Knowledge of this success spread quickly to Japan and China, and, in 1964, Tamai began microvascular research in Japan. The following year, after “many failures,” 6 Komatsu and Tamai successfully replanted a completely amputated thumb at the metacarpophalangeal level in a 28-year-old male. In 1967, the Sixth People’s Hospital F. Thomas D. Kaplan, M.D., is an Administrative Chief Resident, NYU-Hospital for Joint Diseases Department of Orthopaedic Surgery, New York, New York. Keith B. Raskin, M.D., is the Associate Chief of the Hand Service, NYU-Hospital for Joint Diseases Department of Orthopaedic Surgery, and Clinical Associate Professor of Orthopaedics, New York University School of Medicine, New York, New York. Reprint requests: Keith B. Raskin, M.D., 317 East 34th Street, New York, New York 10016.

in Shanghai reported 20 successful digital replantations.7 Replantation centers were developed in the United States and Australia, and the field of microsurgery was born.

Mechanism of Injury Amputation of the fingers can result from a multitude of causes, and not all amputated fingers are indicated for reimplantation. The manner in which the injury occurred, the amount of contamination, and the length of extraction, among other factors, is critically important information for the replant team. This knowledge allows the surgeon to determine the indications for replantation in a particular patient and to properly plan the surgery. Common etiologies of digital amputation include lacerating, local crush, extensive crush, and avulsion-type injuries. In a survey of replantations performed in the United States in 1996, Chung and colleagues found that most injuries occur in the workplace, though 25% of amputations occur in the home. 8 The most frequent mechanism of amputation is by machinery (41%), followed by powered hand tools (17%), crush injuries (14%), and stab wounds (8%).8

Epidemiology Though finger replantations have been performed for over thirty years, there has been little epidemiological data regarding the number of replants performed, injury trends, and use of healthcare dollars. This information is important for both physicians and healthcare policy makers. Prior to the year 2000, only two epidemiology studies had been performed. In a 1976 Danish study, Kiil9 identified 445 hand and finger amputations. Ninety percent were finger amputations, of which over 70% were at, or distal to, the distal interphalangeal joint. In a Swedish study, Nylander and associates 10 reviewed a 1979

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database of worker’s injuries and identified over 70 amputations suitable for replantation. Of these amputations, replantation was attempted in only 10% of cases, thus highlighting the under utilization of replantation in Sweden at the time. Recently, Chung and coworkers8 reviewed the 1996 Healthcare Cost and Utilization Project-3 Nationwide Inpatient Sample (NIS) Release 5. This database captures a 20% stratified sample of community hospitals in the United States. In NIS Release 5, there was inpatient data on over 6.5 million inpatient hospital stays from 906 hospitals in 19 states. From their review, 304 cases of finger replantation were identified. Interestingly, replants were performed in only 15% of hospitals. Most hospitals (60%) performed only one replant during the year, while only 2% of hospitals performed more than 10 cases; university hospitals performed 24% of replantation cases. In the same report, Chung and colleagues estimated the total number of replantations performed in the United States, using a formula provided by the Healthcare Cost and Utilization Project database.8 They calculated 1,153 thumb and finger replantations were performed, incurring hospital charges of approximately $24 million. The authors concluded that the number of replantations performed seemed low for our country and hypothesized that the under utilization may be related to the limited experience seen in the majority of hospitals.

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The treatment of a patient with a finger amputation begins at the location of injury, with both the patient and

the amputated part requiring immediate attention. Basic first-aid should be given immediately. The injured hand should be wrapped in a clean dressing, elevated, and direct pressure applied to limit bleeding. Attempts to ligate arterial bleeding should be avoided, as this results in further injury to the vessels. The amputated part should be retrieved, even if it appears unlikely that replantation is possible. It should then be properly preserved and prepared for transport with the patient. Prompt transport of the amputated part is crucial, and is directly related to the ultimate outcome for the patient. Replantation viability has been correlated with the duration of warm ischemia time,11-13 though replantation after 33 hours of warm ischemia time has been reported.14 Cooling of the amputated part has been shown to slow cellular metabolism and extend the critical ischemia time.15 Muscle can withstand 6 hours of warm ischemia time and 12 hours of cold ischemia time. Amputations distal to muscle can withstand longer periods, including warm ischemia of 8 to 12 hours and cold ischemia of 24 hours. Once the amputated part has been retrieved, it should be wrapped in a saline-soaked gauze to keep it moist (Fig. 1). It should then be placed in a sealed plastic container, and that container placed inside a second bag filled with ice (Fig. 2). In this manner, the part is kept moist and cool, while it is protected from freezing and becoming waterlogged. It is important to remember to assess the perfusion of incomplete amputations as well as to cool non-perfused attached parts in a similar fashion. When the patient arrives in the emergency room, the patient should receive antibiotics and tetanus prophy-

Figure 1 The part is first wrapped in moist gauze and placed in a sealed container. (From: Weiland AJ, Raskin KB: Philosophy of replantation 1976-1990. Microsurgery 11:224, 1990. With permission.)

Figure 2 The container with the amputated part is placed in a second container filled with ice. (From: Weiland AJ, Raskin KB: Philosophy of replantation 1976-1990. Microsurgery 11:224, 1990. With permission.)

Initial Evaluation and Transport


laxis. A thorough history and physical examination is necessary to identify all co-morbidities and any concomitant injuries the patient may have. Radiographs of the injured and amputated part should be taken. If it is determined that replantation is indicated, the amputated part can be taken to the operating room ahead of the patient. There, the replant team, can inspect the part and prepare it for replantation.

Classification There are several ways to classify finger amputations: mechanism of injury, level of amputation, and number of amputated digits. These classifications are useful in determining which fingers are indicated for reimplantation. Commonly seen mechanisms include lacerations, local crush, extensive crush, and avulsions. Lacerations have limited, local tissue damage. Local crush injuries have a wider zone of injury, but can generally be converted to clean injuries with adequate debridement. Extensive crush injuries have a much larger zone of injury and larger amounts of contamination. Avulsion injuries also have a wide zone of injury and often require extensive vessel resection and vein grafting to achieve viability. The environment in which the injury occurred can be an important factor. Farming injuries often have a large amount of tissue contamination, will require extensive debridement, and may have a higher rate of infection. Similarly, amputations resulting from machinery may present with a substantial amount of contamination.

Operative Indications The decision to perform a replantation is based on the many factors that affect the overall outcome of replantation and the chance for viability of the replanted part. These can be divided into patient factors and injury characteristics. It is important to remember that the goal of replantation is to provide the patient with a hand that will be a functional improvement over completion amputation or ray resection. Only one patient characteristic is an absolute indication for replantation, if he is a pediatric patient. Pediatric replantation has been recommended for any amputated part that can be technically reattached, including single digit, avulsion, and crush injuries.16 Greater efforts are taken to replant digits in the pediatric population due to their remarkable ability to heal and recover function. The other commonly reported indications for replantation are amputations of the thumb, multiple digit amputation, amputations distal to the insertion of the flexor digitorum superficialis (FDS), partial hand amputation, and wrist or forearm amputation. Thumb amputations cause a disproportionate loss of hand function due the inability to oppose. Thumb length is also important for


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hand function, and every effort should be taken to preserve it. The recommendation for replantation of forearm, wrist, and partial hand amputations is based on the devastating loss of function at these levels. Compared with prosthetic use, functional outcomes are superior with replantation. The indications for single digit amputations are more controversial. Digits that have been amputated distal to the FDS insertion have good functional recovery and generally do not interfere with hand function. Digital amputations proximal to the insertion of the FDS have less consistent outcomes. Several authors who have reported on the poor function of digits replanted at this level found that the replanted digit was often a detriment to overall hand function. 11,17-19

Contraindications Contraindications to replantation can also be divided into patient factors and injury characteristics. Replantation surgery can involve a long operative time with extensive blood loss. For patients who are poor operative candidates with significant medical co-morbidities, the potential benefits of replantation must be carefully weighed against the risk of a prolonged surgery. Similarly, for patients with life-threatening injuries, replantation is of secondary importance. Other patient characteristics, which are relative contraindications to replantation, are advanced age and severe mental illness. Older patients are more likely to have significant co-morbidities and atherosclerotic vessels. Patients with major psychiatric disorders need to be carefully screened if replantation is to be performed. The patient must be able to follow through with a restrictive postoperative protocol and intensive rehabilitation process. Additionally, replantation in a self-amputee may be futile. Injury characteristics that are absolute contraindications for replantation are severely crushed or mangled parts, amputation at multiple levels, and massively contaminated injuries. Each of these factors indicates severe damage to the part that precludes successful replantation. Relative contraindications are single digits amputated proximal to the FDS insertion, single border digits (index and small fingers), and prolonged warm ischemia time. Replantation of digits proximal to the FDS insertion has been found to have worse functional recovery, especially with regards to range of motion, when compared with amputations distal to the FDS insertion.11,17 These digits often create a hand with worse function that if a completion amputation or ray resection was performed. Poorly functioning reimplanted border digits can severely impair hand function. A stiff small finger may decrease grip strength, while the thumb often bypasses a stiff or poorly sensate index finger. Prolonged ischemia time leads to a decrease in the

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viability and functional result of the replanted part.11 Ischemia causes the tissues in the amputated part to revert to anaerobic metabolism. Depletion of cellular ATP results in an increase in cytoplasmic metabolites, which triggers the production of inflammatory mediators and leads to increased cellular edema.15 By cooling the amputated part, the cellular metabolism can by slowed and the critical ischemia time can be prolonged. Current recommendations for replantation are less than six hours of warm ischemia time when muscle is present in the amputated part, or less than 12 hours when there is no muscle. With proper cooling of the amputated part to 4° C, the critical ischemia time can be prolonged to 12 hours when muscle is present and 24 hours for digits, since there is no muscle present.

Surgical Technique Replantation surgery is a complex undertaking that requires a properly equipped hospital and experienced surgical team. The hospital must have an operating room equipped with a microscope and microvascular equipment. There must also be an intensive care unit with trained personnel to monitor the patient postoperatively. The surgical team should have experience in microvascular techniques and be able to consistently obtain 90% patency rates in 1 mm vessels. Two teams are preferable, if possible, so that one team can prepare the amputated part, while the other team operates on the proximal stump. The patient should be prepared for a prolonged surgical procedure. A Foley catheter should be inserted. All bony prominences should be properly padded. Sequential compression stockings placed on the legs can help prevent the formation of deep venous thrombosis. A body warmer assists in maintaining core temperature and preventing coagulopathy. General anesthesia is often necessary for long cases, but axillary or infraclavicular blocks are useful adjuncts, as the sympathetic blockade limits arterial spasm. The sequence of procedures is crucial for a timely and efficient reimplantation. First, a complete debridement of all obviously necrotic or contaminated tissue is done (Table 1). The importance of an adequate debridement cannot be overemphasized as the persistence of necrotic tissue leads to an increased risk of infection. Following debridement, mid-lateral incisions are made to enhance exposure, and the structures to be repaired are identified and tagged (Fig. 3). The digital neurovascular bundles should be found and the digital nerves and arteries mobilized, approximately, 1 cm. A 9-0 or 10-0 nylon suture is placed on the arteries and nerves to facilitate identifying these structures. Dorsal veins should be similarly explored and tagged. The flexor tendon(s) should be identified and a Kessler-type locking suture placed into each end.

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Table 1 Surgical Technique of Digit Replantation Initial Preparation for Replantation Debride necrotic and contaminated tissue Midlateral incisions to enhance exposure Mobilize/tag digit’s neurovascular bundles and arteriovenous vessels Place Tajima suture in flexor tendon(s) Shorten and Fix bone Preference to shorten amputated part Achieve bony stability Take care to ensure correct rotation Extensor Tendon Repair (hand prone) Flexor tendon(s) Repair (hand supinated) Arterial Repair (hand supinated) Resect back to healthy intima Check pulsatile flow Treat for spasm, if necessary Tension-free repair or use vein graft Digital Nerve Repair (hand supinated) Realign with epineural repair Tension-free repair or use nerve graft Vein Repair (hand prone) Minimum of one vein for each artery Tension-free repair or use vein graft Obtain Hemostasis; Assess Viability Close Skin Wounds Loose closure Option: mid-lateral incisions open to prevent arterial compression Postoperative Care Bulky, sterile, non-compressive dressing/splint Splint with fingertips exposed Foam pillow for hand elevation 24 hours: monitor digit every hour 48 hours: monitor digit every 2 hours Dressing evaluated daily – beware of blood tourniquet Room kept at 75º to 80º Avoid caffeine, chocolate, nicotine Anticoagulate Maintain hydration

The next step is to shorten and stabilize the bone. Shortening of 5 to 10 mm is performed to ensure good bony contact for healing as well as to accomplish a shortening of the overall length of the digit for improving the likelihood of tension-free neurovascular anastomoses. Bone should be preferentially shortened in the amputated part so that the amputated stump will have the maximum possible length if the replantation fails. Once the bone has been shortened, it should be stability fixed. Several fixation techniques have been described including longitudinal Kirschner wire, crossed K-wires, intraosseous wiring, intramedullary screws, or plate fixation20 (Fig. 4). Longitudinal K-wires can be placed quickly and


Figure 3 Mid-lateral incisions are made to facilitate the identification and tagging of the digital arteries and nerves. (From: Goldner RD, Urbaniak JR: Replantation. In: Green DP, Hotchkiss RN, Pederson WC (eds): Green’s Operative Hand Surgery, (4th ed). Philadelphia: Churchill Livingstone 1999, p. 1147. With permission.)

allow for correction of digit rotation if it is determined that the finger was placed in a malrotated position. It also requires less bone stock and less bone exposure.


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Crossed K-wires are also relatively simple to insert. Intraosseous wiring and plate fixation provide a more stable construct, but are more time-consuming and more difficult to revise if digital malrotation is identified. After bony stability has been achieved, the next step is to repair the extensor tendon while the hand is pronated. Alternately, the extensor can be repaired later, prior to vein repair. After ensuring that the tendon ends have been debrided to a clean margin, 4-0 non-absorbable suture is used in an interrupted or horizontal mattress fashion. The hand is next supinated and the flexor tendon identified. If the level of amputation is proximal to the FDS insertion, three repairs have been described that may be applied: repair of both the FDS and the FDP, repair of the FDP alone, or repair of the proximal FDP to the distal FDS tendon.11 If 4-0 tagging sutures have been placed in a Kessler fashion into each tendon stump, these ends can simply be tied together (Tajima method) (Fig. 5). Alternately, a new Kessler suture can be placed. A fourstrand repair is usually not necessary. An epitendonous repair is then performed for increased strength of the repair. Following flexor tendon repair, the arteries are repaired. Before repair is attempted, an adequate exploration of the artery should be performed. Any arterial segment with intimal damage must be resected, as repair of a damaged segment will lead to thrombosis. A coiled or twisted appearance of the distal arterial stump, described as the ribbon sign (Fig. 6), indicates disruption of the

Figure 4 Several methods of bone fixation: A, Intramedullary K-wire (single/solid line, second, if necessary/dotted line); B, Intraosseous wiring; C, Chevron-type fusion; D, Bone screw; and E, Mini-plate and screws. See source for further details. (From: Goldner RD, Urbaniak JR: Replantation. In: Green DP, Hotchkiss RN, Pederson WC (eds): Green’s Operative Hand Surgery, (4th ed). Philadelphia: Churchill Livingstone 1999, p. 1149. With permission.)

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Figure 5 Tajima sutures are initially placed in each tendon end. Following bone fixation, the suture ends are tied, without need to replace the sutures. (From: Goldner RD, Urbaniak JR: Replantation. In: Green DP, Hotchkiss RN, Pederson WC (eds): Green’s Operative Hand Surgery, (4th ed). Philadelphia: Churchill Livingstone 1999, p. 1150. With permission.)

Figure 6 The ribbon sign: the digital artery rests in a coiled state indicating a previous stretch injury.

layers in the vessel wall, and occurs following avulsion injuries.21 After the arteries have been trimmed back to normal anatomy and healthy tissue, the proximal arterial stumps are checked for pulsatile flow. If flow is poor, there has been either inadequate arterial resection, or the artery is in spasm. Spasm can be relieved by the addition of a regional block to produce a sympathetic blockade, application of local lidocaine, application of warm saline, and by warming the patient. After pulsatile flow has been obtained, vascular clips can be placed, and the vessel’s end coapted with 10-0 interrupted nylon sutures. A tension-free repair is critical, as tension across the anastomosis will lead to thrombosis. If the vessel ends cannot be re-approximated without tension, an interpositional vein graft is needed. Veins of similar caliber can be obtained from the volar distal forearm. The graft should be reversed prior to insertion to avoid valvular obstruction. The next step is repair of the digital nerves. Again, it is important to fully trim the nerves back until healthy fascicles are present. The fascicles should be realigned, and an epineurial repair with 8-0 or 9-0 nylon performed. The nerve should also be repaired without tension. If a direct repair is not possible, a primary graft can be placed using a nerve from a digit not able to be replanted, or from a sural nerve or lateral antebrachial cutaneous nerve graft. Alternatively, delayed nerve grafting can be performed after healing. The hand is pronated and the veins repaired. The veins are largest on the dorsum of the digit and run in repeating arcades. These arcades can be selectively ligated to allow for greater mobilization of the veins and to increase the number of veins available for repair (Fig. 7).

If adequate length cannot be obtained, intercalary vein grafts can be used. Ideally, two veins are repaired for each arterial anastomosis. At minimum, there should be one venous repair for each arterial repair. In many instances, compromise is necessary, and repair of two or three veins with one or two arteries is sufficient.22

Figure 7 Selective ligation and mobilization of dorsal venous arcades can increase the number of available venous anastomoses. (From: Goldner RD, Urbaniak JR: Replantation. In: Green DP, Hotchkiss RN, Pederson WC (eds): Green’s Operative Hand Surgery, (4th ed). Philadelphia: Churchill Livingstone 1999, p. 1151. With permission.)


The last step is to obtain hemostasis and loosely close the skin wounds. The mid-lateral incisions can be left open if needed to avoid compression of the neurovascular bundles. A bulky, sterile, non-compressive dressing is applied, incorporating a plaster splint to hold the wrist slightly extended. The fingertips should be left exposed for postoperative monitoring. The arm is supported by a foam pillow to assist keeping the hand elevated.

Postoperative Management Close postoperative monitoring is essential for successful replantation. The patient should have hourly monitoring of digital color, surface temperature, Doppler pulse, and oxygen saturation for the first 24 hours. For the next 48 hours, vascular assessment should be performed every 2 hours. The room should be warmed, to 75 to 80 degrees Fahrenheit, prior to the patients’ arrival, and kept at that temperature. Patients are not allowed to eat or drink for the first 24 to 48 hours, as this is the period of highest risk for thrombosis. They are then progressed to a regular diet with the avoidance of caffeine and chocolate, as both can cause vasoconstriction. Nicotine is prohibited as well, also due to its vasoconstrictive properties. The patient is placed on prophylactic antibiotics for 5 to 7 days. Proper analgesia is important, as pain and anxiety in the patient leads to increased sympathetic tone and vasoconstriction. Anxiolytics can be useful, especially in children. The patient should be kept well hydrated with intravenous fluids. Perioperative anticoagulation is also recommended. The choice of medication varies with the treating surgeon and type of injury. In general, intravenous heparin is used in amputations that involved a crushing component or required vein grafts. For sharp amputations, aspirin and low-molecular weight heparin or dextran is used. The dressing should be evaluated on a daily basis. Replants have a tendency to have sanguineous oozing. This blood can dry on the dressings and a “blood-tourniquet” created which causes vascular constriction. The dressing should be changed on the second or third postoperative day, and the finger cleaned of dried blood. The rehabilitation protocol consists of immobilization of the affected digits for the first 2 weeks. Active range of motion is begun for the shoulder and elbow, and passive range of motion begun in the uninvolved digits. At week 3 to 4, active range of motion is begun for all digits. If joint stiffness is still significant at week 6, static progressive splinting is initiated. Sensory reeducation is begun when two-point discrimination is within 15 mm.23

Complications Early complications following replantation include infection, decreased perfusion, and bleeding. Infection can be minimized by a thorough debridement at the time of


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surgery. Most infections can be successfully treated with intravenous antibiotics. Blood loss during and after replantation surgery can be significant. Patients must have blood available in the blood bank both intra-operatively and postoperatively. Hematocrit should be checked postoperatively and then daily until it has stabilized. Vascular thrombosis is the most common cause of replant failure. Decreased digital perfusion is most likely to occur during the first 72 hours. There are several important signs that should be monitored in order to detect worsening flow to the finger. Loss of a Doppler pulse, decrease in skin turgor, and decreased capillary refill all indicate a change in the vascular supply. A decrease in skin surface temperature of 2° C or more within an hour and a skin surface temperature below 30° C at any time also indicate vascular insufficiency. Oxygen saturation monitoring is also useful. A SaO2 greater than 95% indicates adequate perfusion. If the SaO 2 falls between 85% and 95%, venous insufficiency is likely. A SaO2 of 0% indicates arterial occlusion. Once decreased perfusion is diagnosed, prompt action is required. If the cause is thought to be due to venous congestion, the hand should be elevated and the bandage loosened. If this fails to improve the blood flow, suture removal and a form of external bleeding can be used. This can be achieved through the application of leeches, removal of the nail plate and application of heparinsoaked pledgets, or through periodic digital massage. Leeches are particularly useful; once applied, they will help drain the finger by becoming engorged with blood. Once engorged, usually within 30 to 60 minutes, they will drop off the fingertip and should be retrieved. Their saliva leaves behind a powerful anticoagulant, Hirudin, which will allow for persistent bleeding from the tip for 6 to 8 hours, after which time the leeches should be reapplied. The major complication with leech use is the possibility of infection from Aeromonas hydrophilia, a bacteria found in leech saliva. Arterial thrombosis or spasm will also result in decreased digit perfusion. Treatment begins with lowering the hand. Warming the patient, analgesics and anxiolytics, and sympathetic blockade should be used to treat spasm. If these measures fail, the surgeon should perform prompt exploration of the anastomoses. Surgical exploration is most effective when performed within the first 6 to 8 hours after noting decreased perfusion. Whether the cause is felt to be venous or arterial, all anastomoses should be explored. If an anastomosis is not patent, it should be excised and a new one performed. If there is not sufficient length to obtain a tension-free repair, vein grafts should be used. Prompt exploration and revision anastomosis have been found to improve survival rates.24 Late complications after replantation are common, and 35% of patients require secondary reconstructive proce-

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dures.11 Problems include decreased joint motion, tendon ruptures, tendon adhesions, bony malunion or nonunion, and cold intolerance. Loss of motion following replant surgery is common, and is due to either capsular restriction or tendon adhesions. If the patient has a loss of both active and passive motion, the cause is capsular contracture, which is treated with capsular release. If the patient has full passive motion, but is lacking active motion, the cause is tendon adhesions, treated with delayed tenolysis at 3 to 6 months postoperatively. Several factors predispose to early tendon ruptures. Splinting of the digits postoperatively puts tension on either the extensor or flexor tendon repairs. The fingers are usually splinted in flexed position in order to protect the volar nerve and artery repair, which results in tension on the extensor tendon repair. Additionally, altered blood supply to the vincula may limit tendon nutrition. Tendon ruptures may be unrecognized in the immediate postoperative period since range of motion does not begin until the second or third week postoperatively. Even if a rupture is discovered acutely, re-operation during the early postoperative period may not be recommended in order to avoid potential vascular compromise. Instead, patients are treated by substituting dynamic splints for the lost motion in the early postoperative period, followed by delayed reconstruction in 3 to 6 months. Malunions or non-unions of the bone may also occur following replantation. The incidence of these complications is low.25 Non-unions are treated as they would be elsewhere – with bone grafting and stable fixation. Malunions, which are usually caused by rotation, are treated with osteotomy and stable fixation.26 Cold intolerance occurs universally following replantation, with a reported incidence of 80% to 100%.27,28 Symptoms are related to cold-induced vasospasm, which decreases digital perfusion and causes pain. The exact mechanism of vasospasm following digital nerve injury is unknown. Arterial inflow into the finger is normal until a cold stimulus is applied, at which point marked vasospasm occurs. 27 Interestingly, blockade of alpha-receptors does not prevent the phenomenon. Improvement generally occurs within 1 to 2 years, and is related to the recovery of sensibility. If the digital nerve recovers pain and touch sensibility, with good localization of stimulus and static two-point discrimination between 7 to 15 mm, then symptoms of cold insensitivity are minimal and vasoregulation approaches normal.28

Outcome Survival rates of replanted digits are excellent, with average viability rates of 85% to 90% reported in most studies.6,11,17,18,29 The factor that correlates best with survival rate is the type of injury. Sharp lacerations with a limited zone of injury have the highest survival rates, while extensively crushed or avulsed fingers have lower

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viability rates. 11 Other factors that correlate with improved survival are the experience of the treating surgeon, a more distal level of injury, and patient age. Survival rates in children have been found to be lower than those of adults, with viability of 63% to 90% reported.11,16,30 It is unclear why children may have lower survival rates. Taras and colleagues hypothesized several possible factors: a higher percentage of crushing or avulsion injuries in this age group, a more aggressive attitude toward replantation with more extensively damaged digits replanted, higher technical difficulty due to smaller vessels, and a greater degree of vasospasm due to increased sympathetic tone and anxiety.16 However, as stated by Ch’en Chun-Wei, “survival without restoration of function is not success.”31 Several components go into the functional evaluation of replanted digits. Range of motion, return of sensibility, ability to return to work or play, severity of cold intolerance, and patient satisfaction are all important components of the final outcome. Range of motion following replantation generally returns to approximately 50% of normal. Worse results are seen if the amputation involves a joint or occurs proximal to the FDS insertion. In a series of 59 patients, Urbaniak found that average proximal interphalangeal (PIP) joint motion averaged 82 degrees when the level of amputation was distal to the FDS insertion, while PIP joint motion only averaged 35 degrees in amputations proximal to the FDS insertion. 17 Similar results were found by Waikakul and associates in a study of 1,018 replantations. 11 The authors compared three different tendon repair configurations when the injury was proximal to the FDS insertion: repair of both superficialis and profundus, repair of profundus only, and repair of the proximal profundus stump to the distal superficialis stump. The best recovery of overall motion was found in the proximal profundus to distal superficialis group, followed by profundus repair only, with worst results when both tendons were repaired.11 Recovery of sensibility is a crucial part of useful hand function following replantation. It is graded on a scale from S0 to S4, based on the classification proposed by Highet and Sanders.28 An anesthetic finger (S0), or a finger with only deep cutaneous pain (S1), can be an impediment to overall hand function. Fortunately, most patients regain at least protective sensation (S1+, S2). Useful two-point discrimination of 7 to 15 mm (S3+) or complete recovery (S4) is achieved in greater than 50% of fingers and 60% of thumbs.6,28 This level of recovery correlates with diminished symptoms of cold intolerance. Factors that correlate with better recovery of sensibility include young age, lacerating trauma with a narrow zone of injury, and more distal injuries. Additionally, patients that participate in a formal sensory re-education program obtain an improved speed and


quality of recovery.32 The final important factor in determining the success of replantation is the satisfaction of the patient. Despite the impossibility of returning a patient to their pre-operative condition, most patients are satisfied with their replanted digits and infrequently request ray amputation. In a study of 1,018 replantations, Waikakul and coworkers found that all of their patients who had single digit amputations were satisfied with the results and were glad their fingers had been replanted, despite the fact that many had poor functional results.11 Most patients will be able to accommodate their hand and injured digits to their work, though some find that the replanted digit gets in the way. Cultural norms probably play a role, and the cosmetic and psychological importance of a normal-appearing hand should not be underestimated.

Summary Finger amputations are devastating, life-changing injuries. They can occur from many different types of injury, but most often are caused by power tools or machinery in the workplace. Modern microvascular surgical techniques have enabled surgeons to successfully reattach fingers that have been amputated at almost level of injury. Patient outcome and digit viability have improved as surgeons have gained more experience with microvascular techniques, and have narrowed the operative indications for replantation. Currently, replantation is recommended for amputated thumbs, multiple digit amputations, and single digit amputations distal to the FDS insertion, as well as all amputations in children. Replantation surgery is technically demanding. Success relies on patient selection, meticulous operative technique, and postoperative monitoring. Most patients have successful outcomes with at least protective sensation and useful range of motion in the replanted digit. Though complications, including joint stiffness, tendon adhesions, malunion, and cold intolerance are not infrequent, patient satisfaction following replantation is high.

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