- Email: [email protected]
External Fixators as an Adjunct to Wound Healing
Foot Ankle Clin N Am 13 (2008) 145–156
External Fixators as an Adjunct to Wound Healing Mark W. Clemens, MDa, Pranay Parikh, MDa, Melanie M. Hall, BSb, Christopher E. Attinger, MDa,* a
Division of Wound Healing, Department of Plastic Surgery, Georgetown University Medical Center, 3800 Reservoir Road NW, Washington, DC 20007, USA b Georgetown University, 37th and 0 Streets NW, Washington, DC 20057, USA
Traditionally, the most straightforward treatment for complex lowerextremity wounds and major soft tissue defects was amputation of an affected limb. Uncontrollable wounds caused by infection, size, vascular insufficiency, compromised immune status, and unstable skeletal framework require multiple operations by different specialties and prolonged healing times to salvage the limb with no guarantee that the result yields a functional limb [1]. Amputations are a straightforward and rapid solution to complex wounds that can have the patient back ambulating in short order. Amputations, however, carry risks of their own: increased energy of expenditure, decreased life expectancy, and increased risk of contralateral limb amputation [2–4]. In addition, an amputation subjects a patient to lifetime dependence on prosthetic devices and, for those who never go on to wear prosthesis, a wheelchair-bound existence. Reconstructive surgeons are called on to address lower-extremity wounds that result from trauma, ischemia, or infection [5]. The first task is to convert the existing wound into a healthy wound. This often requires a multidisciplinary effort with vascular surgeons re-establishing adequate blood flow to heal, orthopedic surgeons re-establishing skeletal stability, infectious disease clinicians addressing the existing infection, and medicine clinicians stabilizing the patient. The wound is aggressively debrided until only normal tissue is left. It is then covered with an appropriate dressing regimen to promote healing. Closure should be considered only when the wound is clean and healthy granulation tissue appears. Most wounds are then closed using soft tissue techniques in the reconstructive ladder, such as delayed primary * Corresponding author. E-mail address: [email protected] (C.E. Attinger). 1083-7515/08/$ - see front matter Ó 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.fcl.2007.12.001 foot.theclinics.com
146
CLEMENS
et al
closure, skin grafts, local flaps, and free tissue transfer [6]. Because of advances in wound healing techniques, the trend has been away from microsurgery and toward simpler modes of reconstruction [7]. A significant portion of wounds breakdown or fail to heal in the postoperative period, however, because of repetitive shear forces around an active joint, decubitus pressure, or premature ambulatory pressure in a noncompliant patient. The detrimental effect of motion on wound healing is well established [8,9]. This article evaluates the adjunctive role of external fixation (Ilizarov and monoplanar) in soft tissue reconstruction to ensure healing in patients requiring reliable off-loading or immobilization of joints.
External fixation External fixation has an established role for the treatment of trauma and osteomyelitis [10–12]. In these clinical applications, the external fixator allows for the salvage of severely infected or traumatized bone or joints that required major amputation in the past [13]. The fixator maintains bone and joint alignment through rigid external fixation despite often significant bone resection for osteomyelitis or skeletal realignment. It does that without having to resort to internal fixation with plates and screws that are counterindicated in infected wounds. The fixator markedly decreases soft tissue trauma by using smaller pins and by significantly reducing the amount of soft tissue dissection required with open reduction with internal fixation with plates and screws [2]. The Ilizarov fixator has been shown to shorten healing time, decrease pin track infections, and allow early weight bearing by the addition of a protective plantar plate [14]. In terms of soft tissue reconstruction, the disadvantages associated with external fixation (Ilizarov more so than external monoplanar fixator) include cost and a cumbersome construct. Applying a fixator carries a relatively high cost ranging from $2000 to $10,000. In addition, the Ilizarov restricts soft tissue access because of the multiple pins and rings required to maintain fixation. As a result, the frame narrows soft tissue reconstruction options because the pins limit access for flap dissection or microsurgical anastomosis. The external fixator frame can be cumbersome for the patient and may result in trauma to the contralateral leg [15].
Soft tissue reconstruction options Closure techniques include allowing the wound to heal by secondary intention or by closing it with (1) delayed primary closure, (2) skin graft, (3) local flaps, (4) pedicled flaps, (5) free flap, or (6) any combination thereof. If surgical closure is chosen, there should be two setups of instruments in the operating room. The first set of instruments is used to debride the wound. Culturing those instruments postdebridement yields a quantitative
EXTERNAL FIXATORS AS AN ADJUNCT TO WOUND HEALING
147
culture of up to 103 bacteria. Reusing those same instruments during the closure needlessly recontaminates the freshly debrided wound and increases the risk for postoperative infection. The debrided wound should be cleansed using pulsed lavage and then redraped while the surgeon changes gloves and a new set of uncontaminated instruments is brought to the field. These steps ensure that the wound is as clean as possible for the definite closure to decrease the risk of subsequent infection and tissue necrosis. Wounds can be allowed to heal by secondary intention by applying modern dressing change regimens. To speed up the process, wound healing adjuncts, such as growth factors, cultured skin, hyperbaric oxygen, or application of Vacuum Assisted Closure device ([VAC] KCI, San Antonio, Texas), can be applied. Correction of the underlying biomechanical abnormality is critical. For example, a diabetic forefoot ulcer caused by excessive plantar pressure because of a tight Achilles tendon is difficult to heal without addressing the tendon surgically. Delayed primary closure is easier to accomplish when the edema and induration of the wound edges has resolved. The VAC can be very helpful here in decreasing the periwound edema so that the wound edges become more pliable. After primary closure, one should always check that relevant pulses have not diminished because the closure was too tight. Adequate soft tissue envelope can also be created by removing bone (eg, distal fibula in a tibial-talar fusion) or by converting a large wound to a partial foot amputation and using the resultant soft tissue envelopes for closure. Technically, deep sutures should be avoided because they could potentiate reinfection. Simple vertical mattress sutures with monofilament suture are the least likely to facilitate reinfection. Skin grafting requires a healthy granulating bed that can be achieved by using any one or combination of the following: VAC, cultured skin, growth factor, and hyperbaric oxygen. In addition, a healthy neo-dermis can be built up over inhospitable wounds, such as bone, by applying a collagen lattice framework, such as Integra (Integra Lifesciences, Plainsboro, New Jersey) and waiting for it to revascularize. Skin graft take is helped by shaving down the superficial granulation tissue to remove bacteria that may still reside in the interstices of the granulation buds. The wound is then pulselavaged and new instruments are used to avoid recontaminating the wound base. The skin graft is meshed to prevent build up of seroma or hematoma that could prevent graft revascularization. The use of the VAC on low continuous suction as a temporary dressing for the first 3 to 5 days ensures the highest possible skin graft take rate. It provides excellent adhesion of the skin graft to the underlying bed, thereby preventing graft disruption from shear forces. It absorbs all excess fluid and keeps the wound relatively sterile. If the skin graft is over moving muscle or joint, it is likely to be disrupted by shear forces. In this instance, it is critical to immobilize the foot and ankle by splinting or placement of an external fixator until the skin graft has completely healed.
148
CLEMENS
et al
The use of any flap requires an accurate assessment of the blood flow. For local flaps, there should be a Dopplerable perforator close to the base of the flap. For pedicled flaps, the dominant arterial branch to the flap should be open. For free flaps, there should be an adequate recipient artery and veins. If there is any question, either a duplex scan, magnetic resonance angiogram, or normal angiogram should be obtained. Local flaps are very useful in coverage of lower-extremity wounds because they only need to be large enough to cover the exposed tendon, bone, or joint while the rest of the wound is skin grafted. This frequently obviates the need of larger pedicled or free flaps. In addition, it is a useful mode of reconstruction when trying to close a wound around or through an Ilizarov external fixator. The frame often makes it impossible to perform extensive dissection required for pedicled flaps or to provide the necessary space to perform the microsurgical anastomosis for free flaps. For plantar wounds, local flaps are very useful because the wounds are then closed with healthy plantar tissue rather than allowing them to heal by secondary intention that can lead to thick scar tissue and later become a source of recurrent callous formation. Knowledge of the various pedicled flaps in the foot and ankle area is critical for closing those wounds that cannot be closed with simpler methods. These are often more difficult to dissect and have a higher complication rate than performing a free flap. Harvesting a pedicled fasciocutaneous flap often leaves a donor deficit that has to be skin grafted. Pedicled flaps, however, allow the surgeon to perform a rapid operation with a shorter hospital stay that yields excellent long-lasting results. The anatomy and techniques of dissection are discussed elsewhere in flap anatomy books [16]. The most useful muscle flaps in the foot and ankle include the abductor hallucis muscle flap; the abductor digiti minimi muscle flap; the flexor digitorum brevis muscle flap; the extensor digitorum brevis muscle flap; the reverse extensor hallucis longus muscle flap; the reverse extensor digitorum longus muscle flap; and the reverse anterior tibial muscle flap (provided the ankle is fused). The most useful skin or fasciocutaneous flaps in the foot and ankle include the supramalleolar flap, the medial plantar flap, the lateral calcaneal flap, the reverse anterior tibial artery flap, the reverse peroneal artery flap, and the sural artery flap. When using reverse flaps based on the anterior tibial or peroneal artery, it is important that all other vessels are intact and the distal arterial-arterial connections are patent. Otherwise, ischemia or tissue necrosis may result. It is important to practice these flaps on cadaver legs before performing them because the dissections are often tedious and can be difficult. The distal reach of the flap often provides insufficient tissue so that it is very important to understand the size limitations of each flap. Free flaps in the foot and ankle carry the highest failure rate in the microsurgical literature and should be planned carefully. One of the reasons for this is that complications arise when the vascular anastomosis is performed at or near the zone of injury. In addition, the arteries are often calcified and
EXTERNAL FIXATORS AS AN ADJUNCT TO WOUND HEALING
149
special hardened microneedles are often required. Anastomoses should be performed away from the zone of injury. They can be done proximal or distal to the zone of injury providing that the neurovascular bundle is intact. An end-to-side anastomosis to the recipient artery should be done whenever possible. Two veins should be done whenever possible to minimize postoperative swelling. The use of an anastomotic device for veins speeds up the procedure. The choice of which free flap to choose depends in large part on the length of pedicle needed. For long pedicles, the serratus muscle, the latissimus muscle, the vastus lateralis muscle, or the rectus femoris muscles are excellent. It is important to remember that a longer pedicle can be obtained when the pedicle dissection is continued within the muscle belly. For the dorsum of the foot and ankle, thin fasciocutaneous or cutaneous flaps work best. For the plantar foot, muscle flaps and skin graft seem to hold up better in the long run. Immobilization of joint and off-loading Motion along a joint where there is soft tissue reconstruction often leads to dehiscence or breakdown. Immobilization with a cast makes it difficult to follow the wound and can place pressure on the reconstruction. Placing external fixators across a given joint immobilizes that joint while allowing excellent care of the wound. The fixator can then be removed when the wound has healed. Premature weight bearing on a reconstructed site also leads to breakdown. If the reconstruction involves the sole of the foot, off-loading for 6 weeks is often necessary to ensure healing. One can cast the patient with the knee flexed to avoid accidental weight bearing or hang the leg in a trapeze by a calcaneal pin until the wounds heal. Both these methods have significant side effects: the first may lead to a partial knee flexion contracture, whereas the latter exposes the patient to the medical risks of being in a bed for 6 weeks. Using an Ilizarov frame with a footplate is a reliable option if conservative measures cannot ensure success. The same problems exist with patients with decubitus ulcers. With posterior heel wounds, multipodos boots work reasonable well. This is a good solution providing that the wound is small and the patient complies with keeping on the boot. For larger wounds involving a free flap or sural artery flap reconstruction, an Ilizarov frame is ideal because it not only protects the heel but also the flap regardless of the patient’s activity. Patient compliance with off-loading schemes has proved to be the undoing of many reconstructions and averages over 20% in the authors’ institution. Armstrong and colleagues [17] have shown that when diabetics continually wear an off-loading boot, it works as well as contact casting to heal the wound. Unfortunately, patient compliance with the off-loading regimen is only 28% and wound healing suffers accordingly. Compliance with a non–weight-bearing regimen can be difficult because obesity, lack
150
CLEMENS
et al
of coordination, incapacitation of the contralateral limb, and spasticity all contribute an inability to adhere to off-loading regimens. Sagebien and colleagues [18] have recently reported the successful use of external fixation to protect free-flap soft tissue reconstruction of the lower extremity. Similarly, others have previously reported the use of a fixed frame for joint immobilization to support free-flap reconstruction [19]. The use of external fixation for soft tissue healing The authors reviewed their experience over a 6-year period and identified 24 consecutive patients in whom external fixation was used solely to protect the soft tissue reconstruction until it healed. To immobilize joints (usually the ankle) to allow healing, a monoplanar external fixator was used. To guarantee complete off-loading off of the weight-bearing surface (sole or posterior heel), a multiplanar external fixator was used. In 12 patients, a multiplanar external fixator was used to ensure offloading of wounds on weight-bearing surfaces (Fig. 1, 2, 5). This patient group had failed to heal for an average of 285 days with conservative offloading measures. The overall limb salvage rate in this group was 83%, and mean time to healing was 128 days after frame application. The modes of reconstruction included one delayed primary closure, five split-thickness skin graft, four local or pedicled flap, and two free flaps. Within this patient group, there were six complications (50%), including four pin site infections (33%) and two failed salvages that ultimately required amputation (17%). In this complex patient population with multiple comorbidities, close follow-up and vigilance are critical to prevent wound recurrence. Wounds recurred in five patients (42%) at a mean of 192 days after removal of the frame despite off-loading shoe wear. In the other 12 patients, a monoplanar external fixator was used to immobilize wounds near mobile joints (Figs. 3, 4). This patient group had failed to heal for an average of 232 days with conservative off-loading measures The overall limb salvage rate in this group was 73%, and mean time to healing was 66 days after frame application. Complications in this group consisted of two pin site infections (17%). Wounds recurred in two patients (17%) after removal of the frame and resumption of protected ambulation. These data expand the indications for external fixation for soft tissue reconstruction in the lower extremity. In addition to protecting free flap reconstructions, external fixation can be useful in reconstructions involving simpler procedures, such as skin grafts and local and pedicled flaps. The key is the excellent off-loading or joint immobilization that provides the environment to allow the wound to heal without having to deal with disrupting shear forces. The principle complication is that of pin tract infections that can usually be handled with good wound care, although they may necessitate early removal of the hardware or changing pin sites until the wound is healed.
EXTERNAL FIXATORS AS AN ADJUNCT TO WOUND HEALING
151
Fig. 1. This patient has a heel ulcer and caclaneal osteomyelitis. The wound was debrided. When the wound was ready, a plantar rotation flap was used to cover the exposed calcaneus and the rest of the wound was skin grafted. An Ilizarov frame with foot plate was used to offload the heel until it healed.
Of note is the high recurrence rate in the patients who underwent external fixation to off-load the weight-bearing surface. The fact that the recurrence rate was so high suggests poor patient selection. One has to screen patients vigorously to ensure that they are able to use the salvaged limb effectively once healed. If that is not the case, then amputation may be the better solution.
Technical considerations Space limitations imposed by the fixation device present significant challenge in selecting appropriate reconstructive options. Careful preoperative planning as to the timing and location of the pin placement is required with the orthopedic surgeon so that access for the planned reconstruction
152
CLEMENS
et al
Fig. 2. This patient developed calcaneal gait and a subsequent plantar heel ulcer. The ulcer was debrided. When the wound was ready,it was closed with flexor digitorum muscle flap and skin graft. An Ilizarov frame with footplate was placed to protect the reconstruction until it healed. When the wound healed, the frame was removed.
is possible. One has to remember that significant damage to the reconstruction can occur during placement of the fixation. If the fixation can be placed without limiting access to the wound, then it should be done after the wound has been debrided and is clean. If access to the wound is to be limited, then the external fixation should either be partially placed or be placed after the reconstruction. When a local transposition flap is planned, the flap donor site surrounding the wound should be wire free. If a pedicled muscle flap is planned (eg, abductor digiti minimi or abductor hallucis brevis flap), those muscles should remain pin free so that they can easily be harvested. If a free flap is planned, then access to the wound and recipient vessels must be preserved. This may require temporary removal of a ring or delay of placement of a ring while the free flap is performed. Alternatively, external fixation may be applied after the reconstruction during a two-team surgery. Based on these studies, the authors have developed the following algorithm assuming that the wound is adequately vascularized. If an open wound persists, initial debridement is performed, antibiotics are started, and the wound is dressed with a VAC. If infection persists (either clinically or based on culture results), wound debridement is repeated and VAC therapy continued until the wound is clean and there is evidence of healing. Only then is the wound considered ready for reconstruction. In the setting of exposed tendon, bone, or joint less than 10 cm2, a single or combination of local flaps is used to cover the vital structures while the rest of the wound is skin grafted. Wounds with more than 10 cm2 of exposed bone, joint, or tendon usually require combined local and pedicled flaps or free tissue transfer. Skin grafts can then be used to cover the remainder of the defect without exposed tendon, joint, or bone.
EXTERNAL FIXATORS AS AN ADJUNCT TO WOUND HEALING
153
Fig. 3. This paraplegic patient had a dehisced ankle incision that was radically debrided and later closed with a rotation flap. A monoplanar frame was used to immobilized the ankle until the flap healed.
Close coordination with other surgical teams during application of the external fixator is necessary to maximize reconstructive options. At the authors’ institution, Ilizarov or monoplanar frames are placed by an orthopedic surgeon at time of reconstruction. The timing of the external fixator placement (prereconstruction or postreconstruction) depends on the factors discussed previously. If a graft or flap is in an area where joint motion could disrupt the graft or flap (ie, ankle or distal forefoot), then immobilization with a posterior splint, cast, or external fixator is used until the wound heals completely (3–6 weeks). For heel wounds, the Ilizarov frame is very useful because it not only immobilizes the ankle but it also suspends the foot in mid air so that the patient cannot disrupt a delayed primary closure, skin graft, or flap. If the reconstruction is on the plantar aspect of the foot, there should be no weight bearing until the flap has matured (usually 6 weeks). The use of a foot plate is critical to ensure success.
154
CLEMENS
et al
Fig. 4. This patient had an exposed anterior tibial tendon that we debrided. When the wound was ready, the tendon was covered with a rotation flap and the rest was skin grafted. The ankle was immobilized with a mono-planar fixator until the wound healed.
Fig. 5. This patient was bed-bound and developed decubitus ulcers of his right leg. He refused amputation and we serially debrided him. We placed an ilizarov frame to offload the area. We then placed xenograft on the wound to prepare the wound bed for a skin graft. We then skin grafted him successfully. The wounds recurred soon after the frame was removed. Proper patient selection is critical in such cases and the patient would have been better served with a disarticulation at the knee.
EXTERNAL FIXATORS AS AN ADJUNCT TO WOUND HEALING
155
Summary Ensuring that the wound is ready for closure is accomplished by first correcting medical and vascular deficiencies, by aggressively debriding the wound and covering the infection with appropriate antibiotics, and by treating the wound with dressings that promote healing. Only when the wound shows signs of healing should the reconstruction be considered. Properly selected patients undergoing lower-extremity soft tissue reconstruction may benefit from external devices that are usually reserved for bone stabilization. They can be used to immobilize a joint or off-load a wound surface until the reconstructed wound has healed. Close coordination with the orthopedic team is necessary to use the external fixator effectively.
References [1] Holden CEA. The role of blood supply to soft tissue in the healing of diaphyseal fractures. J Bone Joint Surg Am 1972;54:993–1000. [2] Stephen P, Aitken R. Morbidity survey of lower limb amputees. Clin Rehabil 1987;1:181–6. [3] Studenski S, Duncan P. Measuring rehabilitation outcomes. Geriatric Rehabilitation 1993; 9:823–30. [4] Lange RH. Limb reconstruction versus amputation decision making in massive lower extremity trauma. Clin Orthop 1989;243:92–9. [5] Aldea PA, Shaw WW. The evolution of the surgical management of severe lower extremity trauma. Clin Plast Surg 1986;13(4):549–67. [6] Francel TJ, Vander Kolk CA, Hoopes JE, et al. Microvascular soft-tissue transplantation for reconstruction of acute open tibial fractures: timing of coverage and long-term functional results. Plast Reconstr Surg 1992;89:478–87. [7] Matros E, Pribaz JJ, Orgill DP. Lower extremity trauma: trends in the management of soft tissue reconstruction of open tibia-fibula fractures. Plast Reconstr Surg 2006;117(4):1315–22 [discussion: 1323–4]. [8] Wray JB. Factors in the pathogenesis of nonunion. J Bone Joint Surg Am 1965;47:168–73. [9] Mooney V, Ferguson AB. The influence of immobilization and motion on the formation of fibrocartilage in the repair granuloma after joint resection in the rabbit. J Bone Joint Surg Am 1966;48:1145–55. [10] Dendrinos GK, Kontos S, Lyritsis E. Use of the Ilizarov technique for treatment of nonunion of the tibia associated with infection. J Bone Joint Surg Am 1995;77:835–46. [11] Ghoneem HF, Wright JG, Cole WG, et al. The Ilizarov method for correction of complex deformities. J Bone Joint Surg Am 1996;78:1480–5. [12] Agarwal S, Agarwal R, Jain UK, et al. Management of soft tissue problems in leg trauma in conjunction with application of the Ilizarov fixator assembly. Plast Reconstr Surg 2001;107: 1732–8. [13] Vasconez HC, Nicholls PJ. Management of extremity injuries with external fixator or Ilizarov devices: cooperative effort between orthopedic and plastic surgeons. Clin Plast Surg 1991;18(3):505–13. [14] McKee MD, Yoo D, Schemitsch EH. Health status after Ilizarov reconstruction of posttraumatic lower-limb deformity. J Bone Joint Surg Br 1998;80:360–4. [15] Cooper PS. Application of external fixators for management of Charcot deformities of the foot and ankle [review]. Foot Ankle Clin 2002;7:207–54. [16] Masqualet AC, Gilbert A. An atlas of flaps in limb reconstruction. Philadelphia: J.B. Lippincott Co; 1995.
156
CLEMENS
et al
[17] Armstrong DG, Nguyen HC, Lavery LA, et al. Off-loading the diabetic foot wound: a randomized clinical trial. Diabetes Care 2001;24(6):2153–4. [18] Sagebien CA, Rodriguez ED, Turen CH. The soft tissue frame. Plast Reconstr Surg 2007; 119:2137–40. [19] Buford GA, Trzeciak MA. A novel method for lower-extremity immobilization after freeflap reconstruction of posterior heel defects. Plast Reconstr Surg 2003;111:821–4.
External Fixators as an Adjunct to Wound Healing Mark W. Clemens, MDa, Pranay Parikh, MDa, Melanie M. Hall, BSb, Christopher E. Attinger, MDa,* a
Division of Wound Healing, Department of Plastic Surgery, Georgetown University Medical Center, 3800 Reservoir Road NW, Washington, DC 20007, USA b Georgetown University, 37th and 0 Streets NW, Washington, DC 20057, USA
Traditionally, the most straightforward treatment for complex lowerextremity wounds and major soft tissue defects was amputation of an affected limb. Uncontrollable wounds caused by infection, size, vascular insufficiency, compromised immune status, and unstable skeletal framework require multiple operations by different specialties and prolonged healing times to salvage the limb with no guarantee that the result yields a functional limb [1]. Amputations are a straightforward and rapid solution to complex wounds that can have the patient back ambulating in short order. Amputations, however, carry risks of their own: increased energy of expenditure, decreased life expectancy, and increased risk of contralateral limb amputation [2–4]. In addition, an amputation subjects a patient to lifetime dependence on prosthetic devices and, for those who never go on to wear prosthesis, a wheelchair-bound existence. Reconstructive surgeons are called on to address lower-extremity wounds that result from trauma, ischemia, or infection [5]. The first task is to convert the existing wound into a healthy wound. This often requires a multidisciplinary effort with vascular surgeons re-establishing adequate blood flow to heal, orthopedic surgeons re-establishing skeletal stability, infectious disease clinicians addressing the existing infection, and medicine clinicians stabilizing the patient. The wound is aggressively debrided until only normal tissue is left. It is then covered with an appropriate dressing regimen to promote healing. Closure should be considered only when the wound is clean and healthy granulation tissue appears. Most wounds are then closed using soft tissue techniques in the reconstructive ladder, such as delayed primary * Corresponding author. E-mail address: [email protected] (C.E. Attinger). 1083-7515/08/$ - see front matter Ó 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.fcl.2007.12.001 foot.theclinics.com
146
CLEMENS
et al
closure, skin grafts, local flaps, and free tissue transfer [6]. Because of advances in wound healing techniques, the trend has been away from microsurgery and toward simpler modes of reconstruction [7]. A significant portion of wounds breakdown or fail to heal in the postoperative period, however, because of repetitive shear forces around an active joint, decubitus pressure, or premature ambulatory pressure in a noncompliant patient. The detrimental effect of motion on wound healing is well established [8,9]. This article evaluates the adjunctive role of external fixation (Ilizarov and monoplanar) in soft tissue reconstruction to ensure healing in patients requiring reliable off-loading or immobilization of joints.
External fixation External fixation has an established role for the treatment of trauma and osteomyelitis [10–12]. In these clinical applications, the external fixator allows for the salvage of severely infected or traumatized bone or joints that required major amputation in the past [13]. The fixator maintains bone and joint alignment through rigid external fixation despite often significant bone resection for osteomyelitis or skeletal realignment. It does that without having to resort to internal fixation with plates and screws that are counterindicated in infected wounds. The fixator markedly decreases soft tissue trauma by using smaller pins and by significantly reducing the amount of soft tissue dissection required with open reduction with internal fixation with plates and screws [2]. The Ilizarov fixator has been shown to shorten healing time, decrease pin track infections, and allow early weight bearing by the addition of a protective plantar plate [14]. In terms of soft tissue reconstruction, the disadvantages associated with external fixation (Ilizarov more so than external monoplanar fixator) include cost and a cumbersome construct. Applying a fixator carries a relatively high cost ranging from $2000 to $10,000. In addition, the Ilizarov restricts soft tissue access because of the multiple pins and rings required to maintain fixation. As a result, the frame narrows soft tissue reconstruction options because the pins limit access for flap dissection or microsurgical anastomosis. The external fixator frame can be cumbersome for the patient and may result in trauma to the contralateral leg [15].
Soft tissue reconstruction options Closure techniques include allowing the wound to heal by secondary intention or by closing it with (1) delayed primary closure, (2) skin graft, (3) local flaps, (4) pedicled flaps, (5) free flap, or (6) any combination thereof. If surgical closure is chosen, there should be two setups of instruments in the operating room. The first set of instruments is used to debride the wound. Culturing those instruments postdebridement yields a quantitative
EXTERNAL FIXATORS AS AN ADJUNCT TO WOUND HEALING
147
culture of up to 103 bacteria. Reusing those same instruments during the closure needlessly recontaminates the freshly debrided wound and increases the risk for postoperative infection. The debrided wound should be cleansed using pulsed lavage and then redraped while the surgeon changes gloves and a new set of uncontaminated instruments is brought to the field. These steps ensure that the wound is as clean as possible for the definite closure to decrease the risk of subsequent infection and tissue necrosis. Wounds can be allowed to heal by secondary intention by applying modern dressing change regimens. To speed up the process, wound healing adjuncts, such as growth factors, cultured skin, hyperbaric oxygen, or application of Vacuum Assisted Closure device ([VAC] KCI, San Antonio, Texas), can be applied. Correction of the underlying biomechanical abnormality is critical. For example, a diabetic forefoot ulcer caused by excessive plantar pressure because of a tight Achilles tendon is difficult to heal without addressing the tendon surgically. Delayed primary closure is easier to accomplish when the edema and induration of the wound edges has resolved. The VAC can be very helpful here in decreasing the periwound edema so that the wound edges become more pliable. After primary closure, one should always check that relevant pulses have not diminished because the closure was too tight. Adequate soft tissue envelope can also be created by removing bone (eg, distal fibula in a tibial-talar fusion) or by converting a large wound to a partial foot amputation and using the resultant soft tissue envelopes for closure. Technically, deep sutures should be avoided because they could potentiate reinfection. Simple vertical mattress sutures with monofilament suture are the least likely to facilitate reinfection. Skin grafting requires a healthy granulating bed that can be achieved by using any one or combination of the following: VAC, cultured skin, growth factor, and hyperbaric oxygen. In addition, a healthy neo-dermis can be built up over inhospitable wounds, such as bone, by applying a collagen lattice framework, such as Integra (Integra Lifesciences, Plainsboro, New Jersey) and waiting for it to revascularize. Skin graft take is helped by shaving down the superficial granulation tissue to remove bacteria that may still reside in the interstices of the granulation buds. The wound is then pulselavaged and new instruments are used to avoid recontaminating the wound base. The skin graft is meshed to prevent build up of seroma or hematoma that could prevent graft revascularization. The use of the VAC on low continuous suction as a temporary dressing for the first 3 to 5 days ensures the highest possible skin graft take rate. It provides excellent adhesion of the skin graft to the underlying bed, thereby preventing graft disruption from shear forces. It absorbs all excess fluid and keeps the wound relatively sterile. If the skin graft is over moving muscle or joint, it is likely to be disrupted by shear forces. In this instance, it is critical to immobilize the foot and ankle by splinting or placement of an external fixator until the skin graft has completely healed.
148
CLEMENS
et al
The use of any flap requires an accurate assessment of the blood flow. For local flaps, there should be a Dopplerable perforator close to the base of the flap. For pedicled flaps, the dominant arterial branch to the flap should be open. For free flaps, there should be an adequate recipient artery and veins. If there is any question, either a duplex scan, magnetic resonance angiogram, or normal angiogram should be obtained. Local flaps are very useful in coverage of lower-extremity wounds because they only need to be large enough to cover the exposed tendon, bone, or joint while the rest of the wound is skin grafted. This frequently obviates the need of larger pedicled or free flaps. In addition, it is a useful mode of reconstruction when trying to close a wound around or through an Ilizarov external fixator. The frame often makes it impossible to perform extensive dissection required for pedicled flaps or to provide the necessary space to perform the microsurgical anastomosis for free flaps. For plantar wounds, local flaps are very useful because the wounds are then closed with healthy plantar tissue rather than allowing them to heal by secondary intention that can lead to thick scar tissue and later become a source of recurrent callous formation. Knowledge of the various pedicled flaps in the foot and ankle area is critical for closing those wounds that cannot be closed with simpler methods. These are often more difficult to dissect and have a higher complication rate than performing a free flap. Harvesting a pedicled fasciocutaneous flap often leaves a donor deficit that has to be skin grafted. Pedicled flaps, however, allow the surgeon to perform a rapid operation with a shorter hospital stay that yields excellent long-lasting results. The anatomy and techniques of dissection are discussed elsewhere in flap anatomy books [16]. The most useful muscle flaps in the foot and ankle include the abductor hallucis muscle flap; the abductor digiti minimi muscle flap; the flexor digitorum brevis muscle flap; the extensor digitorum brevis muscle flap; the reverse extensor hallucis longus muscle flap; the reverse extensor digitorum longus muscle flap; and the reverse anterior tibial muscle flap (provided the ankle is fused). The most useful skin or fasciocutaneous flaps in the foot and ankle include the supramalleolar flap, the medial plantar flap, the lateral calcaneal flap, the reverse anterior tibial artery flap, the reverse peroneal artery flap, and the sural artery flap. When using reverse flaps based on the anterior tibial or peroneal artery, it is important that all other vessels are intact and the distal arterial-arterial connections are patent. Otherwise, ischemia or tissue necrosis may result. It is important to practice these flaps on cadaver legs before performing them because the dissections are often tedious and can be difficult. The distal reach of the flap often provides insufficient tissue so that it is very important to understand the size limitations of each flap. Free flaps in the foot and ankle carry the highest failure rate in the microsurgical literature and should be planned carefully. One of the reasons for this is that complications arise when the vascular anastomosis is performed at or near the zone of injury. In addition, the arteries are often calcified and
EXTERNAL FIXATORS AS AN ADJUNCT TO WOUND HEALING
149
special hardened microneedles are often required. Anastomoses should be performed away from the zone of injury. They can be done proximal or distal to the zone of injury providing that the neurovascular bundle is intact. An end-to-side anastomosis to the recipient artery should be done whenever possible. Two veins should be done whenever possible to minimize postoperative swelling. The use of an anastomotic device for veins speeds up the procedure. The choice of which free flap to choose depends in large part on the length of pedicle needed. For long pedicles, the serratus muscle, the latissimus muscle, the vastus lateralis muscle, or the rectus femoris muscles are excellent. It is important to remember that a longer pedicle can be obtained when the pedicle dissection is continued within the muscle belly. For the dorsum of the foot and ankle, thin fasciocutaneous or cutaneous flaps work best. For the plantar foot, muscle flaps and skin graft seem to hold up better in the long run. Immobilization of joint and off-loading Motion along a joint where there is soft tissue reconstruction often leads to dehiscence or breakdown. Immobilization with a cast makes it difficult to follow the wound and can place pressure on the reconstruction. Placing external fixators across a given joint immobilizes that joint while allowing excellent care of the wound. The fixator can then be removed when the wound has healed. Premature weight bearing on a reconstructed site also leads to breakdown. If the reconstruction involves the sole of the foot, off-loading for 6 weeks is often necessary to ensure healing. One can cast the patient with the knee flexed to avoid accidental weight bearing or hang the leg in a trapeze by a calcaneal pin until the wounds heal. Both these methods have significant side effects: the first may lead to a partial knee flexion contracture, whereas the latter exposes the patient to the medical risks of being in a bed for 6 weeks. Using an Ilizarov frame with a footplate is a reliable option if conservative measures cannot ensure success. The same problems exist with patients with decubitus ulcers. With posterior heel wounds, multipodos boots work reasonable well. This is a good solution providing that the wound is small and the patient complies with keeping on the boot. For larger wounds involving a free flap or sural artery flap reconstruction, an Ilizarov frame is ideal because it not only protects the heel but also the flap regardless of the patient’s activity. Patient compliance with off-loading schemes has proved to be the undoing of many reconstructions and averages over 20% in the authors’ institution. Armstrong and colleagues [17] have shown that when diabetics continually wear an off-loading boot, it works as well as contact casting to heal the wound. Unfortunately, patient compliance with the off-loading regimen is only 28% and wound healing suffers accordingly. Compliance with a non–weight-bearing regimen can be difficult because obesity, lack
150
CLEMENS
et al
of coordination, incapacitation of the contralateral limb, and spasticity all contribute an inability to adhere to off-loading regimens. Sagebien and colleagues [18] have recently reported the successful use of external fixation to protect free-flap soft tissue reconstruction of the lower extremity. Similarly, others have previously reported the use of a fixed frame for joint immobilization to support free-flap reconstruction [19]. The use of external fixation for soft tissue healing The authors reviewed their experience over a 6-year period and identified 24 consecutive patients in whom external fixation was used solely to protect the soft tissue reconstruction until it healed. To immobilize joints (usually the ankle) to allow healing, a monoplanar external fixator was used. To guarantee complete off-loading off of the weight-bearing surface (sole or posterior heel), a multiplanar external fixator was used. In 12 patients, a multiplanar external fixator was used to ensure offloading of wounds on weight-bearing surfaces (Fig. 1, 2, 5). This patient group had failed to heal for an average of 285 days with conservative offloading measures. The overall limb salvage rate in this group was 83%, and mean time to healing was 128 days after frame application. The modes of reconstruction included one delayed primary closure, five split-thickness skin graft, four local or pedicled flap, and two free flaps. Within this patient group, there were six complications (50%), including four pin site infections (33%) and two failed salvages that ultimately required amputation (17%). In this complex patient population with multiple comorbidities, close follow-up and vigilance are critical to prevent wound recurrence. Wounds recurred in five patients (42%) at a mean of 192 days after removal of the frame despite off-loading shoe wear. In the other 12 patients, a monoplanar external fixator was used to immobilize wounds near mobile joints (Figs. 3, 4). This patient group had failed to heal for an average of 232 days with conservative off-loading measures The overall limb salvage rate in this group was 73%, and mean time to healing was 66 days after frame application. Complications in this group consisted of two pin site infections (17%). Wounds recurred in two patients (17%) after removal of the frame and resumption of protected ambulation. These data expand the indications for external fixation for soft tissue reconstruction in the lower extremity. In addition to protecting free flap reconstructions, external fixation can be useful in reconstructions involving simpler procedures, such as skin grafts and local and pedicled flaps. The key is the excellent off-loading or joint immobilization that provides the environment to allow the wound to heal without having to deal with disrupting shear forces. The principle complication is that of pin tract infections that can usually be handled with good wound care, although they may necessitate early removal of the hardware or changing pin sites until the wound is healed.
EXTERNAL FIXATORS AS AN ADJUNCT TO WOUND HEALING
151
Fig. 1. This patient has a heel ulcer and caclaneal osteomyelitis. The wound was debrided. When the wound was ready, a plantar rotation flap was used to cover the exposed calcaneus and the rest of the wound was skin grafted. An Ilizarov frame with foot plate was used to offload the heel until it healed.
Of note is the high recurrence rate in the patients who underwent external fixation to off-load the weight-bearing surface. The fact that the recurrence rate was so high suggests poor patient selection. One has to screen patients vigorously to ensure that they are able to use the salvaged limb effectively once healed. If that is not the case, then amputation may be the better solution.
Technical considerations Space limitations imposed by the fixation device present significant challenge in selecting appropriate reconstructive options. Careful preoperative planning as to the timing and location of the pin placement is required with the orthopedic surgeon so that access for the planned reconstruction
152
CLEMENS
et al
Fig. 2. This patient developed calcaneal gait and a subsequent plantar heel ulcer. The ulcer was debrided. When the wound was ready,it was closed with flexor digitorum muscle flap and skin graft. An Ilizarov frame with footplate was placed to protect the reconstruction until it healed. When the wound healed, the frame was removed.
is possible. One has to remember that significant damage to the reconstruction can occur during placement of the fixation. If the fixation can be placed without limiting access to the wound, then it should be done after the wound has been debrided and is clean. If access to the wound is to be limited, then the external fixation should either be partially placed or be placed after the reconstruction. When a local transposition flap is planned, the flap donor site surrounding the wound should be wire free. If a pedicled muscle flap is planned (eg, abductor digiti minimi or abductor hallucis brevis flap), those muscles should remain pin free so that they can easily be harvested. If a free flap is planned, then access to the wound and recipient vessels must be preserved. This may require temporary removal of a ring or delay of placement of a ring while the free flap is performed. Alternatively, external fixation may be applied after the reconstruction during a two-team surgery. Based on these studies, the authors have developed the following algorithm assuming that the wound is adequately vascularized. If an open wound persists, initial debridement is performed, antibiotics are started, and the wound is dressed with a VAC. If infection persists (either clinically or based on culture results), wound debridement is repeated and VAC therapy continued until the wound is clean and there is evidence of healing. Only then is the wound considered ready for reconstruction. In the setting of exposed tendon, bone, or joint less than 10 cm2, a single or combination of local flaps is used to cover the vital structures while the rest of the wound is skin grafted. Wounds with more than 10 cm2 of exposed bone, joint, or tendon usually require combined local and pedicled flaps or free tissue transfer. Skin grafts can then be used to cover the remainder of the defect without exposed tendon, joint, or bone.
EXTERNAL FIXATORS AS AN ADJUNCT TO WOUND HEALING
153
Fig. 3. This paraplegic patient had a dehisced ankle incision that was radically debrided and later closed with a rotation flap. A monoplanar frame was used to immobilized the ankle until the flap healed.
Close coordination with other surgical teams during application of the external fixator is necessary to maximize reconstructive options. At the authors’ institution, Ilizarov or monoplanar frames are placed by an orthopedic surgeon at time of reconstruction. The timing of the external fixator placement (prereconstruction or postreconstruction) depends on the factors discussed previously. If a graft or flap is in an area where joint motion could disrupt the graft or flap (ie, ankle or distal forefoot), then immobilization with a posterior splint, cast, or external fixator is used until the wound heals completely (3–6 weeks). For heel wounds, the Ilizarov frame is very useful because it not only immobilizes the ankle but it also suspends the foot in mid air so that the patient cannot disrupt a delayed primary closure, skin graft, or flap. If the reconstruction is on the plantar aspect of the foot, there should be no weight bearing until the flap has matured (usually 6 weeks). The use of a foot plate is critical to ensure success.
154
CLEMENS
et al
Fig. 4. This patient had an exposed anterior tibial tendon that we debrided. When the wound was ready, the tendon was covered with a rotation flap and the rest was skin grafted. The ankle was immobilized with a mono-planar fixator until the wound healed.
Fig. 5. This patient was bed-bound and developed decubitus ulcers of his right leg. He refused amputation and we serially debrided him. We placed an ilizarov frame to offload the area. We then placed xenograft on the wound to prepare the wound bed for a skin graft. We then skin grafted him successfully. The wounds recurred soon after the frame was removed. Proper patient selection is critical in such cases and the patient would have been better served with a disarticulation at the knee.
EXTERNAL FIXATORS AS AN ADJUNCT TO WOUND HEALING
155
Summary Ensuring that the wound is ready for closure is accomplished by first correcting medical and vascular deficiencies, by aggressively debriding the wound and covering the infection with appropriate antibiotics, and by treating the wound with dressings that promote healing. Only when the wound shows signs of healing should the reconstruction be considered. Properly selected patients undergoing lower-extremity soft tissue reconstruction may benefit from external devices that are usually reserved for bone stabilization. They can be used to immobilize a joint or off-load a wound surface until the reconstructed wound has healed. Close coordination with the orthopedic team is necessary to use the external fixator effectively.
References [1] Holden CEA. The role of blood supply to soft tissue in the healing of diaphyseal fractures. J Bone Joint Surg Am 1972;54:993–1000. [2] Stephen P, Aitken R. Morbidity survey of lower limb amputees. Clin Rehabil 1987;1:181–6. [3] Studenski S, Duncan P. Measuring rehabilitation outcomes. Geriatric Rehabilitation 1993; 9:823–30. [4] Lange RH. Limb reconstruction versus amputation decision making in massive lower extremity trauma. Clin Orthop 1989;243:92–9. [5] Aldea PA, Shaw WW. The evolution of the surgical management of severe lower extremity trauma. Clin Plast Surg 1986;13(4):549–67. [6] Francel TJ, Vander Kolk CA, Hoopes JE, et al. Microvascular soft-tissue transplantation for reconstruction of acute open tibial fractures: timing of coverage and long-term functional results. Plast Reconstr Surg 1992;89:478–87. [7] Matros E, Pribaz JJ, Orgill DP. Lower extremity trauma: trends in the management of soft tissue reconstruction of open tibia-fibula fractures. Plast Reconstr Surg 2006;117(4):1315–22 [discussion: 1323–4]. [8] Wray JB. Factors in the pathogenesis of nonunion. J Bone Joint Surg Am 1965;47:168–73. [9] Mooney V, Ferguson AB. The influence of immobilization and motion on the formation of fibrocartilage in the repair granuloma after joint resection in the rabbit. J Bone Joint Surg Am 1966;48:1145–55. [10] Dendrinos GK, Kontos S, Lyritsis E. Use of the Ilizarov technique for treatment of nonunion of the tibia associated with infection. J Bone Joint Surg Am 1995;77:835–46. [11] Ghoneem HF, Wright JG, Cole WG, et al. The Ilizarov method for correction of complex deformities. J Bone Joint Surg Am 1996;78:1480–5. [12] Agarwal S, Agarwal R, Jain UK, et al. Management of soft tissue problems in leg trauma in conjunction with application of the Ilizarov fixator assembly. Plast Reconstr Surg 2001;107: 1732–8. [13] Vasconez HC, Nicholls PJ. Management of extremity injuries with external fixator or Ilizarov devices: cooperative effort between orthopedic and plastic surgeons. Clin Plast Surg 1991;18(3):505–13. [14] McKee MD, Yoo D, Schemitsch EH. Health status after Ilizarov reconstruction of posttraumatic lower-limb deformity. J Bone Joint Surg Br 1998;80:360–4. [15] Cooper PS. Application of external fixators for management of Charcot deformities of the foot and ankle [review]. Foot Ankle Clin 2002;7:207–54. [16] Masqualet AC, Gilbert A. An atlas of flaps in limb reconstruction. Philadelphia: J.B. Lippincott Co; 1995.
156
CLEMENS
et al
[17] Armstrong DG, Nguyen HC, Lavery LA, et al. Off-loading the diabetic foot wound: a randomized clinical trial. Diabetes Care 2001;24(6):2153–4. [18] Sagebien CA, Rodriguez ED, Turen CH. The soft tissue frame. Plast Reconstr Surg 2007; 119:2137–40. [19] Buford GA, Trzeciak MA. A novel method for lower-extremity immobilization after freeflap reconstruction of posterior heel defects. Plast Reconstr Surg 2003;111:821–4.