Fibula Tissue Transfer

Until the advent of free tissue transfer, reconstruction of mandible and midface defects was suboptimal. Anterior mandibular arch defects resulted in the so-called "Andy Gump" deformity, a term, coined in 1978 in a dental publication, that referred to the appearance of a chinless cartoon character from early in the 20th century. These patients not only had an obvious cosmetic deformity but also severe functional problems such as poor oral competence and drooling. Patients with small lateral defects of the mandible had less severe problems, but they too had difficulties with chewing, swallowing, and speaking.

Some surgeons addressed this problem by plating across defects with or without nonvascularized bone. However, this technique tended to eventually result in plate exposure, particularly in irradiated patients. (See the image below.) Bulky, pedicled flaps were also used to cover these plates, with improved but varying degrees of success.

The fibula free flap was introduced in the mid-1970s for the reconstruction of tibial defects. Its use in mandibular reconstruction was first described in 1989, by Hidalgo, with fibular reconstruction now being the criterion standard for the reconstruction of mandibular and maxillary bony defects. The presence of endosteal and periosteal blood supplies to the bone allows for multiple osteotomies and therefore precise contouring to approximate the shape of the native mandible. Pedicle diameter allows relatively easy anastomoses; veins are 1.5-3 mm and the artery is 2.5-3.0 mm. One drawback is the relatively short pedicle length. Although its exact length depends on the amount of proximal bone discarded, it is generally 3-6 cm.

Since its initial description as an osseus flap, the flap has been modified to include a cutaneous portion and has thereafter been described with a sensate paddle of skin. In the early 1990s, many surgeons were reluctant to use the osteocutaneous flap because of reported problems with vascular reliability of the skin. This resulted in some surgeons advocating that the flap be used only as an osseous flap. However, experience and an improved understanding of skin paddle anatomy have led to an improved ability to maintain the delicate perforators. Surgeons now realize that skin viability is more technique-dependent with this flap than in many other free flaps. Cutaneous perforators may be septocutaneous or musculocutaneous. Harvesting a piece of the Soleus muscle ensures adequate blood supply to the skin.

Size of the skin paddle, whether to design the paddle proximally or distally, and use of a tourniquet are dictated by individual preferences and patient requirements.

Preoperative evaluations in all patients should be done in conjunction with the ablative team. The extent of tumor,[3] presence of regional and distant metastases, bone involvement, and general medical condition are all factors that must be taken into consideration in order to determine a surgical plan. Special attention must be paid to the patient's dorsalis pedis and tibialis posterior pulses if a fibular flap is being considered. The feet and legs must also be assessed, for color, edema, scars, any signs of venous congestion, and/or any other abnormality.

Dental, oral surgery, social work, and physical therapy consults should be obtained. In many cases, dental extraction is needed and can be done before or at the time of surgery. The fibular free flap is also an excellent choice for patients interested in having osseointegrated implants. These devices can be implanted in the flap when used for mandibular and maxillary reconstruction; however, such devices are very expensive and their cost is seldom covered by insurance.

Patients with abnormal pedal pulses or abnormal skin texture should undergo further testing. The role of preoperative Doppler examination, angiographic imaging, or magnetic resonance angiography (MRA) to evaluate the vascular anatomy of the leg is undetermined. It is our practice to perform physical and Doppler examinations, reserving other techniques for use only as needed.

The fibular free flap is well suited for any reconstruction of the head and neck. It is ideal for defects of the anterior mandibular arch or lateral defects in patients who wish to undergo osseointegrated dental reconstruction. (See the image below.) The palate and midface can also be reconstructed successfully with this flap. The temporomandibular joint may be reconstructed with a suture to anchor the sculpted fibula to the joint disc.[4]

An osteocutaneous flap can be harvested in patients who require soft-tissue coverage to replace intraoral or external skin defects. The skin of the flap is anchored to the bone by the septum, through which the septocutaneous perforators run. Thus, the skin paddle is only moldable to fit a two-dimensional defect. Three-dimensional defects require different reconstructive techniques. The volume of tissue that can be harvested is also limited, and some situations require a two flap technique or a different donor site.

A retrospective study by Mericli et al indicated that vascularized fibula free flaps can provide an effective means of repairing bony extremity defects resulting from oncologic resection. Used on upper and lower extremities, the flaps had an overall union rate of 91.7%. Full weight-bearing following lower extremity reconstruction was achieved in a mean 16 months. The investigators did find, however, that complications led to reoperation in 43% of patients. Moreover, subgroup analysis of immediate femur reconstruction revealed that compared with procedures employing intramedullary placement of the flap, those using onlay fibula flap orientation were associated with a significantly greater complication risk, the odds ratio (OR) being 6.3. The same femur analysis also showed that the risk for needing conversion to an endoprosthesis as a consequence of nonunion was higher for onlay, as opposed to intramedullary, procedures (OR 12.1).[5]

Three vessels provide the vascular supply to the lower leg. In the knee, the popliteal artery bifurcates into the anterior tibial artery and the tibioperoneal trunk. The latter divides into the posterior tibial artery and the peroneal artery. In the lower leg, the anterior tibial vessels lie on the dorsum of the foot and are palpable as the dorsalis pedis pulse. The posterior tibial vessels run deep in the leg along the lateral aspect and can be palpated as the posterior tibial pulse. The peroneal vessels lie in close proximity to the fibula, coursing the entire distance of the bone along its medial aspect. The artery is accompanied by paired venae comitantes, which may join together proximally.

Although variations of the lower leg anatomy are uncommon, they are important to identify if a fibular free flap is planned. When a dominant peroneal artery exists, pedal circulation is more dependent on this vessel. Sacrifice of the peroneal artery in such cases renders the foot susceptible to ischemia when the fibula flap is harvested.

Preservation of the peroneal nerve is important to avoid complications. It lies superficial to the upper lateral fibula and crosses the fibula about 3 cm distal to the proximal fibular head, where it is most susceptible to injury during bone harvest. To minimize risk, the superior 4-6 cm of fibular bone is preserved. Reinnervation of the cutaneous paddle is possible via the lateral sural cutaneous nerve, which can be traced medially when the soft tissue is harvested. However, the skin paddle may or may not actually be supplied by this nerve.

The skin paddle is supplied by perforators from the peroneal vessels that enter the skin via the posterior crural septum, which is identified between the peroneus longus and soleus muscles. One to three perforators are identified for skin harvest. They can be identified preoperatively with duplex Doppler imaging or in the operating room before the incision is made with a hand-held Doppler unit. They should be directly visualized in the fasciocutaneous tissues of the septum during the dissection. Perforators may also be encountered coming directly from the muscle, which do not course through the septum. These may or may not originate from the peroneal vessels. Harvesting a cuff of soleus muscle may help to preserve these muscular perforators.

The maximum density of perforating vessels in the leg appears to be in its proximal and distal aspect rather than in the midportion of the lower extremity. In deciding ideal placement of the skin paddle, the surgeon is typically limited by the need to harvest a pedicle of sufficient length; thus, distal harvest is usually chosen. The paddle is centered at the junction of the middle third and distal third of the fibula.

Skin paddles have become increasingly reliable, probably owing to the harvesting of larger (longer) skin paddles, an increased understanding of perforating vessel anatomy, more reliable identification of perforating vessels, and more expert dissection of the septum. Trauma, tension, or injury to the septum may result in loss of the skin paddle because of perforator injury.

Abnormalities in vascular anatomy of the lower leg may preclude safe harvesting of the fibula. (See the images below.) Dominant peroneal circulation may be present in patients with congenital absence or underdevelopment of the anterior tibial vessels. An enlarged peroneal artery is known as peroneus magnus and is a major blood supply to the foot. Patients with peroneus magnus or impaired circulation to the leg should not undergo fibula transposition, due to risk of ischemic damage to the foot.

Caution is advised in patients who have had extensive leg trauma or surgery prior to planning fibular surgery. Diabetic patients are also poor candidates due to the risk of having significant venous stasis or peripheral edema, poor circulation or healing, and cutaneous ulcers. Alternatives include no reconstruction, plating only, an iliac crest or scapula flap, an osseocutaneous radial forearm flap, or soft-tissue coverage only. One should carefully evaluate the functional status of the patient, because he or she will have some temporary impairment following harvest.

Although not contraindicated per se, patients with large bone and skin defects may require 2 flaps to properly reconstruct the defect. Some surgeons would choose another flap rather than using 2 free flaps. In these patients, a separate fasciocutaneous flap may be required to resurface the skin, especially if the skin defect is not in immediate proximity to the bony loss. The fasciocutaneous portion of the fibula flap limits its ability to conform to complex three-dimensional defects.

See the list below:

• Laboratory studies based on patient history

• Coagulation panel

See the list below:

• Chest radiography to assess chronic obstructive pulmonary disease and metastasis

• Computed tomography (CT) scanning

  • CT scan findings augment the physical examination findings to assess the anticipated defect size.[6]

  • Consider the size and orientation of the anticipated soft-tissue defect.

  • Three-dimensional modeling may facilitate reconstruction.[7]

See the list below:

• The role of preoperative Doppler examination or angiographic imaging to evaluate the vascular anatomy of the leg is disputed (see Future and Controversies).

• Magnetic resonance angiography (MRA) has been used to assess the vascular supply of the leg. Expense has relegated its use to a small number of centers.[8]

• Physical examination remains the primary method of evaluation. Abnormal results following physical examination is often enough to mandate a different flap.

Obtain informed consent, including the possibility of a second skin flap, as indicated.

Unlike several other free flaps used for head and neck reconstruction, the fibula flap can be harvested simultaneously with the extirpation of the tumor by a second surgical team. (See the image below.)

The authors have found that the contralateral leg lends itself well to pedicle orientation for a mandibular defect. Reconstruction of the temporomandibular joint, however, is facilitated by harvesting the ipsilateral fibula. We do not routinely use a tourniquet for harvest; however, it may be used, and if so, is inflated to 350 mm.

Because the fibula takes longer to harvest and requires osteotomies, the period of primary ischemia is usually longer than that for radial forearm and other fasciocutaneous flaps. Although literature shows that a reconstruction plate (see the image below) or miniplates may be used with equal efficacy, we prefer to use a 2.0 microvascular reconstruction plate, which is contoured prior to tumor extirpation if possible. Newer, patient-specific reconstruction plates are now available; these help to decrease ischemia and surgical time because the plate is bent according to patient needs.

The lateral leg is evaluated with a Doppler examination to identify perforating vessels in the septum. These are marked, and the skin flap is then designed to incorporate at least one vessel. The intermuscular septum is located by palpation and anatomic landmarks.

Proximally, a 6-cm segment of bone is preserved to avoid injury to the peroneal nerve. Distally, an 8-cm segment of bone is left to support the ankle mortise. The skin paddle is made slightly larger than the anticipated defect size, and the incision is carried out around the skin paddle. Proximal and distal extensions allow for bone harvest and pedicle dissection. The anterior portion of the skin paddle is dissected first. The peroneus longus is reflected anteriorly, and the fibular bone is identified.

The posterior crural septum is located. Once visualized, the septum is examined for perforators. Further dissection anteriorly around the fibula is performed, transecting the extensor hallucis longus. The thick interosseous septum is identified. Posterior dissection is performed to free up the skin paddle from the soleus and gastrocnemius muscles, and the septum is identified from its posterior aspect. Bony cuts are made with an oscillating saw. The bone is pulled laterally with Dingman bone retractors as the interosseous membrane is transected.

The chevron-shaped tibialis posterior is transected carefully with monopolar cautery. Just underneath this muscle lies the pedicle, which is identified distally and ligated. The flexor hallucis longus and soleus muscles must be transected. Dissection is continued proximally to the posterior tibial bifurcation. The anterior and posterior tibial pulses are palpated prior to transecting the peroneal vessels.

The length of bone needed for reconstruction is measured. Proximal elevation of periosteum along the fibula allows sizing of the bone and lengthening of the pedicle. Some surgeons prefer to contour the bone while the flap is still vascularized in the leg while others prefer to transect the pedicle at this time and perform osteotomies on a back table. The authors have found that the ability to compare the bone with the defect facilitates contouring, therefore we routinely remove the flap from the leg for placement of the osteotomies.

The leg wound can be closed primarily if the defect is small or no skin was harvested. More commonly, a split thickness skin graft is needed. The skin graft is harvested from the lower leg donor site prior to harvesting the flap. This avoids the need for a second surgical site on the thigh. Pie crusting the graft with a sharp blade provides better cosmetic results than putting the graft through a mesher. (See the image below.) Xeroform and a bolster are placed over the skin graft, if used. A posterior leg splint is fabricated and applied, either at this point or at the end of the case.

The bone is plated and inset into the defect following osteotomies. The pedicle is positioned along the lingual aspect of the flap, and the skin paddle is adjusted. After tension-free positioning is achieved, the skin paddle is inset with horizontal mattress sutures. The anastomosis is then performed with standard microvascular techniques.

Suction drains are carefully placed in the neck. The drains should be loosely held in position with absorbable sutures to prevent migration of the drain in proximity to the pedicle. If possible, a suture is placed on the external neck (skin) prior to closure to mark the location of the pedicle for postoperative Doppler examination. The remaining wounds are then closed. A feeding tube is placed if necessary.

The skin paddle is monitored frequently for signs of vascular compromise in patients with osteocutaneous flaps. Good perfusion to the skin means that the pedicle is patent and thereby providing blood to the periosteum and bone. Conversely, patients may have inadequate perforators to the skin and compromised blood supply to the skin paddle yet still have good perfusion to the bone. If a question of bone viability exists, nuclear medicine imaging can be of benefit in assessing flow. This study is not routinely performed for an osseous flap.

The ideal technique by which a flap can be assessed is only theoretical and practically varies depending on the flap, the patient, the available equipment, and other factors. Based on individual preference, cost, and familiarity with monitoring techniques, various monitors are available. Direct visualization and assessment of capillary refill with or without needle prick is very reliable in trained hands. An implantable Doppler device is an excellent tool for the well-trained surgeon, as well as for the ancillary staff and family members involved in patient care.[9] This technology is routinely used in our practice and has been proven to increase the detection of immediate/incipient vascular problems with a sensitivity of 87% and specificity of 99%. Arterial problems usually manifest within 24 hours; venous congestion often develops 48-72 hours postoperatively. Frequent evaluation and careful monitoring allow for early identification of problems.

Fluid balance and overall patient condition are monitored, as well. The authors use prophylactic antibiotics for 24 hours, although many routinely use prophylactic antibiotics for much longer periods. We do not routinely heparinize or give preoperative or postoperative aspirin to these patients.

The patient is allowed to ambulate in a non–weight-bearing fashion on the second postoperative day. The splint is removed and the skin graft assessed on the fifth postoperative day. The patient is then allowed to bear weight, using a walker or other assistive device, if necessary. When a skin graft is not used, the splint is not placed, and the patient is allowed to bear weight on the second day following surgery.

It is not our practice to routinely discharge patients on anticoagulation. The first postoperative visit generally occurs 1-2 weeks after release from the hospital. Flap and skin graft viability are assessed. Any remaining sutures are removed. If not already initiated preoperatively or as an inpatient, physical therapy is instituted to restore ankle function when the donor site has healed. The recipient site is evaluated for complications. Removal of the feeding tube and/or tracheotomy tube, if still present, is considered. A speech pathologist, physical therapist, and other specialists also evaluate the patient, as needed. Patients generally resume an oral diet approximately 2-3 weeks following discharge if no complications arise. Continuing dental/oral surgery evaluation and management allows for placement of dentures or implants at an appropriate time.

As with any free flap, complications may be divided into donor and recipient site problems. Major donor site complications with a fibula free flap are uncommon. Loss of the skin graft or a portion thereof is possible. As with any surgery, hematoma or infection may develop. Drains are used in the leg until output is sufficiently low for removal. Compartment syndrome is prevented by avoiding overtight closure of the leg, using skin grafts, and using drains to avoid hematomas. The posterior splint should allow for visualization of the toes and palpation of the pedal pulses. Ischemia to the foot is rare but must be evaluated urgently.

Ankle instability is possible if the distal fibula is overresected. Range of motion of the foot may be limited because of scarring and muscle resection. Prolonged pain is rare but may also develop. The authors have found that with the increasing use of other boney flaps our selection of patients allows us to eliminate those with any evidence of circulation problems. This greatly reduces the incidence of lower leg healing issues.

As with any microvascular surgery, free flap failure is a risk. Flap salvage following venous or arterial thrombosis is possible if early identification of vascular compromise leads to early (urgent) operative intervention. If thrombosis is identified and appropriately managed or pedicle geometry is optimized if twisting had occurred, the flap may be saved. Thrombectomy and revision of thrombosed vessel(s) are performed if required; occasionally, this necessitates vein grafting.

For flaps with venous congestion where patients cannot be returned to the OR immediately, leeches may be used to temporarily relieve the congestion. This technique should not be considered first line. Leeches work by removing the engorged blood from the flap and thereafter allowing an artificial venous outflow through their bite in the patient's flap skin. Blood flow through the bite is enhanced by an enzyme found in the leech saliva called hirudin. This enzyme is a powerful anticoagulant and, together with removal of the tiny clot that forms at the bite site, allows flaps to slowly bleed for hours. Leeches can transmit Aeromonas hydrophila, a gram-negative rod when used, and patients should prophylactically receive an antibiotic that covers beta-lactamase–resistant organisms if leech therapy is used.

If one or all of the veins are thrombosed, the arterial anastomosis may be allowed to remain intact at the discretion of the surgeon. Venous drainage occurs through the unattached veins. The authors irrigate University of Washington solution (streptokinase and heparin), shown to improve flap survival, through the flap. Systemic heparin should generally be started in the operating room and continued in the postoperative period for 7 days. Hematomas may develop as a result of anticoagulation. Drains should be carefully placed in the OR and not removed until the heparin has been discontinued. Venous return through the bone marrow has been cited in survival of fibular reconstruction despite venous thrombosis of the pedicle. If the skin appears thrombosed at the time of take back, but the bone is viable, the perforators through the septum should be evaluated. If the skin fails, but the bone survives, the bone may be covered with a second free flap (fasciocutaneous) or a pedicled flap.

Plate exposure and extrusion are rare complications. Patients who report postoperative pain with chewing are evaluated with radiographic imaging. If screw loosening is suspected, patients are returned to the OR for removal of the plate, if necessary. A single loose screw may occasionally be removed under local anesthesia in the clinic setting. Trismus is possible as a result of surgical manipulation and/or resection of the masticator muscles and disturbances in mandibular integrity. Patients are monitored by speech therapists and counseled on jaw-opening exercises to minimize the impact of this complication. Patients continue exercises through radiation therapy because significant scarring of the muscles may develop.

A study by Al-Bustani et al suggested that in head and neck cancer patients undergoing mandibular reconstruction with a free fibula flap, fixation of the flap with miniplates leads to more hardware removal associated with infection or persistent symptoms than does fixation with reconstruction bars. This outcome differed from that of other studies, although the report also found that overall complication rates did not significantly differ between the two fixation methods.[10]

Functional and cosmetic outcomes are generally excellent with this technique. Near-normal contour can be restored with appropriate osteotomies and plating. The skin is a poor color match for the head and neck, and its thickness precludes good camouflage. Some patients opt for tattooing, serial excision, or dermabrasion to lessen the abrupt change in color and consistency. Often, its color more closely approximates normal neck or facial skin once the flap has been exposed to sunlight or irradiated.

Functional rehabilitation is excellent. Patients who are fit with osseointegrated implants can have near-normal mastication and speech. (See the image below.) Patients who are unable to afford implants may be fit with dentures, but their ability to chew is not as good. Postoperative voice and deglutition depends on the amount and type of soft-tissue that was resected. Resection of structures such as the lingual and hypoglossal nerves and tongue base limits restoration of normal function.

A retrospective study by Pellegrino et al indicated that in oncology patients who undergo jaw reconstruction with a fibula free flap, osseointegrated dental implants subsequently positioned on the flap have an acceptable long-term survival rate. Implant survival rates at 12-, 60-, and 120-month follow-up were 97.2%, 86.5%, and 79.3%, respectively, with implant success rates being 95.4%, 73.5%, and 64.7%, respectively. The frequency of implant failure was greater in patients who underwent radiation therapy prior to implant placement. The investigators also found that the rate of peri-implantitis was lower in patients who received a connective tissue or skin graft (9.5%) than in those who did not (18.2%).[11]

A temporary limp is not uncommon following fibular harvest. As healing progresses, patients are instructed to work with physical therapists to resume their preoperative functional status. Elderly patients require additional time for recovery necessitating ongoing physical therapy for optimal rehabilitation.

The primary controversy related to the fibula free flap relates to the use of preoperative imaging to identify aberrant vascular anatomy. Angiography has been the criterion standard and was recommended by most reconstructive surgeons prior to performing a vascularized fibula flap. However, the invasiveness of the test and the possible morbidity, as well as the risk for peroneal spasm as a result of the vascular irritation, has led to more conservative approaches.

Direct evaluation of the appearance, temperature, and pedal pulses is currently used at the authors' institution to evaluate the presence and patency of all 3 vessels. Many surgeons are confident in proceeding without any imaging, provided the patient has normal pedal pulses. The authors consider the data provided by the duplex Doppler examination worth the added cost of the test in the event of any physical abnormalities to avoid a potential disaster for these few patients with aberrant anatomy. MRA and CT angio have reported results similar to angiography.