Mega Fibula Free Flap for Reconstruction of an Extensive Mandibulofacial Defect

Introduction

Since Hidalgo introduced the fibula free flap as an option for mandible reconstruction in 1989, it has become the pillar for bony reconstruction. ¹ However, in large mandibulofacial defects involving intraoral and extraoral components, the distal skin paddle traditionally harvested may not provide sufficient coverage. Double free flaps are an option in these cases, but an additional free flap increases operative time, donor site morbidity, and need for recipient vessels.^2,3

Anatomical studies of perforator anatomy have found a common musculocutaneous perforator that can supply a separate, proximal skin paddle in the fibula free flap, which has expanded its reconstructive uses.^4-10 We present the reconstruction of a complicated and extensive mandibulofacial defect using one of the largest reported fibula free flaps.

Case Report

An 81-year-old female nonsmoker presented with a T4aN0M0 oral cavity squamous cell carcinoma. The disease involved the ventral tongue, floor of mouth, and mandible as well as skin of the chin and neck. Surgery involved composite resection of the mandible extending from the right angle to the left body. Soft tissue resection included the bilateral floor of mouth and ventral tongue, while the extraoral component involved the chin, submental neck, and near total lower lip.

Operative Technique

Reconstructive options included the use of a single fibula free flap, a fibula with a second soft tissue free flap, or a scapula osteocutaneous free flap. A single free flap from the fibula was favored given the ability to harvest a maximum length of quality bone for a significant mandibular defect (angle to body). Preoperative computed tomography angiography of the lower extremities confirmed three vessel runoff. Perforators could not be definitively identified on imaging, but this did not influence our decision to begin with a single fibula free flap harvest while preserving the option to harvest a second soft tissue free flap such as the radial forearm. The added benefit of a single flap over two flaps would be the reduction in operative time and donor site morbidity, which would be more relevant in an elderly patient. We anticipated that intraoperative factors at the ablative and donor site would determine if a single fibula flap would ultimately be sufficient. Ablative factors included the extent of the final osseous and soft tissue defect, while the number, location, and quality of the cutaneous perforators in the leg would have impacted our reconstructive plan. The right leg was positioned on a footrest with the knee flexed and hip rotated away. Initial harvest of the fibula free flap was approached in the standard fashion with the intent of harvesting the maximum length of bone possible, while preserving 6 cm of bone from the fibular head and lateral malleolus to maintain knee and ankle stability while avoiding injury to the peroneal nerve.

A large anterior skin incision was designed and taken down to the anterior compartment muscles (Figure 1). One large and several smaller septocutaneous perforators supplying the distal skin paddle were identified. Additionally, one robust proximal musculocutaneous perforator was identified supplying the proximal skin paddle. With the identification of at least two separate perforators to the distal and proximal skin paddles, the decision was made to proceed with a single fibula free flap.

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Figure 1.

Intraoperative markings of the fibula free flap with wide anterior skin incision. With the identification of at least two separate perforators to the distal and proximal skin paddles, the decision was made to proceed with a single free flap. The posterior incision was then made in order to harvest a large skin paddle involving nearly the entire lateral compartment.

We continued dissection along the anterior aspect of the fibula to enter the anterior compartment down to the interosseous membrane. The posterior incision was then made in order to harvest a large skin paddle involving nearly the entire right lateral leg. A minimal cuff of soleus muscle was taken. The peroneal artery and vein were isolated and taken distal to the take-off of the posterior tibial branches. We confirmed that septocutaneous perforators were supplying the distal skin paddle, and the proximal transverse musculocutaneous perforator was originating from the peroneal artery distal to the tibioperoneal trunk and supplying the proximal skin paddle. The pedicle was then divided.

For closure of the donor site defect, as much skin as possible was advanced for primary closure. The remaining defect was covered with a split thickness skin graft harvested from the right thigh. A wound vacuum was used to bolster the skin graft and facilitate healing. The wound vacuum was taken down on postoperative day 7, revealing complete take of the graft. At the conclusion of the case, the leg was placed in a preformed boot.

We then moved on to the reconstructive portion of the procedure. Three osteotomies, with careful attention to position of the perforators, were made to reconstruct the 11 cm mandibular defect. Flap vessels were oriented to exit along the right posterior mandible. Microvascular anastomosis was performed to the right facial artery and external jugular vein.

The mega skin paddle was now divided into two islands – the proximal and distal skin paddles (Figure 2). We confirmed adequate blood flow to both paddles prior to division. The proximal paddle measured 10 × 8 cm and the distal paddle measured 10 × 12 cm. The proximal paddle was used to reconstruct the intraoral soft tissue defect with the most proximal edge of the paddle sewn to the left buccal mucosa. The skin paddle was then wrapped across the floor of mouth and ventral tongue defects with the distal edge of the paddle sewn to the right buccal mucosa (Figure 3). With three-fourths of the lower lip resected, a Karapandzic flap was used to reconstruct the lip. Curvilinear incisions were made down to the orbicularis oris muscle. Buccal nerves and labial arteries were preserved. Both ends were advanced to recreate oral competence without significant microstomia.

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Figure 2.

Fibula free flap skin paddle split into proximal and distal paddles.

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Figure 3.

Reconstruction of intraoral and lower lip defects utilizing the proximal skin paddle and Karapandzic flap.

The distal skin paddle was now draped over the mandible and neck to provide coverage. Excess skin from the paddle was de-epithelialized and used to provide additional coverage over the reconstruction plate (Figure 4). The postoperative course was uncomplicated and the flap remained healthy without wound complications at the reconstruction or donor site. The patient was discharged on postoperative day 7 (Figure 5).

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Figure 4.

Reconstruction of extensive external skin defect using distal skin paddle.

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Figure 5.

Reconstruction on postoperative day 7. The free flap remained healthy without signs of wound dehiscence at the reconstruction and donor sites.

Discussion

Two flaps were initially considered necessary to provide adequate coverage in oral cavity cases involving soft issue, bone, and skin.^2,3 Wei et al. initially used fibula paired with radial forearm or rectus abdominis flaps for soft tissue coverage. ² They ultimately replaced these soft tissue options with the anterolateral thigh because of donor site morbidity from the rectus abdominus flap and thinness of the forearm flap leading to plate extrusion. ³

The chimeric fibula free flap with double skin paddles later became an option.^6-10 Studies on perforator anatomy by Jones et al. and Yu et al. showed the traditional distal skin paddle to be extremely reliable with up to 3 septocutaneous perforators.^4,5 A proximal musculocutaneous perforator was present in 67%-84% of cases that could supply the proximal skin paddle.^4,5 The origin of this proximal perforator can be variable with branching off the tibioperoneal trunk, posterior tibial artery, or peroneal perforator.^4,10 In our case, the proximal perforator came off the main pedicle. Jones et al. described the combined area of their largest harvested flap to be 26 × 10 cm (260 cm²) to reconstruct a gunshot wound to the face in a male patient. ⁷ The largest flap in a case series by Leclere et al. was 160 cm². ⁸ In our case, the total area of both the proximal (80 cm²) and distal skin paddles (120 cm²) was 200 cm², which provided sufficient coverage of the intraoral and skin defects without the need for an additional free flap.

Conclusion

Extensive mandibulofacial defects can be a challenge for the reconstructive surgeon. We discuss the planning and use of a mega, double skin paddle fibula free flap for successful reconstruction.