# Fibula Free Flap Reconstruction of the Mandible

## Introduction

The vascularized fibula free flap (FFF) is the gold standard for reconstruction of segmental mandibular defects. First described by Hidalgo in 1989, it provides a reliable source of well-vascularized bone with a long pedicle, allowing reconstruction of extensive mandibular defects and subsequent dental rehabilitation with osseointegrated implants.

## Indications

The fibula free flap is indicated for segmental mandibulectomy defects from tumor ablation (ameloblastoma, OSCC, and other neoplasms), osteoradionecrosis with mandibular discontinuity, traumatic bone loss with failed conventional reconstruction, medication-related osteonecrosis with segmental deficiency, extensive atrophic mandible fractures not amenable to conventional repair, and congenital mandibular deficiency such as severe hemifacial microsomia.

## Surgical Anatomy of the Fibula

### Vascular Supply

The primary pedicle is the peroneal artery, a branch of the posterior tibial artery that runs along the medial aspect of the fibula in the posterior compartment. It is accompanied by two venae comitantes. The pedicle length is 6 to 8 cm with a vessel diameter of approximately 2 to 3 mm. Periosteal and endosteal perforating branches supply the bone and allow multiple osteotomies to be performed while maintaining vascularity. Septocutaneous perforators supply a skin paddle through the posterior crural septum.

### Bone Characteristics

Up to 25 cm of bone is available for harvest, provided that 6 to 8 cm are preserved distally for ankle stability. The cross-sectional shape is triangular with a bone height of approximately 12 to 14 mm. The cortical bone density is excellent for implant placement. Multiple closing-wedge osteotomies can be performed to contour the fibula to the mandibular shape.

### Skin Paddle

The skin paddle is based on septocutaneous or musculocutaneous perforators and can be harvested for intraoral lining or external skin coverage. Dimensions depend on perforator anatomy but typically measure up to 10 by 20 cm.

![Surgical anatomy of the fibula free flap showing the peroneal artery, venae comitantes, and septocutaneous perforators](/images/residency/omfs/fibula-flap-anatomy.jpg)

## Preoperative Planning

### Donor Site Assessment

CT angiography or MR angiography of the lower extremity is obtained to confirm three-vessel runoff and map the peroneal artery anatomy. An Allen test equivalent ensures adequate blood supply via the anterior and posterior tibial arteries. The patient is assessed for peripheral vascular disease and prior lower extremity surgery or trauma. Peronea arteria magna, a variant in which a single dominant vessel supplies the foot, must be excluded.

### Virtual Surgical Planning (VSP)

3D CT-based planning allows precise design of osteotomies and mandibular contour. Patient-specific cutting guides are fabricated for both the fibula and mandible. Pre-bent reconstruction plates or patient-specific plates are produced. Implant positions for future dental rehabilitation can be planned in advance. VSP reduces operative time and improves accuracy of reconstruction.

### Mandibular Defect Classification (Urken)

The Urken classification uses letters to describe the segments involved: C for a condyle-containing segment, R for ramus, B for body, and SH for symphysis (mental foramen to mental foramen). Combinations describe the defect extent, such as RB or BSB.

| Segment | Anatomic Region | Key Considerations |
|---------|----------------|-------------------|
| C | Condyle-containing segment | Requires TMJ reconstruction or prosthesis |
| R | Ramus (condyle to angle) | Muscle attachments; vertical height restoration |
| B | Body (angle to mental foramen) | IAN canal; implant rehabilitation zone |
| SH | Symphysis (mental foramen to mental foramen) | Anterior projection; aesthetic impact; requires multiple osteotomies for contour |

### Comparison of Donor Sites for Mandibular Reconstruction

| Donor Site | Bone Length | Bone Type | Skin Paddle | Advantages | Disadvantages |
|-----------|-------------|-----------|-------------|------------|---------------|
| Fibula | Up to 25 cm | Cortical (triangular) | Yes (septocutaneous) | Long bone stock; reliable pedicle; allows implants; two-team approach | Limited bone height (12-14 mm); donor site morbidity |
| Iliac crest | 10-14 cm | Corticocancellous | Yes (DCIA flap) | Natural mandibular contour; bone height; large volume | Bulky soft tissue; limited pedicle length; gait disturbance |
| Scapula | 10-14 cm | Thin cortical | Yes (multiple paddles) | Multiple skin paddles; versatile soft tissue | Lateral decubitus position; limited bone stock; short pedicle |
| Radius | 10-12 cm | Cortical | Yes (fasciocutaneous) | Thin pliable skin paddle | Weak bone; fracture risk at donor site; largely abandoned |

## Surgical Technique

### Fibula Harvest (Two-Team Approach)

The patient is positioned supine with the knee flexed and hip externally rotated in a frog-leg position. A lateral approach is made through the intermuscular septum between the peroneus longus and soleus muscles. The superficial peroneal nerve is identified and protected. Subperiosteal dissection of the fibula is performed, and osteotomies are completed distally first, then proximally, preserving 6 to 8 cm distally. The pedicle (peroneal artery and veins) is dissected from distal to proximal. The skin paddle is harvested based on perforators identified preoperatively. The pedicle is divided only when the recipient site is prepared.

### Mandibular Reconstruction

Cutting guides are applied to the native mandible and osteotomies are performed. The fibula is shaped using closing-wedge osteotomies per the virtual plan, and the segments are fixed with miniplates or a reconstruction plate. The flap is inset into the defect and secured with the reconstruction plate. Microvascular anastomosis is performed end-to-end or end-to-side to the facial artery and vein (or external carotid and internal jugular branches). The skin paddle is inset for intraoral lining if harvested. Flap perfusion is confirmed with Doppler and clinical assessment.

![Intraoperative photograph showing the harvested fibula free flap with osteotomies and the skin paddle](/images/residency/omfs/fibula-flap-harvest.jpg)

## Postoperative Management

Flap monitoring consists of hourly clinical checks (color, capillary refill, turgor) and implantable or external Doppler monitoring for 48 to 72 hours. The head of bed is elevated, and neck flexion or compression of the pedicle is avoided. An anticoagulation protocol with low-molecular-weight heparin or aspirin is followed per institutional protocol. Broad-spectrum antibiotics are administered for 24 to 48 hours. Tracheostomy is considered if significant floor-of-mouth resection or bilateral neck dissection was performed. Nasogastric or gastrostomy feeding is provided until oral intake is safe. At the donor site, skin graft or primary closure is performed, and progressive weight-bearing with physical therapy is initiated.

## Complications

Total flap loss occurs in 3 to 5% of cases, most commonly due to venous thrombosis. Other complications include wound dehiscence and fistula formation, plate exposure or fracture, and hardware failure requiring revision. Donor site complications include ankle instability, peroneal nerve injury, flexor hallucis longus weakness, and wound healing issues.

![Postoperative 3D CT reconstruction showing fibula free flap reconstruction of an anterior mandibular defect](/images/residency/omfs/fibula-reconstruction-3dct.jpg)

## Clinical Pearls

Preoperative CT angiography is mandatory to confirm donor site vascular anatomy and three-vessel runoff. Virtual surgical planning with patient-specific guides significantly improves accuracy and reduces operative time. The two-team approach, with ablative and reconstructive teams working simultaneously, minimizes ischemia time. Meticulous flap monitoring in the first 48 to 72 hours is critical for salvage of compromised flaps. The fibula free flap allows future dental implant placement and prosthetic rehabilitation.

## References

1. Hidalgo DA. Fibula free flap: a new method of mandible reconstruction. *Plast Reconstr Surg*. 1989;84(1):71-79.
2. Urken ML, Buchbinder D, Costantino PD, et al. Oromandibular reconstruction using microvascular composite flaps. *Arch Otolaryngol Head Neck Surg*. 1998;124(1):46-55.
3. Okay DJ, Genden E, Buchbinder D, Urken M. Prosthodontic guidelines for surgical reconstruction of the maxillofacial region. *J Prosthet Dent*. 2001;86(4):352-363.
4. Tarsitano A, Ciocca L, Scotti R, Marchetti C. Morphological results of customized microvascular mandibular reconstruction: A comparative study. *J Craniomaxillofac Surg*. 2016;44(6):697-702.