# Mandible Reconstruction with Fibula Free Flap

## Introduction

The **fibula free flap** is the gold standard for segmental mandibular reconstruction, first described by **Hidalgo in 1989**. Provides up to **25 cm of bicortical bone** with reliable vascularity, sufficient height for dental implants, and a versatile skin paddle. Indications include **segmental mandibulectomy** for oral cavity and mandibular tumors, osteoradionecrosis, traumatic bone loss, and benign aggressive tumors (ameloblastoma). **Virtual surgical planning (VSP)** with patient-specific cutting guides has transformed accuracy and efficiency of reconstruction. Success rates exceed **95%** in experienced centers with meticulous technique.

## Anatomy of the Fibula Flap

### Vascular Anatomy

**Peroneal artery**: primary pedicle; arises from the tibioperoneal trunk ~3 cm below the popliteal bifurcation. Artery diameter: **2-3 mm**; accompanied by two **venae comitantes** (2-3 mm each). **Pedicle length**: 6-8 cm (can be increased by dissecting proximally to the tibioperoneal trunk). The peroneal artery gives **nutrient endosteal branches** to the fibula and **musculocutaneous perforators** through the flexor hallucis longus and soleus muscles to supply the skin paddle.

**Septocutaneous perforators** emerge along the posterior crural septum (between peroneus longus and soleus) in the distal two-thirds of the leg.

### Bone Anatomy

Fibula is a **non-weight-bearing** bone (transmits only 6-17% of axial load). **Usable bone length**: leave 6 cm proximal (protect common peroneal nerve and lateral collateral ligament) and 6 cm distal (preserve ankle mortise stability). Cross-sectional dimensions: approximately **15 mm wide x 20 mm anteroposterior**; bone height is the main limitation for dental rehabilitation. Bone receives a **dual blood supply**: periosteal (from peroneal artery branches) and endosteal (nutrient artery entering midshaft).

### Skin Paddle

Skin paddle is based on **septocutaneous and musculocutaneous perforators** from the peroneal artery. Centered over the **posterior crural septum** between the peroneal and soleus compartments. Maximum reliable skin paddle: **10 x 20 cm**; may require skin grafting of donor site if width exceeds 5-6 cm. Perforator mapping with **handheld Doppler** or CT angiography preoperatively identifies perforator locations.

<image>Anatomical illustration of the lateral leg showing the fibula with its peroneal artery blood supply, the relationship of septocutaneous perforators passing through the posterior crural septum, and the planned skin paddle orientation</image>

## Preoperative Planning

### Vascular Assessment

**CT angiography of lower extremities**: evaluates peroneal artery patency, identifies dominant vessel (peronea magna variant in 0.1-8%), and maps perforators. **Peronea magna**: rare variant where the peroneal artery is the dominant vessel to the foot; fibula harvest is contraindicated. **Ankle-brachial index (ABI)**: should be >0.9 bilaterally; peripheral vascular disease is a relative contraindication. Assess for prior trauma, fractures, or surgical scars on the legs.

### Virtual Surgical Planning

**3D CT reconstruction** of the mandible and fibula allows precise planning of osteotomies. **Patient-specific cutting guides**: printed guides attach to both the mandible and fibula to ensure exact cuts matching the planned reconstruction. **Plate prebending**: reconstruction plates are prebent on the stereolithic model before surgery, reducing operative time. VSP improves **bony union rates, dental implant placement accuracy**, and reduces ischemia time. Planning sessions are typically conducted **1-2 weeks** before surgery with the surgical team and biomedical engineers.

## Surgical Technique

### Mandible Ablation

Performed simultaneously with flap harvest by a **two-team approach** to minimize operative time. Mandibulotomy or segmental mandibulectomy with adequate oncologic margins (1-2 cm). VSP cutting guides placed on the mandible to create precise osteotomies matching the planned fibula segments. **Recipient vessels** prepared: facial artery and vein, superior thyroid artery, or external jugular vein.

### Fibula Harvest

**Lateral approach**: incision along the posterior crural septum. Identify and protect the **common peroneal nerve** proximally at the fibular neck. Elevate peroneus longus anteriorly off the fibula; identify the anterior crural septum. Perform **subperiosteal dissection** anteriorly; osteotomies with oscillating saw or reciprocating saw at planned locations.

Dissect from anterior to posterior, ligating branches to the tibialis posterior and entering the deep posterior compartment. Identify and preserve the **flexor hallucis longus (FHL)** muscle cuff when including a skin paddle (maintains perforator integrity). Ligate peroneal artery and veins proximally; complete dissection of pedicle. Apply cutting guides to the fibula; perform closing wedge osteotomies for mandibular contouring.

### Insetting and Fixula Fixation

Shape the fibula to match the mandibular contour using **closing wedge osteotomies** (maintain periosteal hinge on one side to preserve blood supply). Fix fibula segments to each other and to native mandible stumps using **reconstruction plates and monocortical screws**. Alternatively, use **patient-specific reconstruction plates** designed during VSP. Ensure proper **occlusion**: verify with dental splints or maxillomandibular fixation when applicable.

Inset skin paddle for **intraoral lining** (floor of mouth, buccal mucosa) or external skin coverage. **Microvascular anastomosis**: typically end-to-end arterial to facial artery; end-to-end or end-to-side venous anastomosis.

<image>Step-by-step surgical illustration showing the mandible reconstruction process: (A) segmental mandibulectomy defect with cutting guide in place, (B) fibula free flap on the back table with closing wedge osteotomies performed, (C) shaped fibula secured to reconstruction plate matching the native mandibular contour, (D) final insetting with skin paddle providing intraoral lining</image>

## Donor Site Management

**Primary closure** of skin paddle if width <5-6 cm; otherwise split-thickness skin graft. Repair the **interosseous membrane** and approximate muscle compartments to prevent herniation. Prophylactic **fasciotomy** is rarely needed but should be performed if compartment pressures are elevated. Place drain; apply bulky dressing and posterior splint with ankle in neutral dorsiflexion.

Early weight bearing (48-72 hours) with progressive mobilization; most patients walk without assistive devices by 6-8 weeks.

## Dental Rehabilitation

The fibula provides approximately **15 mm of bone height**, compared to the native mandible height of 25-35 mm. **Vertical distraction osteogenesis** or stacked (double-barrel) fibula techniques can increase bone height. **Double-barrel fibula**: folding the fibula onto itself creates a neomandible with height approaching the native mandible; sacrifices pedicle length. **Osseointegrated dental implants**: placed primarily (at time of reconstruction) or secondarily (6-12 months later).

Primary implant placement reduces overall treatment time but adds complexity and may be affected by adjuvant radiation. Implant survival rates in irradiated fibula: **85-90%** (compared to >95% in non-irradiated bone).

## Complications

### Recipient Site

**Flap failure**: 2-5%; most commonly from **venous thrombosis**; requires emergent re-exploration within 1-2 hours of compromise. **Hardware exposure**: plate exposure through thin intraoral tissue; may require plate removal and soft tissue coverage. **Nonunion/malunion**: at osteotomy sites; increased risk with radiation; may require bone grafting. **Malocclusion**: from inaccurate bone positioning; VSP has reduced this complication significantly. **Fistula**: orocutaneous communication; rates of 5-15%; increased in irradiated patients.

### Donor Site

**Ankle instability**: rare with preservation of 6 cm distal fibula; more common in patients with pre-existing ligamentous laxity. **Peroneal nerve injury**: foot drop from injury to the common peroneal nerve; meticulous proximal dissection essential. **Flexor hallucis longus weakness**: from muscle cuff harvest; rarely functionally significant. **Wound healing complications**: skin graft loss (10-15%), wound dehiscence; more common in smokers and diabetics. **Compartment syndrome**: rare; maintain high clinical suspicion in the immediate postoperative period.

<image>Postoperative 3D CT reconstruction showing a fibula free flap mandible reconstruction with visible osteotomy sites, fixation hardware, and restored mandibular contour from angle to angle</image>

## Key Clinical Pearls

Always obtain preoperative CT angiography to confirm peroneal artery patency and rule out peronea magna variant. Virtual surgical planning with patient-specific cutting guides has become standard of care; it improves accuracy, reduces ischemia time, and facilitates dental rehabilitation. Preserve a muscle cuff (FHL) around septocutaneous perforators to ensure reliable skin paddle perfusion. Leave at least 6 cm of proximal and distal fibula to preserve knee stability and ankle mortise integrity. Consider primary dental implant placement at the time of fibula reconstruction to reduce total number of surgical procedures and speed dental rehabilitation.

## References

1. Hidalgo DA. Fibula free flap: a new method of mandible reconstruction. *Plast Reconstr Surg*. 1989;84(1):71-79.
2. Largo RD, Garvey PB. Updates in head and neck free flap reconstruction. *Curr Opin Otolaryngol Head Neck Surg*. 2018;26(4):231-237.
3. Rodby KA, Turin S, Jacobs RJ, et al. Advances in oncologic head and neck reconstruction: systematic review and future considerations of virtual surgical planning and computer aided design/computer aided modeling. *J Plast Reconstr Aesthet Surg*. 2014;67(9):1171-1185.
4. Qaisi M, Kolodney H, Engel E, Kokot N. Fibula free flap for mandibular reconstruction: optimal number of osteotomies. *J Craniofac Surg*. 2016;27(8):e725-e728.