Free Fibula Flap - Operative Steps

Preoperative Planning

• Vascular assessment: Confirm three-vessel (anterior tibial, posterior tibial, peroneal) flow to the foot by ankle-brachial index or CT/MR angiography. Harvesting the peroneal artery must not compromise the foot.
• Laterality selection: Choose the leg based on ideal pedicle geometry at the recipient site. Ipsilateral leg is preferred for mandibular body defects (pedicle exits posteriorly toward neck vessels). Contralateral leg is used for condyle/ramus defects.
• Virtual surgical planning (VSP): 3D CT renderings of the face and leg allow simulation of mandibular resection, osteotomy positions on the fibula, cutting guide fabrication, and dental implant planning.
• Mark the common peroneal nerve on the skin surface preoperatively.

Patient Positioning & Setup

• Supine with hip slightly internally rotated, knee flexed ~20-30°, and a bump under the ipsilateral buttock.
• The leg is prepped and draped free; tourniquet may be applied but is not always inflated.
• A two-team approach (simultaneous harvest and ablation) is possible - one advantage over other flaps.

Step 1 - Skin Marking

• The skin paddle (up to 5 cm wide) is designed over the lateral lower leg, centered over septocutaneous or musculocutaneous perforators (typically 1-2 perforators found in the posterior crural septum between peroneus longus and flexor hallucis longus).
• Mark the safe harvest zone: from 2 cm distal to the fibula neck proximally (to protect the common peroneal nerve) to 6 cm proximal to the lateral malleolus distally (to preserve ankle syndesmosis integrity).

Step 2 - Lateral Incision & Skin Paddle Dissection

• A longitudinal incision is made along the posterior border of the fibula (or centered on the perforator if a skin paddle is needed).
• The skin paddle is incised on all four margins. The anterior skin flap is elevated deep to the deep fascia.
• The superficial peroneal nerve (exits the anterior compartment ~10 cm above the lateral malleolus) is identified and carefully protected.

Step 3 - Anterior Compartment Dissection

• The anterior intermuscular septum is incised.
• Extensor hallucis longus (EHL) and extensor digitorum longus (EDL) are elevated off the anterior fibula.
• Dissection proceeds to the interosseous membrane, which is divided close to the bone, protecting the anterior tibial vessels.

Step 4 - Posterior Compartment Dissection

• The posterior crural septum between peroneus longus and the flexor hallucis longus (FHL) is identified.
• Skin perforators are identified and protected; a small cuff of FHL or soleus muscle is included with the flap to encompass musculocutaneous perforators and improve skin paddle reliability.
• The common peroneal nerve is identified proximally and protected throughout.

Step 5 - Bony Cuts (Osteotomies)

• Distal cut first: Performed with a saw or osteotome, leaving ≥6 cm of fibula above the lateral malleolus.
• Proximal cut: Leaving ≥2 cm below the fibular neck.
• The fibula is gently elevated after both cuts, facilitating access to the deep peroneal vessels.

Step 6 - Pedicle Dissection

• After bone cuts, the fibula is carefully elevated and the peroneal artery and venae comitantes are identified on the deep (medial) surface.
• The pedicle is dissected proximally toward its origin from the tibioperoneal trunk to achieve adequate pedicle length (up to 15 cm can be obtained if needed).
• Small muscular branches are ligated. The posterior tibial artery and nerve are preserved.

Step 7 - Flap Harvest & Division

• Once adequate pedicle length is confirmed, the pedicle is ligated distally (at the level of the distal bone cut) and proximally only when the recipient site is ready.
• The flap is kept on its pedicle until the recipient team signals readiness, minimizing ischemia time.
• Pedicle is divided and the flap is transferred to the back table for bench shaping.

Key rule: Hardware (plates, screws) should NOT be changed once vascular anastomosis is complete, as repositioning can compromise pedicle perfusion.

Step 8 - Bench Work / Flap Shaping

• Fibula is shaped using closing wedge osteotomies to match the mandibular contour (anterior arch, body, angle, ramus).
• The periosteum must NOT be stripped circumferentially - preserve it to maintain endosteal blood supply.
• Patient-specific cutting guides (from VSP) are used to guide osteotomy positions.
• A reconstruction plate (pre-bent to the native mandible preoperatively in the preplating technique) is secured to the shaped fibula segments.

Step 9 - Inset at Recipient Site

• The shaped fibula with plate is transferred to the mandibular defect.
• Bony segments are fixed to the remnant native mandible using locking screws through the pre-bent plate.
• The skin paddle is inset to close the mucosal defect.
• Intermaxillary fixation (IMF) may be applied to protect the reconstruction from torque.

Step 10 - Microvascular Anastomosis

• The peroneal artery is anastomosed (end-to-end or end-to-side) to a recipient artery in the neck - typically the facial artery, superior thyroid artery, or a branch of the external carotid artery.
• The venae comitantes are anastomosed to the internal jugular vein, facial vein, or external jugular vein.
• Anastomosis is performed under microscope using interrupted 9-0 or 10-0 nylon sutures.
• A coupling device (mechanical anastomotic coupler) is commonly used for venous anastomosis to reduce time and improve patency.
• Flap perfusion is confirmed by return of skin paddle color, Doppler signal, or intraoperative SPY angiography.

Step 11 - Donor Site Closure

• If skin paddle width ≤5 cm, primary closure is usually possible.
• Larger paddles require a split-thickness skin graft (STSG) to the donor site.
• A drain is placed. The leg is dressed and elevated.

Intraoperative & Postoperative Monitoring

• Clinical checks every 2-3 hours for the first 4 days (skin paddle color, turgor, capillary refill).
• For osseous-only flaps (no skin paddle): daily Doppler ultrasound of the pedicle.
• Implantable Dopplers may be used for continuous monitoring.

Key Anatomical Points

Advantages of the Fibula Flap

• Up to 25 cm of bone available (the "most donatable bone in the body") - Cummings Otolaryngology Head and Neck Surgery
• Dual blood supply (endosteal + periosteal from peroneal artery)
• Bone stock adequate for osseointegrated dental implants
• Long pedicle length
• Simultaneous two-team harvest
• Allows multiple osteotomies without compromising vascularity (periosteum intact)
• Skin paddle option for composite defects

Disadvantages

• Skin paddle size limitations for large soft tissue defects
• Variable perforator anatomy
• Peroneal artery sacrifice (requires confirmed three-vessel runoff preop)
• Prolonged ambulation pain in some donor site patients

1. Donor Site Marking, Harvest & Bone Cuts

• A - Preoperative marking of the donor leg with the common peroneal nerve outlined
• B - Initial dissection down to the fibula, protecting the superficial peroneal nerve
• C - Fibula exposed after anterior and posterior compartment dissection
• D - Mobilization of the fibula segment after proximal and distal bone cuts
• E - X-ray showing the tibial defect (pathologic fracture/osteomyelitis) to be reconstructed
• F - Defect with cement spacer prior to free fibula transfer

2. Fibula Inset, Plate Fixation & Final Outcome

• G - Fibular graft inset into the tibial defect with plate fixation
• H - Final healed clinical outcome showing restored leg contour
• I - AP radiograph with fibular graft in situ, secured by locking plate

3. Mandibular Reconstruction with Osteocutaneous Fibula Flap

• A - Rhabdomyosarcoma of the mandible in an 11-year-old (arrow marks tumor)
• B - Fibula free flap harvested from the lower leg
• C - Mandible replaced by fibula bone - osteotomized segments secured to a reconstruction plate
• D - Skin paddle inset and microvascular anastomosis completed in the neck