Free Vascularised Fibular Graft

Surgical Indications

Segmental Bone Defects

• Large defects: Typically indicated for long-bone defects greater than 6 cm.
• Oncology: Reconstruction after intercalary or intra-articular wide resection of primary bone sarcomas.
• Trauma: Severe open fractures with segmental bone loss where conventional grafting would fail.
• Infection: Reconstruction of defects following radical debridement for chronic osteomyelitis or infected nonunions.
• Congenital: Congenital pseudarthrosis of the tibia.

Femoral Head Osteonecrosis (AVN)

• Pre-collapse AVN: Ficat/Steinberg stage I or II, or early stage III with minimal collapse (less than 2 mm).
• Mechanism: The vascularised fibula provides structural support to the subchondral plate (preventing collapse) and brings a new blood supply to revascularise the necrotic segment.
• Patient selection: Most successful in younger patients (under 50 years) with symptomatic pre-collapse disease.

Advantages over Non-Vascularised Bone Graft

• Maintains osteocyte viability and heals by primary bone healing rather than creeping substitution.
• Undergoes rapid hypertrophy in response to mechanical stress (Wolff's law).
• Superior performance in poorly vascularised or irradiated recipient beds.
• Lower rate of late stress fracture and resorption.

Evidence Summary

Defect Reconstruction

• Vascularised fibular grafts achieve primary union rates of 70-90 percent in large defects.
• The Capanna technique (combining a vascularised fibula inside a massive structural allograft) provides immediate mechanical stability from the allograft and long-term biological viability from the fibula, significantly reducing the risk of stress fracture compared to FVFG alone.

Femoral Head AVN

• Multiple studies demonstrate that FVFG delays or prevents the need for total hip arthroplasty (THA) in young patients with early-stage osteonecrosis.
• Survival of the femoral head is closely correlated with the stage at the time of surgery; post-collapse heads (greater than 2 mm) have high failure rates.

Fibular Anatomy and Blood Supply

Osteology

• The fibula is a long, thin strut of cortical bone.
• It is non-weight-bearing in its proximal and diaphyseal regions but critical for ankle stability distally.
• Limits of harvest: The proximal 6-8 cm must be preserved to maintain the insertion of the lateral collateral ligament (LCL) and biceps femoris, and to protect the common peroneal nerve. The distal 6-8 cm must be preserved to maintain the integrity of the distal tibiofibular syndesmosis and the ankle mortise.

Vascular Supply (The Peroneal Artery)

• The peroneal artery is a branch of the tibioperoneal trunk.
• It descends in the posterior compartment, deep to the soleus and between the tibialis posterior and flexor hallucis longus (FHL).
• Nutrient artery: Enters the fibula in the middle third (endosteal supply).
• Periosteal/Muscular branches: Multiple segmental vessels supply the periosteum and overlying musculature.
• Septocutaneous perforators: Pass along the posterior intermuscular septum to supply the overlying skin, allowing for the harvest of a vascularised skin paddle for post-operative monitoring.

Muscular Compartments and Septa

• Anterior: Extensor digitorum longus, extensor hallucis longus, tibialis anterior.
• Lateral: Peroneus longus and brevis.
• Posterior: Soleus, gastrocnemius, tibialis posterior, flexor hallucis longus (FHL).
• The lateral approach utilises the intermuscular plane between the lateral compartment (peroneals) and the posterior compartment (soleus/FHL).

Neurological Structures at Risk

• Common Peroneal Nerve: Wraps around the fibular neck. Risked by proximal dissection.
• Superficial Peroneal Nerve: Exits the lateral compartment in the distal third of the leg. Risked during the superficial skin incision and anterior dissection.

Positioning and Preparation

• Position: Supine with a sandbag under the ipsilateral buttock to internally rotate the leg slightly. A radiolucent table is essential.
• Tourniquet: Applied high on the thigh. Inflated after exsanguination.
• Simultaneous teams: Often performed with two surgical teams — one harvesting the fibula and one preparing the recipient site to minimise ischaemia time.

Fibular Harvest — Step-by-Step

Step 1: Incision and Skin Paddle

Make a longitudinal incision along the lateral aspect of the leg, along the line of the fibula. If a skin paddle is required for monitoring or soft tissue defect coverage, design it over the posterior intermuscular septum (posterior border of the fibula), incorporating the septocutaneous perforators.

Step 2: Anterior Dissection

Elevate the anterior skin flap. Identify the intermuscular septum between the peroneals and the soleus. Retract the peroneal muscles anteriorly. Take care to identify and protect the superficial peroneal nerve as it exits the lateral compartment distally. Perform an extraperiosteal dissection of the anterior fibula.

Step 3: Posterior Dissection

Elevate the posterior skin flap. Retract the soleus muscle posteriorly. The flexor hallucis longus (FHL) muscle belly lies directly over the posterior fibula.

Step 4: Proximal and Distal Osteotomies

Measure and mark the required length of fibula, ensuring strict preservation of the proximal 6-8 cm and distal 6-8 cm. Pass curved retractors subperiosteally at the osteotomy sites to protect the deep vessels. Perform the osteotomies using an oscillating saw or Gigli saw.

Step 5: Mobilisation and Pedicle Isolation

Place a bone hook in the proximal fibula segment and apply gentle lateral traction. Divide the interosseous membrane from anterior to posterior. Roll the fibula laterally. Divide the tibialis posterior muscle. Identify the peroneal artery and venae comitantes proximally and distally. Ligate the distal peroneal vessels. Carefully dissect the FHL off the fibula, leaving a 1-2 mm cuff of muscle attached to protect the periosteal blood supply and perforators.

Step 6: Pedicle Dissection

Trace the peroneal artery and veins proximally to their origin at the tibioperoneal trunk to gain maximal pedicle length. Ligate all muscular branches.

Step 7: Ischaemia and Harvest

Once the recipient site is ready, ligate the proximal peroneal vessels, noting the ischaemia time. Flush the graft with heparinised saline if indicated by local protocol. Transfer the graft to the recipient site.

Recipient Site Reconstruction

Step 8: Recipient Vessel Preparation

Identify and isolate suitable recipient artery and veins at the defect site outside the zone of injury or radiation. Ensure adequate flow and healthy intima.

Step 9: Inset and Fixation

Shape the fibular ends to fit the defect. Inset the graft. Rigid fixation is essential — typically achieved using a bridging locking plate or an intramedullary nail. The graft must be mechanically stable to protect the microvascular anastomosis and promote union. For AVN, the fibula is impacted into a core decompression tract in the femoral neck.

Step 10: Microvascular Anastomosis

Perform the microvascular anastomosis under the operating microscope using 8-0 or 9-0 nylon. Typically, one artery and one or two veins are repaired. Ensure the pedicle is not kinked, twisted, or under tension.

Step 11: Reperfusion and Verification

Release clamps and verify perfusion. The bone marrow should bleed, and the skin paddle (if present) should become pink with good capillary refill. Intraoperative Doppler ultrasound can confirm flow.

Step 12: Closure

Close the recipient site over drains. Ensure the skin paddle is visible. Close the donor site; skin grafting may be required if the skin paddle was large. Do not close the fascia tightly to avoid compartment syndrome.

Post-operative Protocol

Early Phase (Day 0-7)

• Monitoring: Frequent checks of the skin paddle (colour, capillary refill, Doppler signal) — hourly for the first 24-48 hours.
• Positioning: Elevate the recipient limb slightly. Avoid pressure over the pedicle or skin paddle.
• Anticoagulation: Low molecular weight heparin (LMWH) for DVT prophylaxis. Some centres use aspirin or dextran for microvascular thrombosis prophylaxis.
• Donor leg: Elevate. Encourage active ankle and toe movements (especially great toe extension) to prevent FHL contracture.

Intermediate Phase (Weeks 1-6)

• Mobilisation: Strict non-weight-bearing on the reconstructed limb.
• Donor leg: Progress to full weight-bearing on the donor leg as tolerated. Continue aggressive FHL and Achilles stretching.
• Imaging: X-rays to confirm alignment and fixation.

Late Phase (Months 2-12)

• Weight-bearing: Progression of weight-bearing on the recipient limb depends on radiographic evidence of union at the docking sites and graft hypertrophy.
• Hypertrophy: The fibula takes 6 to 18 months to hypertrophy to match the mechanical strength of the recipient bone (tibia or femur).
• Return to activity: High-impact activities are restricted until substantial graft hypertrophy is visible on imaging.