Introduction to Free Vascularized Fibular Transfer
The free vascularized fibular transfer (FVFT) represents a cornerstone in the armamentarium of reconstructive orthopaedic and microsurgeons. Since its initial description by Taylor et al. in 1975, the vascularized fibula has become the most common and preferred autologous bone graft for the reconstruction of massive long bone defects. Its unique anatomical and biomechanical properties—specifically its length, linear contour, and dense cortical structure—make it the ideal donor tissue for bridging intercalary defects exceeding 6 centimeters, where non-vascularized grafts predictably fail due to creeping substitution exhaustion.
Unlike conventional non-vascularized autografts, a vascularized fibular graft retains its intrinsic blood supply, allowing it to bypass the slow and often incomplete process of creeping substitution. The transferred bone heals to the recipient site via primary fracture healing mechanisms, maintaining its structural integrity and demonstrating a remarkable capacity for stress-induced hypertrophy over time. Furthermore, the fibula is considered a highly expendable bone, provided the proximal and distal articular stabilizing structures are meticulously preserved.
Surgical Anatomy and Biomechanics
A profound understanding of the vascular anatomy of the lower leg is mandatory for the safe and successful harvest of the fibula.
Vascular Supply
The fibula possesses a dual blood supply, both of which are captured when the bone is harvested on its primary pedicle:
* The Peroneal Artery: Arising from the tibioperoneal trunk, the peroneal artery (typically 1.5 to 3.0 mm in diameter) descends along the medial crest of the fibula, deep to the flexor hallucis longus (FHL) muscle. It is accompanied by two venae comitantes. The pedicle length typically ranges from 6 to 8 cm, providing excellent reach for microvascular anastomosis.
* Nutrient Artery (Endosteal Supply): The primary nutrient artery enters the fibular shaft at the junction of the proximal and middle thirds.
* Periosteal Vessels: Segmental musculoperiosteal branches supply the outer cortex. To preserve these delicate vessels, a protective sleeve of muscle (typically from the FHL, soleus, and peroneals) must be harvested en bloc with the bone.
Biomechanical Profile
The fibula is a dense, tubular cortical bone. While its native diameter is significantly smaller than that of the femur or tibia, its robust cortical thickness allows for rigid internal fixation using standard plates and screws. When subjected to physiological loading at the recipient site, the vascularized fibula undergoes Wolff's Law–mediated hypertrophy, eventually doubling or tripling in diameter to match the mechanical demands of the reconstructed limb.
Clinical Pearl: The fibula can be harvested as a simple osseous flap, a bone-muscle complex (incorporating the FHL or soleus to fill dead space), or an osteocutaneous flap (incorporating an overlying skin paddle based on septocutaneous perforators) to simultaneously reconstruct composite bone and soft-tissue defects and provide a reliable monitor for flap perfusion.
Indications and Preoperative Planning
Indications
- Oncologic Reconstruction: Following wide resection of primary bone sarcomas (e.g., osteosarcoma, Ewing sarcoma) or aggressive benign tumors (e.g., giant cell tumor).
- Traumatic Bone Loss: High-energy open fractures with massive segmental bone loss.
- Infectious Nonunions: Radical debridement of chronic osteomyelitis resulting in large intercalary defects.
- Congenital Deformities: Congenital pseudarthrosis of the tibia or radius.
- Avascular Necrosis: Core decompression and vascularized fibular grafting for early-stage osteonecrosis of the femoral head.
Preoperative Evaluation
Thorough preoperative planning is critical. Standard orthogonal radiographs of the donor and recipient sites are obtained.
* Vascular Imaging: A CT angiogram (CTA) or conventional angiography of the donor lower extremity is mandatory. This confirms a patent three-vessel runoff to the foot and rules out anatomical variants, such as a peronea arteria magna (where the peroneal artery is the dominant supply to the foot), which is an absolute contraindication to fibular harvest.
* Templating: The required length of the graft is templated. Up to 26 cm of fibula can be safely harvested in an adult.
Surgical Technique: The Posterior Approach (Taylor)
While many modern microsurgeons favor the lateral approach for its speed and supine positioning, the posterior approach described by Taylor remains a foundational technique, particularly useful when simultaneous access to the posterior recipient structures is required. The following details the step-by-step execution of the posterior approach.
1. Anesthesia, Positioning, and Preparation
Following the administration of epidural or general anesthesia, the patient is placed in the prone position. An indwelling urinary catheter is inserted due to the anticipated length of the procedure.
* The legs are abducted onto separate operating tables to allow two surgical teams to work simultaneously—one preparing the recipient site and the other harvesting the fibula.
* A pneumatic tourniquet is applied to the proximal thigh of the donor leg to maintain a bloodless surgical field. Exsanguination is performed carefully, avoiding tight Esmarch wrapping over the delicate perforators if an osteocutaneous flap is planned.
2. Incision and Superficial Dissection
- The incision is initiated in the popliteal fossa of the donor leg.
- It is extended obliquely and laterally toward the fibular head, then continued distally along the palpable course of the fibular shaft.
- The deep fascia is incised, and the plane between the soleus (posteriorly) and the peroneal muscles (anteriorly) is developed. This deep dissection is extended medially into the popliteal fossa.
- Skin flaps are reflected to expose the underlying muscular anatomy.
3. Nerve Identification and Proximal Preservation
- Nerve Protection: The common peroneal nerve (lateral popliteal nerve) is identified at the medial border of the biceps femoris and traced as it winds around the fibular neck. Its deep and superficial branches must be meticulously preserved.
- Proximal Attachments: The proximal peroneal and extensor muscle attachments to the tibia and the fibular head are preserved. The proximal fibula must remain intact to preserve the insertion of the fibular collateral ligament (LCL) and the biceps femoris tendon, ensuring lateral knee stability.
- The anterior tibial vessels are identified and protected as they pass through the interosseous membrane.
4. Muscle Sleeve Preservation and Posteromedial Dissection
- To protect the periosteal blood supply, a 5- to 10-mm sleeve of muscle is preserved on the lateral and anterior aspects of the fibula.
- The posteromedial dissection begins posteriorly. The lateral head of the gastrocnemius and the plantaris muscle are detached from the femur.
- The popliteal vessels and the tibial (medial popliteal) nerve are gently retracted medially.
- The soleus muscle is divided longitudinally, 1 to 2 cm parallel to the fibula.
- The surgeon follows the popliteal and posterior tibial vessels distally to identify the origin of the tibioperoneal trunk and the subsequent takeoff of the peroneal vessels.
Surgical Warning: The bifurcation of the tibioperoneal trunk can be highly variable. Meticulous sharp dissection and bipolar electrocautery are essential to avoid inadvertent injury to the posterior tibial artery, which must remain intact to perfuse the foot.
5. Isolation of the Peroneal Pedicle
- The peroneal vessels are traced distally to the origin of the flexor hallucis longus (FHL) muscle.
- During this dissection, several large muscular branches supplying the soleus are encountered; these must be carefully ligated and divided.
- Using sharp dissection, the FHL muscle is divided along the course of the peroneal artery. A 1-cm sleeve of FHL muscle is left attached to the posterior aspect of the fibula to protect the descending peroneal pedicle and the nutrient artery entering the bone.
6. Fibular Osteotomy
The length of the required graft dictates the levels of the proximal and distal osteotomies.
* Distal Preservation: It is an absolute biomechanical imperative to preserve the distal 25% of the fibula (approximately 6 to 8 cm above the lateral malleolus). This retains the integrity of the distal tibiofibular syndesmosis, preventing catastrophic ankle valgus instability.
* Pediatric Considerations: In children, the distal fibular remnant must be secured to the tibia with a transverse syndesmotic screw. This prevents proximal migration of the lateral malleolus and subsequent valgus drift of the ankle during growth.
* The osteotomies are performed using a reciprocating saw or a Gigli saw. Care is taken to place retractors (such as malleable ribbons) deep to the fibula to protect the peroneal pedicle during the cuts.
7. Final Harvest and Ischemia Time Management
- Beginning distally, the interosseous membrane and the tibialis posterior muscle are divided parallel to the fibula. The fibula is now entirely isolated on its vascular pedicle.
- The periosteum is stripped from the proximal and distal 1 to 3 cm of the fibular graft. This exposes bare cortical bone, which is necessary for insertion into the medullary canals of the recipient bone (if a step-cut or invagination technique is used).
- Perfusion Check: The tourniquet is released. Hemostasis is achieved, and the graft is observed for 15 to 20 minutes. Adequate circulation is confirmed by pulsatile flow in the pedicle, bleeding from the medullary canal at the osteotomy sites, and capillary refill in the muscle sleeve (or skin paddle).
- Once the recipient site is fully prepared and the recipient vessels are isolated, the peroneal vascular pedicle is carefully transected. The ischemia time clock begins.
- The donor defect is irrigated, and the wound is closed in layers over closed-suction drainage tubes. The deep fascia is left open to prevent compartment syndrome.
Recipient Site Preparation and Fixation
The success of the FVFT relies heavily on the rigid fixation of the graft at the recipient site.
Fixation Strategies
- Intercalary Reconstruction: The fibula is typically inset into the medullary canal of the recipient long bone (e.g., femur or tibia). Rigid fixation is achieved using bridging locking plates.
- The Capanna Technique: For massive defects, particularly in the femur or tibia, the vascularized fibula can be placed inside a massive structural allograft. The allograft provides immediate mechanical strength, while the vascularized fibula provides the biological engine for union and hypertrophy.
- Intramedullary Nailing: In certain tibial reconstructions, an intramedullary nail can be passed parallel to the vascularized fibula, provided the pedicle is not compressed.
Microvascular Anastomosis
The microvascular anastomosis is performed under an operating microscope.
* The peroneal artery is anastomosed to a major recipient artery (e.g., superficial femoral, anterior tibial, or radial artery) in an end-to-end or end-to-side fashion using 8-0 or 9-0 nylon sutures.
* The venae comitantes are anastomosed to the deep recipient veins. Venous outflow is critical; utilizing a venous coupler device can significantly reduce anastomosis time and improve patency rates.
Pitfall: Redundancy or kinking of the vascular pedicle is a primary cause of graft thrombosis. The pedicle must lie in a relaxed, gentle curve without tension or compression from overlying fascia or hematoma.
Postoperative Care and Rehabilitation
The postoperative protocol is designed to monitor flap viability and promote osseous integration while protecting the microvascular anastomosis.
Flap Monitoring
- If an osteocutaneous flap was harvested, the skin paddle is monitored clinically (color, capillary refill, temperature) every hour for the first 48 hours, then every 4 hours.
- If a purely osseous or bone-muscle flap was used, an implantable venous Doppler probe is highly recommended to continuously monitor venous outflow.
- The patient is kept well-hydrated, and the room is kept warm to prevent vasospasm. Anticoagulation protocols vary by institution but typically include daily aspirin (81 mg) and prophylactic subcutaneous heparin.
Rehabilitation and Weight-Bearing
- Donor Leg: The donor leg is placed in a bulky Jones dressing or a posterior splint for 1 to 2 weeks to allow soft tissue healing. Weight-bearing as tolerated in a controlled ankle motion (CAM) boot is usually permitted after 2 weeks, provided the syndesmosis is stable.
- Recipient Leg: The recipient limb is strictly non-weight-bearing. Radiographic evaluation is performed at 6 weeks, 3 months, and 6 months.
- Progressive partial weight-bearing is initiated only when radiographic evidence of bridging callus is observed at the osteotomy junctions. Full weight-bearing is delayed until complete union and early signs of fibular hypertrophy are evident, which may take 9 to 18 months depending on the patient's age and the mechanical environment.
Complications
While highly successful, FVFT carries potential complications that the surgeon must anticipate.
- Donor Site Morbidity: Includes transient or permanent weakness of the FHL (resulting in clawing of the great toe), common peroneal nerve neuropraxia, and ankle instability if the distal fibula is inadequately preserved. Compartment syndrome of the donor leg is rare but catastrophic; hence, the deep fascia must never be tightly closed.
- Graft Thrombosis: Arterial or venous thrombosis typically occurs within the first 72 hours. Immediate return to the operating room for thrombectomy and revision of the anastomosis is required to salvage the graft.
- Nonunion and Stress Fracture: Despite vascularity, nonunion at the host-graft junction can occur, particularly if fixation is not perfectly rigid. Stress fractures of the fibula may occur during the hypertrophy phase if weight-bearing is advanced too rapidly. These are typically managed conservatively with cast immobilization, as the vascularized bone retains the ability to heal the fracture.
