Vascularized Bone Flaps

10.1 Introduction

A non-vascularized bone graft fails in long defects and in poor beds, because it depends on the bed for its blood supply.

A vascularized bone flap is bone transferred together with its artery and vein. The vessels are either kept attached (pedicled flap) or joined to vessels at the recipient site by microsurgery (free flap). The bone stays alive. It does not depend on the bed.

History:

• 1975: Taylor performed the first free vascularized fibula, for a tibial defect.
• 1986: Wei described the skin perforators of the fibula flap, so that skin could be taken reliably with the bone.
• 1989: Hidalgo used the fibula, with osteotomies, to reconstruct the mandible.

10.2 How vascularized bone differs from a bone graft

Hypertrophy and fracture. De Boer and Wood (1989) reviewed 62 vascularized fibula transfers. The fibula became thicker with time, more so when the limb was loaded. But 25% fractured, at a mean of 8 months, before the bone had thickened. So the flap must be protected in the first year, but also loaded gradually so that it hypertrophies.

10.3 Indications

Vascularized bone is indicated when a non-vascularized graft is likely to fail:

• Long segmental defect (commonly quoted as more than 6 cm)
• Poor recipient bed: irradiated, scarred or previously infected
• Composite defect needing bone and soft tissue together
• Nonunion with avascular bone (for example the scaphoid)
• Children who have lost a growth plate

10.4 The free fibula flap

The fibula is the most used vascularized bone flap, so it is described first and in most detail.

10.4.1 Anatomy

• Vessel: peroneal artery and its two veins.
• Bone: up to about 25 cm of straight cortical bone. The distal 6 to 8 cm is left in place to keep the ankle stable.
• Blood supply to the bone: one nutrient artery (endosteal supply) and many periosteal branches along its length.
• Skin paddle: supplied by perforators that pass through the posterior crural septum.

More detail:

• The peroneal artery arises from the tibioperoneal trunk and runs down between tibialis posterior and flexor hallucis longus, close to the fibula.
• The nutrient artery enters the middle third of the fibula. The periosteal branches are segmental, which is the basis for multiple osteotomies.
• The pedicle is short at its origin. It is lengthened by removing proximal bone subperiosteally and using the distal fibula for the reconstruction.
• Skin perforators are mostly septocutaneous in the distal and middle thirds of the leg, and more often musculocutaneous (through soleus) proximally. The skin paddle is centered over the posterior border of the fibula at the junction of the middle and distal thirds.
• Proximally, about 6 cm of fibula is preserved to protect the common peroneal nerve and the knee. Distally, 6 to 8 cm is preserved for ankle stability.
• Flexor hallucis longus muscle can be included to fill dead space.

Preoperative assessment: palpate dorsalis pedis and posterior tibial pulses. Imaging (CT or MR angiography) is used when pulses are abnormal, after leg trauma, or with vascular disease. It excludes peronea arteria magna and significant atherosclerosis.

10.4.2 Why the fibula can be osteotomized

When the fibula is cut into segments, the endosteal supply to each segment is interrupted. Each segment survives on its periosteal supply. For this reason:

• the periosteum is never stripped from the fibula, and
• the bone is cut from the side opposite the pedicle.

10.4.3 Shaping the fibula for the mandible

The fibula is straight and the mandible is curved. The fibula is cut into segments (closing wedge osteotomies) to follow the curve. A larger defect needs more osteotomies.

Every junction must unite. A gap of 1 mm or more at a junction greatly increases the risk of nonunion. The osteotomies must close with good bone contact.

Classification of mandibular defects (Brown 2016). The mandible has four "corners": the two angles and the two canines. The class depends on which corners are removed.

Each corner removed needs one more osteotomy in the fibula.

The older HCL classification (Jewer 1989) is still widely used: H = lateral defect including the condyle; C = central segment including both canines; L = lateral defect without the condyle. Letters are combined (LC, HC, LCL, HCL). Central (C) defects are the most disabling if not reconstructed with bone, because the chin, lip and tongue lose their support ("Andy Gump" deformity).

Goals of mandibular reconstruction: restore continuity; keep the condyles seated and the occlusion correct; restore lower facial height and projection; give enough bone height and width for dental implants; provide intraoral lining and a seal against saliva.

Additional points:

• Height: a single fibula is about half the height of a dentate mandible. Options: place the fibula at the alveolar level, double-barrel the fibula, or later vertical distraction.
• Condyle: if it can be preserved, the fibula is plated to it. If not, the end of the fibula is rounded and placed in the fossa, or a costochondral graft or prosthesis is used.
• Dental implants osseointegrate in fibula. They can be placed at the same operation or later; radiotherapy reduces implant survival.
• Virtual surgical planning: CT of the jaw and leg is used to plan the resection and osteotomies. Cutting guides and a pre-bent or custom plate are made. This improves accuracy and shortens ischemia time.

10.4.4 USM experience

• Chai et al. (2019): 27 patients over 20 years (1997 to 2017) with ameloblastoma of the mandible. All had radical resection and immediate free fibula reconstruction. Flap survival was 100%. Two needed re-exploration for venous thrombosis. There was no tumor recurrence at a mean follow-up of 5.6 years.
• Imran et al. (2004): the skin paddle is used to monitor the buried bone. In 13 fibula flaps, the skin paddle detected all 4 anastomotic failures early.
• Imran et al. (2003): 13 long bone reconstructions with vascularized fibula. Mean time to union was 32 weeks.

10.4.5 Donor site complications

• Ankle stiffness or instability, weakness of great toe flexion.
• In children, the ankle may drift into valgus as the child grows. In a USM review of 8 children, 2 developed ankle valgus; both had surgery before 6 years of age (Sulaiman 2015).
• Check the blood supply of the foot before surgery. Rarely the peroneal artery is the main supply to the foot (peronea arteria magna); a USM case of this was reported (Rosli 2022b).

10.5 Other vascularized bone flaps

The fibula is not suitable for every defect. Two things decide the choice of flap: the shape of bone that is needed, and the amount of soft tissue that is needed with it.

10.5.1 The main alternatives to the fibula

10.5.2 Choosing a flap for the maxilla

The maxilla is where these other flaps are used most. It is a different problem from the mandible.

• The mandible is a single load-bearing arch, so the main need is a long, strong strut of bone. The fibula fits this well.
• The maxilla is thin and hollow. It supports the eye, separates the mouth from the nose and sinus, holds the upper teeth and gives the cheek its projection.
• A maxillary defect may therefore need closure of the palate, support for the orbital floor, bone for teeth, or only a prosthesis (obturator). Often it needs more soft tissue than bone.

What is needed depends on how much of the maxilla is removed. Brown and Shaw (2010) classify the defect in two directions:

• Vertical extent (class I to VI): how high the resection goes, from the palate up to the orbit.
• Horizontal extent (a to d): how much of the palate and alveolus is lost. a = palate only, alveolus intact; b = half or less of the alveolus and palate, on one side; c = half or less but crossing the midline, or the front of the maxilla; d = more than half.

The higher the defect, the more the flap must support the orbit, and the more bone and soft tissue it needs.

10.6 Vascularized bone for long bone defects

In the limbs, plastic surgeons provide vascularized bone for defects after tumor resection, trauma and infection.

The problem: a fibula is alive but thin compared with a femur or tibia. There are two solutions.

10.6.1 Fibula combined with allograft (Capanna technique)

In this technique a vascularized fibula is placed inside the canal of a large (massive) allograft. The two are used together to fill a long gap in the femur or tibia.

Where it came from

Massive allografts were widely used after bone tumor resection, but many failed through nonunion at the junctions, fracture or resorption. In Florence, Capanna and colleagues used a vascularized fibula to rescue these failed allografts, with very good results. From 1988 they combined the two grafts at the first operation, instead of waiting for the allograft to fail (Capanna 2007).

Why two grafts are better than one

In short, the allograft solves the mechanical problem and the fibula solves the biological problem.

Indications

• Intercalary defects of the femur or tibia longer than about 6 to 7 cm, mostly after resection of a bone sarcoma in a young patient who is expected to live long and be active (Houben 2019; Campanacci 2024).
• Resections next to a joint that leave less than about 3 cm of epiphysis, where the allograft gives a better hold for screws and for tendon reattachment (Campanacci 2024).
• Long post-traumatic defects. In 19 patients with distal femoral defects of 9.5 to 20 cm, 18 united at a mean of 6.6 months (Jayaramaraju 2019).
• Defects after chronic osteomyelitis when other methods have failed, as in the USM case below (Lam 2025).
• Congenital pseudarthrosis of the tibia in children (Van Den Heuvel 2020).

When it is usually not chosen: short defects (an allograft or fibula alone is enough), metastatic disease or short life expectancy, patients older than about 70 years, and some patients who will need radiotherapy after surgery (Campanacci 2024).

How it is done

1. Plan. The resection length is measured on MRI. An allograft of matching size and side is ordered from the tissue bank, and the canal width is checked on CT so that the fibula will fit.
2. Resect the tumor or dead bone. The orthopedic and plastic teams usually work at the same time: one resects while the other raises the fibula.
3. Prepare the allograft. It is cut to length and the canal is reamed or burred out to take the fibula. A longitudinal slot is cut in the cortex so that the pedicle can leave the allograft without being kinked or compressed.
4. Raise the fibula from the opposite leg, longer than the allograft. A skin paddle can be included for cover and monitoring.
5. Assemble. The fibula is passed into the allograft. Its ends are pushed into the canal of the host bone at each end, so that living bone bridges both junctions.
6. Fix. A long plate spans the allograft and both host segments. Screws are placed so that they avoid the fibula's pedicle. Long-spanning plates reduce later fractures (Campanacci 2024).
7. Anastomose the peroneal vessels to local recipient vessels, then close the soft tissue or use the skin paddle.

If the canal of the allograft is too narrow for the fibula, for example in the distal tibia, the fibula is placed alongside the allograft (onlay) or combined with allograft cortical struts (Campanacci 2024).

This sequence was shown on serial X-rays and CT in 24 patients (Manfrini 2004). In 13 the allograft stayed intact and the fibula slowly enlarged and fused with it. In 8 the allograft fractured or failed to unite, and the fibula responded with rapid hypertrophy that healed the fracture. In 3 the fibula did not change in size or density and the reconstruction fractured without callus. This was taken to mean that the fibula had lost its blood supply. A fibula that does not hypertrophy is therefore a warning sign.

Variations

• Osteocutaneous fibula. Including a skin paddle covers the soft tissue lost at resection and allows the flap to be monitored. This was used in the USM series (Halim 2015).
• Chimeric fibula. The skin paddle is raised on a separate perforator so that it can be placed away from the bone (Lam 2025).
• "Capasquelet". An induced membrane is first created with a cement spacer (Masquelet). The allograft and fibula are then placed inside the membrane at the second stage. It has been reported in 4 patients with femoral defects, including infected cases (Combal 2021).

Evidence

Interpretation. Adding a vascularized fibula to a massive allograft mainly reduces nonunion and the need to remove the graft. It does not prevent infection or fracture. Further operations are common in the first few years, but once the reconstruction has healed it lasts for decades. Patients and families should be told to expect a long course and probably more than one operation.

Complications

• Nonunion at one of the junctions, especially with chemotherapy. It is treated with bone graft and revision of fixation.
• Fracture of the allograft or of the plate, mostly in the first years.
• Infection of the allograft. Deep infection often means the allograft must be removed.
• Loss of the fibula's blood supply. The allograft then behaves like an allograft alone.
• Limb-length difference in growing children.
• Donor-site problems in the leg.

Aftercare

Weight bearing is protected until the junctions unite and is then increased step by step, because load is what makes the fibula hypertrophy. Union usually takes about 6 to 12 months; in the meta-analysis by Elemosho (2025), mean time to union was 9.4 months in children. X-rays are reviewed for union at both junctions and for thickening of the fibula.

USM experience

USM series (Halim 2015): 12 patients after bone tumor resection, reconstructed with free fibula osteocutaneous flap and massive allograft. Mean follow-up 63 months. Patients with lower limb reconstruction reached partial weight bearing at a mean of 4.2 months and full weight bearing at 8.2 months.

10.6.2 Double-barrel fibula

The fibula is folded into two parallel segments on one pedicle. This doubles the thickness.

USM series (Rosli 2022a): total talus reconstruction with a triangular double-barrel fibula after tumor resection in 4 patients. All achieved bony fusion. Median functional (MSTS) score was 74.5%.

10.6.3 Equipment and products used with bone flaps

10.7 Vascularized bone in the hand: scaphoid nonunion

The same principle applies on a small scale in the wrist.

The blood supply of the scaphoid enters distally and runs proximally. After a waist fracture, the proximal pole may lose its blood supply (avascular necrosis). A non-vascularized graft placed against dead bone often fails. Two vascularized grafts are used:

• Pedicled distal radius graft on the 1,2 intercompartmental supraretinacular artery (Zaidemberg 1991).
• Free medial femoral condyle graft on the descending genicular artery (Doi 2000).

Other pedicled vascularized grafts from the dorsal distal radius are used in the wrist, for example the 4,5 extensor compartmental artery graft for Kienböck disease of the lunate.

Jones (2008) compared them in 22 scaphoid nonunions with avascular proximal pole and carpal collapse. Union was achieved in 12 of 12 with the medial femoral condyle graft and 4 of 10 with the distal radius graft.

10.8 Vascularized epiphyseal transfer in children

The last special use is in the growing child. When a tumor resection removes the growth plate (for example at the distal radius or proximal humerus), an ordinary fibula flap will not grow.

In vascularized fibular epiphyseal transfer, the proximal fibula is taken with its growth plate and joint surface. It is based on the anterior tibial artery, because this vessel supplies the proximal fibular epiphysis.

• The commonest complications are peroneal nerve palsy and fracture of the flap (Lee 2023).
• Growth is expected but cannot be guaranteed. The family must be told this.

The technique was developed by Innocenti and colleagues in Florence. Their series grew over more than two decades, and the later papers give longer follow-up and larger numbers:

Interpretation. The later and larger series confirm the early result: a proximal fibula on the anterior tibial artery survives, unites, keeps growing at about 1 cm a year and gives a joint surface that lasts. They also show the price. Peroneal nerve palsy is common, because the nerve winds around the fibular neck next to the anterior tibial vessels, although most cases recover within a year. In the proximal humerus, fracture of the transferred fibula is common in the first years. The technique has since been used for the mandibular ramus and condyle in a 13-year-old after osteosarcoma resection, with an open growth plate at one year (Innocenti 2020).

Figure 10.10. USM case: giant cell tumor of the distal radius. Tumor, resected specimen, fibula harvest and result.

10.9 USM papers on vascularized bone

The reconstructive team at Universiti Sains Malaysia (USM), Kubang Kerian, has published nine papers on vascularized bone. They cover the mandible, long bones, the foot, the skull and the donor leg.

10.10 Summary

• Vascularized bone stays alive, heals like a fracture and does not depend on the bed.
• It is used for long defects, poor beds, composite defects and avascular nonunion.
• The fibula is the main flap. It survives osteotomy because of its periosteal supply.
• It still needs bone contact, stable fixation and good soft tissue closure.

References

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4. Chai KS, Omar FH, Mat Saad AZ, Wan Sulaiman WA, Halim AS. A 20-year experience of immediate mandibular reconstruction using free fibula osteocutaneous flaps following ameloblastoma resection. Arch Plast Surg 2019;46:426–432.
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