Fibula Flap - Clinical Tree

Introduction

With an outstanding length available for harvest, a solid and sizable bone stock, a reliable blood supply, an allowance for manipulation of the components of the flap while maintaining adequate blood supply, and the ability to carry bone, skin, muscle, and fascia, the fibula flap has become one of the most commonly used vascularized osseous and osteocutaneous flaps for reconstruction of osseous defects around the body, particularly the mandible, radius, femur, and tibia. Ueba and O'Brien evaluated the fibula as a donor site for free microvascular bone flap transfer prior to Taylor et al's report in 1975 of the first two clinical cases of microvascular fibula flaps used for reconstruction of tibia bone gaps. Bovet's work, which followed, demonstrated that muscle could be carried along with the fibula bone. It was not until Wei and colleagues' anatomic and clinical study in 1989, that surgeons were convinced of the reliability of the skin paddle of the osteoseptocutaneous fibula flap. Since then, the skin has served a critical role in providing a cutaneous component when necessary, and for providing a good monitor for the bone component. In 1989, Hidalgo was the first to report on a significant series of vascularized fibula grafts for mandibular reconstruction. Free vascularized bone flaps were shown to heal more rapidly, with fewer complications and earlier functional recovery, and their use for larger defects, particularly in radiated beds, has been found to be superior to that of non-vascularized grafts.

Flap Anatomy (see Fig. 52.1 and Fig 13.6 , Fig 13.7 , Fig 13.8 , Fig 13.19 )

The fibula is a long, thin bone with anterior, posterior, medial, and lateral surfaces. The head articulates with the tibia. The biceps femoris and the lateral collateral ligament attach to the fibula.

Arterial Supply of the Flap (see Fig. 52.1 and Fig 13.6 , Fig 13.7 )

The arterial supply of the fibula flap is via both a dominant nutrient endosteal and minor periosteal septal and muscular branches from the peroneal artery. The external diameter of the peroneal artery is 1.5–2.5 mm and the pedicle length is between 2 cm and 6 cm. The pedicle length varies with the amount of bone that is resected.

Dominant:

nutrient artery from peroneal artery

Length: 1–2 cm
Diameter: 1.0 mm

The nutrient artery arises as a branch of the peroneal artery and enters the fibula posterior to the interosseous membrane into the nutrient foramen approximately 15 cm below the styloid process in the posterior medial edge of the mid-fibula two-fifths of the way down. The vessel length is 1–2 cm and the average diameter is 1.0 mm. After traversing a short intracortical path, the nutrient artery divides into an ascending and a descending branch. The descending branch is often longer than the ascending. Occasionally, there are two nutrient arteries.

Minor:

periosteal and muscular branches from peroneal artery

Diameter:

vessel diameters at their origin range from 0.8 mm to 1.7 mm

Periosteal and muscular branches to the fibula. They are derived from the peroneal artery located along the fibular origin of musculature and posterolateral septum. Musculoperiosteal vessels course primarily through the flexor hallucis longus and tibialis posterior muscle. There are typically 4–8 cutaneous arteries arising from the peroneal artery. These vessels are segmental, consisting initially of periosteal and musculoperiosteal branches, entering from a distance of 4–27 cm below the fibular head and continuing within the posterior crural septum, between the soleus and peroneus muscles, or back through the flexor hallucis longus muscle to supply the lateral leg skin. The middle third of the fibula shaft contains the greatest number of these periosteal branches. When there are no septocutaneous branches, musculocutaneous branches can supply adequate circulation to the same skin area.

Venous Drainage of the Flap (see Fig. 13.19 )

Primary:

venae comitantes of the peroneal artery

Length: 2–6 cm
Diameters: 2–4 mm

Comment: often there are two venae comitantes

Secondary:

superficial venous system

Length: 2–6 cm or longer
Diameter: 2–4 mm

Note: In the case of a fibular osteoseptocutaneous flap a superficial vein (commonly the lesser saphenous) draining the skin paddle may sometimes be used as adjunctive drainage of the flap. This is particularly useful when a large skin island is harvested.

Flap Innervation

Sensory:

The lateral sural nerve and terminal sensory branch of the superficial peroneal nerve (see Figs 13.8 , 13.19 ). Sensory innervation to the corresponding lateral calf skin territory is largely supplied by the lateral sural nerve, which is of adequate size to allow microscopic anastomoses. Although not routinely performed, lateral sural sensory or superficial peroneal nerve coaptation may be performed, and this sensory feedback may improve oral function or tactile penile sensation if a phalloplasty is performed.

Motor:

Although a muscle segment can be harvested with this flap, there are no indications for harvesting a functional muscle with this flap.

Flap Components

The fibula flap is harvested as a bone flap and may include regional musculature (soleus or flexor hallucis longus), and/or overlying skin.

Advantages

Provides vascularized bone that is suitable in cases of recipient site wound contamination, scarring, radiation, or infected bone cases following debridement.
A long segment of straight, triangular, high-density cortical bone (20–26 cm in adults) may be harvested, which is capable of bridging long osseous defects and resisting angular and rotational stresses, considered ideal for extremity axial skeleton reconstruction.
Fibula size matches the size of the radius and ulna, and snugly fits into the medullary cavity of the humerus, femur, and tibia.
As an osteoseptocutaneous flap, the overlying skin connected to the bone by the posterior crural septum, may be readily manipulated, allowing greater versatility in wound closure compared with other osteocutaneous flaps (i.e., iliac crest and scapular osteocutaneous flaps).
Well-defined vascular supply allows for multiple osteotomies (2–3 cm bone segments), which is particularly important in craniofacial contouring procedures.
Suitable donor vessels (peroneal artery, 1.5–2.5 mm; vein, 2–4 mm) allow for anastomoses to large vessels in the head and neck, and upper and lower extremities.
Acceptable donor site morbidity due to tolerable loss of peroneal artery and venae comitantes without the need for reconstruction and limited functional disability in most cases

Disadvantages

Obvious donor scar, particularly when a skin component >4 cm is included and skin grafting is necessary. This is even less desirable in females.
The technique of flap harvest requires a steep learning curve and can be lengthy and tedious in inexperienced hands.
Noticeable limitations and discomfort in ankle function and range of motion with aggressive physical activity may result after fibula harvest, particularly if tibiofibular fusion is performed.

Preoperative Preparation

Preoperative assessment to determine whether a patient is a candidate for a vascularized fibula transfer begins with a careful medical history to identify any conditions that could indicate unreliability of the peroneal artery as a pedicle for free tissue transfer. These conditions include peripheral vascular disease, deep vein thrombosis, trauma, venous stasis disease, or arteritis. The knee and ankle joints should be assessed for range of motion and laxity. A foot Allen's test should be performed with a Doppler probe ensuring a signal for the dorsalis pedis and posterior tibial artery with occlusion of the other vessel. Peronea magna, which is associated with hypoplasia or absence of both the anterior and posterior tibial arteries with the peroneal artery as the sole arterial supply for the foot, must be ruled out and may occur in up to 8% of the population. In most centers around the world, in the absence of trauma to the lower extremity and previous surgery, clinical examination is used to evaluate the blood flow to the extremity prior to flap harvest. CT angiograms are used routinely in our center for evaluation of patients' extremities prior to fibula harvest, particularly in patients with a history of trauma. Duplex ultrasonography provides a potential compromise for preoperative evaluation, without the invasiveness, potential risk, and expense associated with angiography. Intraoperatively, prior to transecting the peroneal artery distally, the surgeon should visualize the posterior tibial artery in order to make sure it exists and appears to be normal.

Flap Design ( Figs 52.2 , 52.3 )

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