Fibula Flap

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INTRODUCTION

An excellent source of vascularised bone with a skin paddle.

Bilateral fibular harvest can be performed with minimal additional morbidity.

Great toe flexion weakness or contracture can be a problem.

Ankle instability or discomfort esp on vigarous exercise can also be a problem.

 

CLASSIFICATION                 

Mathes & Nahai classifies this as a type 5 flap.

 

COMPOSITION   

An osteoseptocutaneous flap (however, it is possible to include muscle with the flap eg soleus).

 

PEDICLE                

Artery: Peroneal Artery (1.5 - 4mm) Vein(s): 2 Venae of the artery

- Branch of the posterior tibial artery (arising 2.5cm from it’s origin).

- Supplies the fibula via medullary & segmental periosteal vessels.

- Note that the bone flap remains viable despite osteotomy so long as the periosteal system remains intact.

- Terminates as lat. calcaneal art. + perforating branch (penetrates interosseus septum into ant. comp.).

- Sizable (2-3-mm diameter) and lengthy (up to 15 cm) pedicle.

- Artery runs beneath FHL attachment postero-medial to the fibula in post. compartment.

- Gives off muscle branches to flexor digitorum longus FDL and tibialis posterior (TP).

- Septocutaneous perforators (~4) run in the septum btwn peroneus longus & soleus.

- Perforating branches my run through soleus necessitating intramuscular dissection.

- This posterior crural septum is located at the posterolateral fibula edge.

- The perforators are concentrated at the junction of the middle & distal thirds of the leg.

- Nutrient branch enters fibula at junction of upper & middle third, giving ascending & descending branches.

 

SKIN PADDLE

Reliable, thin, pliable, and sizeable. For mandibular recon it can restore intraoral and/or extraoral soft-tissue defects of almost any configuration with respect to the bone.

22-25cm long. 10-14cm wide (~5cm wide can usually be closed directly).

 

BONE    

22-26cm of length in an adult. Triangular in cross-section.

The head of the fibula does not take part in the knee joint.

It does however articulate with the lateral condyle of the tibia.

The fibular shaft is palpable laterally, somewhat protected by the lateral compartment. 

The distal fibula forms the lateral malleolus and articulates medially with the talus.

 

INNERVATION

None

 

COMMON USES

Mandibular reconstruction (either single or double barrelled).

Osseointegrated implants can be used to enable complete dental rehabiliation.

Segmental long bone defects. Can bridge 22cm. Straight & tubular - gd for weight bearing.

 

TECHNIQUE        

I would arrange a pre-op CT angiogram to assess the vascular anatomy of the leg.

I am aware however that the value of pre-op CT angiogram is debated.

If pre-op CT angiogram is not performed then one must be especially cautious when dividing the peroneal artery.          

Some patient have a peroneum magna (dominant peroneal artery).

I select the appropriate fibula (left/right) carefully.

Left is better for driving needs & for “right-footed” patients.

I always use a skin paddle (for monitoring) and design this paddle based on the lateral perforators.

These are located pre-op along the posterolateral fibular with a doppler.

Often there is a good perforator at the distal-middle third junction.

A paddle of up to 14x25cm can be reliably based on 1 or 2 perforators.

I leave 8cm fibula proximally (distal to common peroneal nerve).

This also serves to preserve knee stability.

Note also that the more distal this osteotomy the longer the pedicle will be.

I leave 6cm fibula distally - preserves ankle stability.

I raise the paddle from anterior to posterior.

- suprafacially over the peroneal tendons (facilitates grafting).

- then subfascial to identify the vessels.

I raise the muscle off the bone anteriorly (leaving periosteum).

The periosteum must be left to preserve blood supply to the bone.

I visualise the anterior tibial vessels. It is reassuring to see them.

If absent I clamp the peroneal to check distal perfusion prior to division.

Note:- In 10% the perforators are said to arise from the post tibial not the peroneal !

In which case the paddle will not survive so there is not point using it.

I preserve the sural nerve posteriorly.

I perform the distal osteotomy first,

the proximal one second and then divide

the interosseous membrane last.

I ligate the peroneal vessels distally where they emerge from the under FHL (flexor hallucis longus).

Proximally, I free the bone preserving the pedicle.

When closing the donor site I avoid excessively tight closure as this can cause compartment syndrome.

 

Fibula Flap Diagram
Fibula Flap Diagram