Free Vascularised Fibula Transfer

• Peroneal (fibular) artery — arises from the tibioperoneal trunk roughly 2.5 cm below popliteus, descends between tibialis posterior and FHL along the posteromedial fibula. Calibre 1.5 to 2.5 mm; paired venae comitantes (often larger than the artery); usable pedicle length 4 to 8 cm, extendable by dissecting to the tibioperoneal trunk and by harvesting a longer proximal fibular segment then discarding bone to lengthen the effective pedicle.
• Nutrient artery — single branch entering the posterior/medial cortex of the middle third, posterior to the interosseous membrane. Supplies the inner two-thirds of the cortex (endosteal system).
• Periosteal/musculoperiosteal branches — segmental arcades from the peroneal artery along the length of the bone; supply the outer cortex. Because this supply is segmental, careful subperiosteal-sparing osteotomies (for double-barrelling or contouring) preserve viability of each segment provided the periosteal sleeve and pedicle remain intact.
• Septocutaneous perforators — 2 to 4 perforators in the posterior crural (lateral intermuscular) septum, concentrated at the junction of middle and distal thirds, supply the skin paddle used for monitoring and soft-tissue reconstruction (osteocutaneous flap).
• Proximal epiphysis — supplied by branches of the anterior tibial artery; epiphyseal transfer for growing reconstruction requires a different pedicle from the standard diaphyseal harvest.

• Common peroneal nerve — at the fibular neck; superficial peroneal nerve within peroneus longus/brevis during the lateral approach.
• Anterior tibial vessels and deep peroneal nerve — immediately anterior to the interosseous membrane; at risk when dividing the membrane.
• Posterior tibial neurovascular bundle — medial to the pedicle in the deep posterior compartment; at risk during proximal pedicle dissection to the tibioperoneal trunk.
• FHL — takes origin from the posterior fibula; its cuff is elevated with the graft, and scarring causes claw hallux.

• Peronea arteria magna (Type III variant) — peroneal artery is the dominant or sole supply to the foot. Reported in roughly 0.2 to 5 percent of limbs. Absolute contraindication to harvest from that leg.
• High peroneal origin or common trunk variants — alter pedicle length; identified on preoperative angiography where performed.
• Angiography controversy — routine preoperative angiography versus selective imaging. Most units now image selectively: normal palpable dorsalis pedis and posterior tibial pulses with triphasic handheld Doppler signals suffice in the young healthy donor; image (CTA/MRA) if pulses abnormal, previous leg trauma or surgery, peripheral vascular disease, or congenital limb anomaly (relevant in congenital pseudarthrosis patients, who have a higher variant rate).

Position — supine with a bump or lateral decubitus; hip and knee flexed, thigh tourniquet (exsanguinate by elevation, not Esmarch, to preserve venous filling for perforator identification).

Landmarks and incision — line from fibular head to lateral malleolus along the posterior border of the fibula; centre the skin paddle over Doppler-marked perforators at the middle-distal third junction.

Sequence (Gilbert-type lateral approach):

1. Incise anterior to the marked paddle; raise the anterior skin flap and identify septocutaneous perforators in the posterior crural septum; include a septal cuff with the paddle.
2. Elevate peroneus longus and brevis off the fibula anteriorly, leaving a 1 to 2 mm muscle cuff on bone to protect periosteal vessels; protect the superficial peroneal nerve; proximally identify and protect the common peroneal nerve at the neck.
3. Release the anterior compartment muscles (EDL, EHL) from the fibula; identify and protect the anterior tibial vessels and deep peroneal nerve on the interosseous membrane.
4. Mark osteotomy levels — preserve 6 cm distally and stay below the neck proximally; confirm the middle third (nutrient foramen) lies within the graft. Perform osteotomies with an oscillating saw under retractor protection.
5. Divide the interosseous membrane; rotate the fibula externally to expose the deep posterior compartment.
6. Ligate and divide the distal peroneal vessels below the graft; dissect the pedicle proximally between tibialis posterior and FHL, taking a cuff of FHL/tibialis posterior with the bone, up to the tibioperoneal trunk for maximal length and calibre.
7. Deflate the tourniquet; confirm perfusion of bone (bleeding osteotomy ends, punctate periosteal bleeding) and paddle; achieve haemostasis; divide the pedicle only when the recipient site is ready.

Closure — loose fascial closure (do not close the crural fascia tightly — compartment syndrome risk), drain, direct skin closure if paddle less than about 4 cm wide, otherwise split-skin graft; below-knee backslab in ankle neutral.

Paediatric addition — distal tibiofibular synostosis or transfixion screw to prevent proximal migration and ankle valgus.

• Docking — prepare host bone ends to bleeding bone; options: intramedullary telescoping of the fibula into the host canal (femur/tibia/humerus), step-cuts, or onlay with compression. Aim for stable bony contact at both junctions.
• Fixation — plate and screws spanning the whole construct (bridge mode over the fibula), or locked intramedullary nail with the fibula alongside/inside; avoid screws through the pedicle side of the fibula and avoid plate or bone compressing the pedicle — leave a clear soft-tissue path for the vessels, and check pedicle lie after fixation in the final limb position.
• Double-barrel technique — for large-diameter bones (femur, tibia): a closing-wedge osteotomy through bone only, preserving the periosteal sleeve and pedicle, folds the fibula into two parallel struts, doubling cross-sectional area and stiffness and improving junctional contact.
• Capanna technique — massive intercalary allograft reamed to accept the fibula through its canal; a longitudinal window/trough in the allograft accommodates the pedicle without kinking; fixation with plate or nail through the composite; fibula extends 2 to 3 cm beyond each allograft end into host bone to drive junctional union.
• Microvascular anastomosis — arterial end-to-side to the recipient axial artery or end-to-end to a branch; one or both venae comitantes to recipient veins; operate outside the zone of injury/radiation. Confirm flow (patency test, paddle refill, bone bleeding) before closure.

• Skin paddle — colour, capillary refill, temperature, pinprick bleeding; hourly checks for 24 to 48 hours then de-escalate. The paddle is the only direct window on a buried bone flap.
• Adjuncts — implantable Doppler on the pedicle, external handheld Doppler over marked perforator; where no paddle is used, implantable Doppler is strongly advised. Late viability can be assessed with bone scan or SPECT-CT if union stalls.
• Threshold for return to theatre — any sustained change in paddle perfusion or loss of Doppler signal: immediate re-exploration; venous congestion (blue, brisk refill, dark bleeding) is more common than arterial failure and is salvageable if recognised within hours.
• Rehabilitation — protected weight-bearing (cast/brace or frame-protected) typically 3 months minimum for lower limb; progressive loading as junctional union appears; full unprotected loading usually deferred until hypertrophy is radiographically evident (often 6 to 12 months lower limb). Upper limb mobilised earlier within fixation stability.
• Donor leg — early ankle and great-toe active range of movement to limit FHL tethering; weight-bearing as comfortable from day 1 to 2 once wounds settle.