**Region:** Lower Extremity # Peroneus Brevis Flap ## Anatomy - Pedicle: peroneal artery via multiple muscular perforators to peroneus brevis; venae comitantes accompany perforators. The muscle receives muscular perforators from all three major leg vessels but has a consistent dominant proximal pedicle from the peroneal artery (one of an average of 4 muscular perforators described). A posterior axial vessel runs along the posterior intermuscular septum through the length of the muscle and connects source perforators. - Perforator pattern: multiple intramuscular/septal perforators coursing through the posterior intermuscular septum; a dominant distal perforator is encountered within 6–8 cm of the lateral malleolus (can be ligated to allow a proximal pivot). Proximal dominant perforator must be preserved. - Course: perforators arise from the peroneal artery (through the posterior intermuscular septum) and enter the muscle along its posterior/intramuscular course supplying the muscle belly and axial vessel. - Angiosomes/choke zones: the muscle fills from multiple source arteries with connecting axial vessel; the peroneal-angiosome supply dominates the dorsolateral/lateral compartment distribution (as described by anatomical series cited in the text). - Nerves: motor innervation to peroneus brevis arises from the common peroneal (fibular) nerve. The superficial peroneal nerve is visualized proximally during harvest and should be protected. - Included tissues: true muscle flap (peroneus brevis muscle) with its tendinous distal portion (to the styloid of the base of the 5th metatarsal) and overlying paratenon preserved for grafting. No intrinsic skin paddle is described; muscle surface is routinely covered with split-thickness skin graft. - Thickness/profile/extent: peroneus brevis is a thin, fusiform muscle lying deep and anterior to peroneus longus in the lateral compartment; it can be muscular up to and beyond the level of the lateral malleolus. - Arc of rotation / variants: flap may be transferred as proximally based (proximal pedicle) or distally based (distal pivot) depending on which perforators are preserved/ligated. Distally based designs are used for lateral ankle and tendo‑Achilles coverage; proximally based designs reach lateral/distal tibial defects. Common variant: partial detachment with tendon used as anchoring handle; epimysial release can fan the muscle to increase surface area. - Common anatomic considerations/variants: preserve peroneus longus where possible to maintain ankle stability; preserve paratenon over distal tendon for graft take; proximal dominant perforator commonly located in proximal 4–6 cm of muscle (preserve this segment). ## Dissection Steps 1. Positioning, markings, landmarks. - Patient supine. Foot placed in plantarflexion to relax the lateral compartment and maximize harvest length. - Landmarks: posterior border of fibula and course of the lateral compartment; incision may be placed just posterior and parallel to the fibula or via access through the posterior intermuscular septum from the adjacent wound. 2. Plane (suprafascial/subfascial), perforator identification (handheld/IO Doppler). - Access the lateral compartment through the intermuscular septum or the incision posterior to the fibula. - Identify peroneus longus (superficial/posterior) and peroneus brevis (deep/anterior). Visualize and protect the superficial peroneal nerve proximally. - No routine skin paddle is harvested; plan for muscle-only harvest with later split-thickness graft. - Identify perforators where visible in the posterior intermuscular septum; intraoperative Doppler may be used to confirm perforator locations if desired (documented practice in similar regional flaps). 3. Pedicle dissection: exposure, control, division; transfer/inset; perfusion checks. - Distal-to-proximal dissection is recommended: - Free peroneus brevis distally along its tendinous portion; preserve distal paratenon to maintain a graftable surface. - Divide the brevis tendon as distally as possible (through the wound or via small incision at its insertion on the base of the 5th metatarsal). Retain the tendinous stump for inset anchorage. - Continue dissection proximally in the subperiosteal/subfascial plane to expose perforators entering from the peroneal artery through the posterior intermuscular septum. - Ligate branches passing to peroneus longus as needed, but take care to preserve the posterior axial vessel running within peroneus brevis over the posterior intermuscular septum. - Identify and preserve the dominant proximal perforator (proximal attachment of the muscle and the dominant pedicle within the proximal ~4–6 cm should be maintained). - If a proximal pivot is planned, ligate the distal perforators (the dominant distal perforator lies ~6–8 cm proximal to the lateral malleolus) to mobilize the muscle on its proximal pedicle. - Insetting: - Fan the muscle by releasing epimysium (particularly parallel to the tendon) to increase surface area and conformality. - Anchor the tendinous stump to the wound edge (useful for inset and tension off-loading). - Cover muscle with meshed split-thickness skin graft over the muscle and paratenon. - Perfusion checks: - Confirm muscle bleeding and graft viability intraoperatively; the text documents rapid graft take and healed reconstruction by 3 weeks in case example—confirm capillary bleeding and graft adherence on routine checks. 4. Donor-site closure techniques. - Donor site in lateral compartment can often be closed primarily by mobilizing remaining lateral compartment contents; extensile incision may be closed primarily without tension in the reported case. - If further soft tissue loss at donor site, use split-thickness grafting as required. - Preserve peroneus longus function if possible to minimize postoperative ankle instability; tenodesis or tendon management described in literature may be considered if tendon sacrifice is necessary (as referenced in the case series). ## Indications and Contraindications - Indications: - Soft-tissue coverage of lateral/distal tibia, lateral malleolus, lateral ankle and tendo‑Achilles region, and small-to-moderate defects of the distal lower leg where locoregional options or free tissue transfer are unsuitable (burns, trauma). - Useful in settings with compromised local fasciocutaneous options or when free flap recipient vessels are within the zone of injury. - Case example covered a defect of approximately 15 × 5 cm using a proximally based peroneus brevis flap. - Can be used proximally based or distally based depending on required reach (distal designs for lateral ankle/tendo‑Achilles). - Contraindications (absolute/relative, as described in source material): - Situations where the peroneal artery or its muscular perforators are absent or irreparably damaged in the planned pedicle distribution (would compromise vascularity). - When peroneus longus is absent or nonfunctional such that donor-site ankle stability would be unacceptably compromised (text emphasizes acceptable donor morbidity when peroneus longus is intact). - Extensive injury to the lateral compartment that destroys the muscle or its proximal perforator territory. ## Postoperative Care - Monitoring schedule/method: - Routine clinical monitoring of flap perfusion and skin graft take (visual assessment of muscle bleeding, capillary refill, and graft adherence). - No specific implantable Doppler protocol reported in the peroneus brevis chapter; adopt standard clinical monitoring intervals used for regional muscle flaps. - Warming/antithrombotic practice: - Not specifically detailed for peroneus brevis in the chapter; follow institutional protocols for lower-limb flap patients. - Positioning/splinting: - Immediate postoperative limb elevation recommended in other lower‑leg muscle flap chapters to reduce edema and promote graft take; foot neutral/comfort position per surgeon preference. (Peroneus brevis harvest was performed with the foot plantarflexed intraoperatively.) - Drains: - Drains are used in analogous lower-limb flap donor sites in the referenced chapters (e.g., placement of closed-suction drains is recommended in soleus/gastrocnemius flaps; a 19‑French round channeled drain was used in soleus donor site examples). Consider closed-suction drainage of large donor sites at surgeon discretion. - Mobilization: - Progressive dangling and graded mobilization protocols are suggested in the soleus chapter; peroneus brevis cases reported early graft take by 3 weeks—mobilization timing should be individualized. - Diet/analgesia: - Standard perioperative nutrition and analgesia optimization; not specifically detailed in the peroneus brevis chapter. - Return-to-OR thresholds and time windows: - No explicit time windows or numeric thresholds provided in the peroneus brevis chapter. Re-explore for clinical concerns such as loss of perfusion, progressive graft failure, or infection per usual surgical judgment. ## Complications (rates & management) - Complications (reported/mentioned in the provided sources): - Graft failure / partial graft loss — managed by standard wound care and re-grafting if necessary. The presented case had complete graft take and healed at 3 weeks. - Heterotopic ossification risk if periosteal component of flap is left superficial over recipient bone — the chapter specifically advises leaving the periosteal portion deep after inset because superficial periosteum may interfere with graft take via heterotopic ossification. - Donor-site contour change or functional loss — peroneus brevis donor site described as cosmetically and functionally acceptable when peroneus longus is preserved; no specific frequency data given. - Venous congestion — not specifically quantified for peroneus brevis, but venous congestion is a common issue with distal pedicled lower-leg flaps (reverse sural chapter). Preventive measures described in other chapters include preserving pedicle tissue cuff and staged delay for high-risk reverse-flow flaps. - Frequencies/rates: no numeric complication rates or percentages were provided in the peroneus brevis chapter. - Management algorithms (what, when, how): - Preserve paratenon distally and epimysium management intraoperatively to maximize graftable surface and reduce graft failure. - If graft compromise or donor skin flap compromise is identified, prompt debridement and re-grafting are indicated (analogous recommendations appear in soleus/gastrocnemius chapters). - For venous congestion in distally based lower‑leg flaps (from reverse sural chapter): minimize by harvesting pedicle with 2–3 cm of tissue on either side, or consider “delay” (4–10 days) and ligation of proximal lesser saphenous vein/superficial components in those flaps — the principle of preserving a cuff of tissue to reduce congestion is transferable to pedicled designs. - Repair/tenodesis: if tendon sacrifice or imbalance is created, tendon management (tenodesis or other reconstructive tendon procedures) has been described in the literature to limit ankle instability (mentioned in peroneus brevis discussion). ## Key Clinical Pearls - Preserve the proximal 4–6 cm of muscle and the dominant proximal peroneal perforator — this is the critical pedicle segment for proximally based transfers. - The dominant distal perforator commonly lies within 6–8 cm of the lateral malleolus; ligate it when a proximal pivot is required. - Perform harvest with the foot plantarflexed to relax the lateral compartment and maximize flap length. - Identify and protect the superficial peroneal/common peroneal neural elements proximally during exposure. - Preserve distal paratenon over the brevis tendon — this preserves a graftable surface and improves skin graft take. - Release the epimysium (parallel to the tendon) to “fan out” the muscle and increase surface area for inset without additional pedicle length. - Use the tendinous distal stump as an anchoring handle to secure the flap inset and reduce tension on the muscle fibers. - The flap can reliably cover moderate lateral/distal tibial defects (case example ~15 × 5 cm) with rapid graft take and acceptable donor-site contour and ankle stability when peroneus longus is preserved.