**Region:** Lower Extremity # Soleus Flap ## Anatomy - Pedicle: dominant arterial supply is segmental — proximal dominant branches from the popliteal artery; medial hemisoleus dominant pedicle from the posterior tibial artery (mean arterial caliber 2.7 mm); lateral hemisoleus dominant pedicle from the peroneal (fibular) artery (mean arterial caliber 1.5–2.5 mm). Venae comitantes accompany each pedicle (posterior tibial venae comitantes mean calibers 2.9 mm and 2.17 mm; peroneal venae comitantes 2–4 mm). (Shridharani & Singh) - Course: popliteal → branches to proximal soleus; peroneal and posterior tibial branches send segmental perforators to middle and distal thirds of the muscle. Distal accessory branches most commonly arise from distal posterior tibial vessels just above the medial malleolus and supply the distal soleus (basis for distally based flaps). (Hanasono / Chang) - Length/pivot: for a fully mobilized proximally based soleus, the distance from pivot (origin of major vascular pedicles at junction of proximal and middle thirds) to the tendocalcaneus insertion averages 6.0 ± 1.7 cm above the calcaneus. (Shridharani & Singh) - Perforator pattern: segmental perforators traverse the deep posterior compartment fascia to the soleus; distal perforators from posterior tibial and peroneal vessels supply distal soleus and can be absent occasionally (making the distally based flap less reliable). Musculocutaneous and septocutaneous perforators may be present in the upper lateral third permitting a skin paddle when required. (Chang; Shokrollahi) - Nerves: - Motor: medial popliteal and tibial nerve branches innervate the soleus — medial popliteal nerve supplies proximal muscle; posterior tibial nerve branches innervate middle and distal regions. Preserve motor branches to remaining hemisphere when harvesting a hemisoleus to maintain plantarflexion. (Chang) - Sensory: cutaneous nerves (sural/lesser saphenous and saphenous in medial approaches) lie in superficial planes; identify and protect greater saphenous when harvesting medial approach and lesser saphenous/sural nerve when approaching laterally. (Shokrollahi) - Included tissues: - Typical harvests: muscle-only flap (soleus or hemisoleus), hemisoleus (split along median raphe), or myocutaneous/musculocutaneous variants when perforators to skin are adequate. Skin paddle possible from lateral upper third musculocutaneous perforators or by including septocutaneous peroneal perforators (same perforators used in fibula osteocutaneous flaps). (Chang; Shokrollahi) - Thickness and profile: muscle-only flap provides a bulky vascularized tissue bed often skin-grafted for coverage; musculocutaneous paddles are thinner but require reliable perforators and intraoperative perfusion confirmation (handheld Doppler/ICG). (Chang; Shokrollahi) - Arc of rotation: proximally based soleus reliably covers middle-third leg defects; distally based medial hemisoleus may be rotated 90–180° to reach distal-third and ankle/heel defects when distal perforators are present. No more than two-thirds of the muscle should be reversed reliably. (Chang; Shokrollahi) - Common variants/anomalies: - Bipennate anatomy with a midline raphe allows longitudinal splitting for hemisoleus harvest. - Distally based flaps rely on variable distal perforators from posterior tibial/peroneal system — absence of these perforators reduces reliability. - Musculocutaneous perforators can be absent or small; intraoperative Doppler/ICG helps identify usable skin paddle vessels. (Chang; Shokrollahi) ## Dissection Steps 1. Positioning, markings, landmarks. - Position: - Medial hemisoleus: supine, knee slightly flexed, hip externally rotated ("frog‑leg" for distal defects). (Chang; Shokrollahi) - Lateral hemisoleus: supine with knee extended or flexed and hip internally rotated; towels under hip to aid exposure if needed. (Shokrollahi) - Surface markings: - Palpate lateral and medial borders of gastrocnemius to identify cleavage plane between gastroc and soleus. - Mark longitudinal incision 2 cm posterior to posterior border of fibula for lateral approach (from ~5 cm below fibular head to just above lateral malleolus) when harvesting lateral or full soleus with fibula exposure. For medial approach mark incision ~2 cm posterior to medial tibial border from proximal leg to just above medial malleolus. (Chang) - For distally based medial hemisoleus, draw a longitudinal incision anterior to Achilles and parallel to tibia; plan to identify distal posterior tibial perforators with Doppler. (Chang) 2. Plane (suprafascial/subfascial), perforator identification (handheld/IO Doppler). - Elevation: - Elevate adipocutaneous flaps conservatively off underlying muscle fascia only if needed for exposure. - Create fasciotomy to access superficial posterior compartment musculature. - A clear avascular plane exists between gastrocnemius and soleus — incise and reflect gastrocnemius origin as needed to expose soleus. Identify and preserve plantaris tendon in the plane. (Shokrollahi) - Perforator identification: - Use handheld Doppler pre- and intraoperatively to locate distal perforators for distally based flaps or musculocutaneous perforators for skin paddles. Consider ICG angiography intraoperatively to confirm perfusion of musculocutaneous paddles. (Chang; Shokrollahi) 3. Pedicle dissection: exposure, control, division; transfer/inset; perfusion checks. - General approach: - Dissect from distal to proximal to isolate and preserve major vascular pedicle(s). Ligate segmental perforators that must be divided while preserving dominant proximal vessels for proximally based flaps. For distally based hemisoleus identify distal perforators first, then ligate more proximal contributions to create a distal pivot. (Shokrollahi; Chang) - For lateral approach: divide lateral origins from fibula and separate soleus from gastrocnemius and Achilles insertion as needed. For medial approach: avoid damage to greater saphenous vein and saphenous nerve; identify posterior tibial neurovascular bundle lying between soleus and flexor digitorum longus. (Chang) - Splitting muscle: - If harvesting hemisoleus, longitudinally divide the median raphe to split bipennate soleus and allow harvest of half muscle while preserving other half for plantarflexion. (Shokrollahi; Chang) - Pivot and inset: - Create subcutaneous tunnel or extend wound/incise skin bridge to pass flap without tension or kinking. Ensure pedicle has adequate length and no compression; confirm arc of rotation and inset without tension. For distally based medial hemisoleus pivot is at distal perforators — divide muscle 2–3 cm above the proximal perforator during elevation to mobilize flap. (Chang; Shokrollahi) - Perfusion checks: - Confirm muscle bleeding and Doppler signals after elevation; consider ICG if including skin paddle or when perfusion uncertain. (Chang; Shokrollahi) 4. Donor-site closure techniques. - The mobilized soleus muscle typically requires split-thickness skin graft for coverage of the transposed muscle. - Donor incision closed primarily with minimal undermining when possible; place a closed-suction drain in donor bed (recommended: single 19-French round channeled drain). Secure drain through separate stab incision. (Shokrollahi) - Ensure meticulous hemostasis; avoid tight closure or repair of fasciotomy in superficial posterior compartment that may risk compartment syndrome. (Shokrollahi) ## Indications and Contraindications - Indications: - Coverage of soft-tissue defects of the middle third of the leg (primary indication for proximally based soleus/hemisoleus). - Distally based medial hemisoleus for selected defects of the distal third, ankle, and sometimes heel when distal perforators are present and reliable. - Reconstruction when a vascularized muscle bed is required (exposed bone, hardware, chronic osteomyelitis) and when free tissue transfer is not preferred or feasible. (Chang; Shokrollahi) - Thin, pliable coverage possible with musculocutaneous/perforator variants for intraoral or head-neck applications (free soleus perforator flaps) when a thin skin paddle is needed. (Chang) - Contraindications: - Absent or unreliable distal perforators (absolute for distally based flap); absence should be confirmed with Doppler/angiography when in doubt. (Chang) - Severe peripheral vascular disease compromising posterior tibial or peroneal inflow to intended pedicle — perform preoperative vascular imaging if indicated. (Chang) - Extensive previous surgery or trauma destroying the vascular pedicle in the intended harvest zone — relative contraindication. (Shridharani; Chang) - Situations where loss of substantial soleus function (if full soleus harvest planned) would significantly impair patient mobility — consider hemisoleus when possible. ## Postoperative Care - Monitoring schedule/method: - Clinical serial checks for flap color, capillary refill, and bleeding from muscle edges for the first 48–72 hours. Use handheld Doppler as adjunct for musculocutaneous paddles or questionable perfusion. Consider ICG intraop or early postop if concerns remain. (Shridharani; Chang) - Warming / antithrombotic practice: - Standard limb warming/avoid cooling; no routine thrombolysis described in the soleus chapters — tailor antithrombotic prophylaxis to institutional VTE protocol and microvascular risk (use clinical judgment). (Shridharani) - Positioning/splinting: - Keep limb elevated strictly to reduce edema and optimize flap perfusion in early postoperative period; initiate progressive dangling protocol per surgeon discretion. Avoid pressure on flap and avoid tight dressings. (Shokrollahi) - Drains: - Maintain closed-suction drain (single 19‑French recommended) until output is acceptable; remove per routine institutional practice. (Shokrollahi) - Mobilization: - Early strict elevation, then progressive dangling and mobilization as healing allows. Weight-bearing/activity restrictions depend on recipient site and underlying orthopaedic stability; if muscle covers bone/hardware, coordinate with orthopedics for weight-bearing timeline. - Diet/analgesia: - Standard post-op diet and multimodal analgesia as tolerated; optimize nutrition for wound healing. - Return-to-OR thresholds and time windows: - Immediate return to OR for signs of acute flap ischemia (absent Doppler signal where expected, frank arterial insufficiency, expanding hematoma under flap, severe pallor/poor capillary refill) — action should be taken emergently within hours. Re-exploration indicated when flap perfusion fails to improve with conservative measures. (General surgical principle, implied by operative emphasis on perfusion checks) ## Complications (rates & management) - Reported rates: - Specific prospective percentages for soleus flaps are not universally reported in the provided soleus chapters; therefore list complications qualitatively and manage as below. (Shridharani) - Flap-related complications and management: - Arterial insufficiency / thrombosis: present as pale, cool flap with absent bleeding; urgent return to OR for exploration, relieve kinks/compression, evacuate hematoma, revise pedicle or perform microvascular repair if indicated. (Technique principles described) - Venous congestion: manifests as dusky, edematous flap with slow capillary refill; management includes relieve compression, remove constricting dressings, consider widening pedicle, perform surgical delay in high-risk patients preoperatively, or intraoperative/early postoperative supercharging techniques when necessary (include cuff of fascia/vein, preserve venous outflow). For severe venous congestion in salvage scenarios consider temporary exteriorization of venous segment or leech therapy for soft-tissue flaps (discussed in reverse sural literature; apply principles prudently). (Chang; Shokrollahi) - Partial/total flap loss: muscle flaps may fail partially or completely if dominant pedicle compromised — debridement and secondary reconstruction as indicated. - Infection, hematoma, delayed healing, wound dehiscence, skin-graft loss: manage with antibiotics, drainage, debridement, repeat grafting as necessary. (Chang; Shokrollahi) - Donor-site issues: - Need for skin graft over donor site; possible contour deformity and scarring. Drain-related seroma/hematoma — minimized by drain placement and hemostasis. Repair of fasciotomy can precipitate compartment syndrome — avoid tight closure. (Shokrollahi) - Management algorithms: - If perfusion compromised intraop: optimize position/untwist pedicle, confirm no kinking, preserve remaining gastrocnemius insertion if possible. - If postop arterial insufficiency/ischemia: urgent re-exploration (within hours). - If venous congestion without arterial compromise: relieve external compression, consider re-exploration to augment venous outflow (widen pedicle, perform venous anastomosis or exteriorize vein if planned), use medical leeching only as temporizing salvage for fasciocutaneous flaps (consult microvascular team). (Principles described across chapters) ## Key Clinical Pearls - The soleus is bipennate and can be split longitudinally along the median raphe to harvest a hemisoleus and preserve plantarflexion of the foot. (Chang; Shokrollahi) - Preserve gastrocnemius contribution to the Achilles tendon when possible to reduce donor-site functional morbidity. (Shokrollahi) - Confirm distal perforators with handheld Doppler before committing to a distally based hemisoleus flap; distal perforators most commonly arise just above the medial malleolus from posterior tibial vessels. (Chang) - When elevating a musculocutaneous skin paddle, harvest a cuff of muscle around the dominant perforators and confirm perfusion (Doppler and consider intraoperative ICG) prior to inset. (Chang; Shokrollahi) - Average distance from pivot (origin of major vascular pedicles at junction of proximal/middle thirds) to tendocalcaneus insertion is approximately 6.0 ± 1.7 cm — useful when estimating pedicle length and arc of rotation. (Shridharani & Singh) - No more than two-thirds of soleus should be reversed for distally based flaps; absence of distal perforators makes reversal unreliable. (Shokrollahi) - Place a closed‑suction drain in donor site (single 19‑French recommended) and perform meticulous hemostasis; avoid tight fasciotomy repair that could cause compartment syndrome. (Shokrollahi) - Use conservative distal‑to‑proximal dissection to preserve dominant pedicles; when in doubt about skin paddle viability, skin graft muscle and delay or plan second-stage procedures. (Chang; Shokrollahi)