**Region:** Chest and Shoulders # Thoracodorsal Artery Perforator Flap ## Anatomy - Pedicle: thoracodorsal artery (branch of the subscapular system) with venae comitantes. - Pedicle course: thoracodorsal pedicle courses toward the latissimus dorsi (LD), entering the deep surface of the muscle about 2–3 cm medial to the muscle edge and approximately 4 cm inferior to the tip of the scapula (or 8–10 cm inferior to the posterior axillary fold). The thoracodorsal pedicle bifurcates into a descending (vertical) and a transverse (horizontal) branch. The descending branch commonly supplies the main perforators. - Typical pedicle length: usually 14–18 cm when dissected toward the origin; pedicle can be shortened by stopping at bifurcation or lengthened by dissection to the subscapular origin. (numbers as reported) - Vessel caliber: descending branch artery diameter reported in the literature ~0.8–1.5 mm; transverse branch of similar caliber. Perforator count: each branch reliably supplies one to three perforators. - Perforator pattern and course: - First reliable perforator along the descending branch typically about 6 cm inferior to the tip of the scapula (alternatively described as the main perforator arising 7–8 cm below the axillary crease at the level of the vascular hilus). Additional perforators may be found at roughly 2–4 cm intervals inferior to the first. - Perforators typically have an intramuscular course of about 3–5 cm before reaching the skin; more distal perforators occasionally originate from intercostal vessels instead of the thoracodorsal system. - Direct cutaneous branch (wrapping around anterior border of LD) is present in a substantial fraction of patients (reported range 55–75%). - Number/location: usually 1–3 sizable perforators along the descending branch; their size diminishes from proximal → distal. - Venous drainage: venae comitantes accompanying thoracodorsal artery; additional lateral thoracic venous system may be present but often drains separately (may permit extra venous outflow if incorporated). - Nerves: - Motor: thoracodorsal nerve runs along inferior aspect of the pedicle to the LD muscle and should be preserved during pedicle dissection to avoid donor-site functional deficit. - Sensory: posterior rami of the lateral cutaneous branches of the intercostal nerves provide cutaneous sensation to the TDAP skin paddle; these nerves run transversely atop the LD and enter skin slightly anterior to perforators and can be included for sensate flaps. - Included tissues and variants: - Typical flap: cutaneous/adipocutaneous (adipofascial) flap elevated suprafascially/through LD fascia and islanded on one or more TDAP perforators, sparing the LD muscle. - Can be harvested as: pure TDAP (muscle-sparing), small muscle cuff inclusion, split-LD, or combined/chimera flaps including serratus branches, LD muscle, thoracodorsal fascia, scapular/parascapular skin, rib or scapular bone depending on reconstructive need. - Thickness profile: contains superficial fat layer and deeper fat; deep fat under the superficial fascia accounts for approximately one-third of the flap thickness and can be debulked after harvest if indicated. - Size limits reported: skin paddles as large as 14 × 25 cm have been described on a single perforator. - Arc of rotation (pedicled): longitudinally oriented pedicled TDAP can reach distal third of upper arm and elbow, neck, shoulder, and upper back; transversely oriented pedicled TDAP commonly used for breast/axillary coverage and can be hidden under brassiere in women. ## Dissection Steps 1. Positioning, markings, landmarks. - Patient: lateral decubitus is standard for harvest (arm abducted to 90° and elbow flexed 90°); ipsilateral arm may be positioned on an arm board or padded Mayo stand. Pedicled flaps are best inset after donor-site closure with patient repositioning as required. - Landmarks: palpate and mark anterior border of LD, tip of scapula, axillary crease. Mark flap ellipse over the descending branch; anterior edge of flap should extend anterior to the LD anterior border to ensure perforator capture. Skin pinch test to determine maximal donor width amenable to primary closure. - Perforator mapping: surface Doppler may help identify TDAP perforators, but it is less reliable than for some other perforator flaps because perforators may run for variable distances on the muscle fascia and the descending branch itself can be audible. CT/duplex may be used but transferring imaging coordinates to surface is less straightforward. 2. Plane (suprafascial/subfascial), perforator identification (handheld/IO Doppler). - Initial incision strategy: perform posterior/caudal border incision first and elevate in the loose areolar plane between LD fascia and subcutaneous fat proceeding anteriorly toward the anterior LD border (several authors describe either anterior-first or posterior-first incisions; limit initial incision to allow repositioning if perforator falls outside planned skin island). - Dissection plane: suprafascial dissection on top of LD fascia in loose areolar plane to identify perforators as they emerge; incise fascia along muscle fibers as needed to follow perforator intramuscular course. Handheld Doppler can be used intraoperatively but interpret with caution. - Perforator selection: identify dominant perforator(s). Proximal perforators require shorter intramuscular dissection; distal perforators provide longer pedicle length but require deeper intramuscular dissection and may arise from intercostal vessels. If a direct cutaneous branch is present anterior to LD border, consider it as a potential pedicle. 3. Pedicle dissection: exposure, control, division; transfer/inset; perfusion checks. - Intramuscular dissection: island the flap and dissect perforator through intramuscular course, carefully ligating/clipping muscular side branches; preserve thoracodorsal motor nerve running on deeper plane. Keep dissection close to pedicle and use clips/bipolar to control small branches. Continuous irrigation with warm saline helps prevent spasm and desiccation. - Level of pedicle dissection: stop dissection at thoracodorsal bifurcation if short pedicle suffices and vessel caliber acceptable; if longer pedicle or larger-caliber vessel required for free transfer, continue dissection to origin at subscapular system. Total pedicle length typically 14–18 cm when dissected proximally. - Islandization and division: once pedicle is skeletonized and hemostasis achieved, divide and transfer as free flap or rotate/tunnel as pedicled flap. For pedicled TDAP, passing the flap through a split in latissimus fibers (rather than around muscle edge) increases reach. - Perfusion checks: deflate any tourniquet and assess flap color, capillary refill, and Doppler signal; expect transient flush/reperfusion edema after reconnection—distinguish from venous congestion by trend (see Complications). For pedicled transfer, confirm arc of rotation and freedom from pedicle kinking before inset. 4. Donor-site closure techniques. - Primary closure: perform skin pinch test preoperatively; flaps up to reported large widths can often be closed primarily depending on patient laxity and flap orientation; wide undermining and progressive tension sutures facilitate closure under tension. - Drains: closed suction drains are used routinely. Muscle-sparing harvest is associated with reduced seroma formation compared with traditional full LD harvest. - Scar placement: transverse scars can be concealed under brassiere in women; longitudinal scars may be more visible. ## Indications and Contraindications - Indications: - Regional/pedicled coverage: axillary, shoulder, chest wall defects; oncoplastic partial breast reconstruction and autologous augmentation (particularly useful in patients after massive weight loss where tissue volume needed). - Free-flap uses: thin, pliable resurfacing for shallow defects of extremity, head and neck, as well as breast reconstruction when indicated. TDAP allows compound/chimera constructs (include LD muscle, serratus, scapular/parascapular skin, bone/rib) on single thoracodorsal pedicle when multicomponent reconstruction needed. - When sensate reconstruction is desired: posterior rami of lateral intercostal nerves can be included for sensory reinnervation. - Contraindications / relative limitations (as described in source texts): - Obesity: large adipose component may make flap too bulky; thinning/delamination possible but consider alternative thin donor sites for primarily thin resurfacing requirements. - Absent or unsuitable perforator anatomy at planned site: if no suitable perforator is found intraoperatively, alternatives include harvesting a small strip of LD muscle with the paddle, using direct cutaneous branches or selecting a different donor site. - The literature notes decreased contemporary use where more tailored perforator donor sites (ALT, SCIP) may be preferred; selection should be individualized. ## Postoperative Care - Monitoring schedule/method: - Frequent clinical flap checks (color, turgor, capillary refill, temperature) during the first 72 hours postoperatively. Use of Doppler to confirm pedicle flow intra- and postoperatively is common; the source texts report routine clinical monitoring—single-dose antibiotics and low molecular weight heparin are standard prophylaxis. - Local care: - Keep donor and recipient sites drained with suction drains until output declines. Maintain flap protection and avoid compression. For pedicled axillary or palmar coverage, position limb to minimize tension (e.g., wrist splinted in mild flexion for palmar defects; extension for dorsal defects, when relevant). - Mobilization and function: - Because muscle is spared, arm motion is generally unrestricted postoperatively; early passive range-of-motion assessments in OR help ensure flap is not under tension. Begin formal therapy per surgeon/therapist guidance; avoid movements that place tension on inset in the immediate postoperative period. - Return-to-OR thresholds and time windows: - Immediate return to OR for any concern for arterial inflow compromise or evolving venous congestion (hematoma, kinking, pedicle compression). Early re-exploration is advocated; the highest vigilance is in first 72 hours when salvage likelihood is highest. ## Complications (rates & management) - Thrombosis / pedicle spasm / perfusion issues: - Pedicle spasm and traction-related intimal injury are highlighted risks; continuous irrigation and avoidance of traction help mitigate spasm. If arterial thrombosis or absence of flow is suspected (pale flap, absent Doppler, cool skin), urgent re-exploration is indicated. Management on re-exploration includes thrombectomy, revision of anastomosis, checking for kinking/compression, and revision of pedicle orientation. - Venous congestion: - TDAP flaps may show brisk capillary refill after reperfusion (reperfusion flush) that is not necessarily venous failure. Signs of venous insufficiency include progressive bluish hue, swelling, prolonged bleeding from wound edges, drop in flap temperature, and progressively worsening clinical parameters. Early re-exploration is recommended for suspected venous thrombosis. For venous congestion occurring after revascularization and where salvage surgery may be less desirable, leech therapy is described as a viable adjunct for TDAP skin island salvage in the literature. - Donor-site complications: - Seroma: muscle-sparing TDAP harvest reduces seroma formation compared with traditional LD muscle harvest, but closed suction drains are still used. - Scar/contour deformity: transversely oriented donor scars can be concealed but may still lead to contour irregularity; longitudinal scars may be more visible. Lateral breast distortion can occur when large transverse flaps are closed in females. - Fat necrosis / partial flap loss: - Not specifically quantified in the provided texts for TDAP; authors advise careful perforator selection and avoidance of excessive thrombosis/venous congestion to minimize fat necrosis risk. - Management algorithms (synthesized from source guidance): - Immediate concern for compromised flap → remove dressings, perform focused clinical exam and Doppler → if hematoma/kinking/pedicle compression suspected, return to OR urgently for evacuation and pedicle inspection. - If venous thrombosis identified on exploration → revise venous anastomosis; consider second venous outflow if available. If late venous congestion with limited reoperative options → consider medicinal leech therapy as temporizing/salvage measure for the skin paddle. - For arterial thrombosis → urgent re-exploration, thrombectomy, revision of arterial anastomosis. Time to re-exploration: the earlier the better; highest salvage rates reported with interventions within hours (first 72-hour window emphasized). ## Key Clinical Pearls - Surface Doppler is useful but imperfect: perforators may travel variable distances on LD fascia and the descending branch itself may give a false-positive signal — interpret Doppler findings with caution. - The perforator does not need to be centered in the skin paddle: angiosomes in the TDAP territory are large; the dominant perforator may be off-center and still reliably perfuse sizeable paddles. - Expected anatomic landmarks: anticipate the main descending perforator approximately 6 cm inferior to the scapular tip (or ~7–8 cm below axillary crease) and additional perforators roughly every 2–4 cm inferiorly. - Preserve the thoracodorsal motor nerve: it runs on the inferior side of the main pedicle; sparing it avoids donor muscle dysfunction. - Avoid traction and desiccation of the pedicle: continuous warm saline irrigation and gentle handling minimize spasm and intimal injury; avoid excessive traction on the pedicle during dissection and transfer. - If a longer pedicle is required, continue dissection proximally to the subscapular origin; stop at thoracodorsal bifurcation if a short pedicle and vessel caliber are sufficient. - For pedicled reach, pass the skin island through a split in latissimus fibers rather than around the muscle edge to increase arc of rotation. - Donor-site planning: use skin pinch testing preoperatively; transverse scars can be concealed in women under the brassiere, but large flaps may still produce visible contour changes.