**Region:** Chest and Shoulders # Latissimus Dorsi Flap ## Anatomy - Pedicle: thoracodorsal artery with single venae comitantes. Mean arterial caliber 2–4 mm (≈3 mm); mean venous caliber 2–5 mm (≈3.5 mm). Typical pedicle length 6.5–12 cm (mean ≈8.5 cm); when dissected to the subscapular artery pedicle length may reach ≈15 cm. Thoracodorsal artery typically divides into transverse (horizontal) and descending (vertical) branches 1–2 cm before entering the muscle (reported bifurcation ~1.3 cm proximal to muscle). The descending branch runs ~2 cm parallel to the lateral border; the transverse branch runs ~3.5 cm parallel to the superior border. Collateral supply: posterior intercostal and lumbar perforators (segmental minor pedicles); 4–6 posterior intercostal/lumbar perforators contribute to secondary perfusion. Venous drainage has two preferential zones: (1) inferior/medial via intercostal/lumbar systems; (2) superior via thoracodorsal/circumflex scapular system — explainable clinically by venous congestion patterns with muscle-only harvest. - Course: thoracodorsal is terminal branch of subscapular system (subscapular → thoracodorsal ± circumflex scapular). Vessel enters muscle on deep surface ≈4 cm distal to inferior scapular border and ≈2.5 cm lateral to medial border; distance from subscapular origin to muscle entry ≈8.7 cm (average). - Perforator pattern: myocutaneous perforators arise from thoracodorsal branches and run parallel to muscle fibers into overlying skin. Perforator concentration: anterior aspect of muscle — within ~5 cm of the anterior border at a level 8–13 cm caudal to the posterior axillary crease. Cutaneous perforators from thoracodorsal may be septocutaneous on occasion (TDAP), and more proximal perforators are generally larger. Myocutaneous perforators are denser in proximal two-thirds of muscle. - Choke vessels/angiosomes: segmental intercostal/lumbar perforators provide medial/transverse vascular territory (basis for reverse/transverse/medially based flaps and extended flaps). Significant collateral circulation exists between thoracodorsal branches and posterior intercostal/lumbar perforators. - Nerves: motor — thoracodorsal nerve (C5–7), runs inferolateral to pedicle and divides into branches ~1–2 cm before entering muscle; sensory to overlying skin is segmental via lateral cutaneous branches of intercostals (T4–T12 ventral rami and T7–T12 dorsal branches); for TDAP/myocutaneous flap preservation of T7–T8 lateral cutaneous branches preserves sensation if required. Thoracodorsal nerve is commonly divided when animation is undesirable (e.g., breast reconstruction) or preserved when performing functional transfers. - Included tissues: muscle (large, fan-shaped; dimensions reported ~38 cm × 20 cm × 0.8 cm), optional skin paddle, subcutaneous fat, Scarpa’s/deep subcutaneous fascia. Skin paddle width typically limited to 8–10 cm (to permit primary closure); traditional length descriptions up to 20 cm but larger myocutaneous designs up to 12 × 25 cm have been described. Extended designs may include additional subcutaneous/submuscular fat. Composite options: include serratus slips, rib (usually 5th or 6th), scapular tip (angular branch), parascapular/scapular skin, osteomyocutaneous ribs (max bone ≈12 cm in rib flap), chimeric harvests on subscapular axis. - Arc of rotation / reach: pedicled arc allows chest, axilla, shoulder, upper thorax coverage; muscle-sparing descending-branch island has arc ≈25–30 cm. Common variants/anomalies: thoracodorsal arising directly from axillary or lateral thoracic artery (~3%); absence of medial thoracodorsal branch in ~14% cadaveric series; variable branching to serratus and circumflex scapular. ## Dissection Steps 1. Positioning, markings, landmarks. - Position: lateral decubitus (target side up) is standard for harvest; prone or “sloppy lateral” alternatives for specific reconstructions. For combined breast work sequence may be supine → lateral harvest → supine inset. Arm: ipsilateral shoulder abducted ~90° and elbow flexed (Carter‑Braine arm support) to expose axilla; avoid abduction >90° that risks brachial plexus stretch. - Mark: standing preop with brassiere to map muscle borders: anterior border (posterior axillary line), superior to scapular tip, medial along paraspinal origins; mark posterior midline, iliac crest, and tip of scapula. Mark skin island ellipse over muscle with planned orientation (breast: inferolateral; head/neck: oblique anterior edge). Identify “danger zone”: within ~7 cm posterior to anterior border — descending branch location. - Perforator mapping: handheld Doppler useful for TDAP/perforator planning; CT/MR angiography optional for detailed mapping; expect perforators concentrated anteriorly 8–13 cm caudal to posterior axillary crease and within ~5 cm of anterior border. 2. Plane (suprafascial/subfascial), perforator identification (handheld/IO Doppler). - Incision beveled outward to capture deep subcutaneous fat and more perforators; initial dissection in subsuperficial fascial plane (just below Scarpa’s/deep subcutaneous fascia) when including deep subcutaneous fat with skin paddle (especially for breast contour). - For muscle-only harvest, dissect superficial fascia and identify muscle fascia plane; elevating muscle from anterior border over serratus facilitates plane. - For TDAP or muscle-sparing variants, raise skin flaps and identify perforator(s) at the anterior muscle aspect or 2–3 cm posterior to lateral border; use handheld or sterile Doppler/intraop transillumination to identify descending branch and perforators. 3. Pedicle dissection: exposure, control, division; transfer/inset; perfusion checks. - Elevation: free anterior edge of LD, separate from serratus anterior, then elevate inferomedially off thoracolumbar fascia and iliac crest origins; ligate posterior intercostal/lumbar perforators encountered. - Pedicle exposure: identify thoracodorsal neurovascular bundle on deep undersurface near axilla (≈2–3 cm medial to lateral border). Trace descending branch proximally to thoracodorsal and, if needed, further to circumflex scapular/subscapular origins to gain length. Ligate serratus branch if additional length required; ligate angular branch if not using scapular tip; preserve circumflex scapular when future scapular/parascapular options are desired. - Motor nerve: thoracodorsal nerve runs alongside vessels; transect nerve when denervation/avoidance of animation desired; preserve nerve when functional transfer planned. - Partial tendon release or full disinsertion at humeral insertion may be performed to increase reach; partial release often adequate and protects pedicle from traction. - Transfer/inset: create wide axillary tunnel (high in axilla) when pedicled transfer; pass flap gently (Ellis forceps from chest into back) ensuring no twist/kink on pedicle; avoid compression at tunnel; for free transfer, prepare recipient vessels and anastomose — pedicle caliber (2–4 mm artery, 2.5–5 mm vein) facilitates microvascular anastomosis. - Perfusion checks: clinical inspection (color, turgor, capillary refill), handheld Doppler flow in skin paddle/perforator; in flap variants, transillumination and palpation of pulsations may help to confirm arterial inflow; intraoperative bleed and distal capillary refill assessment used. 4. Donor-site closure techniques. - Meticulous hemostasis and dead-space obliteration (quilting/progressive tension sutures) recommended to reduce seroma. Place closed suction drains; typical practice to leave drains until output <20 mL/day for three consecutive days (reported protocol). Multilayer closure: reapproximate superficial fascia, subcutis, and skin. Primary closure usually achievable for skin width ≤8–10 cm; wider paddles may require skin grafting. Preserve a fat pad around scapular tip as gliding surface to avoid scapular stiffness. ## Indications and Contraindications - Indications: - Pedicled: breast reconstruction (immediate/delayed, with/without implant, including radiated chest), chest wall/axillary/shoulder/upper trunk coverage, Poland’s syndrome contouring, salvage after partial autologous flap loss, caudal head/neck defects; intrathoracic coverage with pedicled slips (e.g., bronchopleural or airway defects). - Free: large scalp or head–neck defects, extremity coverage with bulk or dead-space fill (e.g., distal third leg, prosthetic joint exposure), free functional muscle transfer (reanimation), composite reconstructions when rib/scapular bone included. - Muscle-sparing (descending branch) variant: implant-based breast reconstruction where preservation of most LD function and reduced donor morbidity desired. - Composite options: TDAP, muscle-sparing LD, chimeric flaps including serratus, parascapular/scapular skin, rib or scapular tip for osteocutaneous needs. - Size/volume considerations: muscle dimensions allow large flat coverage; skin paddle width typically kept ≤8–10 cm for primary closure; muscle-only provides bulk ~250 mL (muscle-sparing provides less; supplementary implant often required in breast reconstruction — common implant volumes reported in one series ~340 mL average). - Contraindications (relative/absolute as implied in sources): - Compromised thoracodorsal pedicle (prior axillary dissection/radiation) — confirm patency before committing to LD harvest. - Prior surgeries that damaged subscapular/thoracodorsal axis or used serratus branch as recipient may limit options — consider retrograde perfusion via serratus branch in specific prior-axillary-dissection scenarios. - Extensive peripheral vascular disease not a contraindication for serratus/LD composite use but may direct choice of donor site for osteocutaneous flaps. ## Postoperative Care - Monitoring schedule/method: - Clinical monitoring (hourly in early postop for free flaps): color, turgor, capillary refill of skin paddle; handheld Doppler to confirm arterial/venous signals. (Use of implantable probes not detailed in provided texts.) - Warming/positioning: - Keep patient warm and well hydrated; avoid compression/tension at pedicle. For pedicled breast reconstructions avoid compression in axillary tunnel. - Antithrombotic practice: - Specific protocols not detailed in provided sources; standard perioperative DVT prophylaxis and microvascular anticoagulation considerations should follow institutional protocols (not specified in source material). - Drains: - Closed suction drains at donor site; leave until output <20 mL/day for 3 consecutive days (reported practice). Single Blake drain commonly used for muscle-sparing donor site. - Mobilization/splinting: - Ambulation immediately permitted in many series; avoid heavy lifting for ~3 weeks after harvest. Maintain shoulder precautions per institutional guidance. - Analgesia/diet: - Local infiltration/long-acting local anesthetic used for harvest plane; standard multimodal analgesia otherwise (specific regimens not mandated in sources). - Return-to-OR thresholds and time windows: - Immediate return to OR indicated for clinical signs of vascular compromise (loss of Doppler signal, pallor, rapidly worsening congestion or ischemia) or expanding hematoma. (No rigid time window specified in source texts; urgency emphasized.) ## Complications (rates & management) - Flap-specific complications: - Venous congestion / arterial thrombosis / flap loss: specific numeric rates not uniformly reported in provided texts. Management: urgent re-exploration for suspected vascular compromise (loss of doppler signal, acute color/turgor changes). For pedicled flaps consider relieving compressive tunnel or pedicle kinks; for free flaps proceed to microvascular revision/anastomosis revision per microsurgical principles (detailed protocols not provided in sources). - Partial skin-paddle necrosis / fat necrosis: not quantified in source materials; manage by local debridement and secondary procedures as required. - Infection: treat with antibiotics and local wound care; debridement if deep infection. - Donor-site issues: - Seroma: most commonly cited donor-site morbidity; frequencies described variably but noted as a common complication. Prevention: minimize dead space, quilting/progressive-tension sutures, closed suction drains. Management: percutaneous aspiration and compression garments; refractory seromas — operative excision of seroma capsule and primary closure (source-supported). - Hematoma: monitor and evacuate if expanding or threatening flap/skin viability. - Contour deformity / bulk: expected; fat grafting or implant adjustments described as staged refinements. - Shoulder function/weakness: typically little functional deficit reported after LD sacrifice; muscle-sparing variants aim to preserve function. - Management algorithms (what, when, how) drawn from provided texts: - Seroma: aspirate as first-line; if refractory → OR for capsule excision and definitive closure. - Pedicle length issues: ligate serratus branch to gain pedicle length; if additional length needed dissect proximally to subscapular artery (gain up to ~15 cm). - Scapular vascular preservation: preserve circumflex scapular artery when future scapular/parascapular harvest may be required. - Re-exploration for vascular compromise: urgent operative exploration for loss of perfusion signs; texts emphasize immediate action but do not provide fixed time windows. ## Key Clinical Pearls - Always confirm thoracodorsal pedicle integrity before committing to LD harvest in patients with prior axillary surgery or radiation; explore axilla via existing incision or anterior approach if necessary. - Skin island planning: keep width ≤8–10 cm for reliable primary closure; length commonly limited to ~20 cm in standard myocutaneous design; place the skin paddle anterior enough to capture the majority of thoracodorsal perforators (anterior third of muscle). - Danger zone: the descending branch resides within ~7 cm of the anterior border — be cautious during anterior dissection and use this as the landmark when planning muscle-sparing/TDAP harvest. - Pedicle handling: trace descending branch proximally to thoracodorsal; ligation of serratus branch yields extra arc length but be mindful of potential retrograde perfusion if serratus has been used previously. - Donor‑site seroma prevention: use quilting/progressive-tension sutures and closed suction drains; leave drains until output <20 mL/day for consecutive days to minimize seroma risk. - Muscle-sparing option: include only the strip of muscle around the descending branch (4–6 cm) to preserve the remainder of LD and reduce donor morbidity while providing ≈25–30 cm arc for implant-based breast reconstruction. - For free transfer: thoracodorsal pedicle vessel diameter (artery 2–4 mm; vein 2.5–5 mm) facilitates microvascular anastomosis — consider dissecting to subscapular origin when additional length/caliber required. - Tunnel wide and high in axilla for pedicled transfer; ensure no kinking/twisting and test rotation/inset before final release.