**Region:** Lower Extremity # Transverse Upper Gracilis (TUG) Flap ## Anatomy - Pedicle: dominant pedicle from the medial circumflex femoral artery (branch sometimes directly from profunda femoris). Pedicle enters the gracilis deep surface approximately 10 cm (≈10 ± 2 cm) inferior to the pubic tubercle (proximal third) (38; 39; 19). Typical arterial diameter reported 1–2 mm (39); other anatomic series report mean arterial diameter ~1.5 mm and venous diameter ~2.0 mm (range reported in sources) and a pedicle length obtainable of roughly 6–8 cm (19; 38; 39). The artery is accompanied by paired venae comitantes. Minor distal pedicles arise from superficial femoral (and occasionally popliteal) branches and are divided during harvest (19; 38). - Course: main pedicle travels deep to adductor longus in a loose areolar plane to enter proximal gracilis. Prior to entering the muscle the main pedicle divides into multiple branches that supply muscle and skin; musculocutaneous perforators predominate in the proximal two‑thirds and are concentrated in the proximal third (19; 39). Septocutaneous perforators can arise in the septum between adductor longus and gracilis, including from the first minor pedicle distal to the main pedicle (19). - Perforator pattern: musculocutaneous perforators more numerous and smaller, located more proximally; septocutaneous perforators less numerous and may be contributed by the minor distal pedicle. Perforators tend to orient transversely over the upper gracilis territory — the physiologic rationale for a transverse skin paddle (19; 39). Cutaneous perfusion links (linking vessels/choke vessels) exist between adjacent perforasomes; vascular territory extends more posteriorly than anteriorly over the thigh (39). - Venae/venous drainage: paired venae comitantes accompany the artery. Preservation of anterior branch of great saphenous territory is recommended during anterior dissection (38; 39). - Nerves: motor innervation via anterior branch of the obturator nerve entering the muscle belly; the nerve typically enters 1–2 cm proximal to the main pedicle (38; 19). Cutaneous sensory fibers to the medial thigh derive from obturator cutaneous branches; when used as sensate transfer the nerve relationship matters (19; 39). - Included tissues: skin, subcutaneous fat, superficial fascia (Scarpa’s), and variable portion of gracilis muscle. TUG is a myocutaneous flap (most common) using a transverse upper skin paddle centered over the upper third of the muscle; can be harvested as muscle‑only or as a perforator variant sparing muscle (19; 38; 39). Thickness profile: typically thin-to-moderate medial thigh soft tissue; posterior extension provides greater fat/volume (38; 39). - Arc of rotation / reach: pedicle length of ~6–8 cm (commonly obtainable) allows free transfer (microvascular). Pedicled use for perineal reconstruction may be tunneled; flap reach limited by pedicle and donor closure requirements (38; 41). - Common variants/anomalies: double main pedicle occasionally described; main pedicle may arise directly from profunda femoris in ~10% of cases; distal minor pedicles arise from superficial femoral or popliteal vessels (19; 39). ## Dissection Steps 1. Positioning, markings, landmarks. - Position: lithotomy for perineal/pelvic reconstructions or supine with “frog‑leg” for most free TUG harvests (hip externally rotated, knee flexed). Preoperative markings performed with patient standing when feasible (pinch test with standing) (38; 39; 19). - Landmarks and skin paddle: mark line from ischium/pubis to medial tibial condyle to approximate gracilis course in obese patients; posterior border of adductor longus then a line 2–3 fingerbreadths posterior approximates gracilis axis (38; 19). For TUG: transverse ellipse/crescent centered over upper third of gracilis; superior incision generally 1–2 cm below inguinal crease/gluteal fold; anterior border medial to femoral neurovascular bundle; posterior border near posterior midline of inferior buttock fold or gluteal crease (38; 39). - Pinch test: use to determine maximal width closed primarily; usual practical width for direct closure ~9–11 cm depending on source and patient habitus (39; 38). Avoid anterior extension across the inguinal crease to reduce lymphatic disruption and risk of lower‑extremity lymphedema (39). - Mark perforator/Doppler: a handheld Doppler is useful to localize perforators and main pedicle ≈10 cm distal to pubic tubercle (39; 19). 2. Plane (suprafascial/subfascial), perforator identification (handheld/IO Doppler). - Incision and initial elevation: make superior incision and elevate skin/subcutis initially in a suprafascial plane just deep to Scarpa’s fascia anteriorly; include deep fascia over adductor longus where indicated to preserve fascial perforators (38; 39; 19). - Anterior dissection: preserve anterior branch of great saphenous vein if possible; plane deepens medial to saphenous vein to include deep fascia over adductor longus to identify loose areolar plane between adductor longus and gracilis (38; 19). - Perforator identification: use Doppler to identify perforators and center paddle; perforators are concentrated proximally (proximal third) and tend to run transversely; include perigracilis fascia and fat when using a vertical paddle to maximize perforator capture (19; 38). - Posterior dissection: carry flap elevation posteriorly until posterior border of gracilis identified; the majority of flap fat contribution often comes from tissue posterior to gracilis muscle belly (38). 3. Pedicle dissection: exposure, control, division; transfer/inset; perfusion checks. - Locate pedicle: identify pedicle in loose areolar plane deep to adductor longus about 8–12 cm (commonly ~10 cm) inferior to pubic tubercle; the obturator motor nerve typically enters ~1–2 cm proximal to vessels (19; 38). - Skeletonization: once pedicle located, follow/blunt dissect proximally toward profunda femoris/medial circumflex origin to obtain required length (6–8 cm typical) (19; 39). Preserve surrounding structures as needed. - Muscle division and harvest: divide gracilis tendon distally (or divide muscle belly if muscle‑only transfer) and elevate muscle/skin paddle from distal to proximal in most described techniques; for TUG some authors prefer raising from superior to inferior to determine vertical height and preserve pinch closure margins (39; 38). - Hemostasis and check perfusion: inspect bleeding at muscle/skin edges; ensure healthy arterial bleeding before division when planning free transfer (19). If using free flap, place clips at chosen level of pedicle on recipient side and divide pedicle distal to clips; avoid unnecessary trauma to pedicle (19). - Nerve handling: anterior branch of obturator nerve is usually divided unless a functional (innervated) transfer is planned; the motor nerve entry is close to pedicle and should be identified for functional transfers (19). - Transfer/inset: transfer as free flap for breast/head‑and‑neck or pedicled/tunneled for perineal reconstructions. For pedicled perineal use, the proximal muscle may be left intact to prevent twisting; for free use, proximal origin may be divided once recipient prepared (38). - Perfusion checks: clinical assessment of skin paddle and muscle bleeding; for TUG, deepithelialize proximal skin if not needed and tuck under native skin bridge to preserve vascular connections (38). 4. Donor-site closure techniques. - Layered closure over closed‑suction drain is standard (Scarpa’s/fascial layer, deep dermal, subcuticular) (38; 39; 19). - Limit undermining to preserve lymphatics; secure superficial/deep fascia of lower wound edge to Colles’ fascia/superior fascia to reduce scar migration and labial traction (39). - If primary closure not feasible, consider skin grafting; plan flap width with pinch test to avoid grafting when possible (39). ## Indications and Contraindications - Indications: - Primary: small‑to‑medium autologous breast reconstruction when abdominal donor sites are unavailable or undesired (TUG) (39; 19). - Other uses: head and neck, upper and lower extremity soft‑tissue reconstruction, pelvic/genitoperineal defects (pedicled or free), functional muscle transfer (facial reanimation) (38; 39; 19; 41). - Pedicled gracilis (myocutaneous) remains useful for perineal/vaginal reconstruction and to obliterate pelvic dead space (38). - Size limits / volume: - TUG is limited by small harvest volume; can be coned or combined/stacked (bilateral stacked or combined with other flaps) to increase projection/volume (39; 19). - Skin paddle practical width for primary closure ~9–11 cm (subject to patient habitus); skin paddle dimensions reported up to 11 × 25 cm (38) or in other descriptions up to 30 × 10 cm for extended designs but are limited by donor closure considerations (19; 39). - Sensate needs: - Sensate reconstruction possible by preserving cutaneous nerves or including nerve coaptation when indicated; motor nerve can be preserved for functional transfer (19). - Contraindications (relative/absolute from textual sources): - Prior surgery that transected the pedicle or surrounding perforators (prior medial thigh/gluteal flaps) may preclude reliable harvest (41; 34). - Insufficient donor tissue when larger volume is required; poor skin laxity preventing safe donor closure. - Patient factors increasing wound healing risk (smoking, uncontrolled diabetes) should be optimized — cited as general preop considerations (41; 38). ## Postoperative Care - Monitoring and drains: - Donor site closed over a closed‑suction drain; drains commonly left beneath flap closure for donor and recipient sites (38; 39; 41). - Preoperative Doppler mapping recommended; postoperative monitoring specifics (frequency, implantable probes) are not detailed in the provided texts — rely on clinical inspection of color, capillary refill and drain output per institutional practice (39; 38). - Warming / positioning / mobilization: - Positioning considerations: lithotomy or frog‑leg positions used intraoperatively; postoperative positioning depends on defect and donor site — for posterior thigh/gluteal thigh donors wheelchair mapping and pressure redistribution are emphasized prior to resumption of sitting for patients with spinal cord injury (41). - Avoid direct pressure over perineal/pedicled flaps until healing adequate; specific timelines not provided in texts. - Antithrombotic practice / analgesia / diet: - Specific antithrombotic regimens, analgesic protocols, or diet recommendations are not detailed within the supplied chapters and should follow institutional protocols. - Return-to-OR thresholds/windows: - Not specified in source material. Institutional microvascular thresholds (e.g., persistent loss of flow, progressive venous congestion, or arterial insufficiency) guide return to OR; source texts emphasize prompt recognition and management though specific time windows are not provided (general surgical principle). ## Complications (rates & management) - Flap vascular complications: - Distal skin paddle necrosis: distal portions of longitudinal paddles and distal one‑third of thigh territory are less reliable — limit skin paddle length to proximal two‑thirds and favor transverse upper design to reduce distal necrosis (19; 38; 39). - Venous congestion/arterial insufficiency: management algorithms (re‑exploration, leeching, thrombolysis) are not specifically described in these chapters; prevention includes preserving venous drainage (e.g., leaving skin bridge or anterior venous connections) and avoiding pedicle kinking/twisting (39; 41). - Partial/total flap loss: specific rates are not provided in the supplied chapters. - Fat necrosis / infection: not quantified within the supplied texts; standard management principles apply (debridement, antibiotics) but are not specifically outlined. - Donor-site issues: - Seroma/hematoma: drains recommended to reduce seroma risk; meticulous hemostasis and layered closure emphasized (38; 39; 19). - Contour deformity, scar contracture, labial spreading: TUG donor can cause scar contracture and labial spreading; securing superficial fascia to Colles’ fascia and limiting width/undermining help minimize traction and migration (39; 38). - Lymphedema: avoid incision across inguinal crease to limit lymphatic disruption (39). - Functional deficits: gracilis harvest has low functional morbidity but weakness of thigh adduction possible; when used for facial reanimation consider marking length–tension relationships and possibly taking hemigracilis to reduce donor impact (19). - Management algorithms (what, when, how) — guidance present in sources: - Prevention: center skin paddle over muscle, preserve proximal perforators, limit longitudinal paddle length, preserve venous pathways (anterior saphenous branches) and avoid incision across inguinal crease (19; 38; 39). - If distal skin tip shows ischemia intraoperatively: consider debridement or deepithelialization and burying under native skin bridge (38). - For pedicled transfers, preserve a dermocutaneous/dermal base or skin bridge proximally to enhance venous outflow if concern for congestion (41). ## Key Clinical Pearls - Preoperative marking should be done with the patient standing and include a pinch test to ensure primary donor closure; center the transverse skin paddle over the upper third of gracilis for maximal perforator capture (38; 39; 19). - Pedicle location: expect the dominant pedicle ~10 cm inferior to the pubic tubercle and the obturator motor nerve to enter ~1–2 cm proximal to the vessels — identify both during dissection (19; 38). - Limit skin paddle length: place skin island within proximal two‑thirds of gracilis or use transverse upper design to avoid distal tip necrosis (19; 38; 39). - Preserve anterior great saphenous venous territory anteriorly and consider leaving a proximal skin/dermal bridge or sparing venous connections to reduce risk of venous congestion (38; 39; 41). - Include deep fascia over adductor longus during anterior dissection to preserve fascial perforators and to expose pedicle in the intermuscular plane (39; 19). - For donor closure minimize undermining to protect lymphatics and secure lower wound fascia to Colles’ fascia/superficial fascia to prevent scar migration and labial traction (39). - If skin paddle bulk is inadequate for breast projection, coning of flap or combining/stacking bilateral TUGs or posterior extension designs may increase volume (39). - When planning functional transfers, mark gracilis under tension in situ at defined intervals (e.g., per authors’ practice at 5‑cm intervals) to preserve length–tension relationships at recipient site (19).