**Region:** Groin and Gluteal # Iliac Crest (Deep Circumflex Iliac Artery) Flap ## Anatomy - Pedicle: deep circumflex iliac artery (DCIA) with venae comitantes; accessory superficial circumflex iliac artery (SCIA) may communicate with DCIA. - Arterial diameter at origin: approximately 2–3 mm (reported mean ≈2 mm). (Iliac Crest; Deep Circumflex Iliac Artery Flaps) - Venous anatomy: two venae comitantes join 1–4 cm before draining to external iliac/femoral vein; venous pedicle length reported 4–6 cm with diameter ≈2–4 mm. (Iliac Crest) - Reported pedicle length: various series report pedicle lengths in the 5–10 cm range (examples: ~5 cm reported; other series report 8–10 cm at origin). Use intraoperative dissection to confirm available length. (Deep Circumflex Iliac Artery Flaps; Iliac Crest) - Course: - DCIA typically branches from external iliac artery (or femoral artery) deep to transversalis fascia and runs superolaterally toward the ASIS. - DCIA enters a fibro‑osseous tunnel ~2 cm from the inner lip/top of the iliac crest (along line of attachment of iliacus and transversalis fascia), gives off osseous nutrient and periosteal branches while coursing in this tunnel, and then reemerges ~6–9 cm from ASIS to penetrate transversus abdominis and anastomose with iliolumbar vessels. (Iliac Crest) - Perforator pattern (skin/musculocutaneous/osseous): - Skin perforators present in ~92% of cases. (Iliac Crest) - Most consistent skin perforators: between 5 and 10.5 cm lateral to the ASIS and 0.1–3.5 cm (mean ≈0.8 cm) above the iliac crest. (Iliac Crest) - Typical patterns: - Multiple small cutaneous perforators in ~70% of cases (average ≈6 small perforators). (Iliac Crest) - Single dominant cutaneous perforator in ~30% of cases, typically ≈6.5 cm lateral to ASIS and 1–2 cm superior to crest; this dominant branch can support a skin paddle ≈10 × 15 cm. (Iliac Crest) - Osseous supply: DCIA gives nutrient and periosteal perforators to iliac bone—these are the dominant supply for vascularized bone harvest. (Iliac Crest) - Ascending branch (to internal oblique): usually arises before DCIA enters tunnel; commonly lies within 1 cm of ASIS in ≈65% of cases; 2–4 cm in ≈15%; replaced by multiple small branches in ≈20%. This branch can support an internal oblique muscle component if harvested. (Iliac Crest) - Nerves: - Iliohypogastric nerve (L1): courses between transversus abdominis and internal oblique; encountered superior and medial to pedicle—avoid injury. (Iliac Crest) - Ilioinguinal nerve (L1): runs between internal and external oblique; encountered inferior to pedicle; provides proximal medial thigh and genital skin sensation—avoid or repair if injured. (Iliac Crest) - Lateral femoral cutaneous nerve (LFCN): courses on medial surface of iliacus, pierces deep fascia ≈2 cm inferomedial to ASIS; crosses DCIA as vessel approaches ASIS—identify and preserve when possible (repair if injured). (Iliac Crest) - Included tissues / flap composition: - Bone: iliac crest segment — total crest length ≈23 cm; up to ≈16 cm of bone harvestable on DCIA; maximum harvest height ≈4 cm; height required for mandibular reconstruction ≈2 cm; bone thickness ≈1.4 cm at ASIS to ≈1.7 cm at tubercle. (Iliac Crest) - Skin paddle: typical dimensions reported 15–20 cm length × 6–8 cm width (depends on skin laxity); a single dominant cutaneous branch can support ~10 × 15 cm. (Iliac Crest) - Muscle: internal oblique (partial) can be included via ascending branch; gluteal attachments may be detached when harvesting full‑thickness crest. (Iliac Crest) - Options: full‑thickness osteocutaneous, bone only, split‑cortex (inner table) to reduce donor morbidity; chimeric designs (bone + skin + muscle) possible. (Iliac Crest) - Arc of rotation / common variants: - Primarily used as a free flap (mandible, maxilla, long bone reconstruction). Pedicled applications reported for acetabular or femoral head reconstruction. - Variants: duplicated DCIA; dominant ascending branch supplying bone; ascending branch arising directly from external iliac; split‑cortex bone flap. (Iliac Crest) ## Dissection Steps 1. Positioning, markings, landmarks. - Position: supine; place a roll under contralateral hip (improves exposure of iliac fossa). (Iliac Crest) - Skin paddle orientation: design along an axis so medial border at ASIS; superior two‑thirds of paddle can lie superior to crest, inferior third inferior. Typical paddle size 15–20 × 6–8 cm; pinch test to confirm primary closure width. Mark ASIS, inguinal ligament (line ASIS → pubic tubercle), femoral vessels where they cross that line to locate DCIA origin. Mark most consistent skin perforator ≈5 cm lateral to ASIS. (Iliac Crest) - Incision planning: medial incision approximately 1 cm superior to inguinal ligament to begin pedicle dissection; extend laterally and superiorly along intended superior border of skin paddle. (Iliac Crest) 2. Plane, perforator identification. - Initial dissection: incise skin and subcutis; dissect down to transversalis fascia medially and identify inguinal canal structures (round ligament/spermatic cord) and retract medially. Incise transversalis fascia to expose external iliac vessels. (Iliac Crest) - Pedicle localization: find DCIA and DCIV as they branch from external iliac/femoral vessels; trace pedicle laterally toward ASIS. (Iliac Crest) - Superior/inferior skin dissection: - Suprafascial dissection inferiorly toward iliac crest; divide external oblique fascia where perforators encountered. - Identify perforators and trace their source to confirm DCIA origin. Key distinction: perforators from intercostal/iliolumbar vessels often posteriorly oriented and accompanied by a nerve; DCIA perforators usually anterior and without an associated nerve. (Iliac Crest) - Perforator strategy: - If a dominant perforator ≥1 mm is found, perform a perforator-based dissection to minimize bulk. - If only multiple small perforators or bulk desired, include a 2–3 cm muscle cuff (external oblique/internal oblique/transversus) between skin paddle and crest for ≈6–8 cm to include musculocutaneous perforators. (Iliac Crest) 3. Pedicle dissection: exposure, control, division; transfer/inset; perfusion checks. - Retract preperitoneal fat medially to expose iliacus and pedicle within fibro‑osseous tunnel lateral to fusion of transversalis and iliacus fascia (~2 cm from inner lip). Elevate iliacus inferior to tunnel to expose bone and osteotomy field. (Iliac Crest) - Gluteal release: if full‑thickness bone planned, reflect gluteus maximus/medius/minimus off outer lip to expose inferolateral osteotomy. If inner table split planned, leave outer cortex and drill holes for later anchoring. (Iliac Crest) - Osteotomy: outline bone with cutting bur then complete with oscillating saw; osteotomes useful for inner table split. Harvest up to ≈16 cm length × ≈4 cm height. If including ASIS, divide sartorius/inguinal ligament (repair at closure). (Iliac Crest) - Pedicle proximal dissection: trace pedicle proximally to its origin; leave harvested bone on pedicle for 15–20 minutes intraoperatively to relieve spasm before definitive division and inset. (Deep Circumflex Iliac Artery Flaps; Iliac Crest) - Division and transfer: divide pedicle and transfer free flap to recipient site. Shape bone on back table (use bone bur) and inset; for mandibular reconstruction, ipsilateral crest often flipped vertically so ASIS forms angle and crest rim forms mandibular body. (Iliac Crest) - Perfusion checks: confirm arterial pulsation and venous outflow; irrigate perforators and handle under magnification; when perforator-to-perforator anastomosis considered, maintain good hydration to minimize spasm. (Iliac Crest; SCIP literature) 4. Donor-site closure techniques. - Hemostasis and bone bleeding control with bone wax. - Repair iliacus/transversalis fascia; suture iliacus fascia to transversalis. Flex hip to relax tissues and suture external/internal oblique to gluteal musculature. If outer cortex left intact (split), drill holes for fascial anchoring. (Iliac Crest) - Consider prosthetic or bioprosthetic overlay mesh to reinforce repair and prevent hernia when fascial defect significant. (Iliac Crest) - Place closed suction drains; close in layers. If donor site closure tight, flex hip postoperatively (short period) to reduce tension. (Iliac Crest) ## Indications and Contraindications - Indications: - Hemimandibular reconstruction (primary indication). (Iliac Crest) - Maxillary reconstruction. (Iliac Crest) - Short segment long‑bone reconstruction (e.g., tibia) or arthrodesis where curved bone advantageous. (Deep Circumflex Iliac Artery Flaps; Iliac Crest) - Pedicled use (rare): acetabular defects, femoral head reconstruction. (Iliac Crest) - When vascularized bone with associated soft tissue (skin, muscle) and option for chimeric design is needed. (Iliac Crest) - Size/shape limits: - Bone: up to ≈16 cm length; cannot provide a straight bone segment longer than ≈10 cm without curvature limitations. Height up to ≈4 cm available; 2 cm sufficient for mandibular height reconstruction. (Iliac Crest) - Skin paddle: typically up to 15–20 cm × 6–8 cm (donor skin laxity and closure limits determine size). (Iliac Crest) - Need for thin vs bulky soft tissue: - Skin paddle in obese patients can be bulky — perform true perforator dissection (preserve only skin/subcutis) to thin flap; consider a staged secondary thin flap (e.g., radial forearm) if very thin tissue required. (Iliac Crest) - Contraindications / relative limitations: - Obesity: deep, bulky skin paddle and difficult dissection. (Iliac Crest) - Prior surgery/radiation in iliac/inguinal region may compromise pedicle or perforators — assess with imaging and intraoperative exploration. (Iliac Crest / SCIP discussions) - Significant donor‑site morbidity risk if both cortices harvested — consider split‑cortex technique to minimize hernia/gait issues. (Iliac Crest) ## Postoperative Care - Monitoring: - Standard free‑flap monitoring (clinical checks for color, turgor, capillary refill, Doppler) as per institutional protocol. For perforator anastomoses, ensure adequate hydration to minimize spasm. (SCIP; Iliac Crest) - Closed suction drains at donor site; remove when output acceptable. (Iliac Crest) - Analgesia / positioning: - Hip flexion for initial period may reduce tension on donor closure when used intraoperatively; mobilize progressively as per surgeon preference and when closure is secure. (Iliac Crest) - Antithrombotic practice: - Follow standard microsurgical thromboprophylaxis protocols used locally (not specified in source texts). Maintain normovolemia and avoid vasospasm. (SCIP and DCIA technique notes) - Wound care / drains: - Maintain closed suction drains at donor site to minimize seroma; consider incisional negative‑pressure therapy over donor site to reduce seroma/hematoma in selected cases. (SCIP chapter) - Mobilization: - Early but protected mobilization; weight‑bearing restrictions depend on bone harvest and reconstruction site. - Return‑to‑OR thresholds and time windows: - Any sign of vascular compromise (progressive pallor, loss of Doppler signal, increasing flap firmness/venous congestion) warrants immediate re‑exploration—standard microsurgical principle (sources emphasize importance of intraoperative checks; specific time windows not provided). (Iliac Crest; SCIP) ## Complications (rates & management) - Flap complications: - Arterial/venous thrombosis, partial or total flap loss — specific incidence not provided in the DCIA chapters; manage with urgent re‑exploration, thrombectomy, revision of anastomosis, possible thrombolysis per institutional protocols. (General operative practice combined with SCIP/DCIA texts) - Venous insufficiency: if small venae comitantes, include superficial vein or additional superficial vein for reliable outflow (technique emphasized). (SCIP; Groin/SCIP chapters) - Flap bulk/fat necrosis: skin paddle can be bulky in obese patients → consider perforator dissection or secondary thinning. (Iliac Crest) - Donor‑site complications: - Hernia/abdominal wall weakness: significant risk when full‑thickness crest harvested—recommend fascial repair and reinforcement with overlay mesh when indicated. (Iliac Crest) - Seroma, lymphorrhea, wound dehiscence—particularly when lymphatics are transected or full subcutaneous tissue included; closed suction drains and careful ligation reduce risk. (Groin/SCIP; Iliac Crest) - Aesthetic deformity and gait disturbance after full‑thickness harvest. (Iliac Crest) - Reported frequencies (as provided in the sources): - Skin perforators present in ≈92% of cases for DCIA iliac crest flap. (Iliac Crest) - Multiple small cutaneous perforators in ≈70% (avg ≈6); single dominant cutaneous branch ≈30% of cases. (Iliac Crest) - SCIP (related SCIA system) anatomy: superficial branch present in >90% of cases and superficial branch‑based SCIP can be elevated in most patients; SCIP pedicle mean length reported ≈4.8 ± 1.3 cm (range 3–8 cm), microdissection can yield ≈7 cm. (SCIP chapter; Groin/SCIP) - Management algorithms (practical points from sources): - If small concomitant veins are present, include superficial vein or additional superficial cutaneous vein with flap for reliable venous drainage (SCIP/ groin texts). - If pedicle length insufficient for recipient site, consider: - Dissection to more proximal origin where anatomy allows (DCIA can sometimes be dissected to provide additional length). - Use of vein grafts if necessary (noted in SCIP literature for short pedicle scenarios). - For SCIP, pedicle elongation via reverse‑flow arterial perfusion (dissecting distal deep branch and using it as anastomosis site) can extend arterial length (reported up to ≈10 cm in selected cases). (SCIP chapter) - Donor hernia prevention: repair transversalis fascia to iliacus, drill holes in preserved outer cortex for fascial anchoring, and reinforce with prosthetic/bioprosthetic mesh when needed. (Iliac Crest) ## Key Clinical Pearls - Identify and mark ASIS, inguinal ligament, and femoral vessels preoperatively; the most consistent skin perforator for the DCIA skin paddle lies ≈5 cm lateral to ASIS—use Doppler/CTA to map perforators. (Iliac Crest) - Harvestable bone limits: plan bone segment ≤≈16 cm length and ≤≈4 cm height; remember crest curvature — straight segments longer than ≈10 cm are not available without contouring. (Iliac Crest) - Preserve lateral femoral cutaneous nerve when possible; it crosses the DCIA near ASIS and pierces fascia ≈2 cm inferomedial to ASIS—if divided, repair to reduce neuropathic morbidity. (Iliac Crest) - When thin soft tissue is required, perform perforator dissection (trace cutaneous perforator(s) from DCIA and preserve only skin/subcutis) instead of including full cuff of abdominal muscle. (Iliac Crest) - Control bone bleeding with bone wax before closure; leave harvested bone on pedicle for ~15–20 minutes intraoperatively to reduce vasospasm before division. (Iliac Crest; Deep Circumflex Iliac Artery Flaps) - Donor closure reinforcement: suture iliacus/transversalis fascia, reapproximate abdominal wall to gluteal muscles, and consider mesh overlay when full‑thickness harvest creates a large fascial defect to prevent hernia. (Iliac Crest) - If skin perforators appear to arise from other sources (intercostal/iliolumbar), recognize posterior orientation and associated nerve—trace to ensure inclusion of DCIA perforators for cutaneous flap viability. (Iliac Crest) - When venous drainage seems marginal, include the superficial circumflex/ superficial cutaneous vein in the flap—concomitant veins may be too small alone; plan for multiple venous outflows if needed. (Groin/SCIP; Iliac Crest)