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ReconstructionMicrosurgicalOPCS S41

Free flap principles

Free tissue transfer · microvascular flap · perforator flap

A free flap is composite tissue (skin ± fascia ± muscle ± bone) elevated with its named vascular pedicle, then transferred to a distant defect with microsurgical anastomosis to recipient vessels. Free flaps are the workhorses of advanced head & neck, breast, lower limb and complex skin-cancer reconstruction. UK BAPRAS and ENT-UK service specifications underpin training and centralisation; commonly-used flaps include ALT, radial forearm, DIEP, fibula, latissimus dorsi and SCIP.

CurrentLast reviewed 16 May 2026

Principles

  • Composite tissue elevated with its named vascular pedicle.
  • Pedicle disconnected, transferred, anastomosed to recipient artery and vein using microsurgical technique under the operating microscope.
  • Couplers (anastomotic devices) facilitate venous anastomosis.
  • Free flaps allow:
    • Like-for-like tissue replacement.
    • Reconstruction of large / complex / radiated defects.
    • Composite reconstruction (skin + bone, skin + muscle).
    • Reach beyond pedicle radius of regional / pedicled flaps.

Commonly used free flaps

  • Anterolateral thigh (ALT): perforator flap on descending branch of LCFA; pliable, large, can be musculocutaneous / fasciocutaneous; head & neck and limb defects.
  • Radial forearm: thin, pliable; intraoral, oropharyngeal, head & neck; donor morbidity (cosmetic, radial artery loss).
  • Deep inferior epigastric perforator (DIEP): workhorse breast reconstruction; based on DIEP perforators.
  • Fibula osteocutaneous: mandibular / maxillary reconstruction; bone + skin.
  • Latissimus dorsi: large muscle flap; head & neck / breast / lower limb / chest wall.
  • Superficial circumflex iliac perforator (SCIP): thin perforator flap; head & neck.
  • Gracilis: small muscle; facial reanimation, lower limb.
  • Scapular / parascapular: composite scapular bone + skin.
  • Profunda artery perforator (PAP): alternative to DIEP for breast.
  • Toe transfer: thumb / finger reconstruction.

Planning

  1. Defect assessment: site, volume, composite tissue need, function, aesthetic outcome.
  2. Recipient vessels: imaging (CT angiogram, MR angiogram, Doppler USS) to confirm patency and calibre.
  3. Donor vessels: pre-operative imaging for perforator mapping (CT angiogram, Acuson, Doppler).
  4. Patient assessment: comorbidities (DM, smoking, vascular disease, anticoagulation, prior RT).
  5. Anaesthetic plan: long-duration general anaesthesia; arterial line; warming; thromboprophylaxis.
  6. Postoperative ICU / monitored bed.
  7. Donor site closure plan: STSG, primary closure, secondary intention.

Postoperative monitoring

  • Critical window: first 48-72 hours for thrombosis / failure.
  • Clinical assessment:
    • Colour: pink (good); pale (arterial); blue / mottled (venous congestion).
    • Capillary refill: brisk <3 seconds is normal.
    • Temperature: warm = good; cool = ischaemic.
    • Turgor: full vs flat.
    • Pinprick: bright red blood = arterial supply; dark red sluggish = venous congestion; no bleeding = total loss.
  • Doppler ultrasound: implantable / external; serial monitoring.
  • Tissue oximetry (e.g. ViOptix): continuous SpO2.
  • Microdialysis: glucose / lactate / pyruvate; detects early ischaemia.
  • Action on failing flap: emergency return to theatre for re-exploration; salvage thrombolysis; vein graft; release haematoma.

Complications and outcomes

  • Free-flap success rate ~95-98% in modern UK centres.
  • Total flap loss ~2-5% (worse in radiated bed / smokers / diabetics).
  • Partial loss.
  • Venous congestion (commonest reason for re-exploration).
  • Arterial thrombosis.
  • Haematoma / seroma.
  • Infection / dehiscence.
  • Donor site morbidity: scarring, function, sensation, hernia (rectus-based).
  • Long-term: contour irregularity, sensory loss, aesthetic refinement.
  • Salvage: re-exploration within 4-6 hours of ischaemia signs; success ~50-70% with prompt intervention.

References

  1. Wei FC, Mardini S. Flaps and Reconstructive Surgery. 2nd ed. Edinburgh: Elsevier; 2017.
  2. Hallock GG. Direct and indirect perforator flaps: the history and the controversy. Plast Reconstr Surg. 2003;111:855-865.
  3. British Association of Plastic, Reconstructive and Aesthetic Surgeons. UK BAPRAS standards for microvascular reconstruction. London: BAPRAS; 2022.
  4. Khouri RK. Free flap surgery: the second decade. Clin Plast Surg. 1992;19:757-761.
  5. Hidalgo DA, Pusic AL. Free-flap mandibular reconstruction: a 10-year follow-up study. Plast Reconstr Surg. 2002;110:438-449.

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