The terms free flap, free autologous tissue transfer and microvascular free tissue transfer are synonymous terms used to describe the "transplantation" of tissue from one site of the body to another, in order to reconstruct an existing defect. "Free" implies that the tissue is completely detached from its blood supply at the original location ("donor site"), transferred to another location ("recipient site"), and the circulation in the tissue re-established by anastomosis of artery(s) and vein(s). This is in contrast to a local flap or regional flap in which the tissue is left partly attached to the donor site ("pedicle") and simply transposed to a new location; keeping the "pedicle" intact as a conduit to supply the tissue with blood. A free flap may be thought of as an autologous transplant.
Various types of tissue may be transferred as a "free flap" including skin and fat, muscle, nerve, bone, cartilage (or any combination of these), lymph nodes and intestinal segments. An example of "free flap" could be a "free toe transfer" in which the great toe or the second toe is transferred to the hand to reconstruct a thumb.[1]
For all "free flaps", the blood supply is reconstituted using microsurgical techniques to reconnect the artery (brings blood into the flap) and vein (allows blood to flow out of the flap).
Free autologous tissue transfer is performed by many surgical specialties.
Indications
Free flaps are used to reconstruct tissue defects. Particularly when postoperative radiotherapy is indicated, vascularized free tissue is preferred over non-vascularized free tissue.
Free flaps are widely used in head & neck reconstruction, particularly after oncologic resection. In the trauma setting, free flap reconstruction remains viable but can present increased technical complexity due to tissue damage, vascular injury, and the need for airway / functional restoration.[2]
When reconstructing complex head and neck defects, the reconstruction often requires bone and soft tissue from a distant donor site to be harvested. Functional reconstruction in the head and neck area often requires reconstruction of the oral cavity, the mandible (lower jaw), the oropharynx, or the pharynx in order to assist with speech and/or swallow. Free flaps may also be used to cover volume defects (eg, after orbital exenteration or maxillectomy) or to cover the great neck vessels prior to radiation (eg, to minimize risk of carotid blowout). Type of defects include:
Reconstruction of post-traumatic defects: Some areas of the body has missing tissue either from a trauma or from some existing wound. This may include areas on the leg where bone is exposed or any other area on the body that needs soft tissue coverage.
Reconstruction of a defect following removal of a tumor in the mouth or elsewhere: Soft tissue resection requires soft tissue reconstruction. Composite (soft tissue and hard tissue) resection requires composite reconstruction. Soft tissue flaps include the radial forearm free flap and the anterolateral thigh (ALT) free flap amongst others. Composite free flaps include the fibular free flap, the deep circumflex iliac artery (DCIA) free flap, the scapular free flap and the composite radial free flap amongst others. When the cancer resection involves a part of the lower jaw, depending on the patients age and the patients co-morbidities one composite free flap will be preferred over the others for reconstruction of the defect.
Reconstruction of esophageal (food-pipe) continuity using segments of intestine
Breast
Aesthetic (cosmetic) reconstruction most commonly involves creating a breast after a mastectomy. This may happen at the time of mastectomy or at a later date. Free flaps are usually only done if a TRAM flap is not possible. Plastic surgeons usually perform these surgeries.
Upper extremity / compound flaps
Composite free flaps (containing bone and soft tissue) used in the upper limb have been compared with non-bone flaps: a meta-analysis noted higher risk of complications but also improved functional outcomes in selected indications.[3]
Evolution in flap techniques in upper extremities has also been described, emphasizing versatility of perforator designs in complex defect coverage.[4]
Abdominal wall
A 2025 systematic review (32 studies, 104 flaps) found no reports of complete flap loss, partial necrosis ~5.8 %, surgical site infection ~5.8 %, and hernia formation ~4.8 %.[5]
The latissimus dorsi flap is the most commonly used free flap (36 %).
Extremity / lower limb
In lower limb reconstructions, reported flap failure and return-to-OR rates vary; a 2024 systematic review challenges and refines prior estimates.[6]
Moreover, a meta-analysis re-evaluating the classic "Godina principle" showed that early free-flap reconstruction (versus delayed) is significantly associated with lower flap failure and infection rates (p = 0.008 and p = 0.0004, respectively).[7]
Functional
Reconstruction of paralyzed face or hand using functioning free muscle flaps.
Patients with Bell's palsy can have their face re-animated using "free functioning muscle flaps".
Preoperative Considerations
Preoperative planning can help determine the viability of a free flap donor site. Vascular imaging and perforator mapping (e.g. CT angiography, Doppler ultrasound, UHF ultrasound) are increasingly used to improve flap planning and reduce intraoperative surprises. Automated methods (e.g. semi-automatic detection of DIEP perforators) show promise in reducing planning time and inter-observer variability.[8]
Prior to harvesting a radial forearm free flap, the modified Allen test is commonly performed to assess the adequacy of collateral circulation to the hand via the ulnar artery.[9] The test helps determine whether the radial artery can be safely sacrificed without risking ischemia to the hand. A positive (normal) result—demonstrated by prompt reperfusion of the hand following release of ulnar artery compression—suggests sufficient ulnar artery perfusion and supports proceeding with flap harvest. In cases of abnormal or equivocal results, further vascular imaging (e.g., Doppler ultrasound or angiography) may be warranted to guide surgical planning.
Surgical Steps during "free autologous tissue transfer"
A defect is created surgically (either following removal of a tumor or following cleansing of a wound)
An incision is made over the area from where the flap will be taken.
The flap is dissected and freed from the surrounding tissue.
At least one vein and one artery (which constitutes the vascular pedicle) are dissected.
The vein and artery (vascular pedicle) are divided, separating the flap from the rest of the body.
Before the pedicle is divided, the area the flap will be re-attached to is prepared by identifying a recipient artery and vein.
The free flap is brought up to the defect area, and the vein and artery from the flap (vascular pedicle) are anastomosed (re-connected) to the vein and artery identified in the wound. The anastomosis is done using a microscope or a "loupe", hence it is termed "microsurgery"
The free flap is sutured to the defect, while it is monitored to ensure the blood vessels remain patent (i.e. the vessels have good blood flow).
The donor site area is closed primarily. Sometimes a Split Thickness Skin graft (STSG) may be performed and placed on top of the defect site and/or the donor site.
Postoperative Complications/Sequelae
Flap Failure
The most common serious complication of a free flap is loss of the venous outflow (e.g. a clot forms in the vein that drains the blood from the flap). Loss of arterial supply is serious too and both will cause necrosis (death) of the flap. Close monitoring of the flap both by nurses and by the surgeon is mandatory following the completion of the operation.[10][11] If detected early, loss of either the venous or arterial blood supply may be corrected by operative intervention. Many times an implantable Doppler probe or other devices can be installed during surgery to provide better monitoring in the post-operative period. The Doppler probe can be removed before discharge from the hospital.
An institutional review of 5,000 free flaps over 10 years reported a mean take-back rate of 1.53 % and flap loss rate of 0.55 %.[12] In a lower-volume center over 20 years (136 flaps), the overall success rate was ~92.6 %, improving to ~96 % in later years.[13] The take-back rate was ~16 %, with ~60 % flap salvage on re-exploration.
Donor Site Morbidity
Usually the harvest of a "free flap" is performed in such a fashion to cause the least amount of disability. Despite this some disability may occur following removal of this tissue from the "donor site".
Other
Other complications/sequalae which may occur with any surgery are also possible, including infection and pain.
Recent Advances / Future Directions
Supermicrosurgery — defined as anastomoses of vessels ≤ 0.8 mm — is increasingly used in soft-tissue free flaps. In a systematic review, its flap success rate was ~96.6 %.[14]
Flap thinning techniques and superthin flap designs are evolving to improve contour and reduce bulk, particularly in aesthetic regions (e.g. facial, intraoral) — though balanced carefully against vascular risk.
Techniques to minimize donor-site morbidity, reduce muscle sacrifice, and preserve function are active areas of innovation.
↑ Sweeny, Larissa; Kane, Anne C.; Thomas, Carissa M.; Futran, Neal; Curry, Joseph M.; Bur, Andrés M.; Lu, G. Nina; Shukla, Aishwarya; Skoog, Hunter; Pena Garcia, Jaime A.; Alnemri, Angela E.; Alapati, Rahul; DiLeo, Michael; Fuson, Andrew; Tan, Kenneth (December 2024). "Free flap reconstruction following head and neck trauma". Head & Neck. 46 (12): 2981–2992. doi:10.1002/hed.27867. ISSN1097-0347. PMID38984564.
↑ Zhang, Ying; Gazyakan, Emre; Hundeshagen, Gabriel; Fischer, Sebastian; Bigdeli, Amir K.; Marks, Patrick Will; Kneser, Ulrich; Hirche, Christoph (October 2021). "A meta-analysis evaluating risk factors for compound free flaps for upper extremity defect reconstruction comparing complications and functional outcomes of compound free flaps with and without bone components". Microsurgery. 41 (7): 688–696. doi:10.1002/micr.30791. ISSN1098-2752. PMID34357657.
↑ Wu, Robin T.; Lin, Chih-Hung; Hsu, Chung-Chen; Wei, Fu-Chan (January 2024). "Evolution of free flap reconstruction in the upper extremity: perspective from a tertiary plastic and reconstructive institution". The Journal of Hand Surgery, European Volume. 49 (1): 8–16. doi:10.1177/17531934231181995. ISSN2043-6289. PMID37812517.
↑ Kim, Michael I.; Manasyan, Artur; Stanton, Eloise W.; Jimenez, Christian; Carey, Joseph N.; Daar, David A.; Koesters, Emma C. (May 2025). "Free Flap Reconstruction of Abdominal Wall Defects: A Systematic Review and Pooled Analysis". Microsurgery. 45 (4) e70059. doi:10.1002/micr.70059. ISSN1098-2752. PMID40192162.
↑ Haykal, Siba; Roy, Mélissa; Patel, Ashit (May 2018). "Meta-analysis of Timing for Microsurgical Free-Flap Reconstruction for Lower Limb Injury: Evaluation of the Godina Principles". Journal of Reconstructive Microsurgery. 34 (4): 277–292. doi:10.1055/s-0037-1621724. ISSN1098-8947. PMID29536455.
↑ Araújo, Ricardo J.; Garrido, Vera; Baraças, Catarina A.; Vasconcelos, Maria A.; Mavioso, Carlos; Anacleto, João C.; Cardoso, Maria J.; Oliveira, Hélder P. (October 2019). "Computer aided detection of deep inferior epigastric perforators in computed tomography angiography scans". Computerized Medical Imaging and Graphics: The Official Journal of the Computerized Medical Imaging Society. 77 101648. arXiv:1907.10354. doi:10.1016/j.compmedimag.2019.101648. ISSN1879-0771. PMID31476532.
↑ Habib, Joseph; Baetz, Laureen; Satiani, Bhagwan (October 2012). "Assessment of collateral circulation to the hand prior to radial artery harvest". Vascular Medicine (London, England). 17 (5): 352–361. doi:10.1177/1358863X12451514. ISSN1477-0377. PMID22814998.
↑ F. Hölzle, D. Löffelbein, D. Nolte, K.-D. Wolff: Free flap monitoring using simultaneous non-invasive laser Doppler flowmetry and tissue spectrophotometry. J Craniomaxillofac Surg. (2006) 34: 25-33.
↑ F. Hölzle, A. Rau, D. J. Loeffelbein, M. R. Kesting, T. Mücke, K.-D. Wolff: Results of monitoring fasciocutaneous, myocutaneous, osteocutaneous and perforator flaps: 4-year experience with 166 cases. Int J Oral Maxillofac Surg. (2010) 37: 21-28.
↑ Carney, Martin J.; Weissler, Jason M.; Tecce, Michael G.; Mirzabeigi, Michael N.; Wes, Ari M.; Koltz, Peter F.; Kanchwala, Suhail K.; Low, David W.; Kovach, Stephen J.; Wu, Liza C.; Serletti, Joseph M.; Fosnot, Joshua (April 2018). "5000 Free Flaps and Counting: A 10-Year Review of a Single Academic Institution's Microsurgical Development and Outcomes". Plastic and Reconstructive Surgery. 141 (4): 855–863. doi:10.1097/PRS.0000000000004200. ISSN1529-4242. PMID29595720.
↑ Klosterman, Tristan; Siu, Eric; Tatum, Sherard (May 2015). "Free flap reconstruction experience and outcomes at a low-volume institution over 20 years". Otolaryngology--Head and Neck Surgery: Official Journal of American Academy of Otolaryngology-Head and Neck Surgery. 152 (5): 832–837. doi:10.1177/0194599815573726. ISSN1097-6817. PMID25953911.
↑ Escandón, Joseph M.; Ciudad, Pedro; Mayer, Horacio F.; Pencek, Megan; Mantilla-Rivas, Esperanza; Mohammad, Arbab; Langstein, Howard N.; Manrique, Oscar J. (February 2023). "Free flap transfer with supermicrosurgical technique for soft tissue reconstruction: A systematic review and meta-analysis". Microsurgery. 43 (2): 171–184. doi:10.1002/micr.30894. ISSN1098-2752. PMID35551691.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
