Browse the corpus

The term "axial flap" encompasses a broad range of flaps that can be used to reconstruct various tissue defects arising from oncologic resection, trauma, and other causes. Axial flaps may be transferred within the same region from which they are harvested, or inset elsewhere on the body via microvascular anastomosis. Additionally, they may contain skin only, a combination of skin, fascia, and bone, or other tissue types. What all axial flaps have in common, however, is that they each contain a named artery running through them and providing a robust blood supply. This activity reviews the anatomy, indications, contraindications, and complications of axial flap transfer and highlights the role of the interprofessional team in the preoperative, intraoperative, and postoperative care of patients requiring axial flaps. Objectives: Compare the indications for use of axial flaps with those of random flaps in reconstructive surgery. Apply knowledge of axial flap vascular anatomy to reconstructive planning for oncologic, traumatic, and congenital defects. Improve postoperative monitoring protocols for early detection and management of flap compromise. Collaborate with all members of the interprofessional team including specialists such as plastic surgeons, orthopedic surgeons, otolaryngologists and anesthesiologists, to provide efficient, comprehensive, and coordinated care. Access free multiple choice questions on this topic.

Repair of medium- to large tissue defects can be accomplished through a variety of methods. Still, whether bone, soft tissue, or a combination of both is needed, axial flaps provide surgeons with a reliable, workhorse reconstructive option in most cases.[1] The term "axial" is used to refer to these flaps because of the presence of a primary feeding artery that runs from the flap's base through its long axis and its pedicle (the bridge of tissue that connects the flap to its donor site).[2][3] In contrast, "random" patterned flaps, which are used for reconstruction of small to medium-sized soft tissue defects, do not contain named blood vessels and rely solely on perfusion via the subdermal vascular plexus.[4] Random-pattern flaps are therefore potentially less reliable than axial flaps. Still, they are typically more convenient to use because their design and placement are not constrained by vascular anatomy to the same extent as axial flaps.[5] For more information about random-patterned flaps, please see Basic Flap Design.[6] Axial flaps may be categorized in several different ways, depending upon the manner in which the flap is transferred into its recipient site, the type of perfusion, and the sort of tissue involved. Flaps may be moved using advancement, rotation, transposition, interpolation (positioning the flap's pedicle either over or under intact intervening skin), or free microvascular transfer, in which the flap is entirely detached from the donor site, and then connected to an arterial supply and venous drainage (with or without motor or sensory nerve coaptation) at the recipient site (see Images. Posterior Scalp Advancement Flap, Reverse Sural Artery Flap, Anterolateral Thigh Flap Before Inset, and Anterolateral Thigh Flap After Inset).

Axial flaps may be categorized in several different ways, depending upon the manner in which the flap is transferred into its recipient site, the type of perfusion, and the sort of tissue involved. Flaps may be moved using advancement, rotation, transposition, interpolation (positioning the flap's pedicle either over or under intact intervening skin), or free microvascular transfer, in which the flap is entirely detached from the donor site, and then connected to an arterial supply and venous drainage (with or without motor or sensory nerve coaptation) at the recipient site (see Images. Posterior Scalp Advancement Flap, Reverse Sural Artery Flap, Anterolateral Thigh Flap Before Inset, and Anterolateral Thigh Flap After Inset). Rotation and interpolation are the most common means of transferring axial flaps, with some interpolated flaps, such as the inferior turbinate flap when used for repair of a nasal septal perforation, requiring a second operation to divide the vascular pedicle several weeks after inset and others, such as a pericranial flap used for the same purpose, tunneling the pedicle under the surrounding tissue to obviate that requirement and maintain reliable, long-term perfusion of the flap (see Image. Inferior Turbinate Flap Reconstruction for Nasal Septal Perforation). Interpolated flaps whose pedicles contain no skin and pass underneath the tissue between the flap donor site and the recipient site are also known as "island" flaps (see Image. Supraclavicular Artery Island Flap for Facial Reconstruction). Microvascular free tissue transfer, on the other hand, is typically performed as a single-stage procedure. Still, the surgeries are generally lengthy and challenging due to the technical demands of anastomosing small blood vessels and maintaining uninterrupted perfusion. The position of the blood supply is another important factor to consider, as the distance between the axial artery and the tissue paddle being relocated into the defect can affect the flap's reliability. "Direct cutaneous" flaps, in which the vessel runs immediately below the skin, such as the paramedian forehead flap, are very reliable.

Still, the surgeries are generally lengthy and challenging due to the technical demands of anastomosing small blood vessels and maintaining uninterrupted perfusion. The position of the blood supply is another important factor to consider, as the distance between the axial artery and the tissue paddle being relocated into the defect can affect the flap's reliability. "Direct cutaneous" flaps, in which the vessel runs immediately below the skin, such as the paramedian forehead flap, are very reliable. In contrast, "perforator" flaps, such as the deep inferior epigastric perforator flap, may be more tenuous, as they rely upon small branches from the vascular pedicle, often located within or below a layer of underlying muscle, to supply blood to the skin. "Fasciocutaneous" flaps, including the radial forearm flap, have more tissue intervening between the primary artery and the tissue being perfused than direct cutaneous flaps, but do not rely on the long, easily disrupted arterial branches of perforator flaps (see Image. Fasciocutaneous Flap Perfusion). Of note, the term "fasciocutaneous" can be used to describe both the blood supply of a flap and its soft tissue components; conveniently, the 2 descriptions typically align anatomically. In most cases, arterial flow into the flap will proceed in the physiological, antegrade direction of flow; however, there are some regions, particularly in the face, in which robust collateral circulation permits the pedicle to be placed distal to the flap, with respect to the normal direction of blood flow, and still maintain perfusion. This phenomenon may, in certain cases, significantly improve the surgeon's ability to maneuver the desired tissue into the defect; classic examples include the "retrograde" facial artery musculomucosal flap, the reverse sural artery flap, and the distally based radial forearm flap. While many flaps incorporate the distal end of the axial artery, some are based on an artery that traverses the flap and exits the other side, thus requiring ligation of the vessel both distally and proximally.

In most cases, arterial flow into the flap will proceed in the physiological, antegrade direction of flow; however, there are some regions, particularly in the face, in which robust collateral circulation permits the pedicle to be placed distal to the flap, with respect to the normal direction of blood flow, and still maintain perfusion. This phenomenon may, in certain cases, significantly improve the surgeon's ability to maneuver the desired tissue into the defect; classic examples include the "retrograde" facial artery musculomucosal flap, the reverse sural artery flap, and the distally based radial forearm flap. While many flaps incorporate the distal end of the axial artery, some are based on an artery that traverses the flap and exits the other side, thus requiring ligation of the vessel both distally and proximally. When one of these flaps is transferred, typically using a free microvascular technique, another free flap can be connected to the distal aspect of the first. The second flap will receive perfusion and drain its venous output via the first in a "flow-through" fashion. These are complex reconstructions with a relatively high risk of failure because they require serial vascular microanastomoses. Still, they provide the surgeon with options for repairing even very large composite defects. Composite defects are best addressed with axial flaps, as the subdermal plexus by itself is insufficient to support inclusion of tissue elements beyond skin alone. Typical axial flaps are referred to as "fasciocutaneous," due to the presence of nothing more than skin and the underlying fascia within the flap, but "osteocutaneous" flaps, such as the free fibula flap, "myocutaneous," and even solid organ, hand, larynx, and face transplants are considered axial flaps as well (see Image. Fibula Free Flap Harvest and Closing Ostectomy).

The complication that typically worries surgeons most when performing axial flap transfers is flap necrosis, which usually occurs at the distal tip, farthest from the vascular pedicle, but may involve the entire transferred tissue, particularly with a microvascular free flap. Tissue necrosis is caused by vascular insufficiency, which may result from excessive tension or kinking of the pedicle vessels, pressure on the pedicle vessels (generally due to a hematoma or infection), or thrombosis of the vessels.[43] In all of these cases, the venous drainage is 3 times more likely to be affected than the arterial supply because it is a lower-pressure system with lower velocity flow and thinner walls that are less resilient to external compression.[44] A flap that appears edematous, firm, and dusky or ecchymotic, particularly with dark blood oozing from the incision lines, is liable to be experiencing venous outflow insufficiency. With sufficient time, venous obstruction within the flap may also lead to arterial inflow obstruction, making flap salvage even more challenging. If the artery is affected in isolation, the flap will be pale, with minimal or absent capillary refill, supple, and cool (unless it is located within a body cavity). A mnemonic developed by Dr Scott Bevans to guide monitoring of axial flaps via physical examination is "Check with The Chief, Big Dog," which directs the clinician to assess color, temperature, capillary refill, bleeding, and Doppler signal. Doppler examination of a flap with arterial insufficiency will reveal a lack of any pulses, while a flap with venous obstruction may still have an arterial pulse, albeit a sharper "hammer" pulse due to altered hemodynamics. Using a 21-gauge needle to prick a flap without arterial inflow will cause no bleeding, whereas a flap with venous obstruction only will bleed dark blood faster than blood would normally issue from a pinprick.

A mnemonic developed by Dr Scott Bevans to guide monitoring of axial flaps via physical examination is "Check with The Chief, Big Dog," which directs the clinician to assess color, temperature, capillary refill, bleeding, and Doppler signal. Doppler examination of a flap with arterial insufficiency will reveal a lack of any pulses, while a flap with venous obstruction may still have an arterial pulse, albeit a sharper "hammer" pulse due to altered hemodynamics. Using a 21-gauge needle to prick a flap without arterial inflow will cause no bleeding, whereas a flap with venous obstruction only will bleed dark blood faster than blood would normally issue from a pinprick. In some cases, venous obstruction can be addressed by applying leeches to the flap, which will remove venous blood as well as infuse a potentially helpful anticoagulant, but this should always be accompanied by administration of a fluoroquinolone antibiotic to prevent soft tissue infection with Aeromonas hydrophila that is often present in the gut of the leech.[45][46] Alternatively, thrombolytics or anticoagulants may be injected directly into the flap instead.[47][48] Ideally, however, the underlying vascular problem should be addressed, generally in the operating room.

In some cases, venous obstruction can be addressed by applying leeches to the flap, which will remove venous blood as well as infuse a potentially helpful anticoagulant, but this should always be accompanied by administration of a fluoroquinolone antibiotic to prevent soft tissue infection with Aeromonas hydrophila that is often present in the gut of the leech.[45][46] Alternatively, thrombolytics or anticoagulants may be injected directly into the flap instead.[47][48] Ideally, however, the underlying vascular problem should be addressed, generally in the operating room. This may require evacuating a hematoma and securing hemostasis, releasing tension on the pedicle or reorienting it to reduce kinking, or, in the case of free tissue transfer, disconnecting the flap from its blood supply to clear thrombus from the vein and/or artery before restoring the vascular anastomoses. Whatever intervention is required should be performed as soon as possible to limit the extent of tissue necrosis and reduce the likelihood of a "no-reflow" phenomenon, in which disseminated clotting within the flap's microvasculature prevents tissue reperfusion even if all of the other insults have been corrected. Irreversible ischemic damage occurs after approximately 6 hours without blood flow, but perfusion can be restored in over 90% of cases if the problem is recognized and corrected promptly.[49][43] If a flap's blood supply is irreversibly compromised and tissue death occurs, areas of limited necrosis may be managed with local wound care, including conservative debridement and wet-to-dry dressings or antibiotic ointment, with or without hyperbaric oxygen.[50] Complete flap loss, on the other hand, may require debridement and replacement with another flap, a skin graft, or allowing the wound to heal by secondary intention.

This may require evacuating a hematoma and securing hemostasis, releasing tension on the pedicle or reorienting it to reduce kinking, or, in the case of free tissue transfer, disconnecting the flap from its blood supply to clear thrombus from the vein and/or artery before restoring the vascular anastomoses. Whatever intervention is required should be performed as soon as possible to limit the extent of tissue necrosis and reduce the likelihood of a "no-reflow" phenomenon, in which disseminated clotting within the flap's microvasculature prevents tissue reperfusion even if all of the other insults have been corrected. Irreversible ischemic damage occurs after approximately 6 hours without blood flow, but perfusion can be restored in over 90% of cases if the problem is recognized and corrected promptly.[49][43] If a flap's blood supply is irreversibly compromised and tissue death occurs, areas of limited necrosis may be managed with local wound care, including conservative debridement and wet-to-dry dressings or antibiotic ointment, with or without hyperbaric oxygen.[50] Complete flap loss, on the other hand, may require debridement and replacement with another flap, a skin graft, or allowing the wound to heal by secondary intention. Other complications of flap transfer include infection, scarring, contracture, cosmetic dissatisfaction, and damage to surrounding anatomy during flap harvest. Among the more likely potential iatrogenic injuries are sensory and motor nerve trauma, such as damage to the superficial branch of the radial nerve, the frontal branch of the facial nerve, and the proximal obturator nerve, which can cause loss of sensation or adjacent muscle weakness. Cosmetic complaints may arise from poor color, texture, or hair match between the flap and the recipient area, or contour irregularities due to inappropriate sizing of the flap, typically with too much thickness or surface area in too small a defect, which results in a heaped-up or "pincushion" appearance. In some cases, the flap may be debulked without risking damage to its blood supply, but not in all. Differences in skin quality and hair growth are often satisfactorily addressed with laser resurfacing or hair removal.

Other complications of flap transfer include infection, scarring, contracture, cosmetic dissatisfaction, and damage to surrounding anatomy during flap harvest. Among the more likely potential iatrogenic injuries are sensory and motor nerve trauma, such as damage to the superficial branch of the radial nerve, the frontal branch of the facial nerve, and the proximal obturator nerve, which can cause loss of sensation or adjacent muscle weakness. Cosmetic complaints may arise from poor color, texture, or hair match between the flap and the recipient area, or contour irregularities due to inappropriate sizing of the flap, typically with too much thickness or surface area in too small a defect, which results in a heaped-up or "pincushion" appearance. In some cases, the flap may be debulked without risking damage to its blood supply, but not in all. Differences in skin quality and hair growth are often satisfactorily addressed with laser resurfacing or hair removal. Ultimately, each flap has a unique risk profile due to its harvest site. Harvest of extremity flaps, like fibula and radial forearm flaps, can compromise the perfusion of distal anatomy, such as the foot or hand, if an appropriate preoperative vascular evaluation is not performed. Similarly, bone removal can cause pathological fractures or mobility decrements, such as shoulder or ankle instability after incautious harvest of a scapula or fibula flap. Flaps, like the temporoparietal fascia flap, that are harvested under the scalp may cause alopecia if excessive cautery is used. The examples are nearly endless, and it is the surgeon's responsibility to identify, mitigate, and counsel the patient about these risks appropriately.

Optimal outcomes with axial flaps depend on precise surgical judgment, disciplined perioperative strategy, and clear role delineation across the team. Surgeons and advanced clinicians must integrate detailed knowledge of angiosomes and vascular anatomy into preoperative planning, which may include handheld Doppler assessment, computed tomography angiographic mapping in complex cases, and thoughtful flap selection tailored to defect size, location, and patient comorbidities. Intraoperatively, meticulous technique to preserve the vascular pedicle, minimize tension, and ensure adequate inset is critical. At the same time, the anesthesia team supports hemodynamic stability and avoids vasoconstrictive states that could compromise perfusion. Postoperatively, nurses and advanced practitioners play a central role in standardized flap monitoring protocols, serial clinical exams (color, turgor, capillary refill, temperature), adjunctive monitoring when indicated, and early escalation pathways for suspected vascular compromise, facilitating timely return to the operating room when salvage is possible. Interprofessional communication and coordinated care are essential for reducing complications and improving patient-centered outcomes. Pharmacists contribute by optimizing anticoagulation or antiplatelet strategies when appropriate, guiding antibiotic stewardship, and avoiding medications that may impair microvascular flow. Nursing teams ensure adherence to positioning protocols, pressure offloading, and wound care, while also providing patient education on activity restrictions and warning signs. Physical and occupational therapists assist with early, protected mobilization that preserves flap integrity and function. Structured handoffs, shared checklists, and multidisciplinary rounds enhance situational awareness, align goals of care, and reduce variability. This coordinated approach improves flap survival, minimizes infection and thrombotic events, and supports functional recovery and patient satisfaction.