Radial Forearm Tissue Transfer

The radial forearm includes thin, pliable skin that can be molded in three dimensions and transferred as a sensate flap, making it ideal for most head and neck reconstructions.

Loss of tissue resulting from cancer ablation or debridement of infected tissues or secondary to trauma provides the reconstructive surgeon with various challenges. Regional flaps such as the pectoralis major and deltopectoral flaps have been used by reconstructive surgeons since the early 1900s. These flaps are still useful for head and neck reconstruction in select cases; however, advances in reconstructive techniques have led to a shift favoring free tissue transfer (see the image below). Microvascular procedures have allowed surgeons to readily transfer tissue from one region of the body to another. In the ideal situation, one must replace tissue lost with tissue that has similar characteristics. In the head and neck, tumor extirpation may result in loss of the thin mucosal covering of the oral cavity, pharynx, or larynx.

Reconstruction of such defects requires transposition of thin, pliable, and, preferably, sensate tissue to optimize function. A long vascular pedicle is beneficial because the vessels used for the anastomoses are usually found in the neck. The decision about which flap to use is based on the defect size, the type and amount of missing tissue, necessary pedicle length, and requirements for reinnervation.

The reliable anatomy of the forearm makes flap harvest relatively easy and safe. The long pedicle allows anastomoses to be performed on either the ipsilateral or the contralateral neck. The flap may also be harvested with the palmaris longus tendon, radial bone, and/or sensory nerves, making it extremely versatile. The cephalic vein may be harvested as the sole venous outflow or as an optional accessory to the venae comitantes. (See the images below.)[1]

The microvascular radial forearm flap was first described in the Chinese literature in the early 1980s. The Chinese flap became known for its reliable anatomy, pliable skin, ease of elevation, and long pedicle. The biggest drawback was the relatively unsightly donor site appearance. Multiple techniques to improve the appearance of the donor site have been published, but to date there is no consensus on the ideal technique. Functional and cosmetic outcomes appear similar with split- or full-thickness grafting or with acellular dermis covered with a thin split-thickness graft.

The development of an osteocutaneous flap, which included a segment of the radius, increased the utility of the radial forearm flap. As originally described, however, the harvested bone weakened the remaining radius and was associated with a 25% fracture rate. Modifications of harvest technique and prophylactically plating the radius have virtually eliminated this problem and expanded the reconstructive versatility of this flap. Very little other long-term morbidity has been associated with this flap.

Ease of harvest, versatility, and unsurpassed reliability have made the radial forearm flap the fasciocutaneous flap of choice for head-and-neck reconstructive surgeons. It has many uses, ranging from reconstruction of skin and scalp defects to repair of composite intraoral defects. A fascial flap may be harvested to repair skull base defects, and partial or total pharyngectomy defects can be repaired with the flap tubed or sewn as a patch to the remaining pharynx. It is the best source of healthy, vascularized skin without the bulk of a myocutaneous flap for reconstructive surgeons trained in microvascular techniques.

Transfer of tissue from the forearm to the head and neck can be performed effectively with microvascular techniques. Various defects can be successfully repaired with this flap.

The patient is preoperatively evaluated by both the extirpative and reconstructive surgeons. Medical and radiation oncology consultations are obtained, when appropriate. A speech pathology evaluation is often performed as well, if indicated. An Allen test is an integral part of the physical examination and must be performed on all patients considered to be candidates for a radial forearm free tissue transfer. Any previous scars or surgery to the forearm is a relative contraindication.

Radiographic images are reviewed, and the surgery is discussed in detail with the patient. Assessment of patient support systems and the patient's educational and social status is useful.

Deciding which flap would offer the best functional and cosmetic outcome is based on multiple factors, including defect size (diameter, depth, bulk), location, and missing components (eg, skin, muscle, bone). Patient factors, such as contraindications to a particular flap, systemic diseases, and overall health must also be considered. Potential donor site morbidity as related to each patient must be considered. Training of the surgeon is, of course, paramount in the decision-making process.

The tissue from the forearm harvested as a radial forearm flap allows various head and neck defects to be reconstructed with a vascularized, thin, pliable piece of fascia and skin. This is advantageous in patients with complicated three-dimensional defects (as seen below), circumferential pharyngeal defects, and oral or scalp defects, especially those who have undergone prior irradiation. Small defects involving bone may be reconstructed by harvesting vascularized radius. Caution is necessary because of the possibility of radial fractures following bone harvest, but the likelihood of such fractures is minimized by harvesting the bone in a keel shape (beveling the proximal and distal cuts) and prophylactically having the bone plated postharvest by an orthopedic surgeon.

As in any procedure, intimate knowledge of the anatomy is key. The anatomic consistency of the forearm is one of the most attractive aspects of the radial forearm flap. The volar aspect of the forearm contains 2 major arteries (radial and ulnar) with their accompanying venae comitantes. The ulnar artery and its venae comitantes lie along the medial aspect of the arm. Although it is usually deep and protected during dissection, the ulnar vessels are sometimes quite superficial (see the image below).[2] Extra care and attention during the medial dissection help to avoid transecting this pedicle, which would compromise circulation to the hand.

The radial vessels lie laterally (thumb side) in the arm. The pedicle is found in the lateral intermuscular septum, between the flexor carpi radialis (FCR) medially and the brachioradialis (BR) laterally. There are two venae comitantes that run parallel to the radial artery in the intermuscular septum which usually join into one vein in the proximal third of the forearm. The cephalic vein lies superficially along the lateral arm. This vein can be harvested with the flap or left in the arm if venous drainage from the venae comitantes is sufficient.

Medial and lateral antebrachial cutaneous (MABC and LABC) nerves supply the skin of the forearm. With elevation of the flap, they are identified and isolated proximally. The LABC lies in proximity to the cephalic vein. This nerve provides sensation to the lateral digits. Superficial branches of the radial nerve lie lateral to the BR tendon distally. Pay attention when elevating a radial forearm flap to preserve the integrity of this important nerve.

The palmaris longus, absent in 5-15% of patients, is a tendon that may be harvested with the flap. It lies medial to the FCR. It can be used to provide support for lip or midface reconstruction as a vascularized sling.[3]

The most important contraindication for harvesting a radial forearm flap is related to the vascular supply of the hand. The deep and superficial palmar arches, arising from the radial and ulnar arteries respectively, normally anastomose to provide the blood supply to the hand and digits. A small number of individuals have a superficial arch that does not join with the deep arch; if the radial artery is sacrificed, these patients are at risk of ischemia of the first finger and thumb, an unacceptable morbidity for this procedure.

An Allen test should be performed preoperatively in all patients to assess ulnar collateral flow in the thenar region (see the image below). This is performed by manually occluding both the radial and ulnar arteries simultaneously. The patient clenches his/her hand, causing the palm to blanch, and then opens it to a relaxed position. If the fingers are extended straight out, they may blanch from overextension, which may lead to a false-positive result.

The ulnar artery is released, and return of color is evaluated, especially in the region of the thenar eminence. If flow is questionable or if the patient is pale and flow is difficult to assess, a Doppler device may be placed in the thenar region and the test repeated. The return of a pulse should be audible with release of the ulnar artery.

Pulse oximetry may also be used by placing the oximeter on the thumb. When the radial and ulnar arteries are occluded, the signal should be lost; if, when the ulnar artery is released, the signal returns, the test is negative and one can proceed with the surgery. A quantitative Doppler study, although more time consuming and expensive, may also provide information if the test results are uncertain.

A questionable or positive Allen test result should prompt the surgeon to select a different flap. Approximately 3-5% of the population manifests such a finding.

Another relative contraindication to a radial forearm flap is a history of surgery on the ipsilateral hand. If operative reports can be obtained and the vascular supply to the hand is found to have not been disrupted, the flap can be considered. The presence of an ipsilateral arteriovenous (AV) shunt in a patient with persistent renal failure is an absolute contraindication to a forearm flap; the presence of a contralateral AV shunt is a relative contraindication to surgery.

Although the radial forearm flap remains an excellent supply of fascia and skin, alternatives do exist. In the setting of contraindications to a radial forearm flap, the surgeon should consider these alternatives. An ulnar fasciocutaneous flap shares many of the radial forearm flap's properties, although it cannot be designed as an osteocutaneous flap.

Other available fasciocutaneous free flaps include scapula, lateral thigh, and lateral arm flaps. Although well suited to most skin or mucosal and fascial defects in the head and neck, all flaps must be tailored to the specific patient. A fibula or iliac crest flap is probably a better choice for large bone defects or in patients who desire osseointegrated implants for dental restoration. Large defects of the tongue or of the orbit may necessitate more bulk and are better replaced with a rectus or latissimus flap.

See the list below:

• Complete blood count (CBC)

• Type and screen

• Chemistry panel

An informed consent is obtained.

A two-team approach may be used and is ideal for minimizing time under anesthesia for the patient. The skin paddle is marked centered on the palpable radial artery and designed to fit the estimated defect size. The cephalic vein is also marked because it usually decompresses with tourniquet inflation and may be difficult to visualize. The arm is exsanguinated with an elastic wrap, and the tourniquet is inflated to 250 mm Hg.

A number 15 blade is used to incise the periphery of the flap, beginning on the medial (ulnar) aspect of the flap and extending in a curvilinear fashion into the proximal forearm (as seen below). The dissection is carried down medially to the flexor carpi radialis in a subfascial dissection to expose the intermuscular septum. The flexor carpi radialis is followed back into the proximal arm, and the pedicle is identified proximally and dissected free. The lateral (radial) aspect of the skin incision is then carried down through the skin and subcutaneous tissue to the BR.

A subfascial dissection is then performed on the BR, with the superficial branch of the radial nerve, which lies on the lateral aspect of the BR muscle, identified and preserved. It is important to stay on the muscle. The intermuscular septum containing the pedicle is then dissected off of the BR. If there is no concern for ulnar artery viability, the distal pedicle can be divided at this point. The cephalic vein is identified proximally and either harvested with the flap or left intact. The LABC nerve is identified in proximity and harvested if required for neural anastomosis.

Tiny perforating vessels that provide the blood supply to the radius are identified and cauterized or clipped; otherwise, they will bleed when tourniquet pressure is released. If bone harvest is planned, these distal perforators are preserved and followed to the radius. The bone is cut obliquely (keel shaped) so as not to overcut and weaken the radius. It is safe to take 40% of the diameter of the radius. Care is taken not to shear the vessels from the bone during harvest.

The skin paddle and the pedicle are then dissected free from all surrounding subcutaneous tissue. The pedicle is identified to one artery and one vein if possible. If it is not possible to identify the venous pedicle to one vessel, two venous anastomoses can be done or, if the venae comitantes are of adequate caliber, venous drainage can be based on only one branch. The tourniquet is then released, and the vessels are further cleaned of their adventitia under loupe visualization.

At an appropriate time, the pedicle is ligated proximally, and the flap is inset in the defect. If bone was harvested, it is our practice to have an orthopedic surgeon plate the remaining radius. The donor site defect is minimized using a purse-string suture of 3-0 Vicryl. The donor site is carefully closed with acellular dermis and a split-thickness skin graft that covers any tendon denuded of paratenon with nearby muscle prior to skin grafting. A skin graft that has been pie crusted by hand rather than run through a mesher has a better cosmetic appearance.

Suitable recipient vessels in the neck should previously have been identified. The vessels are cleaned of adventitia under the binocular microscope. Using microvascular techniques, the anastomoses are then performed. The authors use a 9-0 nylon suture for the arterial anastomosis and either 9-0 nylon or a venous anastomotic device for the venous anastomosis or anastomoses. The vascular clamps are removed from the vessels, and flow is reestablished and verified. Papaverine is placed on the pedicle, and closure is completed. Suction drains are carefully placed in the neck and secured with sutures to avoid direct contact with the pedicle. It is the authors' practice to place an implantable Doppler device on the arterial anastomosis for postoperative monitoring.

The arm is dressed with Xeroform and a bolster and loosely wrapped with Kerlix. A splint is placed, as is a feeding tube, if necessary, and the patient is transferred to the recovery room. An intensive-care bed may be necessary, depending on the experience of the nursing personnel.

Postoperative care is similar to that for any free tissue transfer, although details may vary from institution to institution. Patients are closely monitored in the hospital, and the transplanted forearm skin is frequently evaluated for signs of vascular compromise.

The ideal technique by which a flap can be assessed is only theoretical and practically varies depending on the flap, the patient, available equipment, and other factors. Based on individual preference, cost, and familiarity with monitoring techniques, various monitors are available. Direct visualization and assessment of capillary refill, with or without needle prick, is very reliable in trained hands.

The use of an implantable Doppler device is an excellent tool for the well-trained surgeon, as well as the ancillary staff and family involved in the care of these patients. This technology is routinely used in our practice; it has been proven to increase the detection of immediate/incipient vascular problems with a sensitivity of 87% and a specificity of 99%.[4] Arterial problems usually manifest within 24 hours; venous congestion often develops 48-72 hours postoperatively. Frequent evaluation and careful monitoring allow for early identification of problems.

Fluid balance and overall patient condition are monitored as well. The authors use prophylactic antibiotics for 24 hours, although many routinely use prophylactic antibiotics for much longer periods. We do not routinely heparinize or give preoperative or postoperative aspirin to these patients. (A literature review by Swartz et al indicated that anticoagulant drugs studied in the report—aspirin, low–molecular weight dextran, unfractionated heparin, low–molecular weight heparin, and prostaglandin-E1—do not improve the survival of or lower the complication rate for radial forearm free flaps used in head and neck reconstruction.[5] )

The arm splint is changed on the fifth postoperative day, and the skin graft is evaluated. The patient continues to wear a splint until the skin graft site has healed completely. Active physiotherapy is instituted to ensure recovery of wrist and hand function.

It is not our practice to routinely discharge patients on anticoagulation. The first postoperative visit generally occurs 1-2 weeks after release from the hospital. Flap and skin graft viability are assessed, any remaining sutures are removed, and the recipient site is evaluated for complications. If not already initiated preoperatively or on an inpatient basis, physical therapy is instituted to restore function when the donor site has healed. Removal of the feeding tube and/or tracheotomy tube, if still present, is considered. A speech pathologist, a physical therapist, and other specialists also evaluate the patient as needed.

Patients generally resume an oral diet approximately 2-3 weeks following discharge if no complications arise. Continuing dental/oral surgical evaluation and management allows for placement of dentures or implants at an appropriate time.

The primary problem with the radial forearm free flap is the cosmetic outcome of the donor site. The surgical defect almost always requires skin grafting. Aggressive attempts at primary closure can result in compartment syndrome, a dreaded complication that can compromise the limb. Methods to decrease the defect size have been reported and may improve cosmetic outcome. Meticulous attention to closure is the most reliable technique for optimizing the cosmetic result the donor site.[6, 7]

Tendon exposure with delayed wound healing has been reported in up to 40% of patients, but basing the flap more on the radial side and covering the tendons with proximal muscle has drastically reduced the frequency of this complication, to less than 10% of cases.[8]

Reports on the use of cadaveric dermis on the wound have been presented. This technique provides a better cosmetic result but may take up to 3 months to heal. A full-thickness skin graft alone has not been shown to increase cosmetic or functional outcome. In our experience, we find that the use of AlloDerm with a split-thickness skin graft over it can provide thicker coverage of the forearm defect, with minimal donor site morbidity and superior cosmetic results compared with a split-thickness skin graft alone (see the image below).[9] Problems with the skin graft donor site are rare, but infection and delayed healing have been documented.

The development of donor site infection or hematomas is possible but rare. The authors do not routinely place drains in the arm, although many surgeons rely on closed-suction drains to evacuate any blood from the midforearm and proximal forearm.

Compartment syndrome is a rare, but serious, problem. The arm should not be closed under significant tension in an effort to avoid a skin graft.

Patients treated with radial forearm free flaps do not usually notice a subjective loss of range of motion or function in the arm. However, an objective decrease in absolute strength can often be measured. Radial forearm osteocutaneous flaps (see the image below) may result in fracture of the radius. Prophylactic intraoperative plating and postoperative casting are of benefit and have minimized this complication.

A study by Emanuelli et al indicated that preoperative physical exam and ultrasonographic findings do not predict donor-site morbidity following the harvesting of radial forearm flaps. Using the modified Cold Intolerance Symptom Severity and Quick Disabilities of the Arm, Shoulder and Hand questionnaires, the investigators found that 20% of donor arms were positive for cold intolerance and that 76% of patients reported extremity-related disability. In neither case did the preoperative results of an Allen test or ultrasonographic evaluation correlate with the outcome.[10]

As with any microvascular surgery, free flap failure is a risk. Flap salvage following venous or arterial thrombosis is possible if early identification of vascular compromise leads to early (urgent) operative intervention. If thrombosis is identified and appropriately managed or if pedicle geometry is optimized after twisting has occurred, the flap may be saved. Thrombectomy and revision of thrombosed vessel(s) are performed if required; occasionally, this necessitates vein grafting.

For flaps with venous congestion, if the patient cannot be returned to the operating room immediately, leeches may be used to temporarily relieve the congestion. (However, this technique should not be considered first line.) Leeches remove the engorged blood from the flap and thereafter allow an artificial venous outflow through the bite they have made in the patient's flap skin. Blood flow through the bite is enhanced by an enzyme, hirudin, found in leech saliva. This enzyme is a powerful anticoagulant and, together with removal of the tiny clot that forms at the bite site, allows flaps to slowly bleed for hours.

Leeches can transmit Aeromonas hydrophila, a gram-negative rod, so patients should prophylactically receive an antibiotic that covers beta lactamase–resistant organisms if leech therapy is used. Blood loss in leech therapy can be significant, and the patient's hemoglobin should be carefully monitored. Leeches are placed directly on the flap at intervals throughout the day. When they are sated, they fall off the flap and are discarded as medical waste.

If one or all of the veins are thrombosed, the arterial anastomosis may be allowed to remain intact at the discretion of the surgeon. The vein can be transected, with venous drainage occurring through the unattached vein. The authors irrigate the artery with Alteplase, which then flows though the flap and out of the unattached vein. Systemic heparin should generally be started in the operating room and continued in the postoperative period for 7 days. Hematomas may develop as a result of anticoagulation. Drains should be placed carefully in the operating room and not removed until the heparin has been discontinued.

The radial forearm flap is extremely reliable. The overall flap success rate of microvascular free tissue transfer in larger series is 90-98%. Nevertheless, all microvascular procedures are dependent on the experience of the surgeon and various patient factors. A take-back rate of 10% is expected, and about half of these flaps are successfully salvaged.

A literature review by Markiewicz et al indicated that there is no difference in flap survival at the recipient site between a variety of microvascular free flaps commonly used for mandibular reconstruction, with the exception of the deep circumflex iliac artery (DCIA) flap. Compared with the radial forearm free flap, according to the study, the DCIA flap has a seven-fold greater chance of failure.[11]

The reliability of the flap and the ability to reinnervate the flap via the MABC or LABC nerves have been well established.[12] The functional implications of such reinnervation have yet to be determined. Techniques for improving donor site morbidity are also being evaluated. Improving cosmesis through different grafting materials and suture techniques will ultimately make this flap even more appealing.

A study by Brinkman et al indicated that in patients who have extensive composite defects due to resection of locally advanced head and neck cancer, acceptable long-term survival and functional outcomes can be achieved with the simultaneous use of two free flaps, including a fibula free flap combined with a radial forearm free flap. Most of the study’s 42 patients underwent double-flap treatment with a combination of either fibula and anterolateral thigh flaps (22 patients) or fibula and radial forearm flaps (14 patients). The postoperative mean 10-item Eating Assessment Tool score was 8.4, while the Intelligibility Rating Scale demonstrated moderate to good speech intelligibility in 90% of patients. Nineteen patients remained alive at mean 55-month follow-up. The complete flap survival rate was 95%.[13]