Radial Forearm Tissue Transfer

Anatomy and Physiology

The radial forearm free flap has a wide variety of tissue transfer options and can be harvested as a fascial, fasciocutaneous, or osteocutaneous flap, with sensory innervation if desired. The skin paddle raised is typically around nine centimeters; however, the entire skin of the forearm can be harvested if needed.[2] The cutaneous paddle is centered over the vascular pedicle, consisting of the radial artery and two venae comitantes and/or cephalic vein.

Distally, this vascular pedicle is located within the intermuscular fascial septum, which separates the flexor carpi radialis and the brachioradialis muscles. Proximally, the pedicle is deep to the brachioradialis muscle. Several vascular perforators supply the muscles, lateral surface of the distal radius bone, and skin. A sensate skin paddle can be achieved by harvesting the medial and/or lateral antebrachial nerves, which are encountered during flap elevation. If osteocutaneous tissue is desired, a 10 to 12 cm segment of the distal radius, with up to 40% of its circumference, may be raised along with accompanying fascial and cutaneous tissue.[3] The palmaris longus tendon may also be harvested as a part of the RFFF and used as a sling in more complex reconstructions in which suspension is needed.

Indications

Defects that commonly require free tissue transfer, with the radial forearm tissue transfer being an ideal donor, include:

• Composite and through and through defects of the oral cavity
• Near-total to total reconstruction for pharyngoesophageal defects
• Large scalp defects
• Salvage surgery after failure of chemoradiation [4]

Contraindications

Radial forearm tissue transfer cannot be considered a reconstructive option for patients who do not show reliable Allen test results of adequate collateral ulnar perfusion to the distal digits when the radial artery is occluded. This test should be repeated up to three times to ensure adequate collateral perfusion. Relative contraindications also include evidence of past surgery or injury to the donor arm.[5] 

Specifically concerning osteocutaneous tissue transfer of the radius, it is not recommended that this bone be used when endosseous dental implants are being considered for the patient. This limitation is due to the recommended 40% of the radial diameter that should be harvested, as larger bone harvests significantly increase the risk of pathologic radius fractures.[6] The non-dominant arm should be used, if possible.

Equipment

The basic equipment for radial forearm free flap harvest must include: individualized to surgeon loupes magnification, bipolar forceps tray, various dissecting tool options that may include Mayo, Stevens, and Metzenbaum scissors, small and medium hemoclip appliers, and a microsurgery instrument tray. Additionally, a dermatome setup must be available for harvesting a split-thickness skin graft. A six-inch latex-free rubber bandage, 18-inch pneumatic tourniquet cuff, and sterile soft roll must all be available for a blood-less dissection and harvest. Two 10 mm suction drains are also necessary at the time of closure. Heparin sodium (5,000 units) in 0.9% 500 ml should be available to irrigate vessels. Papaverine 60 mg in 500 ml 0.9% sodium chloride should be used topically to irrigate and address for vasospasm of the radial artery.

Intraoperatively, a warming blanket should be placed on the patient throughout operative time to keep the body temperature at 37.6 degrees Celcius (99.6 F).

Personnel

Due to its high complexity and long operative times, it is recommended the disease resection and radial forearm free flap reconstruction be undertaken by two microsurgery trained surgeons with consistent experience of the surgical technique. This modality decreases overall morbidity and reduces time under general anesthesia.[7][8] Additionally, an experienced nurse, scrub nurse, and anesthesiologist are vital to the success of this procedure.

Preparation

It is imperative to exclude donor sites with past traumatic injury or surgery in the pre-operative evaluation consultation. The Allen test should also be done in the pre-operative consultation and repeated in pre-operative holding on the day of surgery. The refill of the entire hand in six seconds or less will verify the necessary collateral flow. The communication between the surgical team, anesthesia, and nursing is crucial for the understanding that the donor forearm must not have any IVs or arterial lines. It is necessary to mark the forearm to say "no IVs" and/or "no lines".[9] It is highly recommended to instruct the patient and family that they should not have any needle sticks or IV lines be placed on the forearm in the pre-operative setting. Shaving of the forearm and skin graft donor site should be performed as well to maximize the ideal harvest while minimizing complications. 

Once the patient is brought into the operative suite, and they undergo general anesthesia, the OR table is turned 180 degrees. The donor's arm is placed on an arm board positioned 90 degrees from the body. The arm is then prepped with povidone-iodine or chlorohexidine from the axilla proximally to the distal digits. Sterile towels should be placed against the axilla to separate the flap arm from the rest of the body. The skin graft donor site should also be prepped with povidone-iodine or chlorhexidine and sterile towels placed in all four quadrants.[10]

After the appropriate prepping and draping, a tourniquet is placed around the donor arm superior to the antecubital fossa, and the desired skin paddle pedicle vessels are marked on the forearm. The donor arm is exsanguinated using an Esmarch wrap, and the tourniquet is inflated to the ideal 250 mmHg just before the harvest of the flap.

Technique or Treatment

To achieve a successful harvest and closure of a fasciocutaneous radial forearm free flap, it is imperative to proceed with the following steps: 

1. Begin by elevating the flap toward the flexor carpi radialis, in an ulnar to the radial direction, and superficial to the muscular fascia. Keep in mind that the areolar tissue filling the space between the tendons of the arm and its respective sheaths must be kept intact. Do not incise the proximal aspect of the tissue flap yet. 

2. Continue to elevate the flap from ulnar to radial direction until the brachioradialis tendon is encountered. In this step, it is important to include the cephalic vein with the flap and as well as to identify and preserve the superficial branch of the radial nerve to avoid numbness of its distribution. 

3. Distally, ligate and divide the radial artery and venae comitantes, just proximal to their respective contributions of the palmar branches. An incision is then made at the proximal aspect of the flap, and the flap is elevated in a subdermal plane. This step is crucial to permit the harvest of the proximal subcutaneous tissue while preserving the cutaneous antebrachial nerves that will be part of the flap. 

4. Attention is then focused on the proximal aspect of the skin paddle, and the skin overlying the cephalic vein is incised proximally to the antecubital fossa. Perforating veins and lateral antebrachial cutaneous nerve are identified and are included within the flap. The skin paddle is then elevated off the flexor carpi radialis and brachioradialis while preserving the cutaneous perforator vessels to the flap.

5. Finally, the flap can be raised with its vascular pedicle from distal to proximal by elevating the radial artery and venae comitantes. At this point, the tourniquet can be released, and hemostasis should be meticulously achieved. The flap can be protected with moist towels, and the pedicle should be divided, completing the harvest when the recipient site is ready to accept tissue transfer. 

6. After the flap harvest has been completed, the donor site is closed with the use of a split-thickness skin graft from the thigh. Utilizing the dermatome, the recommended harvesting depth is 0.018 - 0.023 inches. After the harvest of the split-thickness skin graft, epinephrine soaked surgical sponges are placed over the skin graft donor site to achieve hemostasis. The skin graft is used to close the distal aspect of the donor forearm and is inset where the skin paddle of the RFFF was harvested. The proximal aspect of the arm closed in a two-layer fashion after placement of a 10 mm perforated suction drain.

7. Depending on surgeon preference, a non-adherent bolster may be used over the skin graft to apply pressure and allow coaptation for maximal graft take. The donor arm is placed in a volar splint that places the wrist at 45 degrees of extension with care taken to avoid compression of the arm with the placement of the splint.

Complications

Aside from the general complications of microvascular reconstruction, which should be reserved as another topic, the most common complication of this flap is incomplete healing of the skin graft utilized for donor site closure. Less frequent complications include forearm hematoma or seroma, sensory deficits in the distribution of the superficial branch of the radial nerve and weakness, or stiffness of the hand.[11]

The appropriate patient education and expectations by the surgeon regarding the cosmetic outcomes of the donor site are necessary since the skin graft is often discolored for 8 to 12 weeks after surgery. After healing and maturation, the color of the skin graft will improve and more closely match the color of the surrounding forearm skin.

Clinical Significance

Radial forearm tissue transfer provides the ideal microvascular reconstructive option for patients with large defects in the head and neck due to its pliability, accessibility, and reliable anatomy. These flap characteristics are what make radial forearm tissue transfer a workhorse in microvascular reconstruction.

Enhancing Healthcare Team Outcomes

The radial forearm free flap is an incredibly versatile option for head and neck reconstruction and is an excellent option when performed at the hands of an experienced microvascular surgeon. Otolaryngologists, head and neck surgeons, and plastic surgeons should regularly consider this reconstructive option for a myriad of tissue defects, and it is the responsibility of clinicians without microvascular training and expertise to refer the appropriate patient to such surgeons that can provide this excellent treatment option. Communication between nursing, anesthesia, and the surgeon should be a frequent theme throughout the preoperative, perioperative, and post-operative stages to achieve maximal benefit and minimal morbidity. The microvascular surgeon should have a thorough discussion with the patient regarding the surgery and its benefits, risks, and expectations to achieve an excellent outcome.[10] [Level 3]