Continuing Education Activity

The osteocutaneous radial forearm flap is a variant of the fasciocutaneous radial forearm free flap wherein partial thickness of the radius is harvested and perfused by preserving the lateral intermuscular septum and the perforating vessels to the bone. This activity reviews osteocutaneous radial forearm free flaps and highlights the role of the interprofessional team in managing patients undergoing this procedure.

Objectives:

• Identify the indications for osteocutaneous radial forearm free flap transfer.

• Describe the technique of osteocutaneous radial forearm free flap transfer.

• Review the potential complications of radial forearm free flap transfer.

• Discuss interprofessional team strategies for improving care coordination and communication to advance the utilization of osteocutaneous radial forearm free flaps and to improve outcomes.

Introduction

Originally introduced by Dr. Yang and Dr. Gao at the Shenyang Military Hospital in the early 1980s, the radial forearm free flap has since been popularized as a workhorse flap. Though generally raised as a fasciocutaneous flap, the radial forearm is extremely versatile and can also be harvested as an adipofascial flap or with bone from the radius as an osteofasciocutaneous flap. Many studies have demonstrated the benefits of the radial forearm flap in intraoral reconstruction.[1][2][3][4][5] The osteocutaneous radial forearm free flap (OCRFFF) is most commonly used in head and neck reconstruction. It is a good option for bony reconstruction of the mandible or midface.[6]

The osteocutaneous radial forearm flap is a variant of the fasciocutaneous radial forearm free flap wherein partial thickness of the radius is harvested and perfused by preserving the lateral intermuscular septum and the perforating vessels to the bone. Alternatives to this flap include the osteocutaneous fibular free flap, osteocutaneous scapular free flap, and the osteocutaneous iliac crest free flap. The advantages of the osteocutaneous radial forearm free flap are its skin paddle thinness, pliability, long vascular pedicle, and reliable vascular anatomy. The disadvantages of this flap center around the donor site morbidity relative to the size and quality of bone available for harvest. The osteotomized bone is at risk of fracture and causes reduced strength and function in the operated wrist. This article discusses the details of the procedure, as well as the risks and benefits of using this flap in order to facilitate its thoughtful utilization. 

Anatomy and Physiology

The arterial supply for the osteocutaneous radial forearm flap is the radial artery. Both the radial artery and the ulnar artery arise from the bifurcation of the brachial artery within the antecubital fossa. This bifurcation is the uppermost limit where the artery can be taken for microvascular anastomosis without compromising the distal extremity. The average diameter of the artery at that point is about 3 mm. The average length of the pedicle ranges between 14 cm and 22 cm in an adult. The vascular pedicle of the free flap sits in the lateral intermuscular septum between the brachioradialis muscle and the flexor carpi radialis. The flap's skin paddle is centered over the distal one-third of the lateral forearm, wherein lie the fasciocutaneous perforators from the radial artery to the skin paddle. The periosteal feeding vessels from the radial artery to the radius lie within the lateral intermuscular septum as well, and it is important to avoid disrupting the architecture of the septum to ensure the harvested bone has an adequate blood supply.

Patient candidacy for this flap is determined by the viability of the distal extremity (i.e., the hand and digits) with only the ulnar artery supplying it. The radial artery ultimately ends in the distal wrist, where it enters the hand as the deep palmar arch. The ulnar artery ends in the distal wrist as the superficial palmar arch. The flow between the superficial and deep palmar arches is what connects the blood supply from radial and ulnar arteries in the hand. Severeal different patterns of vascular anastomosis between the superficial and deep palmar arches have been described.[7][8][9] Generally speaking, if the palmar arch system is complete, the distal extremity can survive on either the radial artery or ulnar artery alone. If the arch is incomplete or the distal extremity is dependent primarily on arterial inflow from the radial artery (e.g., in the case of traumatic transection of the ulnar artery), harvest of a radial forearm free flap might result in an ischemic hand, and the flap is contraindicated.

A variety of clinical tests can be performed to assess the viability of the distal extremity on ulnar arterial flow alone.[10][11][12] The simplest is the Allen test (see Video. Modified Allen Test). the hand is elevated and clenched for 30 seconds, then the radial and ulnar arteries are compressed. The palm of the hand is opened and should appear blanched. Ulnar artery compression is released (while maintaining radial artery compression), and the palm of the hand is assessed for a speedy return of color. If the palm of the hand, thenar eminence, and fingers return to their natural color within 5 seconds, it suggests that the palmar arch is complete and the hand can survive on ulnar arterial flow only. A more sophisticated test would be to perform an Allen test with an oximeter on the thumb (most distal from the ulnar artery) to assess the waveform after the release of ulnar artery compression. If the waveform on the oximeter is dampened or delayed after the ulnar artery release, it may suggest an incomplete arch. Another useful test is an upper extremity Doppler study with compression of the radial and ulnar arteries. If raising an OCRFFF poses an ischemic threat to the distal extremity, an alternative reconstruction should be considered.

The primary venous drainage of the flap is provided by paired venae comitantes that run with the radial artery in the deep venous system of the flap between the brachioradialis muscle and the flexor carpi radialis. The skin paddle may also drain through a superficial venous plexus into the cephalic vein. This superficial system lies superficial to the brachioradialis muscle and will often join the deep system just distal to the antecubital fossa. The venous system may be harvested and anastomosed as a single system or split into primary (deep) and secondary (superficial) systems to drain the flap. These separate systems allow for the use of one single or two independent drainage systems in the neck (e.g., facial vein and external jugular vein). The typical length of the venous pedicle is about 18 to 20 cm.

The superficial branch of the radial nerve is a sensory nerve that provides cutaneous innervation to the thumb and dorsal hand and is a consistent landmark in radial forearm flap harvest. It is important to identify this nerve in order to reduce morbidity. The nerve is identified in the distal wrist during the elevation of the skin paddle along the radial/lateral aspect. The identity of the nerve can be confirmed by tracing it back to where it emerges from the brachioradialis muscle. It is common to have some degree of cutaneous anesthesia around the thumb postoperatively, due to intraoperative manipulation of sensory nerve branches from the superficial branch of the radial nerve entering the skin paddle, but long-term numbness of the thumb results from a technical error intraoperatively.

The lateral antebrachial cutaneous nerve provides sensation to the lateral half of the volar forearm. This nerve is usually transected, and with little consequence, because the skin it innervates is harvested as the skin paddle. At the recipient site, however, the nerve can be used to provide a sensate flap.

A large skin paddle can be harvested, but it too has limitations. Nearly all the skin of the forearm can be harvested and supplied by the radial artery, but doing so would significantly alter lymphatic drainage of the hand. A 3-5 cm wide strip of skin should be preserved on the posterior extensor compartment to avoid lymphedema in the hand. Up to 30 cm of skin can be harvested along the length of the forearm, with a maximum width of about 15 cm. Primary closure can be achieved with skin paddle widths of 1-2 cm. Most OCRFFFs harvested for head and neck reconstruction have skin paddles too large for primary closure of the harvest site defect and generally require a skin graft. Additionally, when harvesting an osteocutaneous radial forearm free flap instead of a fasciocutaneous flap, is important to preserve the distal forearm skin at the level of the styloid process of the radius so as to minimize the chance of hardware complications after the radius is plated. With the fasciocutaneous flap, the distal forearm incision is made within a crease distal to the styloid process of the radius. In the osteocutaneous version of the flap, the distal incision should be placed on the forearm 1-2 cm more proximal. Alternatively, the incision may be placed in the crease, and the pronator quadratus muscle may be used as a flap to cover the distal plate.

One of the disadvantages of OCRFFF harvest is donor site morbidity, the magnitude of which correlates with the size and quality of the harvested radius. The radius is critical to wrist and hand function. The length of harvestable bone is limited to 10-12 cm, depending on where the pronator teres muscle inserts on the radius. This muscle can be released at its insertion point in order to gain additional bone length, but doing so increases the risk of postoperative morbidity, especially with the flexor digitorum, flexor pollicis longus, and pronator quadratus already being incised in order to harvest bone. If it must be disrupted, the pronator teres should be resuspended from the reconstruction plate after bone harvest is complete. The partial thickness segment of the radius harvested is generally limited to 40-50% of the cross-sectional area of the bone.[13] The amount of bone that can be harvested varies on a case-by-case basis. Like the rest of the skeleton, the radius responds to mechanical stimuli; patients with heavy-loading stimuli to the radius (e.g., weight lifting, manual labor, youth versus older age) may have larger and stronger bones.[14] The amount of bone that can be surgically harvested from an active, tall 50-year-old male patient with occupational or recreational demands may differ greatly from a 75-year-old, short, female patient.

Biomechanical studies have investigated the effect of partial radial ostectomy in the context of the OCRFFF. One study demonstrated that, compared to an intact cadaveric human radius, the radius that remained after partial thickness harvest had a breaking strength of 24% that of the control group.[15] Another study on sheep tibias looking at torsional strength demonstrated that ostectomized bone strength was decreased by 70%.[16] A 1990 study with 17 osteocutaneous radial forearm flaps quoted a fracture rate of 23.5%.[17] That study advocated for the boat-shaped osteotomy over right-angled cuts to reduce the incidence of fracture. A cadaver study in 2000 looked at the biomechanics of prophylactically plating the radius after ostectomy/bone harvest. Right-angled osteotomies were done. They found that the addition of a reconstruction plate significantly strengthened the ostectomized radius to torsion and bending. Since that study, prophylactic plating has become the standard, with several series showing a significantly lower rate of fracture.[18][19][20][21][20] In fact, a 2013 study by the same group that first advocated prophylactic plating reviewed their series of 167 consecutive osteocutaneous radial forearm flaps, all plated after ostectomy, and had just 1 fracture.[22]

Indications

The most common indication for osteocutaneous radial forearm free flap is the osseous reconstruction of the mandible and maxilla. The amount of radial bone harvested is generally limited. It is best used in short segment mandibular and maxilla reconstruction, but its thickness is insufficient to support dental implant placement. Similarly, the osteocutaneous radial forearm can be used to augment bone in the extremities, but the thin bone stock limits its use.[23] The OCRFFF has been used in nasal reconstruction, frontal sinus reconstruction, and airway reconstruction.[24] It has also more recently been used in phalloplasty.[25][26][27][28]

Contraindications

Contraindications to microvascular surgery, in general, are applicable to patients being considered for osteocutaneous radial forearm free flap reconstruction. Contraindications specific to the OCRFFF include the following:

1. High risk of distal extremity ischemia with blood supply from the ulnar artery only.
2. High risk of flap failure due to an insufficient radial artery.
3. Inability to support a free flap with recipient site blood vessels.
4. Inability to reconstruct the defect with 10 to 12 cm of bone.
5. Requirement to place dental implants into the transferred bone.

As discussed in a previous section, the harvest of the OCRFFF also includes the harvest of the radial artery. After harvest of the radial forearm free flap, the remaining blood supply to the hand is based solely on the ulnar artery and the network of collateral flow between the superficial and deep palmar arch. The absence of ulnar artery inflow (e.g., traumatic injury, profound peripheral vascular disease, arterial agenesis) or the suggestion of an incomplete arch are contraindications to harvest the OCRFFF. Likewise, insufficient blood flow in the radial artery is a contraindication to use of the radial forearm free flap. Example etiologies of arterial insufficiency include injury to the radial artery (e.g., trauma, peripheral vascular disease), congenital absence of the vessel, and thromboembolic or hypercoagulable states. If the radial artery is damaged or absent due to these conditions, the flap will not be viable.[29]

If the flap can be harvested, the recipient site must be able to receive the flap. There are a number of arteries in the neck suitable for microvascular anastomosis, including branches of the external carotid system and the thyrocervical trunk vessels. If the neck is depleted of these vessels, one can turn to the contralateral neck because of the length of the vascular pedicle. If both necks are vessel-depleted, the internal mammary artery can be dissected and rotated superiorly into the neck to serve as a recipient vessel. If the use of the internal mammary artery is the primary reconstructive option to perfuse the OCRFFF, patient health and other factors may point toward aborting free flap reconstruction in favor of a regional flap, such as the pectoralis major flap or a construct using a plate wrapped with soft tissue.

The size and quality of the bone harvested are also significant limiting factors in the use of this flap. Reconstructions that require more than 10 to 12 cm of bone, such as a total mandibulectomy, cannot be reconstructed with a single OCRFFF. The thickness of the bone is also limited. Under optimal conditions, the fibular free flap is preferred for bony reconstructions. It offers many of the same qualities the OCRFFF does; it is pliable, thin, and has a long pedicle. It has the added advantage, however, of greater bone stock thickness, and most lower extremity weight-bearing is on the tibia, not the fibula. The fibular free flap similarly requires that blood flow to the distal extremity (i.e., the foot) be sufficient after the loss of the contribution of the peroneal artery. This might not be a major issue in a young trauma patient needing osseous free flap reconstruction. However, head and neck cancer patients, who may have smoking-related vasculopathy, be of older age, and may have other medical comorbidities, may have insufficient blood flow to the distal extremity (or through the peroneal artery) to support the fibular flap as a viable reconstruction option. It is not uncommon for a vascular study to contraindicate the use of the fibular flap, leaving the osteocutaneous radial forearm, scapular/parascapular flaps, or iliac crest flap as the next option. Each of these reconstructive options has advantages and disadvantages associated with it.

Patients with previous trauma to the wrist and prior wrist surgeries should be approached carefully, athough an history of wrist surgery is not an absolute contraindication to use of the OCRFFF. As flap harvest can alter manual dexterity, the author's preference is to harvest from the non-dominant hand. However, the preoperative assessment may favor raising the flap from the dominant arm due to vascular considerations. The need to harvest a flap from the dominant upper extremity could be considered a relative contraindication in the eyes of the surgeon. Similarly, occupations and hobbies with high demand for manual dexterity can be considered relative contraindications to this procedure.

Other patients may have medical comorbidities that increase their risk for flap failure. These include, but are not limited to, severe peripheral vascular disease, coagulopathies, and cardiovascular disease. Patients with severe peripheral vascular disease present a higher risk of flap failure due to vessel stenosis, intimal disease, poor vessel pliability, baseline inflammatory state, and hypercoagulability. Patients with hypercoagulable pathologies, such as Factor V Leiden thrombophilia, also present an increased risk of flap failure with thrombosis of the vessel anastomosis or clotting within the microcirculation of the flap itself. Smokers also have an elevated risk of microvascular free flap failure. Nonetheless, patients with these conditions have frequently undergone successful microvascular reconstructive procedures.

Cancer patients with multiple, severe medical comorbidities may not be healthy enough to undergo lengthy microvascular operations and may opt for alternative reconstructive options instead. For patients with multiple medical comorbidities, the risks and benefits of microvascular reconstruction may need to be weighed against a functionally or cosmetically suboptimal, but lower risk (and perhaps more reliable), pedicled flap. An example would be a mandibular reconstruction bar wrapped with a pectoralis myofasciocutaneous flap.

Equipment

The following equipment is needed:

• Soft tissue set
• Microvascular set
• Operating microscope
• Surgeon preference osteotomy instruments
• Tourniquet (optional)
• Instruments for prophylactic plating of the radius (strongly recommended)

Personnel

Essential personnel for this procedure includes the primary surgeon, 1 or 2 surgical assistants, circulating/operating room nurse, surgical technologist, and an anesthesiologist experienced in providing general anesthesia for lengthy, microvascular surgical cases.

Preparation

The patient is intubated, and the airway is secured. The flap is harvested under general anesthesia. 

Allen Test

An Allen test is performed on the extremity from which the flap will be harvested. The arm is elevated, and the palm of the hand is blanched by informally exsanguinating the hand and quickly applying pressure to the ulnar and radial arteries. With the palm blanched, ulnar artery compression is released and palmar rubor is evaluated. If the palm turns pink or red within five seconds, it suggests that there is a complete palmar arch that can support the distal extremity on ulnar artery blood flow alone. THe Allen test is best performed when the patient is warm; if the patient is cold, the hand's perfusion may appear worse than it actualy is.

It is the author’s preference to use the Doppler as an adjunct to the Allen test as well, especially if refill to the palm is sluggish. This test is ideally performed with two people. The assistant uses the Doppler on the palm of the hand to confirm a distal extremity pulse. The ulnar and radial arteries are then compressed by the surgeon, and the Doppler should go silent due to a lack of arterial inflow. The ulnar artery is then released, and the Doppler signal should resume with the pulse. If there is no return of pulse, the radial artery should be tested by confirming a pulse on the hand with the ulnar artery compressed. If the Doppler detects a pulse on the distal extremity with the ulnar artery compressed, the hand is supplied by the radial artery predominantly, and radial forearm flap harvest should be aborted in favor of another reconstructive option. One disadvantage of this method is that it cannot detect the rare instance of an incomplete superficial palmar arch. The Doppler should be used in conjunction with the Allen test to confirm the signs of capillary refill to the entire hand from the ulnar artery alone. If there is concern about the ability of the distal extremity to rely solely on the ulnar artery, the flap should be aborted in favor of a different reconstructive option.

Patient Positioning

As the majority of osteocutaneous radial forearm free flaps are used in head and neck reconstruction, the patient is usually in a supine position with the patient’s head at the top edge of the bed. The neck is generally extended with a shoulder roll, and one or two belt straps are used to secure the patient to the bed. The arm from which the flap will be harvested is left untucked and placed on an arm board. It is the author’s preference to harvest the flap on a pivoting arm board, as opposed to a hand surgery table, when the free flap is being harvested for head and neck reconstruction. The arm board has a smaller, slimmer profile, which reduces the displacement of the ablative surgeon or assistant from the head and neck if they are operating on the same side as the flap harvest; it will also move along with the operating table, thereby obviating the need to reposition it independently if the abltaive surgeon requires repositioning of the operating table. A hand surgery table, when attached to the operating table, can extend superior to the shoulder and even to the same level as the neck, which can displace the ablative surgeon or assistant from the optimal operating position.[29]

Tourniquet Set-Up

A tourniquet may be placed in an unsterile or sterile fashion. If placed in an unsterile fashion, a cotton undercast is wrapped loosely around the biceps. A size-appropriate tourniquet is then fastened around the cotton undercast. If the tourniquet is placed in a sterile fashion, the entire arm is circumferentially sterilely prepped from the shoulder to the hand.

Sterility

The patient is prepped based on surgeon preference and patient allergies. If the tourniquet was placed in a non-sterile fashion, it is important to drape so as to keep the tourniquet from contaminating the field. If the tourniquet is placed in a sterile fashion, the arm should be circumferentially prepped from the shoulder to the hand. The arm and the operating table extension where the flap will be harvested are draped. Antibiotics are administered prior to skin incision. The antibiotic and dose are determined by surgeon preference.

Technique or Treatment

The procedure can be done under tourniquet ischemia in an exsanguinated or unexsanguinated arm or without the tourniquet at all. Some surgeons prefer to perform this procedure on an exsanguinated arm under a tourniquet set to 250 mmHg for no more than two hours. If desired, the arm can be exsanguinated with an Esmarch wrap prior to tourniqet inflation.

The skin paddle is designed around the radial artery. The distal incision of the skin paddle is placed proximal to the head of the radius (typically, for a fasciocutaneous radial forearm free flap, the distal incision will be placed in a transverse wrist crease, distal to the head of the radius). The skin paddle is placed on an island by cutting through the skin and subcutaneous fat around it in order to identify the fascia of the muscles of the forearm. Medially, the flexor carpi radialis and palmaris longus are identified. Subfascial or suprafascial dissection can be carried out to just short of the lateral border of the flexor carpi radialis muscle belly. Laterally, the brachioradialis muscle is identified; also encountered are the distal cephalic vein and the superficial branch of the radial nerve. Incisions made along the proximal edge of the skin island are also made down to the flexor carpi radialis and brachioradialis muscles; care should be taken during this step, as the cephalic vein is likely to be encountered again. Preservation of the vein may provide a secondary drainage system for the flap. The final incision around the skin paddle is on the distal forearm. The incision is made through the skin and subcutaneous fat. The distal pedicle is found amongst the deep fibrous band of tissue in the distal forearm.

A lazy-S incision is made from the proximal aspect of the skin paddle to the antecubital fossa, through the skin and subcutaneous fat. The fascia of the brachioradialis and the flexor carpi radialis are identified. Medially, flaps are elevated over the flexor carpi radialis muscle fascia. Laterally, flaps are elevated over the brachioradialis muscle fascia. The superficial drainage system generally runs over the brachioradialis; it is dissected out and followed proximally where it can commonly be seen diving to join the deep venous system just distal to the antecubital fossa in the so-called "rat's nest" of venous anastomoses. The septum between the flexor carpi radialis and brachioradialis muscle bellies is opened to expose the radial artery and the venae comitantes that provide inflow and primary outflow to and from the flap, respectively. The vascular pedicle is then isolated by ligating its branches and tributaries along its length. As the skin island is approached, care is taken to preserve deep branching tributaries that may be periosteal feeding vessels to the radius.

At this point, the skin island of the flap can be elevated off the muscles of the forearm. If there is any concern at the start of the procedure of a non-viable distal extremity, an intraoperative Allen test can be performed by placing an Acland clamp on the radial artery at the distal wrist and releasing the tourniquet. This test demonstrates the conditions of ulnar-only artery flow to the hand. If there is a clinical suggestion of ischemia, the flap is aborted. Of course, this test can be done at any time during the procedure, based on the surgeon’s preference. If the surgeon is otherwise confident about the hand’s ability to perfuse the ulnar artery alone, the procedure can be continued by ligating the distal venae comitantes and the radial artery. A silk suture is used to ligate the radial artery with a long tail placed on the flap side to facilitate observation of pulsations in the distal flap after the tourniquet is released and after microvascular anastomosis is completed. With the pedicle, the distal skin island is elevated off the tendons of the brachioradialis and flexor carpi radialis, taking care to maintain the integrity of the paratenons in order to prevent the tendons from adhering to the skin graft postoperatively.

Along the lateral aspect of the skin island, the distal cephalic vein is ligated. The superficial branch of the radial nerve is identified and preserved as much as possible. Some of the nerve branches may be seen diving into the flap and may need to be sacrificed. Along its proximal course, the nerve will be seen diving underneath the brachioradialis muscle. Dissection is then performed along the medial aspect of the brachioradialis muscle with the recruitment of the soft tissues of the lateral intermuscular septum. Paratenon should be preserved during this step to reduce the risk of postoperative tendon complications. The brachioradialis is laterally retracted, and the fibrofatty tissue deep to the muscle belly and tendon is recruited into the flap. It is within this fibrofatty tissue that periosteal feeding vessels are located. Care is taken not only to preserve this drape of fibrofatty tissue but also to preserve the deep course of the superficial branch of the radial nerve. The radius and the deep muscles of the forearm should be in view at this time. The pronator teres muscle defines the proximal limit of bone that can be harvested. Along the medial aspect of the radius, the flexor digitorum superficialis, flexor pollicis longus, and pronator quadratus are transected, each muscle being divided close to the bone. The tourniquet is released. Hemostasis is obtained and attention is then turned to the osteotomies.

How the osteotomies are performed depends upon the surgeon's preference. It is the author's preference to perform right-angle cuts to remove a rectangular block of bone through the distal and proximal limits of the osteotomies, as opposed to a “canoe boat” or “keel-boat” which is often described. When exposing the bone for osteotomy, care is taken to preserve the periosteum over the bone. The length of the bone to be harvested is delineated. The limits of the bone harvest are the head of the radius distally and the insertion of the pronator teres muscle proximally. Roughly 50% of the height of the radius is identified by visual inspection and palpation with the arm pronated and supinated. A scalpel can be used to incise the periosteum and mark the planned osteotomies. Osteotomies can then be made with the saw along the incised periosteum. Care should be taken during the completion of the vertical osteotomies to avoid pass-cutting into the residual radius.  Doing so can weaken the bone that remains after graft harvest. Once the osteotomies are complete, the flap can be elevated out of the forearm, pedicled by the vascular bundle feeding it.

The proximal venous and arterial anatomy is then defined prior to ligation and start of flap ischemia time. The deep (primary) and superficial (secondary) venous systems often come together to create a single, large-caliber vein for anastomosis. The radial artery is followed distally to proximally, where two bifurcations can be observed. The more distal bifurcation is between the radial artery and the recurrent radial artery; the more proximal bifurcation is between the radial artery and the ulnar artery at the termination of the brachial artery. This point is the uppermost limit of where the radial artery can be taken. Injury to the proximal ulnar artery creates an elevated risk of distal ischemia. Often times, taking the radial artery just distal to the branching point of the recurrent radial artery provides ample length and vessel caliber for microvascular anastomosis. It also avoids the risk of injury to the ulnar artery. Once the flap is ready to be transferred, the donor vein and artery are ligated, and the flap becomes ischemic. The flap is then inset according to the reconstruction planned, and microvascular anastomosis is performed.

Prophylactic plating of the radius is strongly recommended, because the radius is significantly weakened by the partial thickness ostectomy. Though the reconstructive surgeon may perform the plating of the forearm, many prefer to have an orthopedic surgeon plate the forearm, if one is available.

For closure, a suction drain is placed in the proximal forearm. The lazy-S is incision is closed in layers according to the surgeon's preference. The plate can be covered by advancing the remaining muscle bellies of the transected flexor digitorum superficialis and the flexor pollicis longus muscle to the brachioradialis tendon. A skin graft is harvested from the thigh and inset to the skin island defect. Negative pressure therapy or a bolster is placed in order to improve the chance of skin graft survival. The wrist is then wrapped and immobilized in a cast for 7 days.

Complications

The fasciocutaneous radial forearm free flap is, in general, a very reliable flap with a very high success rate, which is why it is a workhorse flap. The modification to preserve the lateral intermuscular septum and the periosteal feeding vessels, as well as include a partial thickness segment of radial bone, does not significantly affect the success rate of the use of this flap. 

As with all microvascular procedures, flap failure at the microvascular level is the most concerning complication. Surgeon experience, operative technique, and vessel geometry are important factors that contribute to success or failure. Flap failure can be arterial or venous in nature. Situations in which vessel geometry may lead to kinking, obstruction, or excessive tension should be avoided. Thoughtful flap inset is particularly important when mucosal incisions are being sealed to avoid the effects of a potential salivary fistula on the microvascular anastomosis. However, even in the setting of a smooth, well-scripted surgical procedure, there are many patient and patient care factors that can contribute to a failed free flap intraoperatively and/or postoperatively. Identifying those factors and avoiding them is key to reducing complications and length of hospitalization. Early recognition of flap failure may also salvage a compromised flap; otherwise, secondary or replacement reconstruction may be necessary. In a study by Mirzabeigi et al., they reviewed a series of 2260 microvascular flaps with a 3% take-back rate for delayed microvascular compromise, and had a 49% salvage rate.[30]

Regarding the harvested radial bone graft, fracture, malunion, nonunion, insufficient bone, and bony resorption are also potential risks. Hardware complications, such as plate infection or extrusion, may occur as well. Other recipient site complications include delayed healing, wound breakdown, and poor cosmesis. Wound healing problems may necessitate secondary procedures or reconstructions.

At the donor site, the most devastating complication with any radial forearm free flap is ischemia to the hand, which is rare, fortunately. There are several preoperative and intraoperative tests to help avoid this complication. Injury to the superficial branch of the radial nerve can result in the development of painful neuromas in the forearm. The skin paddle site is often closed with a skin graft, which can be cosmetically displeasing to the patient. Full-thickness skin grafting or augmenting the wound bed with a synthetic dermal regeneration matrix prior to placing a split-thickness skin graft may decrease the likelihood of aesthetic dissatisfaction. Skin graft failure is another potential complication, which may occur as a result of hematoma, denuded tendons, poor wound healing, and/or infection. Delayed skin graft failure may present in conjunction with tendon exposure. Aggressive recruitment of tissue into the flap during harvest, particularly in preserving the perforators to the radius, may injure or denude the brachioradialis tendon or its paratenon, thereby increasing the risk of tendon exposure or injury.

Other complications more specific to the osteocutaneous radial forearm result from loss of radial bone strength, as well as from myotomies of the flexor digitorum superficialis, flexor pollicis longus, and pronator muscles. Biomechanical studies confirm significant loss of strength accompanies loss of radial bone thickness. The risk of pathologic fracture of the radius is higher after radial ostectomy. Prophylactic plating is recommended to reduce the risk of fracture. Plate infection and/or exposure is possible in the donor forearm but is fortunately quite rare.[22] Very little objective or quality of life data have been published with respect to the functional effects of wrist muscle myotomy after OCRFFF. A study in 1994 assessed a small series of consecutive OCRFFF patients for functional deficits; it found a high incidence of decreased pronation, flexion, and extension.[31] Key pinch strength on the operated forearm was a mean of 74% of the non-operated hand. Another study in 2012 also sought to examine the overall effect of the donor site morbidity from this procedure. The investigators concluded that there was minimal objective donor site loss of function. They also stated that mild wrist weakness and stiffness are common but do not significantly impact the activities of daily life.[21] 

Few studies compare complications of the OCRFFF to other osteocutaneous reconstructive options. A retrospective study of 168 patients looked at differences between the osteocutaneous radial forearm and the osteocutaneous fibular flap. The OCRFFF was more commonly used in older patients (63.7 versus 59 years of age). Flap failure rates were similar (~3-4%). In their series, the donor site complication rate was higher in the fibular free flap group (4.3%) versus the OCRFFF group (0%).[20] Another group in 2018 performed a comprehensive literature search to assess morbidities comparing the OCRFFF, fibular free flap, scapular free flap, and the iliac crest free flap. They concluded that the radial forearm and fibular osteocutaneous flaps had the highest rates of delayed healing, nearly double that of the scapular flap and quadruple that of the iliac crest. They reported that the OCRFFF had the highest rates of chronic pain (16.7%) and dissatisfaction with scar appearance (33%). They, too, concluded that the OCRFFF placed no significant limitations on daily activities but advocated the scapular flap over the fibular and osteocutaneous radial forearm flaps.[32] The OCRFFF may not always be the ideal or first choice for reconstruction; however, it is an excellent option for reconstructive surgeons to have in their armamentaria.

Clinical Significance

The radial forearm free flap is one of the most commonly utilized reconstructive modalities in the head and neck. The ability to harvest a partial thickness segment of radial bone for an osteocutaneous radial forearm free flap provides a powerful, versatile option in the armamentarium of the reconstructive surgeon. It is an alternative to other osseous free flaps, namely, the fibular, scapular, and the iliac crest free flaps. Understanding the advantages, disadvantages, and complications associated wtih each reconstruction can help the surgeon and patient set realistic expectations and optimize the outcomes of surgery.

Enhancing Healthcare Team Outcomes

Teamwork involving the surgeon, anesthesiologists, OR nurse, scrub technician, and recovery nurse will result in the best outcomes. Perhaps most important to the survival of the flap in the early postoperative period is the experience of the critical care nurses who will be taking care of the patient and performing regular evaluations of the flap's viability. Experienced nurses who are supported by a responsive surgical call team are more likely to recognize early signs of vascular insufficiency in the flap, generally venous congestion, and are therefore more likely to appropriately request an evaluation by a microvascular surgeon, who can then salvage the flap in a timely fashion, if necessary. Delay of more than 6-8 hours between cessation of adequate blood flow to the flap and restoration of perfusion carries with it a very high risk of flap death, which will then often require that the patient undergo a secondary reconstructive procedure.[33]  [level 3]