**5. Radial forearm flap**

As the radial forearm flap was originally developed in China, it is often named the China flap. [13] Primarily this flap was introduced as a large flap incorporating most of the circumference of the forearm and was applied as a free flap to cover burns contractures, mainly in the head and neck. [14] The radial forearm flap is a good flap for intraoral reconstruction, offering thin, pliable predominantly hairless skin to replace oral mucosa. The vascularity of the area allows considerable variation in the design of this fasciocutaneous flap and offers the possibility of including bone as an osteocutaneous flap. Furthermore, the vascular anatomy of the flap simplifies the technical aspects of free tissue transfer. Based on ten clinical cases the design of the flap is described and its versatility in differing clinical situations is illustrated. [15] The rich vascularity of the flap results in rapid healing and minimizes wound healing complications, and there is a potential for sensory reinnervation. The flap can be harvested at the same time of tumor surgery. [13]

The radial forearm flap has mostly been used to reconstruct the oral floor, tongue and the maxilla [16] (Figure 2). The osteocutaneous radial flap is robust, reliable, and relatively simple to harvest, which will ensure that it remains one of the established reconstructive options in most maxillofacial units. Many surgeons prefer to use a limited number of trusted flaps, and these qualities will ensure that in the intermediate future most surgical trainees will continue to be shown the fasciocutaneous radial flap as both the basic training flap and the established option for reconstruction. Evidence from observational clinical studies and one randomized clinical trial indicates that there is increasing support for the use of the evolutionary technique of suprafascial dissection to minimize morbidity at the donor site. The suprafascial donor site may be repaired with either a meshed or unmeshed partial-thickness skin graft, or a fenestrated full-thickness skin graft, with good rates of successful healing. The application of a negative pressure dressing to the wound seems to facilitate the healing of all types of skin grafts. The subfascial donor site, however, remains more prone to complications. It may be helpful to position the donor site of the flap more proximally, but this has not been proven. These refinements probably produce the best outcomes that can currently be achieved, given the inherent flaws of the radial donor site.[17] Evidence based on clinical observational studies and biomechanical studies supports the routine or selective use of prophylactic internal fixation to strengthen the radial osteocutaneous donor site. This allows safe harvesting of the maximum volume of available bone, up to half of the circumference, with minimal risk of fracture or long term complications. The incidence of fracture with the plate placed either anteriorly or posteriorly is equally low, but the anterior position is technically easier and probably less likely to cause additional morbidity. The introduction of prophylactic internal fixation consolidates the role of the osteocutaneous radial flap for repair of defects that require a relatively small volume of bone and an appreciable area of thin soft tissue, particularly when a long vascular pedicle is desirable. This includes low level defects of the maxilla, some defects of the mandible and niche reconstructions, such as the orbital rim. The radial forearm flap remains useful as a first choice when there is appreciable peripheral vascular disease, when there are other serious coexisting medical conditions, when it is the preferred choice of the patient for functional reasons such as mobility of the lower limb or hip or when it is a salvage flap used when other reconstructive options have been exhausted. [18]

**Figure 2.** A radial forearm flap used to reconstruction of tongue after hemiglossectomy.

#### **5.1. Flap anatomy**

of the forearm and was applied as a free flap to cover burns contractures, mainly in the head and neck. [14] The radial forearm flap is a good flap for intraoral reconstruction, offering thin, pliable predominantly hairless skin to replace oral mucosa. The vascularity of the area allows considerable variation in the design of this fasciocutaneous flap and offers the possibility of including bone as an osteocutaneous flap. Furthermore, the vascular anatomy of the flap simplifies the technical aspects of free tissue transfer. Based on ten clinical cases the design of the flap is described and its versatility in differing clinical situations is illustrated. [15] The rich vascularity of the flap results in rapid healing and minimizes wound healing complications, and there is a potential for sensory reinnervation. The flap can be harvested at the same time

The radial forearm flap has mostly been used to reconstruct the oral floor, tongue and the maxilla [16] (Figure 2). The osteocutaneous radial flap is robust, reliable, and relatively simple to harvest, which will ensure that it remains one of the established reconstructive options in most maxillofacial units. Many surgeons prefer to use a limited number of trusted flaps, and these qualities will ensure that in the intermediate future most surgical trainees will continue to be shown the fasciocutaneous radial flap as both the basic training flap and the established option for reconstruction. Evidence from observational clinical studies and one randomized clinical trial indicates that there is increasing support for the use of the evolutionary technique of suprafascial dissection to minimize morbidity at the donor site. The suprafascial donor site may be repaired with either a meshed or unmeshed partial-thickness skin graft, or a fenestrated full-thickness skin graft, with good rates of successful healing. The application of a negative pressure dressing to the wound seems to facilitate the healing of all types of skin grafts. The subfascial donor site, however, remains more prone to complications. It may be helpful to position the donor site of the flap more proximally, but this has not been proven. These refinements probably produce the best outcomes that can currently be achieved, given the inherent flaws of the radial donor site.[17] Evidence based on clinical observational studies and biomechanical studies supports the routine or selective use of prophylactic internal fixation to strengthen the radial osteocutaneous donor site. This allows safe harvesting of the maximum volume of available bone, up to half of the circumference, with minimal risk of fracture or long term complications. The incidence of fracture with the plate placed either anteriorly or posteriorly is equally low, but the anterior position is technically easier and probably less likely to cause additional morbidity. The introduction of prophylactic internal fixation consolidates the role of the osteocutaneous radial flap for repair of defects that require a relatively small volume of bone and an appreciable area of thin soft tissue, particularly when a long vascular pedicle is desirable. This includes low level defects of the maxilla, some defects of the mandible and niche reconstructions, such as the orbital rim. The radial forearm flap remains useful as a first choice when there is appreciable peripheral vascular disease, when there are other serious coexisting medical conditions, when it is the preferred choice of the patient for functional reasons such as mobility of the lower limb or hip or when it is a salvage

flap used when other reconstructive options have been exhausted. [18]

of tumor surgery. [13]

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The radial artery branches from the brachial artery near the antecubital fossa and courses deep between the flexor carpi radialis and brachioradialis muscles in the proximal forearm. The artery emerges from this muscle approximately 7 cm cephalic to the wrist crease to enter the subcutaneous tissue.[19] Nine fasciocutaneous branches from the radial artery supply the skin of the forearm, four in the proximal forearm arising between the brachio-radialis and pronator teres muscles and nine in the distal forearm arising between the brachioradialis and flexor carpi radialis muscles.[14] Venus drainage is through either the venae comitante that accom‐ pany the radial artery or the much larger superficial venous drainage system via the cephalic vein. The cephalic vein courses subcutaneously on the radial side of the wrist near the superficial radial nerve. The vein goes cephalically supramedially toward the antecubital fossa. Several branches of the superficial radial nerve are found cephalad to the anatomical snuffbox in intimate relation to the cephalic vein. Saving of this nerve is important to maintain sensation over the radial aspect and the index finger. [19]

#### **5.2. Flap component**

This is a true septocutaneous flap with a main vessel lying in the septum, giving perforators superficially to supply the fascia, fat and skin and deeper branches to supply underlying tendons, muscles, nerves and bone.[14] The Allen test is noninvasive and reliably detects circulation problems by evaluation of arterial inflow in the presence of one functioning artery. Edgar V. Allen first introduced the test in 1929 as a non-invasive assessment of hand circulation in patients with thromboangiitis obliterans. The test was modified in the 1950s to assess the ulnar artery before cannulation of the radial artery. A similar method is used today to detect the ulnar artery inflow before harvesting the radial forearm flap. [19] The nondominant arm is usually selected for flap harvest. The design and position of the skin island in the volar forearm depend on several factors, including the desire to include the superficial venous drainage system and specific functional and cosmetic requirements at the recipient site. [19] It is usually projected over the course of the radial artery and one of the subcutaneous veins. The paddle is frequently outlined over the distal radius to obtain a vascular pedicle of greatest length (Figure 3). [13]

**Figure 3.** A radial forearm flap

#### **5.3. Flap dimensions**

The skin part of the flap commonly has 12 cm length (range 4-30 cm) and 5 cm width (range 4-15 cm) and 1 cm thickness (range 0.5-2cm). The bone part of the flap has 10 cm length (range 6-14 cm) and 1 cm width (range 0.7-1.5 cm) and 1 cm thickness (range 0.7-1.5 cm).[14]

#### **5.4. A common radial forearm flap harvesting technique**

A tourniquet is placed. The skin island is outlined over the distal forearm, including the radial artery and cephalic vein, and the flap edges are incised. The incision is extended deeply to include the deep fascia, except along the proximal edge, where the superficial veins and nerves are in the immediate subcutaneous tissue plane. The radial artery is exposed and temporarily closed to assess the adequacy of the circulation to the hand through the ulnar artery. The flap is raised from the ulnar and radial sides. It is necessary to include the deep fascia but saving the final peritenon. [19] Where bone is to be included in the lateral intermuscular septum, the periosteum of the radius must be preserved. Available bone extends from the insertion of the pronator teres to the distal styloid where there is no muscle attachment on the radial border. This provides a length of about 10-12 cm. Dissection can be performed as described, but, at the radial border of palmaris longus, the plane is deepened to expose the flexor pollicis longus and pronator quadratus.

#### **5.5. Complications**

circulation problems by evaluation of arterial inflow in the presence of one functioning artery. Edgar V. Allen first introduced the test in 1929 as a non-invasive assessment of hand circulation in patients with thromboangiitis obliterans. The test was modified in the 1950s to assess the ulnar artery before cannulation of the radial artery. A similar method is used today to detect the ulnar artery inflow before harvesting the radial forearm flap. [19] The nondominant arm is usually selected for flap harvest. The design and position of the skin island in the volar forearm depend on several factors, including the desire to include the superficial venous drainage system and specific functional and cosmetic requirements at the recipient site. [19] It is usually projected over the course of the radial artery and one of the subcutaneous veins. The paddle is frequently outlined over the distal radius to obtain a vascular pedicle of greatest

The skin part of the flap commonly has 12 cm length (range 4-30 cm) and 5 cm width (range 4-15 cm) and 1 cm thickness (range 0.5-2cm). The bone part of the flap has 10 cm length (range

A tourniquet is placed. The skin island is outlined over the distal forearm, including the radial artery and cephalic vein, and the flap edges are incised. The incision is extended deeply to include the deep fascia, except along the proximal edge, where the superficial veins and nerves are in the immediate subcutaneous tissue plane. The radial artery is exposed and temporarily closed to assess the adequacy of the circulation to the hand through the ulnar artery. The flap is raised from the ulnar and radial sides. It is necessary to include the deep fascia but saving the final peritenon. [19] Where bone is to be included in the lateral intermuscular septum, the periosteum of the radius must be preserved. Available bone extends from the insertion of the pronator teres to the distal styloid where there is no muscle attachment on the radial border. This provides a length of about 10-12 cm. Dissection can be performed as described, but, at the

6-14 cm) and 1 cm width (range 0.7-1.5 cm) and 1 cm thickness (range 0.7-1.5 cm).[14]

**5.4. A common radial forearm flap harvesting technique**

length (Figure 3). [13]

626 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

**Figure 3.** A radial forearm flap

**5.3. Flap dimensions**

A major problem with radial forearm flap relates to its donor site and the effect on function and aesthetics (Figure 4). Injury to the superficial radial nerve results in numbness over the anatomic snuffbox and radial side of the thumb and index finger. A devastating complication is vascular problems of the hand because of inadequate blood supply by the ulnar artery. It has been shown that a significant functional forearm and wrist range-of-motion morbidity associated with the harvest of a radial forearm fasciocutaneous free flap may occur in the early postoperative period. [20]

The radial forearm free flap results in measurable quantitative changes in hand function and limited changes in patient perception. [21]

**Figure 4.** A severe scar of the donor site after a radial forearm flap

#### **5.6. Radial forearm flap updates**

The radial forearm flap has been used for reconstruction of palatal defects and for total lower lip reconstruction.[22, 23] It is suggested to use a full-thickness skin graft from the neck to cover the radial forearm free flap donor site in patients undergoing neck dissection and microvas‐ cular reconstruction for ablative head and neck oncologic surgery. The primary advantage is avoiding a third surgical site. Complications were comparable to those using Full-thickness Skin Grafting from other harvest sites. Importantly, cross-contamination from the head and neck with the forearm was not a problem. [24] The pre-operative application of topical tissue expansion tapes produces measurable changes in skin biomechanical properties. The location of this change on the dorsal forearm is consistent with the method of tape application. This increase in skin pliability may account for the improved rate of primary donor site closure reported using this technique. [25] AlloDerm with split-thickness skin graft has been used to cover the donor site after radial forearm flaps. Results demonstrated thicker coverage of the forearm defect, with minimal donor site morbidity and superior cosmetic results. [26]
