Master Techniques in Otolaryngology - Head and Neck Surgery: Reconstructive Surgery, 1ed.

24. The Hemimaxillectomy Defect: Osteocutaneous Radial Forearm Free Flap

Neal D. Futran

INTRODUCTION

The radial forearm free flap (RFFF) was first developed at the Shenyang Military General Hospital in China, and a large clinical series indicated that the flap was used very successfully to reconstruct defects of the head and neck. In 1983, Soutar et al. noted the benefits of this flap, with and without bone, for the reconstruction of intraoral defects. The radial forearm fasciocutaneous flap is ideally suited for intraoral reconstruction due to its pliability and thickness. The availability of vascularized bone for reconstruction of the mandible was later described, and the flap has been used by some for mandibular and maxillary reconstruction. While other donor sites have become popular for reconstruction of the mandible, the radial forearm flaps provides sufficient bone stock to reconstruct infrastructure and alveolar maxillary defects.

When evaluating a patient as a candidate for an RFFF reconstruction, I elicit any history of injury to the forearm, upper extremity vascular compromise, or osteopenia. Any history of osteopenia or osteoporosis should alert the surgeon that if the flap is going to be harvested with a segment of bone, there is an increased risk of fracture at the donor site.

The physical examination should consist of a careful evaluation of the volar surface of the forearm to identify any prior injury, surgery, or congenital or acquired deformity. Additionally, an Allen test to evaluate the continuity of the deep and superficial palmer vascular arches is important to insure that the patient will tolerate harvest of the flap and the radial artery. The physical examination must also include a careful evaluation of the maxillary defect. Because the size of the bone graft is limited, the indications for this donor site are different from other vascular bone graft donor sites.

The radial forearm donor site provides a limited bone graft that is well suited for the reconstruction of alveolar and infrastructure defects but less than ideal for extensive maxillary defects involving a combination of the alveolus, infraorbital rim, and zygoma.

The contraindications for this donor site for maxillary reconstruction are related to limitations of the donor site and the defects. The donor site limitations include any patient with a history of injury or vascular compromise of the forearm. Prior surgery, such as carpal tunnel surgery, and any history of radial fracture are contraindications to using this donor site. Other considerations are a history of osteopenia of the radial bone that may represent a high risk of postoperative fracture.

The radius bone and skin paddle are both supplied through a relatively short intermuscular septum (5 to 6 cm long) that is 2 to 4 cm wide (Fig. 24.1). This allows for a degree of freedom when rotating the skin paddle relative to the bone segment, which is superior to other bone flaps such as the fibula and iliac crest. The length of the bone is limited to 10 to 12 cm by the insertions of the pronator teres and the brachioradialis muscles (Fig. 24.2). Also, to maintain the structural integrity of the radius bone, it is reported that only 40% of the circumference of the bone should be harvested. Thus, the quality of the bone stock is usually insufficient to support dental implants.

FIGURE 24.1 Osteocutaneous radial forearm free flap.

FIGURE 24.2 Diagram noting the extent of radial bone that can be harvested between the brachioradialis and pronator teres muscle insertions.

In an effort to reduce the morbidity at the donor site and therefore safely make use of the superior soft tissue characteristics of the volar forearm, biomechanical studies demonstrated greatly improved strength when a reconstruction plate is prophylactically applied to the donor radius after graft harvest. Studies from two institutions assessing over 100 patients, who underwent osteocutaneous radial forearm free flap (OCRFFF) harvest and prophylactic plating, reported only two instances of postoperative fracture of the radius. In both cases, the fracture occurred distal to the reconstruction plate after the patient fell. The OCRFFF has the advantage of tremendous soft tissue versatility. A long vascular pedicle, large amounts of thin pliable skin, and reliable sensory innervation make the soft tissue components of the RFFF ideal for the reconstruction of the tongue, floor of the mouth, alveolar ridge, pharyngeal wall, and soft palate. The available radius bone (9 to 12 cm) is of adequate length for reconstruction of many limited defects of the mandible and maxilla.

Flap Harvest Technique

The RFFF is based on the radial artery, which branches from the brachial artery in the antecubital fossa. Its venous drainage is provided by the paired venae comitantes that run with the radial artery, and the superficial venous system, which contains the cephalic and basilic veins. The lateral intermuscular septum, which contains perforators from the radial artery supplying the periosteum of the radius, passes between the flexor carpi radialis and the brachioradialis muscles and must be preserved. Sensation of the flap is provided by the lateral and medial antebrachial cutaneous nerves.

Preoperatively, an Allen test is performed to confirm adequate circulation to the hand via the ulnar artery and to assist in the selection of the donor arm. At surgery, the radial artery and cephalic vein are marked, along with the proposed skin paddle. The soft tissue component is measured, and the flap outline is drawn on the volar aspect of the forearm (Fig. 24.3). The skin paddle is positioned at least 2 cm proximal to the wrist crease and with an ulnar bias. This ensures adequate skin coverage of the internal fixation plate. The soft tissue component of the flap is raised in the standard fashion, with care taken to preserve the lateral intermuscular septum. An incision is made in the skin proximal to the paddle up to the antecubital fossa, and the skin flaps are reflected. The skin paddle is the outlined and raised with the deep fascia to the level of the brachioradialis and flexor carpi radialis tendons. Careful dissection medial to the cephalic vein and radial artery to the vascular pedicle preserves the superficial branch of the radial nerve intact. The radial artery and the vena comitans are ligated, and the pedicle and the fascia are raised for approximately 1 to 2 cm. The available bone lies in between the insertion of the pronator teres muscle and the insertion of the tendon of the brachioradialis muscle. Lateral retraction of the brachioradialis tendon exposes the radial surface of the bone.

FIGURE 24.3 Outline of the osteocutaneous radial forearm free flap in anticipation of flap harvest.

The bone is harvested between the pronator teres and brachioradialis tendon insertions. The flexor digitorum superficialis is released from the radius, allowing visualization of the flexor pollicis longus. The flexor pollicis longus muscle belly is divided over the midline of the volar surface of the radius with electrocautery or scalpel until the necessary length of radial bone is exposed. The required length of bone is marked. The distal osteotomy must be made at least 2.5 cm from the radial styloid to allow later fixation of the radius. Proximally, the osteotomy can be made even beyond the pronator teres insertion; however, the pronator teres tendon will require reinsertion. The sagittal saw with a fine blade is used to make a longitudinal osteotomy in the radius through its midportion. This osteotomy is placed to allow harvest of approximately 40% to 50% of the circumference of the radius with beveled osteotomies at the proximal and distal ends (Fig. 24.4). The periosteum is then incised dorsally, completing the harvest of the bone graft. The deep vascular pedicle and the cephalic vein are skeletonized up to the antecubital fossa. The lateral antebrachial cutaneous nerve can then be easily separated from the cephalic vein for approximately 8 to 10 cm. The flap is then left to perfuse on its pedicle, which is divided proximally and distally just before transfer of the flap to the recipient site.

FIGURE 24.4 An osteotomy of the radial bone at approximately 40% of its thickness is carried out between the brachioradialis and pronator teres muscle insertions.

Prophylactic fixation of the radius is begun by exposing the dorsal aspect of the radius proximally and distally. Distally, the radial wrist extensors are retracted. Proximally, the supinator is visualized. Great care is taken to protect the posterior interosseus nerve, which passes through the supinator but is not usually adjacent to the fixation area. An appropriately sized 2.4-mm locking reconstruction plate (Synthes, Davos, Switzerland) is positioned over the radius and bent to the contour of the bone with three holes on either side of the osteotomy site (Fig. 24.5). Bicortical screws are placed only in the three proximal and distal holes.

FIGURE 24.5 A 2.4-mm locking reconstruction plate (Synthes, Davos, Switzerland) is placed over the radial bone, so three holes are on either side of the osteotomy site in the radius. Appropriate-length bicortical screws are placed only in these holes.

After standard closure of the forearm defect including split-thickness skin grafting, the arm is placed in the rigid ulnar gutter splint for approximately 7 days, at which time the splint is removed and the wound inspected. The patient is then encouraged to resume full activity of the wrist and fingers, including weight bearing and rotation, with the donor arm protected with a soft dressing until the wound has healed.

Maxillary Inset Technique

A main indication for the use of this flap is in the reconstruction of limited maxillectomy defects. The thin radial bone that is harvested with this flap closely approximates the thin bone stock of the maxilla. The soft tissue from the forearm also conforms nicely to the palate and separates the oral and nasal cavities reliably. If implants are to be used for the upper denture, I have placed them in the native maxilla lateral to the radial bone. Usually, I do not place implants in the upper arch, because dentures can be formed to fit the slightly altered anatomy of the new anterior maxillary arch, with stabilization of the prosthesis coming from the normal lateral alveolar ridges. If a larger area than the premaxilla is involved, then I tend to choose either the fibula or iliac crest flaps, because dental implants become necessary to hold dentures in place.

The maxillary defect is prepared either by removal of tumor for neoplasm or by debridement of the wound in cases of traumatic injury (Figs. 24.6A–C). A limited neck dissection is done on the ipsilateral side for recipient vessel exposure. Any branch of the external carotid artery can be used, but typically, the facial artery or superior thyroid artery provides optimal vessel geometry and ease of anastomosis. The external jugular vein, internal jugular vein, or facial vein is readily available for venous anastomosis. A subcutaneous tunnel is made from the maxillary buccal area to the neck lateral to the mandible for passage of the flap vascular pedicle. This avoids trauma to the marginal mandibular nerve. The width of this tunnel should be two fingerbreadths to avoid compression of the flap pedicle. After the flap is passed under direct vision through this tunnel, the inset of the radius bone to the maxilla takes place. A single osteotomy can be made in the radius, if necessary, for optimal contour of the neomaxilla. This can be done prior to passage of the flap, and fixation is done with a 1.5-mm titanium miniplate (Fig. 24.6D). The bone is then trimmed to maximize bony contact with the remaining maxilla and fixated with 1.5-mm titanium miniplates. A minimum of two holes in the radius and maxilla is necessary for sufficient fixation (Fig. 24.6E). The soft tissue portion of the flap is then inset into the maxillary defect with 3-0 resorbable suture in an interrupted fashion (Fig. 24.6F). The vascular anastomoses are then performed in the conventional fashion, and the wounds are closed. Long-term results are noted in Figure 24.6G-J.

FIGURE 24.6 A. A axial CT scan of a 32-year-old man status post a gunshot wound to the anterior palate with a persistent oronasal and oroantral defect after Phase I treatment. B. Submental view of the collapsed premaxilla. C. The wound is exposed revealing non-viable bone grafts and necrotic tissue. D. A radial forearm osteocutaneous free flap. The bone is osteotomized to provide the proper contour for the premaxilla. E. The bone is fixated to the remaining maxillary bone with 1.5-mm titanium miniplates. F. The soft tissue component of the flap surrounds the bone and restores the palatal and nasal linings. G. At 1-year follow-up, the flap has conformed to the natural shape of the palate and provides a suitable base for a dental prosthesis. H. Anterior view of the patient 1 year after free tissue transfer with restored form and function. I. Patient with intact donor site function at 1-year follow-up. J. Donor site radiograph at 1-year follow-up showing intact radius.

Postoperatively, the patient is managed with a volar splint for 5 to 7 days. Physical therapy is initiated 2 to 3 weeks after surgery. The maxillary reconstruction requires 5 to 6 weeks for the bone union to occur, so patients are typically instructed to maintain a liquid diet for 5 to 6 weeks to alleviate pressure on the bone graft.

Complications are largely restricted to the risk of donor site morbidity. Postoperative radial fracture is considered the most serious complication. Plating the fracture site has been demonstrated to be effective in preventing this complication.

My results with this technique for maxillary reconstruction have demonstrated that this approach is reliable for small and moderately sized maxillary defects. The bone graft is substantial enough to accommodate osseointegrated dental implants.

• Design the skin paddle with an ulnar bias such that there is more skin remaining on the radial aspect of the defect for advancement closure over the bone.

• Detach the flexor digitorum superficialis muscle from the radius bone during graft harvest. It can be repositioned over the top of the flexor carpi radialis tendon to improve closure over the defect and enhance skin graft takeover of the flexor carpi radialis tendon.

• Harvest 40% to 50% of the circumference of the radius.

• Place a locking reconstruction plate over the ostectomized radius.

• Remove the arm splint after 7 days to allow early mobilization of the wrist to avoid disuse, stiffness, and weakness in the donor arm.

• Mobilize radial nerve adequately to allow retraction and prevent injury.

• Best use of this flap is for limited maxillectomy defects, not those involving both the orbit and alveolus.

• Radius will tolerate a maximum of one osteotomy and maintain adequate blood supply to the bone.

• Reciprocating saw

• Mandibular plating system

• Mini plating system

SUGGESTED READING

Song R, Gao Y, Song Y, et al. The forearm flap. Clin Plast Surg 1982;9:21–26.

Soutar DS, Scheker NS, Tanner NS, et al. The radial forearm flap: a versatile method for intra-oral reconstruction. Br J Plast Surg 1983;36:1–8.

Swanson E, Boyd JB, Mulholland RS. The radial forearm flap: a biomechanical study of the osteotomized radius. Plast Reconstr Surg 1990;85:267–272.

Meland NB, Maki S, Chao EY, et al. The radial forearm flap: a biomechanical study of donor-site morbidity utilizing sheep tibia. Plast Reconstr Surg 1992;90:763–773.

Smith AA, Bowen CV, Rabeczak T, et al. Donor site deficit of the osteocutaneous radial forearm flap. Ann Plast Surg 1994;32:372–376.

Bowers KW, Edmonds JL, Girod DA, et al. Osteocutaneous radial forearm free flaps. J Bone Joint Surg Am 2000;82:694–704.