Osteocutaneous Radial Forearm Flap Free Tissue Transfer

Updated: Jan 22, 2016
  • Author: Terance (Terry) Ted Tsue, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Overview

Background

Reconstruction after head and neck cancer extirpative surgery frequently requires the replacement of bone and soft tissue to provide the most optimal functional and aesthetic result. Microvascular free flaps have the advantage of providing healthy, vascularized, non-irradiated tissue for recipient sites that may have been compromised by surgery, radiation, chemotherapy, or a combination of the three.

The fasciocutaneous radial forearm free flap (FCRFFF) is the most common free flap used in head and neck reconstruction. Previous attempts to use an osteocutaneous radial forearm free flap (OCRFFF) for head and neck reconstruction have been associated with unacceptable donor site morbidity, most commonly fracture of the radius. This morbidity has severely limited forearm function and affected the patient’s quality of life.

This article focuses on the OCRFFF procedure and techniques that minimize donor site morbidity to levels near that of the FCRFFF procedure. When donor site morbidity is reduced, this free flap is a useful alternative to other currently used osteocutaneous free flaps for head and neck reconstruction.

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History of the Procedure

Since its introduction by Yang et al. in 1978, the radial forearm free flap (RFFF) has become a workhorse flap in head and neck reconstruction. [1] The RFFF's popularity has stemmed from its superior soft tissue characteristics, which offer a large amount of thin, pliable skin that conforms well to the native contours of the recipient site. The flap is relatively easy to harvest and can be dissected at the same time as the extirpative procedure. It has a long vascular pedicle with large-caliber vessels, predictable innervation for re-establishing sensory function in the oral cavity and oropharynx, and minimal donor site morbidity. It is particularly useful in the oral cavity.

Although the RFFF is most commonly harvested as a fasciocutaneous flap, perforators to the radius allow it to be developed as an osteocutaneous flap. Two issues have been largely to blame for limiting surgeons' consideration of the osteocutaneous radial forearm free flap (OCRFFF) as an option for single-stage reconstruction of composite defects in the head and neck: the inadequacy of available bone and the potential for radial bone fracture.

The bone available as part of the flap is limited in length and caliber. Most reports describe that the optimal length of the harvested radial bone segment is 6-12 cm. [2] Significantly longer segments can be transplanted as part of the fibular osteocutaneous free flap. The thickness of the bone graft is limited to 33-50% of the cross-sectional area of the radius, which is typically inadequate to support osseointegrated dental implants. Secondly, the donor site morbidity from iatrogenic fracture of the radius can be significant. One early series reported post-harvest radius fracture rates of up to 67%. These patients' arms required treatments that ranged from prolonged immobilization to forearm reconstruction with an additional revascularized bone graft.

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Problem

A defect in the head and neck that involves a large amount of soft tissue and a long segment of bone increases the functional impact on speech and swallowing. In this setting, the reconstructive surgeon must prioritize the various defect components to choose the best reconstructive option. In some instances, the surgeon may need to compromise on either the soft tissue or the bony component of the reconstruction.

For limited defects, choices are more straightforward. If predominately bone is missing, accompanied by only a small soft tissue defect in which sensation and mobility are not likely an issue, the use of an iliac crest or fibular flap may be the best reconstructive option. If the soft tissue defect is more critical, the use of a fasciocutaneous free flap with a mandibular reconstruction plate is an option; however, this has been associated with significant short- and long-term postoperative morbidity. The RFFF is frequently used as the soft tissue component in this situation.

For the most difficult situation, which is a significant defect of both components, one option is to use 2 free flaps, such as a sensate RFFF for the soft tissue and an iliac crest free flap for the bone. This approach carries the obvious disadvantages of increased operative time, morbidity, and cost compared with the use of one donor site. Furthermore, additional anastomoses increase the likelihood of vascular pedicle thrombosis.

The authors believe that a better option is a single microvascular procedure, which has ideal soft tissue characteristics and provides enough bone to reconstruct the mandible and minimize complications. Although the capacity to support osseointegrated implants is desirable, many patients are partially or completely edentulous prior to their cancer surgery and are not interested in undergoing dental restoration. Regardless of interest, this option is not readily available to many patients because of current insurance reimbursement issues.

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Epidemiology

Frequency

More than 50,000 new head and neck malignancies are diagnosed each year. Many of these cancers arise in the oral cavity and frequently involve the mandibular and/or maxillary alveolus. Bony invasion by squamous cell carcinomas (SCCs) necessitates segmental bone resection. These defects require reconstruction with the same type of tissue (eg, bone, skin), for which the OCRFFF procedure is an attractive and safe option. In the maxilla, use of a prosthetic obturator is another alternative.

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Indications

For a large, complex, soft tissue defect accompanied by a moderate, limited, mandibular segmental defect, many head and neck reconstructive surgeons choose to compromise in favor of the soft tissue reconstruction. The authors believe that using a revascularized radius bone graft is better than using a fasciocutaneous flap to cover a mandibular reconstruction plate. Schusterman showed that bridging of the anterior mandibular defects with a reconstruction plate without a vascularized bone graft carries a 67% risk of surgical failure. [3] Furthermore, Arden demonstrated that the surgical complication rate increases significantly for large defects (>5 cm) reconstructed by plate bridging alone. [4]

Despite the limited bone stock that is available with the osteocutaneous radial forearm free flap (OCRFFF), the procedure has been successfully used for oromandibular reconstruction, with few complications. In lateral or anterior mandibular defects, the radius bone graft can support a tissue-borne prosthesis (denture). Posterior mandibular defects (eg, retromolar trigone, ramus and subcondylar defects) can also be reconstructed successfully, restoring adequate integrity of bony structure with enough soft tissue for multi-dimensional intraoral reconstruction. A thin, pliable skin paddle of the radial forearm proves especially useful in re-creating 3-dimensional soft tissue lining of the floor of the mouth and lower alveolar ridge, and facilitates subsequent denture placement.

The large soft tissue paddle is especially useful for through-and-through defects of the oral cavity because the mid-portion of the fasciocutaneous paddle can be deepithelialized and buried. The color match is generally poor in white patients, but can be quite good in patients of African or Asian descent. The fasciocutaneous paddle size is usually not a limitation because the flap can be extended dorsally onto the ulnar side of the forearm. The OCRFFF does not provide bulky soft tissue, but the volume can be increased by burying deepithelialized portions of the flap.

The OCRFFF is useful for midfacial reconstruction of the maxillary alveolus or the malar eminence. Such reconstructions can obviate the need for a prosthetic obturator after maxillectomy. Reconstruction of maxillofacial defects is a challenging problem because of the complex 3-dimensional, esthetic, and functional roles of the midfacial structures. Cordeiro and Santamaria presented a classification of maxillofacial defects and suggested an algorithm for their reconstruction. [5] Type I defects (limited maxillectomy) include resection of 1 or 2 maxillary walls, excluding the palate. Type II defects (subtotal maxillectomy) include resection of the lower 5 walls including the palate, with preservation of the orbital floor. These are the defects amenable to reconstruction by OCRFF.

A combination of a large skin paddle to line the palatal mucosal surface, a small volume of the soft tissue, and a moderate vascularized bone stock are the requirements that are fulfilled very well by a reconstruction with a OCRFF. A radial forearm free flap is an ideal solution to the most problematic aspect of choosing the flap for a midfacial reconstruction: a need for a long, 10-13 cm pedicle, to span the distance between the midface and cervical vessels. Using an OCRFF eliminates the need for vein grafts, which shortens operative time and improves the success of the reconstruction.

Chepeha and colleagues expanded the use of OCRFF for maxillectomy defects with infraorbital rim involvement in 10 patients. [6] They advocate the choice of OCRFF in total maxillectomy defects, with or without the orbital exenteration, that involve less than 40% of the orbital floor. Rather than using the vascularized bone to reconstruct malar alveolar ridge, the authors employed osteotomized radial bone to recontour the infraorbital rim and to provide support for the orbital contents when preserved. Dental rehabilitation was achieved using palatal obturator and denture.

OCRFF has been shown to be an effective tool when used to reconstruct mandibular defects in the setting of osteoradionecrosis. [7]

The radius bone has also been used to provide vascularized skeletal support for laryngotracheal airway reconstructions.

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Relevant Anatomy

Harvest of the fasciocutaneous radial forearm free flap (RFFF) and osteocutaneous radial forearm free flap (OCRFFF) depends on the anatomy of the volar forearm. Both flaps depend on perforators from the radial artery and its 2 venae comitantes. The radial artery arises from the brachial artery in the antecubital fossa. The other arterial branch, the ulnar artery, travels medially in the forearm to the hand. After RFFF harvest, the ulnar pedicle supplies the hand, provided an intact palmar arch network exists (see Workup). The ulnar arterial pedicle is covered by the flexor carpi ulnaris tendon but can run superficial distally near the wrist crease.

The volar fasciocutaneous paddle receives vascular supply from septocutaneous perforators in the lateral intermuscular septum. Periosteal perforators from the radial artery pedicle travel deep through the flexor pollicis longus muscle to vascularize the periosteum of the radius. The vascular pedicle travels between the brachioradialis and flexor carpi radialis muscles and lies superficial to the flexor digitorum superficialis muscle. The pronator teres muscle inserts into the mid radius and approximates the proximal radius bone-graft harvest margin. Distally, the brachioradialis tendon inserts into the radius and delineates the safe distal margin for the radius bone graft. This margin lies 2-2.5 cm proximal to the radius styloid process.

The lateral and medial antebrachial cutaneous nerves that innervate the fasciocutaneous paddle can be followed into the antecubital fossa. These branches can provide sensory innervation to the OCRFFF, if desired. Frequently, the ulnar-bias used during harvest of the OCRFFF fasciocutaneous paddle does not allow inclusion of the lateral nerve. The superficial radial nerve pierces the brachioradialis tendon and runs distally on this tendon. The subfascial dissection of the fasciocutaneous paddle must preserve this nerve in its entirety to ensure preservation of dorsoradial hand sensation. A superficial venous network runs subcutaneously in the fasciocutaneous paddle. The cephalic vein is one of the main branches that receive this superficial venous drainage and travels radially to the antecubital fossa. This superficial system is quite variable but can provide venous drainage to the OCRFFF in lieu of, or in addition to the venae comitantes.

The radius bone lies laterally in the forearm; its caliber increases distally until it protrudes the styloid process in the wrist region.

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Contraindications

General contraindications to microvascular free tissue transfer also apply to the osteocutaneous radial forearm free flap (OCRFFF) procedure, including coagulopathic states, significant peripheral vascular disease, and severe diabetes mellitus with impaired healing. Physical signs and symptoms of poor peripheral digit perfusion or healing contraindicate harvest of the radial artery pedicle. Patients who are in poor general medical condition and cannot tolerate prolonged anesthesia are not appropriate candidates for OCRFFF reconstruction.

Participation in occupational and recreational activities that place significant demands on the forearm can be a relative contraindication to the OCRFFF procedure. Use of the dominant arm or the only remaining functional arm as a donor site can also be a relative contraindication. Previous surgery or trauma to the proposed donor arm must be closely investigated, especially by means of radiography, to ensure normal and intact vascular and musculoskeletal anatomy. A similar workup applies to obvious congenital deformities.

An incomplete palmar arch system (deep and superficial) becomes apparent preoperatively by performing an Allen test. An incomplete palmar arch precludes radial artery pedicle harvest because inadequate blood supply to the lateral digits results when only the ulnar artery perfuses the hand. Radial artery thrombosis or compromise is also apparent on a preoperative Allen test. Evaluate equivocal Allen tests with objective Doppler photoplethysmography. This test can sometimes confirm adequate ulnar artery perfusion to the hand, which then allows safe harvest of the radial artery and use of the OCRFFF. If ulnar perfusion is inadequate, an alternate flap must be used.

When bony defects larger than about 10 cm are anticipated, reconstruction may require more bone than is safely available using the OCRFFF procedure, depending somewhat on the patient's stature. The recipient site must also have acceptable arterial and venous vasculature for anastomosis.

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