Radial forearm fasciocutaneous free flap

The need for reconstruction of mandibular defects is either due to trauma or tumor resection. The vast majority of oral cavity tumors are squamous cell carcinoma, that arise in the mucosa. Therefore the treatment of most early oral cavity tumors involve only the dentoalveolar and/or the inner aspects of the mandible.

The best treatment for these tumors is a surgical excision which includes soft tissue and the periosteum, as well as a thin margin of bone to ensure complete resection. In most cases where there is no bone invasion, the continuity of the mandible can be preserved and therefore form and function is also preserved.

The extent of the tumor resection will dictate the type of soft tissue flap utilized in the reconstruction of the oral cavity.

Larger defects will require pedicled or free tissue flaps.

Some of the most commonly utilized flaps include:

• Pedicled flaps
  - Platysma
  - Submental
  - Nasolabial
• Free microvascular tissue
  - Radial forearm free flap
  - Lateral arm free flap

The choice between these flaps will largely depend on the surgeon's preference. We will describe the use of the radial forearm fasciocutaneous free flap to illustrate the procedure.

Patient is placed in supine position and prepped and draped in the normal sterile fashion. The patient should be given IV paralytic agents by the anesthesiologist to allow for maximal oral opening.

A bite block is placed between the molar teeth on the contralateral side of the tumor.

A self-retaining cheek retractor is placed. A suture is placed in the anterior tongue to facilitate retraction. A tongue retractor may also be used.

The tumor is visualized and 1.5 cm margins are marked (eg. with a Bovie cautery) around all visible or palpable tumor. This includes where the tumor marginates the mandible.

The teeth in the line of the mandibulectomy are extracted as the osteotomy would traverse the tooth roots. A mucosal incision is performed along the lateral aspect of the mandibulectomy exposing the mandibular alveolus.

In an edentulous portion of the mandible without significant mandibular atrophy, the superior aspect of the mandibular bone is exposed by incision and elevation of the mucosa overlying the lateral aspect of the mandibulectomy.

A sagittal osteotomy is carried through the tooth sockets from anteriorly to posteriorly using an oscillating saw. Care is taken not to injure the external cortex as this provides for mandibular continuity.

Cuts are carried inferiorly to near the inferior rim and then angled medially. This is usually superior to the mylohyoid muscle.

The bone segment is mobilized but left attached to the main specimen.

For mandibulectomies near the anterior arch and those involving short segments, a small cutting burr (eg. 2 mm) can be used instead of an oscillating saw.

Final soft tissue incisions can now be carried around and deep to the tumor and the tumor delivered en block with the resected alveolus. Care should be taken to identify the lingual nerve and submandibular duct, during the soft tissue excision if they are to be preserved.

The specimen is submitted en bloc for permanent pathological examination.

Surgical soft tissue margins are now checked with frozen sections to ensure the adequacy of the tumor resection.

Radial forearm fasciocutaneous free flap is harvested in the standard fashion with the following consideration:

• It is harvested of sufficient size to cover mucosal defect.

The flap is placed into the oral cavity and a tunnel is developed between the remaining mandible and the floor of the mouth muscles in order to pass the flap pedicle to the submandibular region to perform the microvascular anastomosis. Care must be taken to avoid any compression or torsion of the pedicle.

The oral mucosa is closed directly to the radial forearm skin with interrupted absorbable suture in a vertical mattress fashion (eg. 3-0 Vicryl). A water tight closure is essential to avoid a salivary leak into the neck with subsequent infection in the surgical site and an orocutaneous fistulae.

Care must be taken during closure to avoid injury to the vascular pedicle which may be traversing the defect.

The detailed procedure for the revascularization is outside the scope of this surgery reference. However, in short the procedure consists of the following steps:

• Appropriate recipient vessels are selected in the neck and dissected so as to be available for anastomosis.
• The recipient and the donor vessels adventitia are cleaned under a microscope.
• Appropriate vessel geometry is assured and the vessels are placed into a microvascular clamp and anastomosis carried out using 9-0 nylon sutures.
• Vascularization is restored after both arterial and venous anastomoses are completed.

The use of the following perioperative medication is controversial. There is little evidence to make strong recommendations for postoperative medications.

• Analgesia as necessary
• Antibiotics (many surgeons use perioperative antibiotics). There is no clear advantage of any one antibiotic but evidence supports their use for 24h. The spectrum should be according to the oral bacterial flora, but the physician should be aware of changes that may occur after the use of radiation therapy.
• Steroids may help with postoperative edema.
• Regular perioral and oral wound care has to include disinfectant mouth rinse, lip care, etc.
• Antibiotic ointment is used on the wounds for 72 hours
• If a free flap is utilized for the reconstruction, 80-100 mg of aspirin/day is recommended.

Remove any sutures from skin after approximately 7 days if nonresorbable sutures have been used. If the patient has had previous radiation, the sutures should be left in for 10 – 14 days.
Wound should be cleaned at least twice daily with hydrogen peroxide or mild soap and water. Moisturizing lotion should be used on the skin wounds to minimize excessive scarring after sutures are removed.
Avoid sun exposure and tanning to skin incisions for several months.

Diet depends on the reconstructive method. In general patients with superficial wounds can begin an oral diet within 48h postoperatively. Patients who have undergone a more significant surgery eg. flap reconstruction are kept NPO for 5-10 days and nutrition is administered via nasogastric tube. Oral feedings are begun using thickened liquids only after swallowing is assessed by the surgeon or the speech pathologist, and the risk of aspiration is minimal. Diet can be advanced as tolerated by the patient.

Typically the patients are seen in clinical follow-up one week after discharge, and then on a weekly basis until such time the clinician determines that less frequent follow ups are needed.

Patients with intraoral incisions and/or wounds must be instructed in appropriate oral hygiene procedures. A soft toothbrush (dipped in warm water to make it softer) or water flosser should be used to clean the surfaces of the teeth. Chlorhexidine oral rinses should be prescribed and used at least 3 times a day to help sanitize the mouth. For larger debris, a 1:1 mixture of hydrogen peroxide/chlorhexidine can be used. The bubbling action of the hydrogen peroxide helps remove debris.

When a free flap is utilized, it should be regularly monitored to ensure vascular integrity. Physical examination, assessing the flap color, turgidity, and capillary refill should be routine for at least the first 48 hours postoperatively. Hand-held Doppler probes can be used to assess blood flow. In case of doubt of the vitality of the flap, pin-prick assessment with a 25 gauge needle to look for bright red bleeding.. In cases of buried flaps, an implantable Doppler placed just distal to the venous anastomosis can be utilized.

Closed suction drains are routinely used at the donor site. The drain is removed when output is <30cc per 8 hour period, for three consecutive periods. Patients are typically discharged from the hospital 5-10 days after surgery, depending on their postoperative course and comorbidites. Close outpatient follow-up after discharge is recommended for evaluation of surgical sites.

Radial forearm free flap
The radial forearm free flap donor site should be closed with a skin graft and a bolster placed over the area. The arm is then cast or placed in a volar splint for 7 days prior to removal to ensure graft take.

Fibula free flap
After a fibula free flap, the donor lower leg should be cast with the ankle slightly dorsiflexed for 5 days. The patient can touch-down their body weight as tolerated. After the cast is removed they can ambulate and work with physical therapy to optimize leg function. A splint should be placed to keep the foot flexed when in bed. The routine use of a compression stocking for one month postoperatively will reduce the amount of lower leg dependent edema and aid in improved wound healing.

Scapula free flap
In the initial postoperative recovery, the ipsilateral arm should be positioned anteriorly and medially, usually supported on the patient’s abdomen by a pillow. Once the patient is ambulating, the arm is supported by a shoulder sling which supports the elbow and prevents inferior drift of the arm. Inpatient physical therapy is initiated once the patient is mobile. A post-operative physical therapy regimen is established with the patient to be maintained after hospital discharge. The sling is used for 2-3 weeks and physical therapy maintained until postoperative function is optimized, usually 4-6 weeks.

Iliac crest
The iiliac crest donor site requires that the patient not strain or lift heavy objects for at least 4 weeks to avoid hernia formation. Patients are typically limited to a bed or chair for 48h postoperatively and then physical therapy is begun with the patient initially ambulating with the aid of a walker or cane and progressing as tolerated.

Latissimus dorsi
No specific rehabilitation is necessary following the use of this flap.