Lip split approach to the mandible

The use of a lip splitting incision (a, b, c) with a lateral extension into the neck incision allows for the elevation of a cheek flap and exposure of the hemi mandible.

The most common form of lip split utilizes a stair step incision across the vermillion and a zigzag incision through the mentum, used to best camouflage the scar (a).

Pitfall: When a straight line is used instead of a zigzag, a tethering scar (illustrated) of the mentum will occur; occasionally the circum-mental incision may cause atrophy of the mental muscle with subsequent asymmetry.

The patient is placed supine with a small shoulder roll at the level of the scapula in order to extend the neck.

The patient is prepared in the normal fashion and local anaesthetic with a vasoconstrictor is infiltrated in the proposed incision line.

In order to ensure a safe airway in the perioperative period and unhindered access to the oral cavity a tracheotomy is performed prior to extensive surgical manipulation in the oral cavity.

Alternatively a prolonged naso-endotracheal intubation may be performed to avoid a tracheotomy.

A 3 cm horizontal incision is made just inferior to the cricoid cartilage and dissection is carried down to the strap muscles. The paired muscles are divided in the midline and retracted laterally. The thyroid isthmus is exposed and either retracted superiorly or divided and suture ligated.

An inferiorly based flap (Björk flap) of the second or third tracheal ring is created and sutured to the overlying skin. A reinforced endotracheal tube is placed into the tracheotomy site and secured to the chest wall. Further ventilation is carried out through this tube.

The vermelion border is scribed using the back of a 15 blade and surgical marking ink to aid in the precise reapproximation of the vermillion border during closure.

A full thickness incision through the lip-chin complex is performed using one of the patterns outlined above.

The cut edges of the inferior labial arteries are cauterized.

The incision is extended below the mentum into a mid-neck skin crease. This incision is carried through skin and platysma muscle. The skin flap is raised superiorly in a subplatysmal plane, until the submandibular fascia is encountered. This is incised and elevated to the inferior border of the mandible, protecting the marginal brach of the facial nerve.

Frequently a resection of an oral carcinoma will be accompanied by a neck dissection. This is commonly performed prior to the resection of the primary oral cavity tumor.

When the oral carcinoma extends beyond the midline or when the lymphatic drainage is bilateral or to the contralateral neck, bilateral neck dissections are performed. In these cases rather than a lip split incision, a lower facial degloving approach (visor flap) may be selected. This approach combines a mid-neck apron incision with a gingival buccal incision.

Intraorally, the incision can be carried straight posteriorly to the gingival buccal sulcus and then laterally within the sulcus approximately 5 mm from the gingival margin as far as needed to provide an adequate exposure of the mandible.

Subperiosteal dissection is carried directly to the mandible and the flaps are elevated to expose the ipsilateral mental nerve which might have to be sacrifice depending on the location of the tumor and the extent of the mandibulectomy.

Dissection is carried posteriorly to the angle of the mandible or as far as needed to provide access for the oncological resection and placement of a mandibular reconstruction plate when indicated. The cheek flap is subsequently held in place with self-retaining retractors (eg. dural hooks).

The mandible should be exposed far enough to allow for the placement of the mandibular reconstruction plate beyond the resected edge on the distal segment. This may require elevation of a mucoperiosteal flap to the level of the contralateral mental nerve.

Every effort should be made to preserve the contralateral mental nerve. If tumors crosses the midline this may not be possible.

The skin paddle of the flap used to reconstruct the intraoral defect is closed directly to the oral mucosa with interrupted absorbable sutures 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 perforators to the skin paddle.

Closed suction drains (eg. Jackson-Pratt drains) are placed in the neck and brought out through separate stab incisions in the skin. If a vascularized flap has been used, the drains must be placed to avoid overlaying the vascular pedicle of the flap.

Lip closure is carried out in 3 layers. The muscle layer is reapproximated with interrupted resorbable sutures (eg. 3-0 Vicryl). The mucosa may be closed with a running suture using resorbable suture (eg. 3-0 Chromic). The skin is closed with a running resorbable suture (eg. 5-0 fast absorbing gut suture)

The neck is closed in layers. The platysma muscle and deep dermis are closed with resorbable interrupted sutures in buried fashion. The skin is closed with a running resorbable suture (eg. 5-0 fast absorbing gut suture) or non-resorbable suture (eg. 5-0 nylon).

Lip closure is carried out in 3 layers. The muscle layer is reapproximated with interrupted resorbable sutures (eg. 3-0 Vicryl). The mucosa may be closed with a running suture using resorbable suture (eg. 3-0 Chromic). The skin is closed with a running stich resorbable suture (eg. 5-0 fast absorbing gut suture)