• Non-vascularized tissue-engineered reconstruction is strictly limited to non-radiated candidates who present with intact or minimal intraoral mucosa or external skin defects, allowing for tension-free, watertight primary closure.  
• Patients requiring postoperative radiation therapy should undergo free flap reconstruction instead of non-vascularized grafting.

• Patients presenting with a history of prior head and neck radiation, an anticipated need for post-operative radiotherapy, or extensive soft tissue defects are excluded from this technique and require microvascular free tissue transfer, such as a fibula free flap.

• Superficial Layers and Fascia: Moving from superficial to deep, the anatomy comprises the skin, subcutaneous fat, and the platysma muscle.

• Subplatysmal Tissue Plane (deep to platysma): The marginal mandibular nerve (a branch of the facial nerve) runs deep to the platysma muscle and sits directly superficial to the submandibular gland capsule. This nerve should be identified, and in this case, it will be raised with the skin flap over the mandible to preserve it. The facial artery and vein course inferiorly to the mandible and continues superior to the mandible to become the angular artery. The marginal mandibular nerve will be located superficial to the facial vein at varying locations. The general rule of cutting the facial vein two fingerbreadths below the mandible to protect the nerve is very crude and not accurate, as the point where the marginal mandibular nerve crosses the vessels varies greatly.

  Mandible: Within the bone, the inferior alveolar nerve enters the proximal mandible and exits the bone at the mental foramen as the mental nerve. The inferior alveolar nerve and lingual nerve arise from CN V3.

  Deep to Mandible: Level 1B and Level II lymph node zones are situated deep to the mandible.

• Level 1B houses the submandibular gland, the submandibular lymph nodes, and the lingual nerve as it enters the floor of the mouth. The hypoglossal nerve, located deep to the digastric muscle, also arises from Level II and travels along the Level 1B region inferior to the lingual nerve. You will typically encounter the lingual nerve along the floor of the mouth, and it is located within the submucosal tissue plane and is prone to injury if caution is not exercised.

  Level 2: The hypoglossal nerve provides motor innervation to the tongue and is identified within Level II/1B zones deep to the internal jugular vein and superficial to the carotid artery structures. Within Level II, the internal jugular vein is located superficially.Deep to the internal jugular vein (IJV) lies the hypoglossal nerve.Deep to the hypoglossal nerve lies the carotid artery.

Patient History: 

• Patient Presentation: 52-year-old female presenting with a mandible lesion biopsied as low-to-intermediate-grade mucoepidermoid carcinoma.

• Surgical Plan: Segmental mandibulectomy with mucosal margins and sacrifice/reconstruction of the inferior alveolar nerve.

• Contingency Planning: Free flap reconstruction was prepared in case of inadequate mucosa for tension-free closure.

• Radiation Considerations: Patients requiring postoperative radiation therapy for high-grade mucoepidermoid carcinoma are planned for a primary fibula free flap instead.

• Aspiration Approach: The anterior iliac crest is palpated, and a long needle is introduced into the marrow space using a mallet, maintaining a trajectory strictly between the inner and outer cortices to avoid the inner cortex and prevent bowel injury.
• Optimization of Cellular Yield: A syringe is attached to create a negative pressure vacuum; if initial aspirate yield is poor, the needle tip is repositioned slightly shallower (withdrawn by a few centimeters) or redirected posteriorly rather than anteriorly to capture a high concentration of mesenchymal stem and progenitor cells.
• Processing: The harvested marrow aspirate is spun down in a fresh centrifuge to separate its distinct biological layers before being combined with cellular allograft matrix.

• Intermaxillary Fixation (IMF) Placement: Intermaxillary fixation (IMF) screws are placed in the maxilla and mandible away from the operative site. Maxillomandibular fixation will be performed after the tumor resection.

• Mucosal Incision: A mucosal incision is performed. In this case, since we are dealing with a malignant condition (mucoepidermoid carcinoma), around 1 cm of mucosal margin is achieved. The mucosal incision is made along the medial and lateral aspects of the abnormal mucosa.

• Sterile Draping: The patient’s mouth is then sealed off using Ioban. The patient is prepped and draped sterilely with povidone-iodine.

• Flap Development: A skin incision marked approximately 2 cm inferior to the inferior border of the mandible. Dissection proceeds through the platysma into the subplatysmal plane using Metzenbaum scissors and electrocautery.

• Nerve Protection: Dissection is performed without neuromuscular paralysis to allow continuous intraoperative nerve stimulation monitoring of muscle responses. The submandibular gland capsule serves as a primary landmark to identify and sweep the marginal mandibular nerve superiorly within the skin flap.

• Soft tissue margin: Soft tissue around the tumor is kept down on the tumor for soft tissue margins. Unlike in a benign lesion where a subperiosteal tissue plane can be maintained, as much soft tissue as possible is left on top of the tumor. The marginal mandibular nerve is lifted while leaving the rest of the soft tissue on top of the tumor for soft tissue margins. Dissection is continued from the inferior to the superior border of the tumor until the previously made intraoral mucosal incision is encountered.

• Cutting Guides: Custom titanium cutting guides matching the inferior and posterior borders of the mandible are secured via monocortical screws, followed by bicortical predictive drilling. If exposure of the posterior mandible is difficult for the posterior cutting guide placement, one can consider making the anterior mandibular osteotomy first to advance the mandible forward for greater exposure.
• Osteotomy Execution: The anterior mandibulectomy is performed first to allow anterior mobilization of the condyle segment. The posterior segment exposure involves releasing soft tissue attachments to the sigmoid notch, removing the coronoid process entirely to eliminate temporalis muscle tension/pull on future hardware, and executing the osteotomy with a side-cutting bur and T-bar osteotome.
• Nerve Reconstruction: The proximal inferior alveolar nerve and distal mental nerve ends are identified and tagged with Prolene sutures. Frozen sections are sent to confirm negative perineural invasion.