see also: Lip Split with Mandibulotomy Approach for Oral and Pharyngeal Access

GENERAL CONSIDERATIONS

1. Indications
   1. The decision to perform either segmental or rim (either horizontal or lingual plate) resection of the mandible is influenced by many factors. The indications and contraindications outlined below are general recommendations that should be interpreted in the context of the multiple clinical variables associated with an individual patient.
   2. Indications for segmental resection of the mandible as determined by physical examination and radiographic imaging: 
      1. Invasion of the medullary space of the mandible
      2. Tumor fixation to the occlusal surface of the mandible in the edentulous patient
      3. Invasion of tumor into the mandible via the mandibular or mental foramen
      4. Tumor fixed to the mandible following prior radiotherapy to the mandible, particularly if the tumor is located on the occlusal surface
      5. Tumor adjacent to carious dentition with involvement of the periodontal ligament
      6. Hypoplastic edentulous mandible with significant loss of vertical height precluding safe performance of rim resection
      7. In selected cases a segmental resection may be indicated for non-oncologic reasons. Heavily irradiated patients with trismus may improve jaw opening with a segment removed and newly vascularized soft tissue interposed.
   3. Indications for rim resection of the mandible as determined by physical examination and radiographic imaging:
      1. Tumor close to but not involving the periosteum of the mandible
      2. Tumor involving only mandibular periosteum
      3. Tumor adjacent to cortical bone of mandible with no evidence of invasion beyond superficial cortex
      4. Tumor adjacent to dentition with no evidence of involvement of periodontal ligament
2. Contraindications
   1. For most cases of oral cancer recurrence after radiation therapy with tumor intimately associated with the mandible, rim resection is contraindicated. In these cases, the route and exact location of tumor invasion into the mandible is not predictable.
   2. Patients with very hypoplastic mandibles in which oncologically safe resection of the tumor would leave less than 1 cm of bone width and height are not good candidates for rim resection.
   3. With the multiple alternative techniques for approaching tumors of the oral cavity and pharynx available, segmental mandibular resection done solely to improve access for tumor extirpation is rarely indicated.
   4. Segmental or rim resection for presumed clearance of mandibular lymphatics is not indicated.
3. Pertinent Anatomy
   1. Involvement of mandibular lymphatics or periosteum of the mandible occurs via direct extension of the primary tumor. There is no evidence that tumors of the oral cavity metastasize to involve the mandibular lymphatics or periosteum.
   2. Cortical thickness on the occlusal surface of the mandible is significantly less than other areas of the mandible.
   3. With atrophy of the edentulous mandible, the occlusal surface is lowered downward, and in the extremely hypoplastic mandible, the alveolar canal may run along the occlusal surface.
   4. In the nonradiated mandible, the most frequent route of tumor spread to invade the mandible is via the occlusal surface of the alveolus. This route of spread accounts for approximately 90% of cases in which oral tumors invade the mandible.
   5. In previously radiated mandibles, the most frequent route of tumor invasion into the mandible is also via the occlusal surface; however, tumor may also invade along other surfaces, and site of invasion is much less predictable than in the nonradiated cases.
   6. Tumor invasion of the mandible follows a leading front of inflammatory bone destruction due to stimulated osteoclastic and osteoblastic activity.
   7. In the nonradiated patient, the mylohyoid muscle serves as a barrier to tumor spread from the floor of mouth; however, this barrier will be breached in larger tumors.

PREOPERATIVE PREPARATION

1. Evaluation
   1. Routine preoperative evaluation for head and neck cancer
   2. Thorough examination of the head and neck, careful examination of tumor relationship to mandible
   3. CT scan with contrast, bone and soft tissue windows from base of skull to clavicles
   4. Orthopantomogram
   5. Maxillofacial prosthetics consult and dental films as required
2. Potential Complications
   1. Infection with or without fistula
   2. Infection with the need to remove fixation hardware
   3. Mandibular fracture following rim resection
   4. Occlusal disharmony in the dentate patient undergoing segmental resection (presumed reconstruction with free tissue transfer)
   5. Delayed or nonunion in the segmental resection patient (presumed reconstruction with free tissue transfer)
   6. Patients undergoing rim resection should be advised that, pending final pathologic evaluation of the resected specimen, further removal of bone and conversion to segmental resection may be advised.

NURSING CONSIDERATIONS

1. Room Setup
   1. See Basic Soft Tissue Room Setup
   2. Back table x 2
2. Instrumentation and Equipment
   1. Standard
      1. Major Instrument Tray 1, Otolaryngology
      2. Major Instrument Tray 2, Otolaryngology
   2. Special
      1. Sterile anesthesia breathing circuit, adult
      2. Roush Laryngoflex 7 mm endotracheal tube
      3. Bipolar Forceps Trays
   3. Special
      1. KLS Free Flap Implant - Instrument Tray or
      2. KLS Locking Reconstruction Threadlock Instrument Tray or
      3. KLS Oto Trauma Implant - Instrument Tray or
      4. KLS mandibulectomy or
      5. KLS maxillectomy
      6. McKesson mouth prop, large adult, adult, and child
      7. Hall Micro Sagittal Saw Tray (Pneumatic) or Midas Rex Drill Tray
      8. Bien Otologic Electric Drill Tray
      9. Tracheotomy Tray
      10. Varidyne vacuum suction controller
      11. Bone wax
3. Medications (specific to nursing)
   1. Antibiotic ointment
   2. 1% lidocaine with 1:100,000 epinephrine
4. Prep and Drape
   1. Standard prep, 10% providone iodine
   2. Drape
      1. Head drape
      2. Towels around operative site, from above nose, entire neck, and chest
      3. Split sheet
5. Drains and Dressings
   1. In the past: varidyne vacuum suction: 7 mm or 10 mm, x 2
   2. Currently: Jackson-Pratt 10 mm fully perforated with 600 cc 'grenade' reservoir suction devices (REF SU 130-1000 Jackson-Pratt reservoir)
   3. Corpak feeding tube
6. Special Considerations
   1. Ask about possible graft or pedicle flap and drape accordingly
   2. Tracheotomy procedure possible
   3. Perioperative antibiotics (see Antibiotic Prophylaxis in Head and Neck Surgery protocol)
   4. Unless contraindicated, most patients should receive three doses of perioperative Decadron (8 to 10 mg IV)

ANESTHESIA CONSIDERATIONS

1. General
   1. No paralysis until after mandibular branch of cranial nerves VII and XI are identified if applicable to the particular case.
   2. The patient will undergo oral intubation and conversion to tracheotomy in most cases. If safe intubation is not possible due to tumor anatomy, the case will start with a local tracheostomy.
2. Specific
   1. The patient will be supine.
   2. The head will be turned 180° away from the anesthesiologist.
   3. See appropriate protocol if flap reconstruction is planned.

OPERATIVE PROCEDURE FOR SEGMENTAL RESECTION

1. Ipsilateral neck dissection is completed; Level I may remain in continuity with oral cancer or removed separately. The neck dissection may be done to address metastases (occult or evident). The neck dissection may alternatively serve the purpose of improving access to the mandible for resection with tumor clearance. The neck dissection may also serve to prepare blood vessels for a free flap reconstruction.
2. Access to tumor is via lingual release, pull-down, or lip-split procedure.
3. Exposure of noninvolved outer cortex of mandible adjacent to area of mandibular involvement is obtained.
   1. For the dentate patient, the reconstruction plate is contoured. Preliminary holes are drilled in order to return the patient to preoperative occlusal state (see Fixation of bone flaps protocol).
   2. For the edentulous patient, the resected specimen will be used to fashion a template from which the bone flap will be contoured.
   3. If bone flap reconstruction is not planned, proceed as in Step 1 above using a locking screw plate to stabilize the bone fragments and restore mandibular arch continuity. This type of reconstruction is recommended for only short-segment posterior defects in patients who will not be loading the mandible postoperatively (ie, edentulous elderly patients).
4. Segmental cuts are made at least 1 cm from suspected bone involvement using a sagittal saw or Midas-Rex.
   1. These cuts are made from external to internal following the intraoral mucosal and periosteal cuts. This leaves the tumor held in place by soft tissues of the oral cavity or pharynx.
   2. Soft tissue within the alveolar canal at the distal and proximal end of the excision may be submitted for frozen section analysis. Any easily removable soft tissue in the cut bone ends of the mandible should be submitted for frozen section evaluation.
5. Completion of soft tissue resection is performed, and the specimen is delivered in continuity with the Level I neck dissection.
6. Careful back elevation of mucoperiosteum adjacent to incisions will facilitate ease of suturing this tissue to the reconstructive flap.
7. In selected cases where the segmental resection has been chosen to improve function (eg to address trismus in resecting a lesion that would otherwise be amenable to a rim resection), preservation of the inferior alveolar nerve may be considered in order to preserve sensation to the lip. This type of resection requires finesse bone removal and is enhanced with use of the B-2 burr of the the Stylus (or Midas) drills. see: Microvascular Surgery Protocols

OPERATIVE PROCEDURE FOR RIM RESECTION

1. Ipsilateral neck dissection is completed; Level I remains in continuity with oral cancer or taken separately.
2. Access to tumor via lingual release or lip-split procedure.
3. Lateral periosteal cuts are made intraorally.
4. The periosteum is gently elevated toward tumor. If mandibular invasion is evident, the procedure should be converted to segmental resection.
5. Lateral mandibular periosteum is elevated inferiorly exposing lateral cortex of the upper mandible.
6. The periosteum of the lower cortex is not elevated.
7. Using a sagittal saw or Midas-Rex, a horizontal rim resection is created by cutting horizontally through the bone at least 0.8 to 1 cm from the tumor. Distally and proximally, the bone cuts form a smooth transition with the occlusal surface. Square corners at the ends of the ostectomy site create points of mandibular weakness.
8. If the tumor is located on the lingual surface of the mandible, a similar vertical rim resection is performed (lingual plate resection).
9. Any soft tissue available along the bone cut should be submitted for frozen section analysis.
10. The remaining soft tissue cuts are made, and the tumor is delivered as a pull-through specimen in continuity with the Level I neck dissection.

POSTOPERATIVE CARE

1. Drains removed when less than 30 cc per 24 hours
2. All patients NPO for 1 week, 2 weeks if previously radiated
3. Begin oral rinse QID with normal saline: peroxide, 1:1 on postoperative day 2
4. Segmental resection patients should be on soft diet for 6 weeks
5. If pathologic review of rim resection specimen demonstrates positive bone margin, further segmental resection should be discussed with the patient.

REFERENCES

Ayad T, Guertlin L, Souliere D, Belair M, Temam S, and Nguyen-Tan PF: Controversies in the Management of Retromolar Trigone Carcinoma. Head Neck 31: 398-405, 2009

Barttlebort SW, Bahn SL, Ariyan S. Rim mandibulectomy for cancer of the oral cavity. Am J Surg. 1987;154:423-428.

Forrest LA, Schuller DE, Lucas JG, Sullivan MJ. Rapid analysis of mandibular margins. Laryngoscope. 1995;105:475-477.

Marchetta FC, Sako K, Badillo J. Periosteal lymphatics of the mandible and intraoral carcinoma. Am J Surg. 1964;108:505-507.

McGregor AD, MacDonald DG. Reactive changes in the mandible in the presence of squamous cell carcinoma. Head Neck Surg. 1988;10:378-386.

McGregor AD, MacDonald DG. Routes of entry of squamous cell carcinoma to the mandible. Head Neck Surg. 1988;10:294-301.

Moloy PJ, Rappaport I, Turnbull FM, Allison GR, Charter RA. Horizontal versus vertical block resection for early floor of mouth carcinoma. Am J Otolaryngol. 1989;10:153-160.

O'Brien CJ, Carter RL, Soo KC, et al. Invasion of the mandible by squamous carcinoma of the oral cavity and oropharynx. Head Neck Surg. 1986;8:247-256.

Shaha AR. Preoperative evaluation of the mandible in patients with carcinoma of the floor of mouth. Head Neck. 1991;13:398-402.