Mandibulectomy - Segmental

Considerations

• • Anatomy

    • Be aware of named vessels and nerves as you make the osteotomies 

      • Mid ramus - May hit internal maxillary artery or inferior alveolar artery and nerve

    • Shifting the osteotomy near the coronoid notch may minimize bleeding

  • Long buccal nerve - courses between the two heads of the lateral pterygoids; Provides sensation to the inner cheek

  • Lingual nerve - most at risk during the posterior osteotomy as well as during the neck dissection 

  • Indications

    • Cancer involving or invading mandible

    • Osteoradionecrosis of the mandible 

    • 2010: Paradigm shifts in the management of osteoradionecrosis of the mandible

    • 2013: Mandibulectomy and Free Flap Reconstruction for Bisphosphonate-Related Osteonecrosis of the Jaws

  • Marginal (rim) versus segmental mandibulectomy

    • If the bone is involved, go with segmental

    • If the periosteum is involved but bone is normal, marginal is preferred  

  • 2000: Review of segmental and marginal resection of the mandible in patients with oral cancer

  • 2002: Marginal mandibulectomy vs segmental mandibulectomy: indications and controversies

  • 2005: Management of mandibular invasion: when is a marginal mandibulectomy appropriate?

  • 2009: Controversies in the management of retromolar trigone carcinoma

  • Mandible parts

  • 1997: Segmental resection of the anterior mandibular arch with fibular microvascular reconstruction

  • 1997: Lateral mandibulectomy and partial glossectomy with plate application

  • Special defects 

  • 2004: Reconstruction of concomitant lip and cheek through-and-through defects with combined free flap and an advancement flap from the remaining lip

  • 2010: Reconstruction of lateral through and through oro-mandibular defects following oncological resections

  • Pre-operative work-up

    • Physical examination

      • Palpate for tumor fixation to the mandible, if fixed, some degree of mandibulectomy is in order

      • Dental evaluation 

    • Imaging

      • CT requires 60-70% loss of bone mineral before visualization of bone involvement 

      • MRI is superior for identifying marrow involvement 

  • Margin planning

    • 1-2 cm gross minimum margins

    • Include the ipsilateral mental foramen, given propensity for perineural spread 

  • Tracheostomy

    • May be required for exposure and security

    • Perform first

  • Neck dissection

    • Dissect the neck prior to mandibulectomy 

    • The clinically N0 neck warrants ipsilateral levels 1-3

      • Level 4 should be included for SCC of the tongue (skip lesions)

    • In level 1, remove all nodes adjacent to the facial artery

    • 2004: Perivascular-submandibular lymph node metastasis in squamous cell carcinoma of the tongue and floor of mouth

    • 2006: Perifacial lymph node metastasis in the submandibular triangle of patients with oral and oropharyngeal squamous cell carcinoma with clinically node-positive neck

  • Technique

  • Perform osteotomies prior to incising the soft tissue around the tumor

  • Transcervical approach

    • Lower lip spliting incision

      • 1995: Lower lip splitting incisions: Anatomic considerations

    • Visor flap incision

      • 2014: Modified visor approach applied to total or subtotal glossectomy and reconstruction: avoidance of lip splitting and mandibulotomy and cutting off mental nerve

      • 2015: Visor approach for the total excision of a large multicystic ameloblastoma of the mandible

    • 2007: Comparison of Approaches for Oral Cavity Cancer Resection: Lip-Split versus Visor Flap

    • Transoral approach

    • 1979: Transoral mandibulectomy in advanced osteoradionecrosis

    • 2015: Transoral mandibulectomy and double barrel fibular flap reconstruction

    • Osteotomies

      • Powered sagital or recipricol saw

      • May cut at fresh dental-extraction sockets 

    • Reconstruction plates

      • Place and fit to the lateral cortex pre-resection

      • Other options

        • Prebent plates  

      • Drill 3 holes on each side of the osteotomies pre-resection

      • If the lateral cortex is not intact, external fixation is needed 

• Virtual Surgical Planning (VSP)

  • • Plan with the company rep

    • Recent high resolution CT required 

• Reconstruction 

• • Rigid bar with out without regional flap 

  • Free flap - see Fibula free flap - Osteocutaneous

  • Prosthesis

  • 2011: Modern concepts in mandibular reconstruction in oral and oropharyngeal cancer (Kevin H Wang) 

• Dental rehabilitation

  • • Plan with MFS using VSP if immediate implants are an option; MFS will handle to follow-up and coordination with the orthodontic prosthetist 

      • The implants can be placed in the fibular in situ prior to ligating the pedicle and starting ischemia time  

• • 2015: Aesthetic and functional mandibular reconstruction with immediate dental implants in a free fibular flap and a low-profile reconstruction plate: five-year follow-up

Preparation

Procedure

• • Perform tracheostomy, if needed 

  • Perform dental extractions, if needed 

  • Perform neck dissection 

  • Identify the inferior border of the mandible anterior to the masseter attachment 

  • Incise the periosteum inferior to the masseter attachment 

  • Elevate the masseter from the angle of the mandible 

  • Divide the lip in the midline 

  • Incise the mucosa antero-lateral to the tumor with 1 cm gross margins (intraoral degloving) in order to raise the cheek flap

  • Divide the mental nerve as the skin flap is raised 

  • If needed, suture the tongue tip for retraction

  • Connect the neck with the antero-lateral intraoral delgoving incision

  • Place Penrose drains on the skin flap for retraction

  • If needed, pre-plate the mandible at the planned osteotomies 

    • Remove and sterilize the hardware

• Complete the anterior osteotomy

  • Include the ipsilateral mental foramen

  • Complete the posterior ostoetomy - variable locations and technqiues

    • If at the mid-ramus, control bleeding upon completion of the osteotomy 

  • Obtain hemostasis 

  • Incise medial and posterior to the tumor with 1 cm gross margins 

  • Identify and preserve the lingual nerve, if possible 

  • Transect the inferior alveolar nerve proximally 

  • If the soft palate is involved, place a suture at its preserved margin for retraction and later identification

  • Work circumferentially posteriorly and superiorly toward the skull base

    • Divide the medial pterygoid muscles and branches of V3 by placing a finger behind the specimen to elevate the soft tissue and protect the carotid artery

    • Ligate branches of the maxillary artery 

  • Once excised, orient and examine the specimen 

  • Obtain margins for frozen section

    • Include the neurovascular pedicle 

    • Do not send bone for frozen section 

  • Optional: Obtain marrow of the preserved distal and proximal bone for permanent pathology

  • Irrigate

  • Obtain hemostasis

  • If a free flap reconstruction is planned, isolate the recipient vessels for anastomosis 

Sample operative report

Post-op

• • Complications 

    • Standard - wound dehiscence, infection, hematoma, pain, cosmetic defects

    • Specific - airway compromise, fistula, nerve injury, injury to salivary ducts, abnormal salivation, mandibular instability, hardware failure, lingual dysfunction and prehension difficulties, dysphagia and anorexia

  • 1990: Results and complications associated with partial mandibulectomy and maxillectomy techniques

  • 1992: Costs and complications in mandibular reconstruction

Pearls & Pitfalls

High-Yield

Links

• eMedicine - Mandibulectomy

• Iowa Protocols - Segmental and Rim Mandibulectomy