Marginal Mandibulectomy

Introduction

• 1.

  The goal of surgical management of any cancer of the head and neck is to remove the cancer in its entirety and preserve form and function. Marginal mandibulectomy (MM) evolved as a surgical technique to obtain the margin around the tumor yet avoiding the cosmetic and functional complications of segmental mandibulectomy (SM). Crile first described the MM in 1923 as an incision that is “carried down to the underlying bone, and thence into the bone by a sharp chisel or saw, so that a slice of bone can be split off in one piece, bearing the undisturbed cancer off as on a bone platter.” The three most common locations of cancer of the oral cavity in which MM plays a role include the floor of the mouth, the gingival ridge, and the retromolar trigone, where carcinoma abuts the mandible.

• 2.

  It was once believed that the oral cancers invade the mandible by draining through the lymphatic channels in the mandibular periosteum on their way to the cervical lymphatics. Hence, segmental mandibulectomies and composite resections were performed for oncologic completeness. Reconstructive surgery was still in rudimentary stages so that resections resulted in suboptimal cosmetic and functional outcomes, including malocclusion, temporomandibular joint dysfunction, Andy Gump deformity, tracheostomy, and gastrostomy tube dependence. Marchetta et al. later demonstrated that mandibular involvement occurs predominantly via direct invasion of the periosteum. This finding eliminated the mandate for SM. Furthermore, Barttelbort et al. proposed a theory of tumor invasion of the mandible. The cancer initially quickly invades the broad plane of the mandible superior to the mylohyoid muscle attachment. Involvement of the inferior lingual cortical plate occurs infrequently and late. Because of this theory, MM became a feasible procedure for removal of the cancer without compromising the mandibular arch.

• 3.

  The local recurrence and survival rates after segmental and MM were shown to be comparable (though one must be aware of the patient selection bias: Patients with gross bone involvement require a more extensive procedure). MM became an oncologically sound procedure in the management of oral cavity cancers and securing the margin around the cancer. The adverse cosmetic and functional outcomes are limited by preservation of the architecture of the mandibular arch and native muscular attachments. In addition, dental rehabilitation is a viable option in the form of a removable dental plate or dental implants. A major and legitimate concern with this procedure is the inability to obtain reliable intraoperative bone margins. Hence, careful preoperative planning must be executed.

Key Operative Learning Points

• 1.

  The goal of MM is to secure the margin around the cancer.

• 2.

  Proper patient selection is the key: Meticulous preoperative clinical and radiologic evaluation should be performed to rule out bone involvement.

• 3.

  Osteotomies must be planned before the surgery.

• 4.

  Osteotomies should be placed with assurance of preservation of healthy residual teeth and allowing for dental rehabilitation.

• 5.

  Most recurrences occur in the soft tissues, not the bone. Hence, careful intraoperative frozen section analysis should be used to avoid recurrence in the soft tissues.

• 6.

  Most MM defects can be successfully reconstructed with the split-thickness skin graft.

Preoperative Period