Open Reduction and Internal Fixation of Mandibular Fracture
In open reduction and internal fixation (ORIF) of a mandibular fracture, the fracture lines are plated across with titanium plates using an intraoral approach. One to 1.2 mm thick mini-plates may be used, unless the fracture is comminuted, infected, or contains a gap, in which case a larger reconstruction plate may be required. ORIF of a mandibular fracture with overlapping fragments should use lag screws instead of plates for fixation. Lag screws may also be used in certain sagittal or oblique fractures. The patient is placed in maxillomandibular fixation (MMF) to maintain proper occlusion during the procedure.
Indications for Surgery:
Mandibular fracture. Unilateral, nondisplaced fractures of the condyle or ramus with normal occlusion may be managed conservatively. Closed reduction with or without maxillomandibular fixation may be performed in cases where open reduction is contraindicated and in some cases of uncomplicated condylar fractures.
Contraindications to Surgery:
- Medical comorbidities that would preclude surgical or anesthesia risk
- A maxillofacial computed tomography (CT) scan is typically obtained at the time of initial trauma evaluation.
- Panoramic tomography (Panorex film) of the mandible is the preferred imaging modality and should be obtained, even if CT has already been performed.
- Dental consultation is recommended if tooth injury has occurred or is suspected based upon location of the fracture.
- Physical examination should include assessment of cutaneous sensation over the chin and lower lip to document inferior alveolar nerve function. Occlusion and presence of trismus should also be evaluated.
- If the patient is seen at the time of initial trauma, he should be placed in MMF and prescribed antibiotic therapy and a soft or liquid diet. The patient may then be discharged home (assuming an inpatient stay is not required for concurrent injuries) and scheduled for elective surgery within 5-7 days.
- The patient is placed supine on the operating table and general anesthesia is induced via nasotracheal intubation.
- The incision site is injected with 1% lidocaine with 1:100,000 epinephrine. A transoral gingivolabial or gingivobuccal incision is then made overlying the fracture site. The incision should be made at least 5-10 mm inferior to the gingival margin to allow for adequate tissue to reapproximate to when repairing the incision.
- The mentalis muscle is divided and the periosteum is elevated, exposing the mandibular bone. Care is taken to avoid damaging or stretching the mental nerve as it exits the mental foramen, if dissection approaches this area.
- The fracture is reduced manually, or by traction on an attached clamp.
- Appropriate sized plates are selected and bent to shape. Care is taken to avoid placing plates in locations that may injure tooth roots or the inferior alveolar nerve.
- Drill holes are made for the screws, and the plates are secured with monocortical self-tapping screws. At a minimum, two screws must be placed on either side of the fracture line.
- The wound is irrigated and checked for hemostasis. The incision is then closed in two layers with absorbable sutures.
- MMF may or may not be removed at this time, depending on the case and surgeon preference. Care of the patient is returned to the anesthesiologist for extubation and recovery.
- ORIF of mandibular fracture can be performed on an outpatient basis. Often, it is performed in an inpatient setting in conjunction with other procedures related to traumatic injuries.
- If the patient is left in MMF, wire cutters should be kept by the hospital bed (or, if the patient is to be discharged, he should be instructed on how to cut the wires at home). This is essential in case the mouth needs to be opened to maintain airway patency, such as if the patient vomits. For inpatients, a tracheostomy tray should be available at the bedside as well, in case the wires cannot be cut in time or access to oral airway is otherwise obstructed.
- The patient is advised to maintain a soft/liquid diet for 4-6 weeks after surgery. Patients left in MMF will need to feed themselves via a syringe attached to a rubber catheter that can be inserted in the corner of the mouth.
- Frequent rinses with chlorhexidine mouthwash are prescribed, and the patient is given instructions on maintaining good oral hygiene.
- An initial post-operative visit should be scheduled approximately 1 week after surgery.
- Wound infection/osteomyelitis
- Injury to local structures including inferior alveolar nerve and tooth roots
- Malunion or nonunion