HPI
An unhelmeted 27-year-old male was involved in a motorcycle crash (MCC) earlier today. He was able to get up from the scene and drive himself to the emergency department (ED). He denies loss of consciousness. He explains that he has pain in his lower face and jaw, his teeth do not occlude correctly, and his left lip is anesthetic.
Assault, motor vehicle accidents, and sporting injuries are the most common causes of mandibular fractures. Malocclusion is a significant indicator of mandibular or dentoalveolar fracture. Paresthesia of the distribution of the third division of the trigeminal nerve (V3) is common and can be caused by neuropraxia, axonotmesis, or neurotmesis of the mental or inferior alveolar nerve at the fracture site.
PMHX/PDHX/medications/allergies/SH/FH
The patient smokes one pack of cigarettes a day and drinks alcohol on the weekends. He denies all other habits. (Both alcohol and tobacco use have been associated with an increased risk of infectious complications with mandibular fractures.)
Examination
Primary survey (advanced trauma life support)
Airway and cervical spine control. The patient speaks without difficulty. (In cases of multiple fragmented mandibular fractures, the upper airway can become acutely compromised because of posterior collapse of the tongue with loss of a stable genioglossus insertion at the genial tubercles.) The cervical spine examination is unremarkable. (Haug and colleagues report an association between cervical spine injuries and mandibular fractures. The stability of the cervical spine is crucial throughout the care of the patient.)
Breathing and oxygenation. Unlabored. Oxygen saturation of 97% on room air.
Circulation. Pulse and capillary refill are unremarkable. No active bleeding.
General. Supine on the ED bed with O 2 .
Vital signs. Blood pressure is 116/78 mm Hg, heart rate is 70 bpm, respirations are 12 breaths per minute, and temperature is 37°C.
Secondary survey
Neurologic. Alert and oriented ×3. Glasgow Coma Scale score is 15.
Maxillofacial. The facial structures are grossly symmetric with edema in the lower third. Examination of the eyes (pupils, visual acuity, visual fields, and extraocular movements) reveals no changes from the patient’s baseline. External ears are without deformity. Tympanic membranes are clear. (Hemotympanum, external auditory canal lacerations, tympanic plate rupture, and fracture of the posterior wall of the joint should be ruled out.) The remainder of the facial bones are stable except for the mandible, which demonstrates mobility in the parasymphysis region on the right and in the left angle region. The mobility of the fractured segments causes pain and malocclusion. Facial edema is present bilaterally, with tenderness to palpation at the fracture sites. Cranial nerves II through XII are intact, except for anesthesia of V3 on the left side. The neck is nontender and demonstrates full range of active movement without pain (it is important to rule out cervical spine injury).
Intraoral. The dentition is in moderate repair. The patient has obvious steps in the occlusal plane between teeth #25 and #26 and distal to tooth #18. There are multiple lacerations involving the gingiva in the associated areas. The occlusal steps and mobility of segments characterize the patient’s malocclusion. There is hematoma formation in the anterior floor of the mouth.
Imaging
Most practitioners consider computed tomography (CT) scans to be the gold standard imaging modality for evaluation of mandibular fractures. A CT scan allows the entire face to be evaluated in one study. Facial bones, including the mandible, can be evaluated in several different anatomic planes. The axial and coronal planes are the two commonly used views. The coronal plane can be useful for viewing condylar fractures, and axial views are useful to assess the remainder of the mandible. Patients with suspicion of cervical spine injury should not have their necks hyperextended for direct coronal imaging. Instead, digitally reconstructed coronal images can be used.
Despite the popularity of CT imaging, in many facilities, the initial imaging studies may consist of a panoramic radiograph or a plain view series of the mandible (posteroanterior, reverse Towne’s, bilateral lateral oblique radiographs). Many hospitals still use a plain view series of the mandible; therefore, familiarity with plain radiographs remains important.
A panoramic radiograph is the imaging modality of choice for patients presenting at the surgeon’s office. This radiograph is inexpensive and is the single best plain film for evaluation of the entire mandible. However, nondisplaced or minimally displaced fractures of the condyle or the symphyseal area may be difficult to detect on a panoramic radiographs. The combination of a reverse Towne’s view and an anteroposterior (AP) radiograph of the mandible results in a sensitivity and specificity like that of a CT scan. The decision to order different imaging modalities should be based on available resources, physical examination findings, and the knowledge of limitations related to particular studies. When available, in-office cone-beam CT scans are excellent for evaluating mandibular fractures.
For the current patient, a panoramic radiograph demonstrates fractures at the left angle and in the right parasymphysis region ( Fig. 50.1 A ) . An AP view of the mandible shows severe displacement at the left angle (which explains the anesthesia of the left V3) and fracture at the right parasymphysis ( Fig. 50.1 B); note that the degree of lateral displacement is not evident on the panoramic radiograph.
Labs
Routine laboratory testing is not mandatory before surgical correction of mandibular fractures unless dictated by underlying medical conditions. In cases of infected mandibular fractures, a white blood cell count should be obtained.
Assessment
A 27-year-old male after an MCC with open mandibular fractures at the right parasymphysis (nondisplaced) and left angle (displaced). Facial Injury Severity Scale score of 4. Also, an associated injury to the left inferior alveolar nerve most consistent with neurotmesis or a Sunderland’s class 5 injury.
Treatment
The treatment of mandibular fractures has a long history, dating back to 1600 bc . The mandible is the foundation of the lower third, requiring special attention for various aspects of treatment (occlusion, esthetics, function) to achieve a good result.
Mandibular fractures with overlying lacerations or involving the tooth-bearing segments are considered open fractures. Treatment tends to be rendered in a timely fashion; however, studies show that delayed surgery may not affect the rate of complications. Preoperative antibiotics have been shown to decrease the incidence of postoperative infectious complications and should be considered regardless of the time interval before definitive surgery can be completed. The use of postoperative antibiotics remains largely practitioner dependent, and no good evidence exists guiding its necessity and potential benefits or the duration of treatment.
Whereas rigid fixation eliminates interfragmentary movement when load is applied, semirigid or nonrigid fixation allows for adequate union of bone but is not sufficient to prevent interfragmentary movement. Rigid fixation is adequate fixation allowing the patient to return to optimal function. Movement at the fracture site not only increases the chance of infection but also the development of fibrous union, malunion, or nonunion. Nonrigid fixation techniques, when correctly applied, can also provide a successful outcome. Lag screws are an acceptable form of rigid fixation but are not applicable to all fractures. Applicable examples include fixation at a symphyseal fracture.
Rigid fixation is indicated in the treatment of complex mandibular fractures. Two important concepts, load bearing and load sharing, are taken into consideration when discussing rigid fixation. Whereas load-bearing fixation bears the functional forces at the fracture sites, load-sharing fixation is unable to bear all functional load. In the latter, stress across fracture repair is shared by fixation technique and by the bone. An example of a load-bearing fixation is the use of a locking reconstruction plate. Locking fixation plates should be used if the screw or plate-to-bone interface is not seamlessly adapted. The use of a nonlocking screw will displace the mandibular fracture if the plate is not seamlessly adapted; therefore, a locking screw is indicated.
Closed reduction of mandibular fractures continues to be an acceptable form of treatment. Indications for closed reduction include high condylar fractures, favorable or nondisplaced fractures, and select pediatric fractures. Closed reduction does not offer the benefit of early function, and the patient must tolerate a prolonged period of intermaxillary fixation. Contraindications to closed reduction include intellectual disability, psychiatric disorders, alcoholic abuse, seizure disorder, nutritional concerns, respiratory disease, obstructive sleep apnea, and unfavorable fractures.
While sequencing repair of multiple mandibular fractures, attention is directed to fixation of the dentate fractured segment first. Reestablishing the patient’s native occlusion will allow appropriate reduction of nondentate segments.
The patient was treated under general anesthesia in an ambulatory care facility with open reduction and internal fixation (ORIF) ( Fig. 50.2 ). Nasoendotracheal intubation was performed to allow for maxillomandibular fixation. Erich arch bars were applied to the maxilla and the mandible with 24-gauge wires, reestablishing the arch form while reducing the fractured segments. Cautery was used to make a transoral incision in mandibular vestibule to expose the parasymphysis and angle fractures. Care was taken to expose the right mental foramen and mental nerve.
