Maxillofacial Trauma
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FRACTURES
Fractures can be classified according to their presentation.
Simple/Closed fractures have no communication with the external environment.
Compound/Open fracture do communicate with the outside environment via the skin, mucosa or periodontal ligament.
Comminuted fractures are broken in multiple places.
Greenstick fractures are the most common in young patients. One side of the bone is fractured, the other side only bent or undamaged.
Pathological fractures occur when a pathology significantly weakens the bone (cyst, tumor, infection, bony disorder).
The goal when treating maxillofacial fracture is to control hemorrhage, restore occlusal function, approximate the fractured segments, and stabilize the fracture to promote healing. The mandible is the second most common fractured facial bone, and in half of cases there is more than one fracture. The nasal bones are the most common.
Favorable fractures are not displaced by the force vector of attached muscles. Unfavorable fractures are the opposite, contraction of attached muscles leads to traction, pulling the fractured sides away from each other. A bilateral mandibular fracture can see the tongue free to displace and block the airway.
MANDIBULAR FRACTURES
Signs of fracture include malocclusion, (occlusal) step defects, abnormal mobility, mucosal lacerations, hematoma formation, and trigeminal nerve paresthesia.
A condylar fracture will present with a deviation to the affected/fracture side upon opening. Orthopantomogram (OPG) may still be considered the gold standard by some, but the three dimensional image from a cone-beam CT provides more information. Treatment depends on the type and position of the mandibular fracture.
Closed reduction/maxillomandibular fixation (MMF) is still performed (wires or elastic bands between the upper and lower jaws, 4-6 weeks), but open reduction and internal fixation (ORIF) may be more common. Prolonged immobilization of the mandibular condyle is not recommended due to the risk of ankylosis (maximum of 2 weeks). Often the occlusion is used as a reference for proper reduction. Teeth involved in the fracture are left to aid with alignment. It is likely that a patient presenting with a mandibular fracture will have associated systemic injuries (e.g. cervical fractures).
MID-FACE FRACTURES
Midface fractures can be classified according to which suture lines are involved.
Le Fort I (horizontal maxillary/transmaxillary fracture) causes mobility of the maxilla only, the fracture line passing through the alveolar ridge, lateral nose and inferior wall of the maxillary sinus. The nasofrontal complex remains unaffected. Signs include malocclusion, epistaxis, and buccal sulcus ecchymosis. Le Fort I is a floating palate (horizontal).
Le Fort II (pyramidal) fractures pass through the posterior alveolar ridge, lateral walls of the maxillary sinus, and inferior orbital rim and nasal bones. Causes the mobility of the maxillary and nasofrontal complex. Signs include periorbital edema and ecchymosis, subconjunctival hemorrhage, paresthesia of the infraorbital nerve, and epistaxis (nose bleed). Le Fort II is a floating maxilla (pyramidal).
Le Fort III (craniofacial disjunction) fractures pass through the nasofrontal suture, maxillo-frontal suture, orbital wall, and zygomatic arch/zygomaticofrontal suture. The temporalis muscle can become trapped because of the involvement of the zygomatic arch. Signs include malocclusion, periorbital ecchymosis and edema, subconjunctival hemorrhage, epistaxis, and cerebrospinal fluid (CSF) leaking in the nasal cavity (Rhinorrhea). Le Fort III is a floating face (transverse).
Zygomaticomaxillary complex fracture (ZMC), accounts for around 40% of midface fractures, second in frequency of midface fractures (nasal bone is number one). The zygoma is fairly strong and a fracture passes to adjacent articulating bones. Recall the zygoma articulates with the frontal, sphenoid, maxillary and temporal bone. The fracture passes along the inferior border of the orbit, through the infraorbital fissure. Can also be seen combined with a zygomatic arch fracture. The temporalis muscle can become trapped. Sign include flattening of the malar prominence and flattening over the zygomatic arch, periorbital edema and ecchymosis, subconjunctival hemorrhage, epistaxis, paresthesia of the infraorbital nerve, buccal sulcus bruising, trismus from coronoid process interference, and diplopia.
Zygomatic arch fracture can be isolated or combined with a Zygomaticomaxillary complex fracture (ZMC). Signs include malar depression and trismus from coronoid process interference. Often identified by the distinct “W” shaped deformity on a submentovertex radiograph or CT scan. Recall the zygoma articulates with the frontal, temporal, maxillary and sphenoid bones.
A blowout fracture refers to a fracture of the orbital floor. The inferior oblique (ocular) muscle can become trapped resulting in diplopia, and the volume of the orbit can be increased resulting in enophthalmos and hypoglobus. Patients usually present with limitation in upwards gaze, infraorbital nerve paresthesia, a “step” along the orbital rim, and subconjunctival and periorbital ecchymosis. Subcutaneous emphysema can indicate maxillary sinus fracture.
Midfacial fractures are repaired via open reduction and internal fixation, through various surgical approaches (intra-oral, sub tarsal lower eyelid, hemicoronal, using existing lacerations etc.). If there is a resultant malocclusion, Maxillomandibular Fixation (MMF) is used to establish proper alignment before the displaced fracture is reduced and secured with miniplate fixation. In the case of a zygomatic arch fracture, a Gillies approach can be used to pop the bones back into position.
A Le Fort I downfracture can be used to mobilize the maxilla. This can be moved anteriorly to treat a Class III, posteriorly to treat a Class II (though this is difficult, and usually is done as segmental osteotomy), vertically up to fix an open bite and long face, or down to reduce an overbite and lengthen the face. Moving the maxilla inferiorly is the least stable surgical procedure.
A bilateral sagittal split osteotomy (BSSO) of the ramus is the preferred procedure for mandibular orthognathic surgery. The mandible can be moved forward (advancement) to correct a Class II, or moved backwards (setback) to fix a Class III. Vertically the jaw can be rotated open to correct for a deep bite, but rotating the mandible closed is not recommended. Inferior alveolar nerve/mental nerve paraesthesia is a common side effect, usually resolving in 2 to 6 months, but in a quarter of patients there can be permanent damage.
Intraoral vertical ramus osteotomy (IVRO) is a useful technique to correct mandibular proportions. The lateral part of the angle and ramus is accessed either externally or intra-orally, and a full thickness vertical osteotomy is prepared distal to the mandibular foramen.
Genioplastly involves repositioning or reshaping the chin to improve facial harmony.
In regards to diagnostic imaging, CT scans are the most informative and versatile, in many cases replacing orthodox plain film views (Water’s view, lateral skull, posteroanterior, submentovertex etc)
