The maxilla is located in the middle of the human face and is in a prominent position. It is one of the areas in the middle of the face that is prone to fracture, and maxillary fractures can occur when the maxilla is subjected to striking forces from directly in front, below, or to the side.
Surgical anatomy
The maxilla is the largest bone in the middle part of the face, one on each side, and is joined together by a suture in the center. The maxilla is a thin bone with a hollow interior and a maxillary sinus. The maxilla is connected to the other surrounding bones by sutures and is involved in forming the oral cavity, nasal cavity, and orbit, and fractures are often compound. Due to its proximity to the skull base, it is often associated with craniocerebral injury. The maxilla is rich in blood flow, and trauma can lead to severe bleeding, strong resistance to infection and fast healing after injury, and should be operated as early as possible.
Fracture classification
1.LeFort classification
Proposed by ReneLeFort (1901), divided into three types.
LeFort type I: i.e., horizontal fracture of the base of the alveolar process, with the fracture line passing through the inferior margin of the pyriform foramen, the base of the alveolar process, around the zygomatic alveolar ridge and the maxillary tuberosity backward to the pterygoid process.
LeFort type II: i.e. a central conical fracture of the maxilla with the fracture line running from the root of the nose to the sides, through the lacrimal bone, the infraorbital rim, the zygomatic maxillary suture, and around the lateral wall of the maxilla posteriorly to the pterygoid process.
LeFort type III: i.e., a high horizontal fracture with the fracture line running through the nasofrontal suture, across the orbit, and then posteriorly down to the pterygoid process through the zygomatic-frontal suture, forming a craniofacial separation.
2. The modified classification is divided into four types as follows.
(1) Low (horizontal) fracture: i.e. maxillary Le
FortI type horizontal fracture. The main clinical manifestation is ? relationship disorder. The treatment principle is to restore the ? relationship.
(2) High (horizontal) fracture: the maxillary fracture line is at the Le
Fort type II and/or type III level. The clinical manifestations are ? disturbance of the relationship and facial deformity. The treatment principle is to restore? relationship and correction of the facial deformity.
(3) Sagittal fracture: The maxilla is vertically fractured and the fracture line is located medially or paracentrically. The clinical manifestation is a widening of the dental arch, which may appear open? , the fracture may injure the skull base. The treatment principle is to resolve the ? relationship to close the traumatic palatal fracture.
(4) Alveolar process fracture: the fracture line is confined to the apical level and only affects the dental bone segment. The treatment principle is to reset and fix the odontoid segment.
Causes of fracture
The most common causes of maxillary fractures are motor vehicle accidents and motorcycle accidents, but they can also be caused by violence, falls, and sports.
Diagnosis of fracture
1.History: Ask the patient or family members about the cause of injury, the nature, size and direction of the force, whether there is a history of coma after the injury, post-injury treatment, the patient’s vision and whether there is diplopia, the sense of smell and nasal ventilation, and the occlusion, etc.
2.Clinical manifestations
(1) Fracture displacement and abnormal motility
The maxillary fracture, especially the whole maxillary fracture, usually occurs to be displaced posteriorly and inferiorly, resulting in the drop of the maxilla. If the fracture displacement is not large, the palatal mucosa is usually intact; if the fracture displacement is obvious and the palatal mucosa is split, “traumatic cleft palate” can be formed.
Clinically, when the patient does chewing movements, the overall abnormal dynamics of the maxilla can be found. To check for fractures in the maxilla, the head is fixed and the anterior maxillary alveolar process is held in one hand and shaken back and forth to feel if there is significant movement of the fractured segment of the maxilla. To check for LeFort type II or III fracture, place the fingers of one hand on the bridge of the nose and hold the maxilla with the other hand and shake it back and forth, if there is movement at the nasofrontal suture, it indicates the presence of LeFort type II or III fracture.
(2) Occlusal malocclusion
The typical manifestations of occlusal malocclusion after maxillary fracture are early contact of the posterior teeth and open or anterior teeth; if the maxilla is displaced laterally as a whole, there is a deviated malocclusion; if the maxilla is fractured sagittally and one fracture segment is sagging, there is early contact of the affected teeth and the healthy side teeth are open.
(3) Functional impairment
Speech impairment, swallowing difficulty and masticatory disorder can occur after maxillary fracture, and masticatory disorder is mainly manifested as weakness of occlusion. When the whole maxilla is fractured and displaced downward, it may cause respiratory difficulty or even asphyxia.
(4) Facial deformity
After the maxillary fracture, it often shows that the mouth cannot be closed, salivation, the middle 1/3 of the face becomes longer and the anterior part collapses. The facial deformity is not obvious for low fractures, but high fractures often show a sunken middle face and a “discoid face” shape. The maxilla may be displaced to one side, causing a distorted deformity of the midface.
(5) Ocular symptoms and signs
A high horizontal fracture often affects the periorbital area and bony structures of the orbit, resulting in periorbital swelling, bruising, subconjunctival hemorrhage, and the typical ophthalmoscopic sign. When the fracture affects the orbital wall of the eye, it may cause displacement of the eye and diplopia. Injury to the infraorbital nerve results in numbness in the infraorbital area and upper lip.
3.Imaging examination is required to confirm the clinical diagnosis of fracture.
(1) Plain radiographs of Fahrenheit and lateral cephalometric films can be used to diagnose maxillary fractures, mostly in the absence of CT examination means, with the disadvantage that the details of the fracture cannot be seen.
(2) CT axial and coronal CT scans of the midface can show fractures in all walls of the maxillary sinus, whether fluid accumulates in the maxillary sinus, and bony orbital and orbital contents damage. In severe midface trauma or displaced maxillae, 3D CT is valuable in making a definitive diagnosis and grasping fracture characteristics from a holistic perspective.
Fracture treatment
1, treatment of low level fracture simple maxillary fracture can be reset by head cap chin pocket brace or intermaxillary traction, then intermaxillary fixation for 3~4 weeks, and supplemented with head cap chin pocket brace jaw upward braking. For displaced maxillary fractures, an incision and repositioning is required to restore the occlusal relationship and fixation with bone splints at the edge of the zygomatic alveolar ridge and the pyriform foramen.
2. Treatment of high horizontal fractures Once a high fracture is displaced, it usually requires incision and repositioning. The surgery should be performed as early as possible. The fracture is exposed and fixed through a combined coronal incision, intraoral incision and small facial incision. If there is an associated orbital floor fracture, the orbital floor needs to be repaired by resetting the orbital contents through a sublid margin or lid conjunctival incision.
3, Treatment of sagittal fractures focuses on restoring the width of the maxillary dental arch as well as the occlusal relationship.
4, Treatment of old fractures Old fractures of the maxilla usually require LeFort fractional osteotomy and repositioning according to the model surgical design and positioning of the fitting plate. In the case of sagittal fracture with displacement, further osteotomy in blocks is required on the basis of LeFort I type osteotomy.
Postoperative precautions for fractures
Apply antibiotics for about 3 days after surgery to prevent infection. After surgery, adjust the occlusion according to the specific situation of occlusion, and perform intermaxillary elastic traction for about 1 week as appropriate. Maintain oral hygiene after surgery. Eat soft food for 2-3 weeks. Postoperative CT examination to clarify the fracture repositioning and fixation. Review 3 months after surgery to check the occlusion and mouth opening, and review CT to observe the fracture healing and the presence of inflammation in the maxillary sinus.