Fracture Introduction
The zygomatic bone and zygomatic arch are located in the lateral aspect of the midface, and their shape is of aesthetic importance. Because of their prominent location, they are one of the parts of the midface that are prone to fracture, mostly due to direct lateral or lateral anterior violence, and their fractures are called zygomatic and zygomatic arch fractures. If the fracture of zygoma and zygomatic arch occurs at the same time, it is called zygomatic complex fracture. Zygomatic fractures often occur in combination with maxillary fractures and are called zygomaticomaxillary complex fractures. The zygomatic bone is involved in the composition of the inferior extra-orbital wall, and the fracture often affects the bony orbit and orbital contents, which is called zygomatic-orbital complex fracture. An Jingang, Department of Maxillofacial Surgery, Peking University Stomatological Hospital
Surgical anatomy
The zygomatic bone has an irregular quadrangular shape with four prominences: frontal, temporal, maxillary and infraorbital rims, which are connected to the frontal, temporal, maxillary and pterygoid bones, respectively. The fracture of the zygomatic complex opens the following four sutures: the zygomatic-frontal, zygomatic-temporal, zygomatic-mandibular, and zygomatic-pteriorbital sutures, and spreads to the surrounding bones. The zygomatic arch consists of the temporal process of the zygomatic bone and the zygomatic process of the temporal bone. The sensory nerve of the zygomatic bone is the second branch of the trigeminal nerve. Its zygomatic, facial, and temporal branches pass through small foramina on the surface of the zygomatic body and innervate sensation in the buccal and anterior temporal regions. The infraorbital nerve exits the infraorbital foramen anteriorly through the orbital floor and innervates sensation in the anterior cheek, nasal side, upper lip, and anterior maxillary teeth. The lateral canthal ligament attaches to the zygomatic tubercle posterior to the outer edge of the orbit. Fractures of the zygomatic complex often result in downward displacement of the lateral canthus due to displacement of the zygomatic bone.
Fracture classification
According to the extent of the fracture, it can be classified as simple zygomatic fracture, simple zygomatic arch fracture and combined zygomatic and zygomatic arch fracture.
Causes of fracture
Currently, most zygomatic and zygomatic arch fractures are caused by motor vehicle traffic accidents. In addition, violence, falls or sports are also causes of fractures.
Fracture diagnosis
Initial examination items include: the condition of the whole body injury, vision, eye and retinal injury, and if eye injury is suspected, an ophthalmologist should be consulted.
1. Medical history
Ask the patient or other witnesses to understand the nature, size and direction of the injurious force, and whether there is a history of post-injury coma, etc. Diagnosis can be made by combining clinical examination and imaging examination
2.Clinical manifestations
(1) The facial deformity is usually displaced inward by external force, resulting in facial collapse and deformity. In rare cases, the fracture is displaced outward, resulting in a lateral facial augmentation deformity.
(2) Restriction of mouth opening The fracture mass is displaced, compressing the temporal and occlusal muscles and impeding rostral movement, which may lead to painful mouth opening and restriction of mouth opening.
(3) Orbital symptoms and signs Early in the fracture, periorbital swelling, bleeding and petechiae under the eyelids and conjunctiva. The orbital cavity may be enlarged due to zygomatic displacement or orbital wall fracture, which may result in secondary orbital entropion deformity. If the fracture damages the extraocular muscles or if the extraocular muscles and orbital contents are embedded in the fracture fissure, ocular motility disorders occur and diplopia may occur.
(4) Symptoms of infraorbital nerve injury can cause numbness in the innervation area.
3.Imaging examination
Imaging examination can help to clarify the diagnosis of fracture and serve as evidence of forensic medicine, and can also clarify the extent of fracture.
(1) Plain film Waldron’s position is the most ideal film position to evaluate zygomatic complex fracture alone in plain film. Zygomatic arch fractures alone can be examined by zygomatic arch axial position or modified skull base position.
(2) CTCT scan is the gold standard for imaging zygomatic fractures. Axial and coronal CT images can show displaced fractures of the zygomatic sutures and allow visualization of orbital wall fractures as well as orbital soft tissue injuries. 3D reconstructed images of CT can provide an overall view of the fracture characteristics and determine the type of fracture, displacement and degree of comminution.
Fracture Treatment
Zygomatic fractures are not fatal and are often treated after the accompanying severe trauma has stabilized and the soft tissue swelling has resolved 4-5 days after the injury.
1, treatment of zygomatic arch fracture: zygomatic arch fracture without displacement does not require special treatment; if the fracture displacement causes facial deformity and/or mouth opening restriction, it should be surgically repositioned as early as possible. The following methods are commonly used for resetting.
(1) Single-tooth hook repositioning is performed by inserting a single-tooth hook percutaneously from the lower edge of the fractured zygomatic arch, with the tip of the hook reaching the most concave point of the “M”-shaped fracture. One hand is placed on the fracture surface to sense the degree of repositioning, and the other hand is used to lift the single-tooth hook to reset the fracture.
(2) A small longitudinal incision is made at the anterior edge of the ascending mandibular branch, and the resetting instrument is inserted. The fracture fragment is stretched under the zygomatic arch through the lateral rostral process and the superficial surface of the temporalis muscle, and the fracture fragment is lifted outwardly with force.
(3) The temporal incision and repositioning method is performed by making a 2-cm-long incision in the temporal hairline, incising the skin, subcutaneous tissue and temporal fascia, inserting a repositioning instrument between the temporal fascia and the temporal muscle, reaching the deep surface of the zygomatic arch, and repositioning the fracture fragment outward with force.
The fracture is then repositioned outwardly. The effect of the repositioning is examined by radiographs immediately after surgery. Once the zygomatic arch regains its natural arch structure, it has good stability and does not require special fixation. However, it should be protected after surgery to avoid re-stressing and premature opening of the mouth.
2, treatment of zygomatic fracture: zygomatic fracture displacement secondary to facial deformity, mouth opening restriction and eye entropion, need to perform incision and reset. The surgery is usually performed by intraoral incision and small facial incision, and the small facial incision usually includes an incision outside the brow arch, under the lower lid margin or lid conjunctiva. The fracture is repositioned in a coordinated multi-point approach with adequate exposure of the fracture section and adequate release of the fracture mass. The fracture is ultimately fixed internally with a strong titanium plate and nail depending on the type of fracture displacement, usually at three sites: the zygomatic alveolar ridge, zygomatic frontal suture, and infraorbital rim. Zygomatic arch fixation is mandatory if there is a concurrent displaced zygomatic arch fracture with multiple segments or comminuted fractures. After the zygomatic fracture is repositioned and fixed, the orbital floor is further explored based on CT cues. During fracture repositioning, if the canthal ligament is stripped, it should be suspended on the zygomatic tuberosity below the zygomatic frontal suture with non-absorbable silk suture.
3.Treatment of old fracture of zygomatic bone
(1) Osteotomy orthopedic surgery: It is suitable for old fractures in which the zygomatic body is intact and the fracture is displaced and then dislocates and heals with secondary facial deformity. In the past, doctors of this type of fracture often performed osteotomy and then moved the fracture block to correct the deformity based on their experience, with great uncertainty. Now, through preoperative design, the surgery is simulated on the computer, and intraoperative computer navigation technology is used to precisely guide the fracture repositioning, which greatly improves the surgical effect of fracture deformity correction.
(2) Bone grafting orthopedic surgery: It is suitable for old fractures with crushed zygomatic body, disrupted contour and collapsed cheek, but no obvious functional disorder. The surgery is mainly performed by bone grafting or implanting artificial materials in the collapsed area for shape reconstruction. Again, with the assistance of computerized surgical navigation technology, the surgical results are stable and reliable.
Postoperative Precautions
Postoperative antibiotics are recommended for 3 days. The antibiotics can be penicillin, cephalosporin antibiotics or clindamycin. The wound should be observed for signs of infection after surgery, and the visual acuity should also be checked and recorded. If there is postoperative restriction of mouth opening due to muscle damage, early mouth opening training is recommended to improve the degree of mouth opening. Postoperative CT examinations are performed to clarify the fracture repositioning. Postoperative review is recommended at 3 months for CT examination to observe the fracture healing and to observe the maxillary sinus for inflammation.