Midfacial traum summary of book and Dental trauma PDF

Preview

Summary

MIDFACIAL TRAUMAMIDFACIAL SKELETON AS A THREE-DIMENSIONAL STRUCTUREThe midface skeleton is a complex structure composed of multiple, mostly paired, bones, intimately linked by sutures. It is connected to and supported by bones of the neurocranium, namely frontal bone, sphenoid bone, and temporal bon...

Description

MIDFACIAL TRAUMA

MIDFACIAL TRAUMA

MIDFACIAL SKELETON AS A THREE-DIMENSIONAL STRUCTURE The midface skeleton is a complex structure composed of multiple, mostly paired, bones, intimately linked by sutures. It is connected to and supported by bones of the neurocranium, namely frontal bone, sphenoid bone, and temporal bone. In individuals with preserved dentition, further support is provided by mandible via contact of the dental arches. The midface can be viewed as a labyrinth of air containing cavities, with the exception of the orbits, surrounded by thin bony lamellae with rims of thick bone. These thicker rims constitute a system of pillars and struts resembling the framework of a building, and the position and stability of each are interrelated. The midface buttress system comprises vertical, horizontal, and sagittal components, of which the sagittal component is the weakest. The well defined, paired vertical buttresses are: ü Nasomaxillary (made up of the frontal process of the maxilla); ü Zygomatico-maxillary (made up of the zygomatico-alveolar crest, body and frontal process of the zygoma); ü Pterygomaxillary (made up of the pterygomaxillary junction and the pterygoid process of the sphenoid bone).

These buttresses developed as an adaptation to masticatory forces that are transmitted by them to the skull base. • •

The horizontal buttresses include the superior and inferior orbital rims, maxillary alveolus and palate, serrated edges of the greater wings of the sphenoid bone and the zygomatic arches. The sagittal buttresses are represented by zygomatic arches, while the central part of the midface lacks a strong sagittal buttress.

The main objective of fracture repair of the midface is the reconstruction of these buttresses using osteosynthetic devices. These buttresses are robust enough bony structures to allow secure insertion of screws. The exceptions are the pterygomaxillary buttresses and the sphenoid greater wings, which are not surgically accessible. The ratio between the small bone volume of the midface and its large surface area provides an excellent blood supply despite the absence of large nutritive vessels. Consequently, fractures of the midface heal and remodel fast and well and are resistant to infection. On the other hand this unique healing capacity can also complicate management of fractures if there is a delay in treatment.

1

MIDFACIAL TRAUMA

EPIDEMIOLOGY The peak incidence of maxillofacial fractures is in the age range of 20–30 years. The incidence is higher in males. The etiological factors vary with societies and geographic location in the world. In developing countries road traffic accident is the main cause of maxillofacial injuries; in more developed countries there has been a decrease in the proportion of road traffic accidents as etiologic factors, especially in the past three decades, due to a more developed and safer traffic environment and the use of seatbelts. Many studies have reported that a life style with high alcohol consumption is a major contributing factor. Maxillofacial injuries due to sports are frequently seen; the etiology varies as different sports are played in different geographic locations. The use of helmets and mouth guards can prevent some injuries. In developing countries, fall injuries are more common due to lack of safety measures. Throughout history there have been maxillofacial injuries caused by weapons. The head and neck region is affected in 16% of all war injuries. Weapons have developed from low velocity to high velocity, and in recent years blast injuries from landmines and road side bombs have become more common. In some societies, where there is easy access to weapons, gunshot injuries occur frequently during peace time and maxillofacial injuries are sustained due to gunshot injuries caused by crimes and suicide attempts. CLASSIFICATION There are several systems for classification of midface fractures. • Fractures can comprise single or multiple fracture lines in the same bone or have fracture lines that communicate with each other, so-called comminuted fractures. • Fractures can also be of the greenstick type which is often seen in young children where the bone is not so highly mineralized. • Fractures can also be classified as closed; when there is no communication with the outer environment through lacerations in the skin, oral mucosa, and gingiva, or through a gingival pocket. An open fracture is defined as a fracture where there is such a communication through a laceration or when the fracture is engaging a dentate area. A fracture can also be complicated if there is a considerable injury or defect in the overlying soft tissue. • Fractures can also be classified in relation to the first or secondary place of energy release. A direct fracture occurs where the first impact takes place, e.g. a blow to the cheek resulting in a zygomaticomaxillary fracture, while an indirect fracture happens in the region of the zygomatic arch and possibly also the skull base. • Orbital fractures are often classified as blow in or blow out; depending on the way the orbital walls are fractured. When most of the maxillofacial bones are engaged in a trauma the term panfacial fracture is used. • From a clinical and treatment point of view, classification using the above terminology in combination with a classification related to the an atomic site of the midface fracture is most often used: 2

MIDFACIAL TRAUMA

ü Fractures can be partial: the fracture line affects only a segment of the bone; fractures of the maxillary tuberosity which occurs mostly during traumatic extractions; alveolar ridge fractures determined by a direct trauma or during extractions, mostly regarding upper or lower frontal teeth; another example of partial fracture is the perforations of the hard palate. These fractures occur mostly in children holding foreign objects (pencil, pen, etc) in their mouth during falling. ü Total fractures can be horizontal or vertical

HORIZONTAL FRACTURES: René Le Fort’s (French surgeon, 1869–1951) experimentally based categorization of midfacial fracture patterns is the most popular one. This simple classification system distinguishes three fracture patterns: •

• •

Le Fort I (also known as Guérin fracture, after Alphonse Guérin, French surgeon, 1816– 1895), separates the whole complex of alveolar and palatal processes of the maxilla, horizontal plates of the palatal bones and lower parts of the pterygoid plates just above the pterygo-maxillary junction; Le Fort II (also known as "pyramidal" fracture) separates the whole maxilla with part of the nasal bones and the lower part of the pterygoid plates. Le Fort III separates both zygomatico-maxillary complexes plus the nasal bones, palatal bones and most of the pterygoid plates, from the rest of the cranium.

However, in clinical practice Le Fort types of fractures are very rarely encountered in pure forms as described above. In most instances the fracture lines of particular types combine in quite unpredictable, often asymmetric patterns. The reason for this variability rests with the many different trauma mechanisms and high energies involved, which were not predicted and were perhaps unimaginable in the time when René Le Fort performed his experiments. There are other, very common and historically recognized fracture patterns that do not fit into the LeFort classification. Prominent among them is a fracture of the zygomatic bone, first reported by Joseph Duverney (French anatomist, 1648–1730). This is currently described as zygomatico-maxillary complex (ZMC) fracture, or zygomatico-orbital fracture, because the zygomatic bone is almost never involved alone, as it is in intimate contact with the temporal, frontal, sphenoid, and maxillary bones. An isolated fracture of the zygomatic arch is a separate clinical entity. Nasal bone fractures are given little attention in maxillofacial literature, perhaps because they are mostly isolated and managed by ear, nose, and throat (ENT) surgeons. Despite that, they are the most frequent facial fractures in general. Another clinically useful concept is the one of naso-orbito-ethmoid (NOE) fracture. It reflects the fact that high-energy injuries to the nasal area break and displace bony structures involving the nasal bones, and also the frontal processes of the maxilla, the lacrimal bones and the ethmoid bone. Avery similar term is frontonasal fracture, which describes the concomitant involvement of the nasal part of the frontal bone, and especially of the frontonasal ostium. The diagnosis of the sagittal palatal fracture is important, although it occurs always in combination with other fractures, often of Le Fort type. The term orbital fracture can mean any fracture involving either the orbital rim or the orbital wall. In clinical practice it is usually understood to be a fracture of the orbital walls. It is obvious that 3

MIDFACIAL TRAUMA

above-mentioned terms and definitions are useful in the description of topographically limited injuries, but when it comes to complex midfacial fractures, a list of separate diagnoses is usually developed. These diagnoses often overlap when adjacent areas of the midface are affected. Moreover, complex fracture patterns can be described in more than one way. This makes communication between clinicians difficult and can have insurance, billing and medico-legal repercussions. On the other hand to describe each fracture line separately would be too intricate, laborious, and perplexing. Assessment of patients with midface injuries It is important to take a through history. Since many patients are unconscious there are often only reports from eyewitness. Such reports are not always reliable. Patients with midface fractures are often examined and treated with a multidisciplinary approach. Responsibilities and routines vary with traditions worldwide. In recent decades the oral and maxillofacial surgeon has taken an increasing responsibility for midface injuries and today is often the leader of the team. Ophthalmologists are consulted for eyeball trauma, blindness, and problems regarding vision, ENT specialists have to be consulted for vertigo and hearing problems related to trauma and neurosurgeons must be consulted when there is cerebrospinal fluid leakage and when intracranial bleeding or air is suspected. Plastic surgeons are consulted when there are large soft tissue defects. • LeFort I Fracture (Low Level, Subzygomatic Fracture) It is also called as horizontal fracture of the maxilla or Guerin’s fracture. It is also known as floating fracture, as there is a separation of complete dentoalveolar part of the maxilla (pterygomaxillary disjunction) and the fractured fragment is held only by means of soft tissues. The fractured fragment is freely mobile and the resultant displacement will depend on the direction of the force. Depending on the displacement of a fragment, variety of occlusal disharmony can be seen in this type of fracture (anterior open bite, cross bite, reverse overjet etc.). A violent force applied over a more extensive area, above the level of the teeth will result in a LeFort I fracture, which is not confined to smaller section of the alveolar bone. Here, the horizontal fracture line is seen above the apices of the teeth, which detaches the tooth bearing portion of the maxilla from the rest of the facial skeleton. The fracture line commences at the point on the lateral margin of the anterior nasal aperture, passes above the nasal floor, and it passes laterally above the canine fossa and traverses the lateral antral wall, dipping down below the zygomatic buttress and then inclines upward and posteriorly across the pterygomaxillary fissure to fracture the pterygoid lamina at the junction of their lower third and upper two-thirds. At the same time, from the same starting point, the fracture also passes along the lateral wall of the nose and subsequently joins the lateral line of fracture behind the tuberosity. The typical LeFort I fracture is always bilateral, with the fracture of the lower third of the nasal septum. But it can be unilateral also. The displacement will depend on the direction and severity of the force. Posterior, lateral displacement or rotation around its axis can be seen. The LeFort I fracture may occur as a single entity or in association with LeFort II and III fractures.

4

MIDFACIAL TRAUMA

Clinical signs and symptoms of LeFort I fracture ü Slight swelling and edema of the lower part of the face along with the upper lip swelling. (Gross edema or facial disfigurement is not present). ü Ecchymosis in the labial and buccal vestibule, as well as contusion of the skin of the upper lip maybe seen. Laceration of upper lip and intraoral mucosa may be seen. ü Bilateral epistaxis or nasal bleeding may be observed. ü The most common significant feature is the mobility of the upper dentoalveolar portion of the jaw, which is frequently mobile to digital pressure. ü Occlusion may be disturbed. Patients will not be able to masticate the food. ü Pain while speaking and moving the jaw. ü Sometimes there will be upward displacement of the entire fragment, locking it against the superior intact structures; such a fracture will be called as impacted or telescopic fracture. A classical anterior open bite may be seen in this case. ü Percussion of the maxillary teeth produces dull ‘cracked cup’ sound.

• LeFort II Fracture (Pyramidal or Subzygomatic Fracture) Violent force, usually from an anterior direction, sustained by the central region of the middle third of the facial skeleton over an area extending from the glabella to the alveolar margin results in a fracture of a pyramidal shape. The force may be delivered at the level of the nasal bones. The fracture line runs below the frontonasal suture from the thin middle area of the nasal bones down one it her side, crossing the frontal process of the maxillae and passes anteriorly across the lacrimal bones, immediately anterior to nasolacrimal canal. From this point the fracture line passes downward, forward and laterally crossing the inferior orbital margin, in the region of zygomaticomaxillary suture. It may or may not involve the infraorbital foramen. The fracture line now extends downward and forward and laterally to traverse the lateral wall of the antrum, just medial to the zygomaticomaxillary suture line. As in LeFort I fracture, this fracture line passes beneath the zygomatic buttress, but after that, it inclines rather more abruptly than in the former instance, traversing the pterygomaxillary fissure at a higher level and fracturing the pterygoid lamina approximately midway from its base. Separation of the entire pyramidal block from the base of the skull is completed via the nasal septum.

Clinical Signs and Symptoms of LeFort II Fracture ü There is a gross edema of the middle third of the face known as ballooning or moon face. Edema sets in within a short-time of injury. ü Presence of bilateral circumorbital edema and ecchymosis (Black eye). Rapid swelling of the eyelids makes examination of the eyes difficult. ü Bilateral subconjunctival haemorrhage confined to medial half of the eye. ü The bridge of the nose will be depressed (flat face). Nasal disfigurement. ü If there is impaction of the fragment against the cranial base, then shortening of the face with anterior open bite will be seen. ü If there is gross downward and back ward displacement of the fragment, then elongation or lengthening of the face will be seen with posterior gagging of the occlusion with anterior open bite (Dish- shaped face). ü Bilateral epistaxis may be present. 5

MIDFACIAL TRAUMA

ü Difficulty in mastication, and speech. ü Loss of occlusion may be seen. ü Airway obstruction may be seen due to posterior and downward displacement of the fragment impinging on the dorsum of the tongue. ü Surgical emphysema—crackling sensation transmitted to the fingers due to escape of air from the paranasal sinuses is seen. ü CSF leak may be present. ü Step deformity at the infraorbital margins maybe seen. ü Anaesthesia and/or paresthesia of the cheek is noted.

• LeFort III Fracture (Transverse or Suprazygomatic) Fracture It is also known as high level fracture. The line of fracture extends above the zygomatic bones on both sides as a result of trauma being inflicted over a wider area, at the orbital level. The force is usually applied from the lateral direction with a severe impact. Here the initial impact is taken by the zygomatic bone resulting in depressed fracture and then because of the severe degree of the impact, the entire middle third will then hinge about the fragile ethmoid bone and the impact will then be transmitted on the controlateral side resulting in laterally displaced zygomatic fracture of the opposite side (craniofacial disjunction). In a typically high level LeFort III fracture, the line commences near the frontonasal suture, causes dislocation of the nasal bones and disruption of cribriform plate of the ethmoid bone with tearing of duramater and consequent CSF rhinorrhea. In such cases, the line of fracture crosses both the nasal bones and the frontal process of the maxilla, near the frontonasal and frontomaxillary sutures and then traverses the upper limit of the lacrimal bones. Continuing posteriorly, the line crosses the thin orbital plate of the ethmoid bone constituting part of the medial wall of the orbits. As the medial orbital wall is very thin, comminution of the fracture line is seen in this region. As the optic foramen is surrounded by a dense ring of bone, the fracture line gets deflected downward and laterally to reach the medial aspect of the posterior limit of the inferior orbital fissure. From this point, the fracture descends across the upper posterior aspect of the maxillae in the region of the sphenopalatine fossa and upper limit of the pterygomaxillary fissures and fractures the roots of the pterygoid lamina at its base. The inferior orbital fissure constitutes a natural line of weakness and from its anterior and lateral end, on each side a further line of fracture passes across the lateral wall of the orbit, adjacent to the junction of the zygomatic bone with the greater wing of sphenoid. The fracture line separates the zygomatic bone from the frontal bone near the suture and then inclines laterally, running abruptly downward across the infratemporal surface, thus in effect joining the previous line of fracture seen on the medial wall of the orbit. The entire middle third is thus detached from the dense cranial base, the occlusal plane of the maxillary teeth in most instances, being tilted downward and backward so that there is gagging with anterior open bite. Clinical signs and symptoms of LeFort III fracture Clinically this fracture appears similar to the LeFort II fracture, but close examination will demonstrate a more serious condition. After stabilizing the head and then gripping of the maxillary teeth with one hand and simple manipulation, will confirm complete movement of the middle third of the face. Mobility of whole skeleton as a single block can be felt. ü Gross edema of the face, ballooning. ’Panda facies,’ within 24 to 48 hours. ü Bilateral circumorbital/periorbital ecchymosis and gross edema ’Raccoon eyes’. Gross circumorbital edema will prevent eyes from opening. ü Bilateral subconjunctival haemorrhage, where posterior limit will not be seen, when patient is asked to look medially. 6

MIDFACIAL TRAUMA

ü There may be tenderness and separation at the frontozygomatic sutures. This will produce lengthening of the face and lowering of the ocular level. Unilateral or bilateral hooding of the eye is seen. ü Characteristic ‘dish face’ deformity ü May be enophthalmos, diplopia or impairment of vision, temporary blindness, etc. ü Flattening and widening, deviation of the nasal bridge. Epistaxis, CSF rhinorrhea.

Midline Separation of the Maxilla It exists a natural line of weakness at the sutural interface between the two palatine bones of the maxilla. This is usually associated with high level impact. Any deg...