The diagnosis and initial management of the fractured mandible

Therapeutics

The Diagnosis and Initial Management of the Fractured Mandible NEIL H. LUYK, BDS, JOHN W. FERGUSON, Mandibularfractures are the second most common facial fracture.’ The usual causes are interpersonal violence and motor vehicle accidents (MVA). Nearly all cases present to an emergency department for initial management. They are rarely life-threatening injuries and must assume low priority in the initial assessment and management of the severely traumatized patient. Following any resuscitation and exclusion of other significant injuries, a clinical and radiologic diagnosis 01 the facial injuries should be undertaken including assessment of the fractured mandible. Initial therapy should be directed at temporary immobilization and pharmacologic treatment, fotlowed by referral for appropriate definitive care. (Am J Emerg Med 1991:9:35X359. Copyright 0 1991 by W.B. Saunders Company) Most patients with facial injuries present initially to an emergency department (ED) for treatment. Fractures of the mandible have been reported to comprise between 40% and 62% of all facial fractures,‘-’ although these figures may not represent the true incidence because isolated nasal fractures are seldom included in such surveys. Gratten and Hobbs4 have reported that 39% of patients involved in road traffic accidents sustained facial injuries; this figure included 0.68% of patients with fractured mandibles. Men are reported to be affected more frequently than women in a ratio ranging from 3:l to 7: 1 depending on the survey and, in particular, the country involved.2,3,“-7 Predictably, such studies show the most susceptible age group for both sexes is between the ages of 21 and 30 years.2.3.5.7 The two principal causes of facial fractures are interpersonal violence and MVA; these vary according to the area in which the survey was undertaken and the socio-economic and ethnic status of the community. 3.5-8Other significant causes are falls and sports injuries. A significant percentage of patients with mandibular fractures have other facial injuries. Surveys by Ellis et al3 and Salem et aIs reported that 20% of patients also sustained fractures in other parts of the facial skeleton, mainly the zygomatico-maxillary complex. Further injury away from the facial region may be present, including multiple system

From the Division of Oral and Maxillofacial Surgery, School of Dentistry, University of Otago, Dunedin, New Zealand. Manuscript received January 9,199O; accepted December 24, 1990. Address reprint requests to Dr Luyk, Division of Oral and Maxillofacial Surgery, Department of Oral Medicine and Oral Surgery, PO Box 647, Dunedin, New Zealand. Key Words: Jaw, mandible, trauma, fracture. Copyright 0 1991 by W.B. Saunders Company 07356757/91/0904-0013$5.00/O 352

MDS trauma. In the study by Ellis et al3 of 2,137 patients with mandibular fractures. 10.5% of subjects sustained other injuries outside the maxillofacial region. Injury patterns are largely dependent on the mechanism of injury, with patients involved in MVA sustaining a greater percentage of other injuries. The mandible is the principal bone of the lower third of the face. Its shape is parabolic when viewed from underneath. Each half can be divided into seven portions: a condylar head and neck that comprise the articulating portion of the bone and attachment of the lateral pterygoid muscle; a coronoid process to which is attached the temporalis muscle: a ramus that connects these two portions with the angle, to which is attached the masseter and medial pterygoid; a body region for strength; an alveolar portion to support the teeth, and the symphyseal region in the mid-line (Figure 1). In one large survey of 3,462 mandibular fractures,j the distribution of principal fracture sites was reported as 33% involving the body region, 29% the condylar region. 23% the angle, and 8.4% the symphysis (Figure 2). It is not unusual to sustain more than one fracture site in the mandible. Although some studies have reported the majority of patients to have sustained only one fracture,6-8 others’.‘.’ have reported a small majority of patients with multiple fracture sites. The anatomic distribution of the fracture sites is largely dependent on the mechanism of injury. This was well documented by Olson et al’ who showed that in MVA, 30.9% of fractures occurred in the subcondylar area. 27.7% in the symphyseal region, 17.3% in the angle, 13.9% in the body and 7.2% in the alveolus and other sites. There was a different distribution in cases resulting from interpersonal violence where 33.3% of fractures were located in the angle, 23.4% in the subcondylar area, 19.4% in the body, 16% in the symphyseal area, and 4.1% in the alveolar and other sites. The left side is more commonly involved, and in particular the left angle, probably because most assailants are righthanded and the left side of the jaw would be the side most likely to be struck.’ Falls account for a greater proportion of subcondylar fractures, as high as 36.3% in one survey.’ When multiple fractures of the mandible are considered, the most common combinations are: angle and opposite body, bilateral body, bilateral angle, condyle and opposite body (Figure 3).’ The site of fracture is also determined by the size, direction, and surface area of the impacting blow. An impact to the chin with a line of force through the symphysis and temporomandibular joints will produce a single subcondylar fracture at 425 lb/in* and a bilateral subcondylar fracture at about 550 lb. whereas symphyseal fractures re-

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FIGURE 1. Anatomical regions of the mandible based on common sites of fracture. (1) Condylar head and neck; (2) coronoid process; (3) ramus and angle: (4) body; (5) alveolar portion; (6) symphyseal region.

quire force between 550 and 900 lb.” An impact to the lateral aspect of the mandibular body using a 1 x 4-inch impact surface will produce a mandibular fracture at 300 to 700 lb/ in’.” When an impact force is delivered to the mandible, the bone bends inward producing compressive forces on the impacted (lateral) surface and tensile forces on the lingual (medial) surfaces of the bone opposite the impact site.” Fracture results when the tensile strain overcomes the resistance of the bone, fractures thus beginning on the medial side of the mandible and progressing through the bone towards the impact point.” Whereas direct fracture may occur at the site of impact, additional indirect fractures may result when higher forces are involved. An example would be a blow to the left angle causing a direct fracture at the left angle region and an indirect fracture in the right body. Occasionally only indirect fracture results, usually in the subcondylar area, for example when a blow on the chin results in a fracture of one or other condylar necks. Indirect fractures demonstrate the opposite tensile strain patterns and fracture outcomes from that of the direct fracture; the tensile strain develops on the

side opposite to the impact.

FIGURE 2. Distribution by percentage mandible. Adapted from3.

FIGURE 3. Most common combinations the mandible.

of bilateral fractures of

PATIENT HISTORY AND EXAMINATION

of fracture sites in the

An accurate history of how the injury was sustained may be of great value in indicating the likely extent and site of damage. The disfiguring nature of some facial injuries, particularly those resulting from motor vehicle accidents, must not be allowed to divert the clinician’s attention away from the possibility of serious injuries elsewhere. A full trauma assessment should be performed. Fractures of the facial skeleton and mandible can be lifethreatening because of the potential for airway obstruction. Significant bleeding may rarely occur from a ruptured maxillary or inferior alveolar artery and will be discussed later. Local examination will include detailed examination of the face and jaws, but again it is the purpose of this paper to concentrate on that area pertinent to the examination of the mandible and its function. The skin of the face and in particular the area around the mandible is inspected for swelling, hematomas, and lacerations. A common site for a laceration is under the chin, and this should alert the physician

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to the possibility of an associated subcondylar and/or symphysis fracture. It is best to begin the examination from behind the seated or supine patient. The fingertips are placed on the inferior border of the mandible and the mandible is palpated from the symphysis to the angle on each side (Figure 4), noting any areas of swelling, step deformity, or tenderness. Patients with a fracture of the body or angle of the mandible will usuaily complain of numbness in the distribution of the mental nerve on the affected side due to damage to the inferior alveolar nerve within the mandible. The next part of the examination is undertaken standing in front of the patient. The clinician should palpate the movement of the condyle via the external auditory meatus and observe the movement of the mandible itself. Any significant deviation on opening may be indicative of subcondylar fracture on the side to which the mandible deviates. The fifth finger placed in each auditory meatus and the patient is asked

is to

open and close the mouth (Figure 5). A fracture in the subcondylar area will produce pain and limitation of movement of the affected condyle. It is important to note that any limitation of mandibular movement may also be a result of reflex muscle spasm, temperomandibular joint (TMJ) effusion, or mechanical obstruction to the coronoid process resulting from depression of the zygomatic bone or arch. The external auditory canal is carefully examined for signs of hemorrhage. Occasionally a subcondylar fracture will produce a tear in the epithelial lining of the anterior wall of the canal producing bleeding from the auditory meatus. It is important to determine that this bleeding is not coming from behind a ruptured tympanic membrane, which may signify a basilar skull fracture. A detailed intraoral examination should be undertaken with good lighting, following the removal of any artificial dentures. It is important to be systematic and it is suggested that examination of the soft tissues be undertaken first. The

FIGURE 4. Palpating the inferior border of the mandible from behind the patient.

FIGURE 5. Palpation of movement of the mandible condyle via the external auditory meatus.

gum tissue should be inspected for tears or lacerations. With the aid of a tongue blade the floor of the mouth is examined; sublingual ecchymosis is almost pathognomonic of a fracture of the mandible (Figure 6). Any areas of bleeding are noted; it is useful to have suction available at this stage. Next the dentition is examined for evidence of broken teeth and for steps or irregularities in the dental arch (Figure 7). The patient is asked to lightly bite his teeth together and asked if the bite feels different from normal; following this, the occlusion is inspected. A normal bite is one where the lower incisors interdigitate behind the upper incisors in what is called a Class I dental relationship (Figure 8). However, there is considerable individual variation from this “normal” situation. Premature occlusal contacts are noted (Figure 9). The three causes of an altered occlusion in the trauma patient are: (1) a displaced fracture, (2) a temporomandibular joint effusion or dislocation, (3) a dental injury such as a displaced tooth. If the patient is edentulous and has his intact dentures with him these can be replaced in the mouth and the occlusion inspected. The mandible should then be grasped on each side of any suspected fracture and gently manipulated to assess mobility (Figure 10). If no fracture can be found but clinical suspicion remains high. the mandible may be compressed by

FIGURE 6. fracture.

Sublingual ecchymosis

associated with a mandibular

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Step in the dental arch indicative of a mandibular

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FIGURE 9. Posterior premature dental contact causing an anterior open biting associated with a bilateral subcondylar fracture.

fracture.

applying pressure over both angles (Figure 11). This nearly always produces pain at a fracture site. In the case of subcondylar fractures, firm posterior pressure on the chin will cause pain in the preauricular region. Radiographs are ordered to confirm the diagnosis when there is suspicion of a fracture based on clinical judgment and should not be routinely ordered where there is no clinical evidence that a fracture exists. Recommended radiographs are an orthopantomograph (OPT), a posteroanterior (PA) mandible and a Reverse Towne’s view of the condylar necks (Figures 12-14). Where an OPT is not available, lateral oblique views of the mandible must be obtained for each side. However, it should be realized that the detection rate for mandibular fractures without the use of an OPT is significantly lower than the detection rate when it is used.” The above films are the routine screening films for mandibular fractures. Occasionally it may be necessary to order supplemental views such as specialized TMJ views for a suspected intracapsular fracture, or an occlusal mandibular view to assess fracture overlap in the anterior mandible. The ordering of these special views should be delegated to the clinician undertaking the definitive management of the fracture.

FIGURE 8.

Class I dental occlusion.

The three basic radiological signs that singly or in combination are indicative of a fracture consist of a demonstrable fracture line, a displacement of adjacent bony segments and deformation of the normal bony shape and contour. Obviously these are pertinent not only to mandibular fractures but also to all fractures. When examining radiographs it is important to bear in mind the appropriate anatomy of the region. One area of confusion often arises when the pharyngeal airspace becomes superimposed over the mandibular ramus giving rise to the appearance of a fracture in OPT. However. careful examination of this radiolucency will show that it extends superiorly and inferiorly to the mandible. It is usual to classify mandibular fractures as favorable or unfavorable. This refers to the likelihood of fracture displacement, depending on the action of muscles acting on the pos-

FIGURE IO. Demonstration of the technique for gentle manipulation of a suspected fracture site in the incision region.

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FIGURE 11. Demonstration of the technique for bimanual compression of the angle region in a case of suspected mandibular fracture.

terior bony fragments, and is assessed radiologically. A favorable fracture is one where the displacement is limited by the disposition of the fracture line and is unfavorable if otherwise (Figures 15A and B).

The first priority in the initial management of the trauma patient is assessment of the airway. It is rare for the patient with a unilateral mandibular injury to have an airway problem. However, with a bilateral body fracture, anterior support for the tongue may be lost with consequent posterior displacement and airway obstruction. Similarly, with severe trauma to the anterior mandible and multiple fractured segments, a “flail” mandible can result with loss of tongue support (Figure 16). This problem can be managed in several ways. If possible the patient should be placed in the recovery position so that there is no tendency for the tongue to fall backwards. A pharyngeal airway is often all that is required to maintain the airway in the supine patient, but if there are other significant injuries or if there is any doubt about the security of the airway, the patient should be intubated. Stabilization of the anterior portion of the mandible with “bridle” wires or definitive reduction and fixation also alleviates the problem. It is unusual for bony maxillofacial injuries to result in significant blood loss. If a patient presents in shock, always suspect a distant site for the blood loss such as an abdominal, thoracic, pelvic, or limb injury. Fractures of the mandible may rarely bleed profusely from rupture of the inferior alveolar artery. This will be difficult to control by direct

FlGURE 12. Orthopantomogram of the mandible illustrating a fracture between the right lateral incisor and cuspid teeth.

FIGURE 13. Posteroanterior (PA) radiograph of the mandible illustrating fracture between the right lateral incisor and cuspid teeth.

FIGURE 14. Reverse Townes projection of mandibular condyles of same patient as in Figures 12 and 13: no fractures are present.

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FIGURE 15. (A) Drawing of favorable and unfavorable mandibular angle fracture patterns in the horizontal plane (ie, viewed from above). (B) Drawing of a favorable and unfavorable mandibular angle fracture patterns in the vertical plane (ie, viewed anteroposteriorly).

while ligation or electrocoagulation places the associated nerve at risk; therefore, expedient reduction and fixation may be required to control hemorrhage. Temporary immobilization of the fragments is often helpful in controlling pain and, to a lesser extent, may reduce contamination of the fracture site with oral organisms by reducing the “pumping” action caused by movement of bony fragments. In the past, barrel bandages have been recommended as a form of temporary immobilization:‘3 however, they are rarely used in clinical practice. Temporary immobilization may be achieved with the use of a “bridle” wire provided there are sound teeth on either side of the fracture site (Figures 17 to 19). The site should be first anesthetized with local anesthetic (LA). Using a 1.5 in 25 or 27 gauge needle, 2 mL of lignocaine 2% with epinephrine 1: 100,000 is administered as an inferior alveolar nerve block. pressure,

FIGURE 16. Radiograph of a posteriorly displaced mandibular fracture (hollow arrow demonstrating displacement and solid arrows indicating narrowing of airway).

The injection technique for this can be learned easily from a dental colleague, and is also useful in the management of dental pain. Often the nerve block needs to be supplemented by an infiltration of 1 or 2 mL of LA solution on the medial and lateral aspect of an intraoral fracture site. Although infiltration of LA adjacent to the fracture site could be criticized on theoretical grounds as a means of introducing organisms into the fracture site, and inasmuch as administration of a vasoconstrictor into the fracture site may hinder healing, clinical experience has shown these theoretical objections unfounded. Once anesthesia is obtained, the fracture is reduced and 0.5 mm (25 gauge) soft stainless steel wire is passed around the teeth on either side of the fracture. Two teeth on each side of the fracture should be used to prevent possible displacement of potentially mobile teeth beside the fracture site and the wire is then tightened. The

FIGURE 17.

“Bridle” wire across a fracture site.

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FIGURE 18.

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“Bridle wire” being placed in position.

patient can still open his mouth following this treatment but he is usuahy far more comfortable without the rubbing together of the bone ends. Following this phase of initial management, consideration must be given to the medication required by the patient. Their tetanus immunization status must be ascertained and treated appropriately. Secondly, consideration must be given to antibiotic therapy that should be initiated as soon as possible. A fracture involving the tooth-bearing areas of the jaws is compound into the mouth and requires antibiotic prophylaxis. The usual choice is penicillin and 2 million units should be administered intravenously if there are no contraindications. Thirdly, pain control must be addressed. The best pain control is achieved with a stable, reduced fracture. However, in the emergency department good pain control can be achieved with the use of local anesthesia as already mentioned. When the control is inadequate or the fracture site is not amenable to local anesthetic administration, systemic analgesics may be required. Here care must be taken to avoid the unnecessary use of narcotic analgesics, particularly in the patient with a possible head injury. In the first instance it is common practice to use a nonsteroidal antiinflammatory analgesic and then assess its effectiveness before administration of a narcotic analgesic. Following initial management, appropriate referral is required for definitive care. Most patients with a fractured mandible should be seen by the appropriate service in your particular area. This service is usually oral and maxillofacial surgery, plastic surgery, or otolaryngology-head and neck surgery. Patients are usually admitted to hospital if one of the following criteria is met: (1)

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compound fractures (this includes any fracture through the dentate portion of the jaw); (2) fractured mandibles associated with other injuries requiring admission to hospital; (3) potential for airway embarrassment such as bilateral body fracture of the mandible. Most dentate fractures are managed either by closed reduction and fixation using arch bars and intermaxillary fixation or by an open reduction via an intraoral or extraoral route and internal fixation with compression or miniplates. Occasionally a combination is used. Most edentulous fractures are managed in a similar manner with splints constructed from the patient’s own dentures for closed reduction and plates being used for open reductions. Therefore, it is important to preserve a patient’s dentures even if broken, as they may be needed in the treatment of the fracture. Occasionally patients with postoperative problems may present to the emergency department. The most common problem is likely to be broken elastics or wires. Replacement of several elastics or wires can be accomplished by the emergency physician if the occlusion is still stable, and review arranged with the treating service. However, once the stable occlusion has been lost, it is better to refer the patient back to the treating service immediately, as a very mobile fracture site is likely to become infected. Another problem for the ED is the vomiting patient. On most occasions vomiting is not a life-threatening situation as the patient has been able to consume only liquids. The liquid diet can pass easily around gaps between the teeth from behind the last molar tooth and through the nose if the patient is correctly postured in a head forward position. As a generalization it is difficult to remove the intermaxillary fixation (IMF) wire expeditiously and in an emergency situation care should be directed to securing the airway via a blind nasal intubation or cricothyrotomy. Elastic IMF can be easily released with scissors. Infected fractures may present at the ED, and these are best handled by the service treating the fracture. CONCLUSION Mandibular fractures are the second most common facial fracture, the majority being the result of motor vehicle accidents or interpersonal violence. A careful, thorough assessment of the patient to identify other injuries must be made. Mandibular fractures are rarely life-threatening and assume a low priority in initial management. A systematic approach to diagnosis is essential if fractures are not to be missed, including radiological assessment in two planes at right angles. The initial treatment consists of airway management. control of fracture segments, and pharmacologic management. REFERENCES

FIGURE 19. ture.

“Bridle wire” tightened to reduce and stabilize frac-

1. Kelly DE, Harrigan WF: A survey of facial fractures: Bellevue Hospital, 1948-1974. Oral Surg 1975;33:146-149 2. Adekeye EO: The pattern of fractures of the facial skeleton in Kaduna, Nigeria. Oral Surg 1980;49:491-495 3. Ellis E, Moos KF, El-Attar A: Ten years of mandibular fractures: An analysis of 2,137 cases. Oral Surg 1985;59:120-129 4. Grattan E, Hobbs JA, in Rowe NL. Williams J (eds): Max-

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illofacial Injuries. New York, NY, Churchill-Livingstone, 1965, pp 37-42 5. Hagan EH, Huelke DF: An analysis of 319 case reports of mandibular fractures. J Oral Surg 1961;19:93-104 6. Van Hoof RF, Merkx CA, Stekelenburg EC: The different pattern of fractures of the facial skeleton in four European countries. Int J Oral Surg 1977;6:3-11 7. Olson RA, Fornseca RJ. Zeitler DL, et al: Fractures of the mandible: A review of 560 cases. J Oral Maxillofac Sura 1962;40:23-26 6. Salem JE, Lilly GE, Cutcher JL, et al: Analysis of 523 mandibular fractures. Oral Sura 1966:26:390-395 9. Chuong R, Donoff RG, Guralnck WC: A retrospective anal-

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ysis of 327 mandibular fractures. J Oral Maxillofac Surg 1963;41:305-309 10. Huelke DF, Compton CP: Facial injuries in automobile crashes. J Oral Maxillofac Surg 1963;41:241-244 11. Huelke DF, Harger JH: Mechanism in the production of mandibular fractures: An experimental study. J Oral Surg 1966;26:66-91 12. Chayra GA, Meador LR, Laskin DM: Comparison of panoramic and standard radiographs for the diagnosis of mandibular fracture. J Oral Maxillofac Surg 1966;44:677-679 13. Bramley P, in Rowe NL, Williams JL (eds): Maxillofacial Injuries (vol 1). New York, NY, Churchill-Livingstone, 1965, pp 46-47