You are in: eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > TRAUMA Mandibular Body FracturesArticle Last Updated: Sep 19, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Jose E Barrera, MD, Instructor, Department of Otolaryngology-Head and Neck Surgery, Stanford University Jose E Barrera is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, and American Academy of Sleep Medicine Coauthor(s): Stephen G Batuello, MD, Consulting Staff, Colorado ENT Specialists Editors: Hassan H Ramadan, MD, MSc, Professor and Vice-Chair, Department of Otolaryngology-Head and Neck Surgery, Professor, Department of Pediatrics, West Virginia University; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Stephen G Batuello, MD, Consulting Staff, Colorado ENT Specialists; Christopher L Slack, MD, Otolaryngology-Facial Plastic Surgery, Private Practice, Associated Coastal ENT; Medical Director, Treasure Coast Sleep Disorders; Arlen D Meyers, MD, MBA, Professor, Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine Author and Editor Disclosure Synonyms and related keywords: mandibular body fractures, jaw fracture, broken jaw, horizontal ramus fracture, mandibular fracture INTRODUCTIONSection 2 of 12
  Fractures of the mandibular body may be classified by anatomic location, condition and position of teeth relative to the fracture, favorableness, or type. Body fractures occur between the distal aspect of the canines and a hypothetical line corresponding to the anterior attachment of the masseter. These fractures are proximal to the third molar. Mandible fractures also are described by the relationship between the direction of the fracture line and the effect of muscle distraction on fracture fragments. Mandible fractures are favorable when muscles tend to draw bony fragments together and unfavorable when bony fragments are displaced by muscle forces. Vertically unfavorable fractures allow distraction of fracture segments in a horizontal direction. These fractures tend to occur in the body or in symphysis-parasymphysis areas. Horizontally unfavorable fractures allow displacement of segments in the vertical plane. Body fractures often are unfavorable because of the actions of the masseter, temporalis, and medial pterygoid muscles, which distract the proximal segment superomedially. Additionally, the mylohyoid muscle and anterior belly of the digastric muscle may contribute to the unfavorable nature of this fracture by displacing the fractured segment posteriorly and inferiorly. For excellent patient education resources, visit eMedicine's Back, Ribs, Neck, and Head Center, Breaks, Fractures, and Dislocations Center, and Teeth and Mouth Center. Also, see eMedicine's patient education articles Broken Jaw and Broken or Knocked-out Teeth. Image 2 depicts the vertical and horizontal forces acting on the mandible, as well as the relationship of muscle pull to fracture angulation. FrequencyIn general, mandible fractures of the body, condyle, and angle have nearly the same incidence, while fractures of the ramus and coronoid process are rare. The literature suggests the following mean frequency percentages based on location: body (29%), condyle (26%), angle (25%), symphysis (17%), ramus (4%), and coronoid process (1%). The mandible is involved in 70% of patients with facial fractures. The number of mandible fractures per patient ranges from 1.5-1.8. Approximately 50% of patients with a mandible fracture have more than 1 fracture. EtiologyVehicular accidents and assaults are the primary causes of mandibular fractures worldwide. The mandible fracture patterns of a suburban trauma center found that violent crimes such as assault and gunshot wounds accounted for the majority of fractures (50%), while motor vehicle accidents were less likely (29%). Data from industrialized nations suggest that fractures have various causes, as follows:
Assault most often causes mandible angle fractures. PathophysiologyOptimal mandible function requires maintenance of normal anatomic shape and stiffness (ie, resistance to deformation under load). Normal occlusion can be defined when the mesiolabial cusp of the maxillary first molar approximates the buccal groove of the mandibular first molar. Fractures result secondary to mechanical overload. Torque results in spiral fractures, avulsion in transverse fractures, bending in short oblique fractures, and compression in impaction and higher comminution. A fracture in which one cortex of the bone is broken while the other cortex is bent is termed a greenstick fracture. Degree of fragmentation depends upon energy stored as a result of overload prior to the fracturing process. Therefore, wedge and multifragmentary fractures are associated with high-energy release. An evidence-based study involving 3002 patients with mandibular fractures found that the presence of a lower third molar may double the risk of an angle fracture of the mandible. ClinicalHistory Obtain a thorough history specific to preexisting systemic bone disease, neoplasia, arthritis, collagen vascular disorders, and temporomandibular joint (TMJ) dysfunction. Knowledge of the type and direction of the causative traumatic force helps determine the nature of injury. For example, motor vehicle accidents (MVAs) have a larger associated magnitude of force than assaults. As a result, a patient who has experienced an MVA most often sustains multiple, compound, comminuted mandibular fractures, whereas a patient hit by a fist may sustain a single, simple, nondisplaced fracture. Knowing the direction of force and the object associated with the fracture also assists the clinician in diagnosing additional fractures. Physical Pertinent physical findings are limited to the injury site. Change in occlusion may be evident on physical examination. Any change in occlusion is highly suggestive of mandibular fracture. Ask the patient how his or her bite feels. Posttraumatic premature posterior dental contact (anterior open bite) and retrognathic occlusion may result from an angle fracture. Unilateral open bite is associated with a unilateral angle fracture. Anesthesia, paresthesia, or dysesthesia of the lower lip may be evident. Most nondisplaced mandible fractures are not associated with changes in lower lip sensation; however, displaced fractures distal to the mandibular foramen (in the distribution of the inferior alveolar nerve) may exhibit these findings. Change in facial contour or loss of external mandibular form may indicate mandibular fracture. A body fracture may cause the lateral aspect of the face to appear flattened. Loss of the mandibular body on palpation may be due to an unfavorable fracture. The anterior face may be displaced forward, causing elongation. In this case, the anterior mandible is displaced downward. Damage to the condylar growth center can cause retarded growth of the mandible and facial asymmetry in children. Lacerations, hematoma, and ecchymosis are associated with mandibular fractures. Lacerations may provide diagnostic evidence of the type of fracture sustained. Hematoma and ecchymosis may alert the clinician to a mandibular fracture. Do not close facial lacerations before treating underlying fractures. Ecchymosis in the floor of the mouth is a diagnostic sign of a mandibular body or symphysis fracture. Pain, swelling, redness, and localized heat are signs of inflammation evident in primary trauma. INDICATIONSSection 3 of 12
Use the simplest means possible to reduce and fixate a mandibular fracture. Because open reduction carries an increased morbidity risk, use closed techniques whenever possible. Indications for closed reduction include (1) nondisplaced favorable fractures, (2) grossly comminuted fractures, (3) edentulous fractures (using a mandibular prosthesis), (4) fractures in children with developing dentition, and (5) coronoid and condylar fractures. Indications for open reduction include (1) displaced unfavorable angle, body, or parasymphyseal fractures, (2) multiple facial fractures, (3) bilateral displaced condylar fractures, and (4) fractures of an edentulous mandible (with severe displacement of fracture fragments in an effort to reestablish mandible continuity). RELEVANT ANATOMYSection 4 of 12
The body or horizontal ramus of the mandible usually includes the third molar and is bounded anatomically from the distal symphysis to a line coinciding with the alveolar border of the masseter muscle. CONTRAINDICATIONSSection 5 of 12
Evaluate and monitor patients' general physical conditions prior to treating mandibular fractures. Any force capable of causing a mandibular fracture also may injure other organ systems. Case reports have documented concurrent posttraumatic thrombotic occlusion of the internal carotid artery and basilar skull fractures. Bilateral cervical subcutaneous emphysema, pneumothorax, pneumomediastinum, and spleen lacerations also have been associated with mandible fractures after trauma. Patients should not undergo surgical reduction of mandible fractures until these issues are addressed. WORKUPSection 6 of 12
Imaging Studies
TREATMENTSection 7 of 12
Medical therapyPatients with isolated nondisplaced or minimally displaced condylar fractures may be treated with analgesics, soft diet, and close observation. Patients with coronoid process fractures may be treated similarly. Additionally, these patients may require mandibular exercises to prevent trismus. If the fractured coronoid restricts mandible movement, medical therapy is contraindicated. Use prophylactic antibiotics for compound fractures. Penicillin remains the antibiotic of choice. Surgical therapyTechniques for closed reduction and fixation of the dentulous mandible vary. Closed reduction and fixation Placement of Ivy loops using 24-gauge wire between 2 stable teeth, with use of a smaller-gauge wire to provide maxillomandibular fixation (MMF) between Ivy loops, has been successful. Arch bars with 24- and 26-gauge wires are versatile and frequently are used. In an edentulous mandible, dentures can be wired to the jaw with circummandibular wires. The maxillary denture can be screwed to the palate. Arch bars can be placed and intermaxillary fixation (IMF) achieved. Gunning splints also have been used in this scenario. Open reduction and internal fixation Multiple approaches to open reduction and internal fixation (ORIF) exist. Consider fracture location, nerve position, and skin crease lines when choosing the appropriate approach. Intraoral versus extraoral approach to body fractures The intraoral approach may be used in fractures with no or only slight dislocation. This approach allows sufficient exposure in the anterior part of the horizontal ramus. The molar area may require additional stab incisions to place screws for plate fixation. With an intraoral approach, exercise caution to avoid injuring the mental nerve. The extraoral approach is necessary with fractures that have a high degree of dislocation or comminution because placing longer and stronger plates is difficult via the intraoral approach. Extraoral approach also is undertaken with fractures lying between the inferior and lingual aspects of the body. Give special attention to the marginal mandibular nerve. General anesthesia is indicated in both intraoral and extraoral approaches. Transverse fracture line without displacement Two 4-hole miniplates (2.0) may be used. Use monocortical screws for the superior plate. Place bicortical screws for the inferior mandibular border. Placing a superior plate helps neutralize tensile forces. In addition, a dental splint may be placed just underneath the tooth root apices. The splint must span at least 3 teeth on either side of the fracture. Transverse fracture line with displacement In this type of fracture, undertake wider surgical exposure. Reduction in the superior aspect of the placement may be secured with a tension-band splint or a 2.0 miniplate in the alveolar crest or tensile area. Fix the inferior border with a 2.4 compression plate (see Image 3). Stronger male patients may require a reconstruction plate with bicortical screws at this site. Oblique fracture lines, which have wider surface area, may be fixed with 3 lag screws or a combination of lag screws and plates (see Image 3A). Fractures of the basal triangle The basal triangle may be reduced and fixed with a reconstruction plate at the mandible base. Lag screws may be used to fix comminuted segments to the plate or adjacent bone. Reduce the tensile aspect of the fracture with a 2.0 miniplate and monocortical screws or a tension-band splint (see Image 3B-D). Comminuted fractures Reduce and approximate fragments with lag screws or 1.5/2.0 miniplates. Bridge fragments with reconstruction plates. Preoperative detailsApproach mandibular fractures methodically. Patients rarely die from mandibular fractures. Perform diagnosis and treatment in an orderly and efficient manner. Use prophylactic antibiotics for compound fractures. Evaluate nutritional needs. Intraoperative detailsThe primary goal of treatment is to reestablish occlusion. Function is compromised with malunion. Most mandibular fractures can be treated by closed reduction. Nondisplaced favorable fractures can be managed by closing with IMF alone. Arch bars or Ernst ligatures may be placed and supplemented with autopolymerizing resin. Three separate techniques for rigid fixation of the mandible have been developed: (1) the bicortical Luhr system, using vitallium plates; (2) the Arbeitsgemeinschaft für Osteosynthesefragen/Association for the Study of Internal Fixation (AO/ASIF) system of stainless steel compression or reconstruction plates with bicortical screws; and (3) the Champy miniplate technique placed along the "line of ideal osteosynthesis," using monocortical screws. A prospective randomized clinical trial comparing 2.0-mm locking plates to 2.0-mm standard plates in the treatment of mandible fractures found the statistically significant difference between the plates. In addition, mandible fractures treated with 2.0-mm locking plates and 2.0-mm standard plates have similar short-term complication rates. With multiple facial fractures, treat mandibular fractures first because the mandible is the foundation on which facial bones can be laid. Perform intraoral surgery prior to an extraoral approach. IMF time varies according to type, location, number, and severity of fracture. Generally, 6 weeks of IMF are prescribed, although this is only an empiric approximation. Treat dental injuries concurrently with the fracture. Fractured teeth may become infected or jeopardize bone union and should be removed. Mandibular cuspids help determine occlusion and should be preserved, if possible. Postoperative detailsAdminister analgesic medications in the postoperative period. With open fractures, employ antibiotic therapy covering gram-positive organisms. Keep wire cutters at the bedside in case of vomiting. Reevaluate nutritional needs. Follow-upMaintain IMF for 4-6 weeks, tightening wires every 2 weeks. After wires are removed, a Panorex radiograph usually is obtained to ensure fracture union. COMPLICATIONSSection 8 of 12
Complications following mandibular fracture repair are rare. The most common complication is infection or osteomyelitis. Contributing factors include (1) oral sepsis, (2) teeth in the fracture line, (3) alcohol abuse and chronic disease, (4) prolonged time prior to treatment, (5) poor patient compliance, (6) displacement of fracture fragments, and (7) fracture of the plate. Material analysis of AO plates used in mandible fractures revealed titanium plate fracture in 4 out of 110 mandibular reconstructions. The plate fracture was most common in angle-type plates because of constriction on the internal side of the plate. OUTCOME AND PROGNOSISSection 9 of 12
Both closed and open reductions of mandibular fractures cause favorable results for bony union. In a study of 922 mandibular body and angle fractures treated with an intraoral approach without IMF, solid bony union was achieved in more than 99% of patients. Rarely does a second fracture following additional assault or vehicular accident occur. However, when it does happen, the cause for the second fracture is usually an assault, with 90% related to alcohol intake. Angle, body, and parasymphysis regions of the mandible were the most common sites to be involved in the first occasion. In a study with 10 cases, an internal rigid fixation procedure was performed for the treatment of a secondary fracture. In the recurrent injuries, none of the fractures occurred at exactly the same anatomical site. Fractures were either in the neighboring side or in the contralateral side of the previously healed area of the mandible. On the second occasion, angle fractures were common, but body and subcondylar fracture rates increased. At second presentation, the complication rate increased from 23.1% to 53.8% and most commonly involved malocclusion. FUTURE AND CONTROVERSIESSection 10 of 12
Controversy exists over open versus closed reduction for angle fractures. Traditionally, MMF has been the mainstay of treatment. Plating techniques have revolutionized open reduction as a treatment modality. Advantages of closed reduction include proven efficacy, low complication rate, and short operating time. This technique may be performed as an office procedure. Disadvantages include long fixation (ie, 3-6 wk), poor nutrition associated with MMF, risk of TMJ ankylosis, and airway problems. Advantages to ORIF include earlier mobilization and nearly exact bone fragment reapproximation. Disadvantages include increased treatment cost and need for operating room time. Another controversy involves disposition of teeth located in the fracture line. In the postantibiotic era, infection of involved teeth is less troublesome. Many teeth may be retained, and they can be useful in reduction and stabilization of fractured segments. Extract teeth if they prevent proper reduction and fracture stability or if they have significant periodontal disease or caries. MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Mandibular Body Fractures excerpt Article Last Updated: Sep 19, 2006 | |||||||||||||||||||||
