Pediatric Mandible Fractures

Frequency

Incidence rates of mandibular fractures in children have been fairly consistent in the literature over the years. In 1956, MacLennan reported that 1% of mandibular fractures occur in children younger than 6 years.[4] Similarly, in Rowe's 1969 study,[5] 5% of mandibular fractures were in children aged 6-11 years; only 1% occurred in patients younger than 5 years. In 1992, Thoren[6] reported that 7.7% of mandibular fractures occur in children younger than 16 years and 2.9% occur in children younger than 10 years. Incidence of mandibular fractures increases with age to young adulthood. Only 12% of pediatric mandibular fractures occur in patients younger than 6 years. While some series report an equal distribution between the sexes, a 2:1 male predominance for all mandibular fractures and an 8:1 predominance for condylar fractures have been reported.[7, 8]

In several series, motor vehicle accidents and falls are the most common causes of pediatric mandibular fractures. However, the frequencies of etiologies of fractures in a Swiss series were 72% due to recreational activities and 17% to traffic accidents. Thoren's 1992 series reports 57% of fractures were due to vehicular accidents and another 18% to falls.[6] The vast majority of the vehicular accidents are attributed to bicycle accidents.

In a retrospective review of 122 Mayo Clinic patients, aged 18 years or younger, with mandibular fractures, Siwani et al found the most common injury mechanisms to be motor vehicle accidents (52 [43%]), sports injuries (24 [20%]), and assault (13 [11%]).[9]

A retrospective study by Morisada et al of patients under age 18 years at a level 1 trauma center found mandibular fractures to be most often caused by motor vehicle collisions, falls, and assault. Falls were a more common source of such fractures, and assault a less common one, in younger children than in older pediatric patients. While condylar fractures occurred most often in children under age 9 years, patients in the study aged 15 years and up sustained a greater percentage of angle/ramus fractures.[10]

Some discrepancy in reported causes exists because some studies classify falls from a bicycle as falls and others classify this type of accident as a vehicular accident. Older school-age children also sustain injuries in sporting activities, while teenagers, like adults, are frequently subject to violent causes of injury.

Mandible development

During the first years of life, the size and proportions of the facial skeleton change markedly. The facial skeleton increases in relation to the rest of the head, and the sinuses and dentition develop postnatally. The mandible is relatively small at birth and grows by remodeling. The eruption of teeth and the development of the alveolar process also contribute to vertical growth. Apposition of bone at other surfaces causes the bone to develop a more adult shape. Thus, the mandible assumes a more forward position and a longer shape. The condylar growth centers are crucial in mandibular development. Each center consists of chondrogenic, cartilaginous, and osseous zones. A thin vascular layer covers the chondrogenic zone. Bone is deposited at the posterior borders of the rami and condyles. Trauma to the growth center just beneath the articular disk is cause for concern. Delayed growth on the affected side can cause facial asymmetry, mandibular deviation, and malocclusion.

A high tooth-to-bone ratio exists in the pediatric bone. Fractures frequently occur through developing tooth crypts. Teeth in the line of fracture may develop with malformations. Teeth begin to erupt at age 6 months, and the full complement of 20 primary teeth is erupted completely at about age 2 years. These teeth are relatively stable until age 6 years when root resorption begins to occur, which causes the teeth to loosen. Permanent dentition erupts, beginning with the first molars and central incisors, at ages 6-7 years. The second molars erupt at age 12 years.

Because the young patient has a high ratio of cancellous to cortical bone and a thick layer of soft tissue covering, greenstick fractures are common. Rapid healing occurs in pediatric bone, and the best reduction is obtained within 5 days. However, if callus is already formed, a slight discrepancy in primary occlusion is acceptable. Some degree of functional remodeling can be anticipated.

Do not neglect a complete trauma evaluation. Children with mandibular fractures are at risk for airway compromise because of the direct trauma, swelling, or hematoma that causes obstruction or impaired consciousness. Often, airway management may be accomplished with positioning. However, presume cervical spine injuries until excluded. Suction the oropharynx of debris and blood as necessary.

Fractures of the mandibular arch may allow a bony segment to be displaced posteriorly. Manual traction or a traction stitch on the tongue may alleviate airway obstruction. If necessary, orotracheal intubation is usually possible and preferable to an emergent surgical airway. Quickly accomplish control of hemorrhage because the blood volume in the child is small. Perform a thorough trauma physical examination.

The youngest patients are unable to provide a history, and slightly older children are limited by descriptive ability, fear of the situation leading to the trauma, as well as anxiety in the hospital setting. The patient may report pain in the jaw region, particularly upon movement. Minor displacement leads to noticeable changes in occlusion. Ask patients whether their bite feels normal.

Young patients are more difficult to examine. Inspect the face first and note obvious asymmetry. Swelling and ecchymosis of the face, especially the preauricular areas, may be clues to underlying fractures. A chin laceration on the young child usually indicates a superiorly directed midline force, which often results in condylar damage. Examination of the jaw during mouth opening and closing may reveal deviation of the jaw or limited mobility. Trismus may also be evident after a mandibular fracture and is commonly due to muscle spasm and pain. However, restriction of jaw motion may be secondary to a displaced zygomatic fracture impinging on the coronoid process of the mandible.

Intraoral examination may reveal lacerations or hematomas. If bone is exposed through an intraoral or cutaneous laceration, antibiotics are indicated. Penicillin covers most mouth flora. A first-generation cephalosporin covers most skin flora. Examination of teeth for injury also is important. Rapid treatment of dental injuries, especially of the permanent dentition, is essential. Examination of the ear may also be rewarding. Fractures of the condyle can cause bleeding or ecchymosis of the anterior wall of the external auditory canal.

Next, perform orderly palpation of the facial skeleton. Step-offs and instability may be apparent. Bimanual examination of the mandible may be helpful. Palpation in the auditory canal during movement of the jaw may reveal crepitation or evidence of a displaced condylar head.

A fracture of the body of the mandible may affect the inferior alveolar nerve, leading to numbness of the teeth or chin. Displaced fractures may also affect the lingual nerve, which innervates the anterior two thirds of the tongue, or they may affect the long buccal nerve, which supplies sensation to the cheek mucosa and corner of the lip.

Assessment of occlusion is more difficult in the child than in the adult. Children often do not have a full complement of teeth. Knowledge of pretraumatic occlusal status is important in evaluation and treatment. In adults, wear facets are useful, particularly when other serious injuries are present. In children, dental wear may not be apparent.

A retrospective study by Swanson et al indicated that pediatric mandibular fracture patients with a value of 14 or higher on the Mandible Injury Severity Score (MISS), normally used in the evaluation of adult mandibular fractures, have a significantly greater risk of complications.[11]

Associated injuries

Mandibular fractures carry the highest rate of associated injuries in pediatric patients with facial fractures. In Kaban's 1977 series,[12] 22 of 29 pediatric patients with mandibular fractures had other injuries, mostly confined to the head and face, which included 1 cervical spine injury. In 1992, Thoren reported associated midface fractures in 8% of patients, most of these in patients aged 13-15 years.[6] Skull fracture or cerebral injury occurred in 13% of patients, and orthopedic injuries occurred in 8%.

Indications for jaw immobilization are bilateral fractures with an open bite or severe movement limitation or deviation. See Surgical therapy for a discussion of the indications for surgical therapy in each type of mandible fracture.

Distribution of mandibular fractures

Patterns of fracture distribution are affected by the force and direction of impact as well as the state of mandibular development of the child. The younger child has relatively more soft tissue cushioning, and the mandibular bone is in a more protected position. The overall force developed in most childhood falls is low. Also, in young children the bone is relatively resilient; therefore, force directed at the chin is transmitted to the condylar heads, which sustain a crush-type injury. In Thoren's 1992 study,[6] the condylar region was the most common location of fracture in all pediatric age groups, accounting for 60% of all fractures; 72% of children had fractures in this region. In a 1993 series reported by Posnick,[13] most mandibular fractures occurred at the condyle (55%), followed by the parasymphysial region (27%), then the body (9%), and angle (8%).

In a study of 120 patients under aged 18 years who presented at a pediatric trauma center with a total of 215 mandible fractures, Smith et al also found that fractures occurred most frequently in the condylar head and neck.[14]

In the aforementioned Mayo Clinic study, the subcondylar and parasymphyseal regions, as well as the angle and body, were the most common mandibular fracture sites.[9]

As the age of the patient increases, the relative number of condylar fractures decreases, while fractures in the body and angle increase. Patients aged 10 years and older are similar to adults in cause and fracture pattern. While most children have only 1 mandibular fracture, approximately a third have 2 or more fractures.

Fractures at multiple sites occur in approximately 40-60% of the cases and are more common among children older than 13 years of age (59% vs 35%).

Fractures of the mandible may also be classified as favorable or unfavorable, in both the horizontal and vertical directions, depending on whether the inherent muscular pull tends to reduce or displace the fractured segments.

In contrast to adult patients, surgery is not indicated in the vast majority of pediatric patients with condylar fractures; they may be treated nonoperatively. Usually, these patients have normal occlusion and range of motion. Also, conservatively manage comminuted fractures of the head and condyle.

See the list below:

• Panorex

  • Panorex is the study of choice. The patient must be cooperative and motionless while the radiograph machine rotates. Patient movement may simulate a fracture. Most available equipment requires the patient to be able to sit upright; therefore, this examination may not be possible in critically ill patients or those with suspected cervical spine injuries. (Some facilities have special equipment for the supine patient.)

  • A series of plain radiograph views may provide similar information and often are easier to obtain in the acute trauma setting.

• Plain radiography: Standard radiograph views that evaluate the mandible include the following:

  • Lateral oblique view - Provides the best view of the mandible from the condyle to the mental foramen

  • Posteroanterior (PA) view - Can visualize displacement of fractures of the ramus, angle, and body and fractures of the anterior mandible that may be obscured by the vertebral bodies

  • Towne occipitofrontal view - Demonstrates condylar fractures and displacement medially or laterally

  • Mandibular occlusal views - Demonstrate symphyseal displacement

  • Dental radiographs - May prove useful in alveolar fractures or dental root fractures

• CT scanning

  • Thin-section (≤ 3 mm) CT scans through the mandible can be useful.

  • Direct coronal images and/or 3-dimensional or multiplanar reconstructions can help to delineate relation of the temporomandibular joint (TMJ).

Management of mandibular fractures

The general principles of the management of maxillofacial trauma are similar in both children and adults, but the ongoing developmental changes in the growing face of a child must be taken into consideration.[15, 16, 17, 18, 19] In the aforementioned study by Smith et al, children over age 12 years were found to be significantly more likely than younger children to be treated surgically.[14]

Using a statewide California database to examine the treatment of pediatric patients who sustained facial fractures, Chopra et al reported that 32% underwent surgical repair. Of those facial fractures that were operatively treated, mandibular fractures made up 40%, compared with 16.2% and 15.1% for nasal and orbital fractures, respectively. There was a positive correspondence between the rate of surgical intervention for facial fracture and age, with such repair peaking in children aged 12 to 15 years.[20]

Adequate treatment of mandibular fractures should accomplish several goals. Restoration of occlusion, function, and facial balance is necessary for therapy to be considered successful. Proper treatment may prevent complications such as growth disturbance and infection.[21] The specific treatment of mandibular fractures depends on location of the fracture, degree of bony displacement, occlusal status, and dentition status of the child. Methods of fixation vary by dental status.[22]

Before age 2 years, the deciduous teeth are not completely erupted. Children at this stage of development are treated as though edentulous. An acrylic splint may be fixed in place with circummandibular wires. If immobilization of the jaw is necessary, the splint may be fixed to both occlusive surfaces with both circummandibular wires and wires through the pyriform aperture.[2, 3]

Once deciduous teeth are established, at about ages 2-5 years, they may be used for fixation. Although the deciduous teeth are conically shaped (rather than having a cervical waist), interdental wiring may be used. Arch bars are somewhat more difficult to secure below the gum line. Redundant support may be necessary. Mini-arch bars attached with resin may be used to treat nondisplaced fractures, avoiding immobilization of the mandible.

A state of mixed dentition exists in children aged 6-12 years. During this period, dental stability is more precarious. Primary tooth roots are resorbing. Teeth often are loose or absent. In children aged 5-8 years, deciduous molars may be used for fixation. In children aged 7-11 years, the primary molars and incisors can be used to anchor fixation. When adequate dentition is not available for fixation, Gunning splints may be used as in the younger patient. In children older than 9-12 years, standard intermaxillary fixation (IMF) with arch bars is possible because enough permanent dentition has been established. Braces may also be used briefly for fixation.

Rapid healing and the possibility of remodeling decrease the duration of immobilization necessary in the pediatric patient. Most studies report 2-3 weeks to be adequate, although a few recommend longer treatment. The rapidity of healing also dictates that management of the fractures should occur early. If treatment is delayed, removal of callus formed at the fracture site often is necessary.

If open reduction and fixation (OR&F) is required, use an intraoral approach, where possible. Place monocortical screws at the inferior border of the mandible to avoid damaging the underlying teeth. The open surgical approach to the condyle is through submandibular or preauricular approach, depending on location of fracture.

Eppley reported the use of resorbable polylactic and polyglycolic acid plates and screws in 14 patients with displaced fractures of the symphysis, parasymphysis, body, and ramus.[23, 24] Patients underwent open reduction and either 1.5-mm or 2.0-mm plate and screw fixation with no long-term implant-related complications.

Condylar fractures

In 1952, MacLennan reported a series of mandibular condyle fractures.[25] Approximately 6% of these fractures occurred in children younger than 15 years. Less than 3% of condylar fractures were in children younger than 10 years.

Condylar fractures are classified into 3 groups. Intracapsular fractures involve the articular surface. High condylar fractures occur above the sigmoid notch and usually are medially dislocated by the force of the impact. Low subcondylar fractures usually are greenstick fractures in children and are the most common type of pediatric mandibular fracture overall.

However, in children younger than 5 years, crush injuries to the articular disk are more common. In the very young child ( < 3 y), the condylar neck is short and thick, and the force of trauma generally dissipates on the articular surface. Injuries to the articular surface may cause hemarthrosis and subsequent bony ankylosis. Early range of motion is important in preventing this complication. Injury to the cartilage also affects the growth of the mandible. In children older than 5 years, neck fractures are more common and are regarded as relatively self-correcting.

In contrast to adult patients, the vast majority of pediatric patients with condylar fractures may be treated nonoperatively. Usually, these patients have normal occlusion and range of motion. Early treatment includes analgesics and a soft diet. Encourage range of motion exercise once edema has subsided. Conservatively manage comminuted fractures of the head and condyle. In the edentulous child, no immobilization is required; in other patients, place IMF for 2 weeks. Even if displaced, the fracture typically heals well. Studies have demonstrated the ability of the condyle to remodel.

Indications for jaw immobilization are bilateral fractures with an open bite or severe movement limitation or deviation. Generally, the period of immobilization is 2-3 weeks followed by a period of 6-8 weeks of guiding elastics to counteract the force of the masseter-pterygoid sling, which pulls the inferior border of the mandible superiorly and tends to shorten the ramus.

Open reduction is indicated in a few situations as follows: (1) dislocation of the mandibular condyle into the middle cranial fossa, (2) condyle prohibiting mandibular movement, and (3) bilateral condylar fractures causing reduced rami height and open bite (although some advocate immobilization alone).

A study by Cascone et al indicated that open reduction and external fixation can be successfully used in children with mandibular condylar fractures. The report involved 21 pediatric patients, including 16 with monocondylar fractures and five with bicondylar fractures. The investigators found that the children achieved good postsurgical recovery with regard to maximal mouth opening, maximal lateral excursion, and vertical height of the ramus, with occlusion returning to preinjury status in all patients.[26]

Arch fractures

When fractures occur in the body of the mandible, fracture lines tend to be long and oblique, extending inferiorly and anteriorly. In adults, fracture lines generally travel in an inferior and posterior direction.

Management options range from observation to open reduction and rigid fixation, depending on the clinical scenario. Greenstick and nondisplaced fractures can be managed with analgesics and a soft diet. Keep patients on a soft or liquid diet. Although initial examination may reveal normal occlusion, 3-4 weeks of close follow-up of these patients is important. Investigate any new symptoms or findings with new radiologic studies.

Muscular pull and masticatory stresses can cause displacement of the fractured segments. If reduction is required, closed reduction can be attempted with a brief period of immobilization, using a technique appropriate to the patient's dental status. However, fractured symphyseal segments are frequently displaced by mylohyoid, geniohyoid, and anterior belly of the digastric muscles. When the fracture is unfavorable, rigid fixation is needed. Perform mini-plate placement after establishing occlusion in IMF. Use monocortical screws when dentition is in jeopardy; take care with placement of drill holes.[27]

Body and angle fractures

Body and angle fractures frequently are greenstick fractures and are managed with a soft diet and pain control. The angle region is not amenable to splints. If the fracture is nondisplaced or if only minimal to moderate displacement exists, closed reduction and IMF or IMF with elastics usually suffice. If open reduction is required, an extraoral approach may be needed.

Dentoalveolar fractures

Dentoalveolar fractures are relatively common. Replacement of primary teeth is unnecessary; however, replacement may provide space maintenance until permanent dentition erupts. Permanent teeth should be replaced within 2 hours. Prior to dental attention, the tooth should be returned to the socket and held in place lightly. If this is not possible, the tooth may be transported in saline or milk. If the fracture fragment is large, reposition it, and place the patient in IMF. In 1993, Tanaka reported that 5 of 21 patients treated in this manner had resultant malocclusion; therefore, he recommended that a longer than 2- to 3-week period of fixation be considered.[28] If the alveolus fragment is large, plate-screw fixation may be used, if this is possible without injuring the teeth.

In the study by Smith et al, a higher adverse outcome rate was associated with surgical management and with the presence of multiple fractures, although in no case did either the patient or surgeon find that an adverse outcome significantly affected mandibular function. Patients in the study were followed up for an average of 19.5 months.[14]

Effects of fracture/treatment on mandibular growth/function

In the literature discussing the effects of fractures on mandibular growth, a dichotomy exists between reports of nearly perfect healing of conservatively managed displaced condylar fractures and reports of severe growth disturbances or ankylosis. Some of this discrepancy may be explained by differences in the types of injuries sustained at various stages of development. The anatomic area of greatest concern is the condylar growth center.[29]

In 1956, MacLennan proclaimed that children younger than 5 years are more susceptible to growth changes. These changes decrease directly with age.[4] Children younger than 5 years are more likely to sustain injuries to the articular cartilage. Similarly, Rowe reported in 1969 that injuries to children younger than 3 years produce severe deformities, injuries to children aged 3-6 years result in moderate deformities, and injuries to teenagers heal in a similar fashion to adults.[5]

In 1971, Leake reported on long-term follow-up of pediatric mandibular condyle fractures.[30] Leake concluded that if occlusion is normal after swelling has resolved, early motion is associated with excellent results and avoids potential complications of fixation. In 13 patients followed up at 2 months to 17 years, no abnormalities of range of motion, deviation, open bite, crossbite, overbite, retrusion, pain, or clicking were noted. Even in initially displaced fractures, eventual repositioning was documented radiographically. These patients ranged in age from 2.5-12 years at the time of injury, with an average age of younger than 6 years.

In 1993, Norholt reported that the dysfunction resulting from condylar fractures increased with increasing age at the time of trauma; however, the patients were aged 5-20 years at the time of the mandibular fracture.[31] Radiologic abnormalities were commonly found but did not correlate with the severity or presence of clinical abnormality. None of the 55 patients whose cases were followed developed ankylosis or serious asymmetry.

McGuirt's 1987 follow-up study of patients after childhood mandibular fractures revealed abnormalities of occlusion and dentition in 35% of patients, including avulsed teeth, nonvital pulps, and hypoplastic teeth; up to two thirds of patients had radiographic abnormalities, and about a fifth had multiple radiographic abnormalities.[32] Sixteen percent had clinical abnormalities. Based on these results, McGuirt recommends 6-8 weeks of guiding elastics after immobilization (to help pull the jaw forward), pterygoid muscle exercises, and long-term follow-up.

The cause(s) of growth disturbances remains unclear. Resultant abnormalities may be due to the loss of the growth stimulus or the mechanical restrictions and decreased blood supply secondary to scarring. Loss of range of motion may also affect growth. Studies show more tooth damage with plating than with wire fixation, possibly secondary to dissection that is more extensive and to manipulation. These findings may also be associated with the larger plates and screws formerly used.