Keywords
comminuted mandible fracture - atrophic mandible fractures - mandible continuity defect
- mandible fractures
Complex fractures of the mandible, which play an important role in both structural
support and masticatory function, pose a significant challenge to the reconstructive
surgeon. Advances in the techniques of rigid internal fixation in atrophic, comminuted,
and defect fractures have allowed for improved surgical outcomes. The application
of basic reconstructive principles and implementation of bone grafting have facilitated
convalescence of function and shortened patient treatment course in this setting.
Herein, we present a contemporary review of evidence-based management modalities in
treatment of complex mandibular fractures.
Management of Initially Infected Mandible Fractures
Management of Initially Infected Mandible Fractures
Although there is a paucity of evidence supporting postoperative administration of
antibiotics in mandible fractures,[1]
[2] preoperative administration has shown substantial benefit in reducing infection.[3]
[4]
[5]
[6]
[7] Patients presenting with open fractures, fractures along the dentate mandible with
violation of the periodontal ligament, should receive antibiotic prophylaxis regardless
of planned treatment modality.[5]
[6]
[7] Antibiotic therapy should also be considered in patients with multiple systemic
medical comorbidities and smokers, as these patients have shown an increased incidence
of infections.[6]
Infected mandibular fractures present in bimodal patient age distribution patterns.[8] Interpersonal violence is the primary cause of the majority of mandibular fractures
in young males.[9]
[10]
[11] These patients may seek care in a delayed fashion once symptomology, consistent
with underlying infection, necessitates evaluation. Similarly, elderly patients with
maxillofacial injury may go unnoticed until infection ensues.[12] In general, some clinicians propose that all patients with mandibular fractures
presenting after 48 hours of onset of injury should be treated as infected.[13] However, the literature supporting this is limited. All patients presenting with
fractures of the mandible should be evaluated for purulent drainage from fracture
site, fistula formation, or surrounding cellulitic reaction. A decision on antibiotic
therapy should be made on a case-by-case basis.
Historically, infected mandibular infections were treated with extraction of involved
dentition with subsequent rigid immobilization of the fracture with maxillomandibular
fixation (MMF), intraoral splints, external fixation devices, or a combination of
these techniques.[14] Drainage of surrounding abscesses with prolonged antibiotic treatment was initially
thought to be of paramount importance in resolution of infectious processes. However,
it was later demonstrated that the nidus of infection, devitalized dentition and osseous
fragments, necessitated debridement to mitigate further infection and prevent sequestrum
formation.[14]
[15] Debridement of infected or devitalized tissue followed by concurrent rigid internal
fixation has shown outcomes comparable to noninfected mandibular fractures.[16] However, debridement of an extensively infected fracture site may result in an osseous
defect. In this case, immediate primary bone grafting with autogenous particulate
marrow has shown to be effective with decreased overall time to recovery.[14]
[15]
[16]
Management of Teeth in the Fracture Line
Management of Teeth in the Fracture Line
Retained teeth were previously thought to act as a conduit for bacterial migration
between the oral cavity and periodontal space and were therefore prophylactically
removed. As mentioned previously, frankly infected or devitalized dentition within
the fracture line should be extracted, as they may serve as a nidus for infection
with resultant sequestrum formation and nonunion.[17] However, extraction of viable uninfected dentition may cause further trauma to the
surrounding bone with destabilization of the fracture. Healthy dentition facilitates
proper alignment of premorbid occlusion and should be attempted to be preserved.[18] Extraction of otherwise healthy dentition may also increase the risk of infection
as coagulum formation does not always occur as anticipated, resulting in a localized
osteitis.[17]
[18]
[19] Indications for removal of dentition within the fracture line include clinical or
radiologic evidence of periodontal disease, partially erupted third molars with pericoronitis,
dentition inhibiting fracture reduction, fragmented dental roots or exposed root apices
with loss of gingival margin, and recurring abscess formation despite prolonged antibiotic
treatment.[17]
[18]
Despite these widely accepted indications, controversy persists surrounding extraction
of third molars in mandibular angle fractures.[17]
[18]
[19]
[20]
[21]
[22]
[23]
[24] Recent evidence supports retention of third molars in the absence of infection or
other previously mentioned indications above, as extraction may destabilize the fracture
line and prevent interfragmentary stabilization required for osteosynthesis.[17]
[20]
Management of the Atrophic Edentulous Mandible
Management of the Atrophic Edentulous Mandible
Atrophic mandibular fractures are classified as those with less than 15 mm of bone
height at the site of fracture.[25] Atrophic mandibles are more susceptible to fracture due to decreased bone stock.
The decrease in bone volume also places these patients at higher risk of nonunion
due to the tenuous blood supply. Studies have shown significantly higher rates of
nonunion if any management modality other than rigid internal fixation is implemented
in patients with atrophic mandibles.[26]
[27]
Controversy also exists surrounding a supraperiosteal or subperiosteal surgical approach
to fixation. Mandibular fractures are usually exposed in a subperiosteal plane to
allow for adequate reduction and placement of fixation plates directly to underlying
bone.[25]
[26]
[27]
[28] However, the bloody supply to the bone is provided via the overlying periosteum.
There has therefore been conjecture that a supraperiosteal dissection in atrophic
mandibles would better preserve perfusion and promote improved healing with decreased
risk of nonunion.[29]
[30] The evidence supporting the supraperiosteal approach is, however, limited and this
plane of dissection provides suboptimal visualization of the fracture line and introduces
an obstacle to the application of fixation devices. This increased difficulty may
result in an inadequate reduction or fixation with an associated risk of malunion.[25]
The application of bone grafts at the time of initial intervention is also a topic
of active debate. Due to the poor vascularity of the atrophic mandible, reconstructive
surgeons have advocated for the addition of bone during initial repair to promote
healing capacity.[25]
[26]
[27] However, the harvest of autogenous graft from the tibia or iliac crest in the debilitated
elderly patient, often presenting with multiple comorbidities, may add further morbidity
to the repair. Traditionally, closed reduction with or without intermaxillary fixation
was the standard of care in this patient population but has since lost favor due to
high rates of malunion and nonunion.[26]
[27]
[29]
[30] The paradigm has thus shifted to open reduction via a subperiosteal extraoral approach
with placement of locking reconstruction plates fixated either along the lateral or
inferior border. Satisfactory results have been reported with use of reconstructive
plates or multiple miniplates placed at various locations.[25]
[31]
[32] Ellis and Price recommend the use of a 2.0-mm locking plate, placed using an extraoral
subperiosteal approach with immediate supplemental autogenous bone grafting, citing
the advantage of thinner plates with lower likelihood for external palpation, plate
exposure, or interference with denture placement. They also report facile adaptability
of a thinner plate in comparison to the thicker 2.4 mm reconstruction plate.[25] The reconstructive surgeon must be cognizant of potential adverse effects of each
technique. Use of large bicortical screws with reconstruction plates may cause further
fracture in the severely atrophied mandible, stripping of the periosteum resulting
in bony necrosis and malunion, or alveolar nerve injury resulting in lower lip dysesthesia.[33]
[34] Despite these disadvantages, placement of a reconstruction plate is the treatment
modality recommended by the Arbeitsgemeinschaft für Osteosynthesefragen/Association
for the Study of Internal Fixation for the treatment of atrophic mandible fractures.
As mentioned previously, the use of immediate autogenous bone grafts remains controversial.
There is currently a paucity of convincing evidence that immediate bone grafting is
necessary. Acceptable results have been demonstrated both with[25] and without[35] supplementation with bone grafts. Justification for use of bone grafts includes
poor vascularity and dense cortical bone with insufficient marrow in the atrophic
mandible resulting in poor healing ability. Therefore, the addition of autogenous
bone grafts is thought to recruit osteocompetent cells to an otherwise deplete area.[25]
[26]
[27]
[28]
[29]
[30] Disadvantages include donor site morbidity, such as gait disturbance if the hip
or lower leg is used, infection, graft resorption, and nonunion.[34]
[35] Currently, there is no consensus for the implementation of bone grafts and treatment
decisions should be based on the training and experience of the reconstructive surgeon.
When utilized, bone grafts (from either the iliac crest, anterior tibia, rib, or calvarial
bone) may be placed within a containment system of either titanium or resorbable mesh
that is contoured to encompass the delineated mandibular defect.[25]
[36] The mesh containment system maintains the shape of the graft while preventing migration
during the consolidation phase.[36] In addition to facilitating osseous healing, utilization of simultaneous bone grafting
during the initial repair is thought to increase bone stock, preventing further pathological
fractures and facilitating dental prosthetic placement.[34]
[36]
[37]
[38]
[39] Use of alloplastic reconstructive materials has recently been investigated to mitigate
the morbidity associated with bone graft harvesting. These materials include hydroxyapatite,
glass ceramics, carbonate, or tricalcium phosphate.[40] Further alternatives to autogenous grafts include tissue-engineered scaffolds with
the integration of osteoinductive proteins such as human recombinant bone morphogenic
protein 2. These bioactive materials have shown promising results in preliminary studies.[41]
[42]
[43]
[44] A review of the bone tissue engineering is beyond the scope of this article. Readers
are directed to the references reviewing biomaterials.[44]
[45]
[46]
[47]
Comminuted Fractures and Continuity Defects
Gunshot Wounds
Gunshot wounds (GSWs) to the head and neck region result in severe, destructive injuries
that often involve the mandible. A retrospective review looking at outcomes among
head and neck GSW patients found that 20% died within the first 48 hours. Of the remaining
cohort, 85% underwent reconstructive surgery, with patients with mandibular trauma
undergoing an average of 1.7 surgical procedures.[58]
The concepts detailed above for comminuted fractures and continuity defects fully
apply to GSW-induced mandible fractures, as most of the injuries will be categorized
in this manner. However, the mainstay of reconstructing the complex mandible injuries
following GSWs is the vascularized free flap. First described in 1989, the fibula
free flap remains the mainstay of mandible free flap reconstruction.[59] Flap options beyond the fibula include the deep circumflex iliac artery, scapula,
and osteocutaneous radial forearm free flap.[60] Fixation of these neomandibles can occur through multiple mini plates or a single
reconstructive plate. While some groups have found no difference in outcomes between
the two techniques,[61] others have found that mini plates required removal for infection more frequently.[62] It is also important to note during surgical planning and patient counseling whether
the GSW was self-inflicted, as this puts the patient at higher risk of postoperative
complications following free flap reconstruction.[63]
The use of computer-aided design, computer-aided manufacturing, virtual surgical planning,
stereolithic models, custom plates, intraoperative navigation, and intraoperative
imaging all represent technological advances that are gradually being implemented
more frequently in complex mandible reconstructions.[60] These advances are leading to decreased operative times, decreased costs, and better
functional and aesthetic outcomes.[60]
Conclusion
Complex mandibular injuries represent a unique challenge for the facial trauma surgeon
due to the overall extent of injury, risk of infection, dentoalveolar compromise,
and possible loss of bone with resultant continuity defects. Rigid fixation of these
fractures is of utmost importance in facilitating reconstitution of the mandible,
restoration of premorbid occlusion, and convalescence of function. Advances in biomaterials,
virtual surgical planning, stereolithic models, and navigation surgery represent future
frontiers that may further optimize surgical outcomes in the treatment of these complex
injury patterns.
