Trauma

TRAUMA: EMERGENCY MANAGEMENT OF MANDIBULAR AND MIDFACE FRACTURES

SPEAKER AND EVENT DETAILS

  • Speaker: Vishtasb Broumand, M.D., D.M.D.

  • Position: Medical Director OMS, University of Arizona

  • Location: Phoenix, AZ

  • Date: 11/1/2024

  • Event: Denver Review Course

MANDIBLE FRACTURES

  • Presented by: Vishtasb Broumand, DMD MD

  • Department: University of Arizona OMS Dept.

  • Date: March 11th, 2024

CLINICAL EVALUATION

  • Bimanual manipulation of the mandible to assess mobility.

  • Assessment of occlusion and premature contacts.

  • Assessment of symmetry and deviation upon mouth opening.

  • Maximum inter-incisal opening measurement.

  • Evaluation of dentition and/or dentoalveolar fractures.

  • Comprehensive cranial nerve evaluation.

RADIOGRAPHIC EVALUATION

  • Imaging should consist of imaging in at least two planes.

    • Panoramic radiograph:

      • Allows accurate assessment of teeth involvement and their relationship to adjacent fractures.

      • Limitation: A panoramic radiograph is not adequate alone.

    • Gold Standard: Panorex & CT.

    • Reverse Townes: Previous standard for evaluation of condyles.

CT SCAN

  • Evaluates:

    • Vertical Buttresses: (zygomatic, nasomaxillary, pterygomaxillary)

    • Axial CT: (Zygomatic Arch, Mandible)

    • Horizontal Buttresses: (maxillary alveolus, palate, pyriform aperture, orbital rims, base of skull)

    • Coronal CT: (Mandible, Orbits)

  • Smaller slice thickness (1.0-1.5mm) allows for more accurate treatment planning.

DIAGNOSIS

  • Indicators of mandibular fractures:

    • Malocclusion.

    • Limited incisal opening.

    • Jaw deviation to the affected side.

    • Mobility of segments.

    • Occlusal or bony step defects.

    • Paresthesia or pain.

    • Intraoral gingival lacerations.

    • Floor of the mouth ecchymosis and edema.

GOALS OF THERAPY

  • Obtain stable occlusion.

  • Restore interincisal opening.

  • Regain full range of motion.

  • Prevent internal derangement of TMJ.

  • Prevent growth disturbances.

  • Prevent facial widening or elongation.

  • Maintain facial/mandibular A-P projection.

CLASSIFICATION OF MANDIBULAR FRACTURES

  • Displaced or non-displaced.

  • Favorable or unfavorable based on vector of muscle pull.

  • Anatomic Locations:

    • Dentoalveolar

    • Symphysis

    • Parasymphysis

    • Body

    • Angle

    • Ramus

    • Condylar Process (Intracapsular vs extracapsular).

    • Subcondylar fractures.

ANATOMIC LOCATIONS

  • Symphysis: Midline of the mandible.

  • Parasymphysis: Bounded bilaterally by vertical lines at the distal canines.

  • Body:

    • Anteriorly bounded by the parasymphysis region.

    • Posteriorly bounded by the anterior border of the masseter.

  • Angle: Triangular region bounded by the anterior border of the masseter.

FREQUENCY PERCENTAGES OF MANDIBLE FRACTURE LOCATIONS

  • Symphysis: 17%

  • Body: 29%

  • Coronoid process: 1%

  • Ramus: 4%

  • Angle: 25%

  • Condyle: 26%

MUSCLE PULL ON MANDIBULAR FRACTURES

  • Muscles involved:

    • Muscles of mastication & suprahyoid strap muscles.

    • Lateral pterygoid displaces the condyle anteriorly and medially due to insertion on the pterygoid fovea.

    • Muscles attached to the ramus cause superior and medial displacement of the proximal segment.

    • Suprahyoid strap muscles pull the distal segment posteriorly and inferiorly toward the cuspid region.

BIOMECHANICAL CONSIDERATIONS

  • The mandible develops zones of tensile and compressive forces during normal function.

  • Fractures tend to occur in areas of tensile strain rather than compression.

  • Exception: The condyle region is fractured by compressive forces when pushed into the glenoid fossa.

    • Tension occurs along the upper margin.

    • Compression occurs at the lower margin.

  • Exception: Mandibular symphysis; incisal load results in tension and separation at the lower border of the fractured mandible.

ISOLATED MANDIBULAR FRACTURES

  • Non-comminuted fractures:

    • Within tooth-bearing region approached via transoral (Vestibular) incision.

    • Upon entering intermaxillary fixation (IMF), bone reduction forceps are used to stabilize osseous segments.

  • Technique involves:

    • Use of two bone plates (both tension and compression bands should be used).

    • Alternatively, two lag screws or one plate or lag screw with arch bars can be used.

  • Plate Selection:

    • Tension band: Arch bar or 2.0 miniplate (monocortical).

    • Compression band: 2.0 miniplate (bicortical).

    • Tension band plate must be placed first to prevent splaying of teeth along the fracture segment.

REGIONAL DYNAMIC FORCES: ISOLATED SYMPHYSIS FRACTURE

  • Incisal load: acts as pivot point, causing lower border separation (Tension) greater than upper border (Compression).

  • Pterygoids action: pulls the ramus segments in and down, causing splaying at the inferior border resulting in compressive strain along buccal aspect and tensile strain along lingual aspect.

  • Fracture propagation: occurs on the lingual side that propagates to the buccal.

DYNAMIC FORCES IN MANDIBULAR FRACTURES

  • Tension at superior border results in gap formation.

  • Increased tendency for lateral or medial displacement in body fractures.

  • Once in IMF, place bone reduction forceps prior to two plate fixation.

  • Tension band should be placed first to prevent splaying of teeth.

REGIONAL DYNAMIC FORCES: BODY FRACTURES

  • Fractures exhibit a zone of tension at superior surface resulting in gap formation and compression at the lower margin.

  • Anterior fractures lead to more torque and mediolateral misalignment of the inferior border.

  • Symphysis incisal load: results in tension and separation at the inferior border.

  • Arch bars' role: provides resistance to gap formation.

REGIONAL DYNAMIC FORCES: ANGLE FRACTURES

  • Fractures exhibit a zone of tension at superior surface resulting in gap formation.

  • Fixation devices at superior border are more effective than at inferior border.

  • There is a lesser tendency for medial or lateral displacement.

BILATERAL MANDIBULAR FRACTURES

  • Lateral muscular forces: can cause facial widening by splaying angles outward.

  • Complications of inadequate accounting for lateral muscular forces include:

    • Diastasis along lingual cortex.

    • Facial widening at angles of mandible.

  • Reduction requires applying manual medial forces at angles, stabilizing the anterior fracture with reduction forceps, and over-bending the plates at the symphysis/parasymphysis.

OPERATIVE MANAGEMENT

  • Primary Goals:

    • Restore patient to pre-injury form and function.

    • Achieve anatomic reduction and predictable osseous union.

  • Considering Technique:

    • Interdental fixation (Arch bars, interdental wires, IMF screws).

    • Open or closed approach (transoral vs transcervical).

    • Hardware selection (Load-bearing vs Load-sharing).

    • Management of teeth in line of fracture (retain or remove).

    • Post-operative rehabilitation (IMF vs immediate function).

ARCH BARS VS IMF SCREWS

  • Erich Arch Bars:

    • Preferable for comminuted fractures and those with concomitant midfacial fractures.

  • IMF Screws:

    • Typically used for isolated, non-comminuted, dentate fractures.

  • Hybrid MMF:

    • Can be utilized for isolated, non-comminuted, dentate fractures.

IMF: INDICATIONS

  • Aids to ORIF of Mandibular Fractures.

  • Intraoperative stabilization.

  • Definitive treatment for:

    • Minimally displaced favorable fractures.

    • Grossly comminuted fractures.

    • Pediatric mandibular fractures.

    • Intracapsular condylar fractures.

    • Re-approximation and reduction of panfacial/midface fractures.

IMF: CONTRAINDICATIONS

  • Individuals unable to tolerate being wired shut:

    • Children/Elderly

    • Obtunded patients

    • Developmentally delayed

    • Alcoholics

  • Specific Concerns:

    • Prolonged IMF of intracapsular fractures may lead to ankylosis.

    • Mitigation through limiting the duration of IMF (2-4 weeks wired followed by guided elastics for another 2-4 weeks).

IMF: ASSOCIATED RISKS

  • Trismus

  • Decreased range of motion

  • Poor oral hygiene

  • Periodontal disease

CLOSED VS OPEN TREATMENT

  • Debate:

    • Closed reduction (MMF) is safe, reliable, and cost-effective.

    • Open reduction (ORIF) allows for immediate return to function and management in complex injuries.

    • Landmark Studies:

      • Hoffman et al.

      • Thaller et al.

      • Dodson and Pfeffle.

MANAGING TEETH IN THE LINE OF FRACTURE

  • Evaluation Criteria:

    • Tooth mobility.

    • Interference with fracture reduction.

    • Pulpal pathology.

    • Location.

  • Indications for Extraction:

    • Grossly mobile teeth.

    • Teeth interfering with fracture reduction.

    • Grossly infected teeth.

COMPLICATIONS

  • Infection:

    • Ensure adequate drainage, removal of the source, and antibiotic therapy. If secondary to hardware but with favorable bony union, remove hardware only.

  • Malunion:

    • Osteotomies are necessary to correct occlusion and restore facial symmetry/projection.

  • Nonunion:

    • Require debridement of soft tissue and nonviable bone, stabilization, and application of a recon plate. Immediate bone grafting may be necessary.

HORIZONTAL FRACTURES

  • Favorable structures:

    • Line begins at alveolar margin and extends anteriorly and downward to the lower border of the mandible, resisting upward displacing forces from masseter and temporalis muscles.

  • Unfavorable structures:

    • Line starts at alveolar margin extending posteriorly and downward to the lower border of the mandible.

VERTICAL FRACTURES

  • Favorable structures:

    • Runs from outer buccal plate obliquely backward and lingually, resisting medial pull from medial pterygoid on proximal fragment.

  • Unfavorable structures:

    • Runs from inner lingual plate obliquely backward and buccally.

RIGID INTERNAL FIXATION

  • Definition: Fixation applied directly to the bone strong enough to prevent inter-fragmentary motion across the fracture.

  • Goal: Primary healing without callus formation and immediate restoration to full function.

  • Examples:

    • Superior Plate (2 holes monocortical) & Inferior Plate (2 holes bicortical).

    • Inferior Plate only (3 holes bicortical).

    • MMF & Inferior Plate (2 holes bicortical).

NON-RIGID INTERNAL FIXATION

  • Fixation applied directly to bone that does not prevent inter-fragmentary motion across the fracture.

  • Goal: Secondary healing under conditions of mobility between fragments that will lead to callus formation.

  • Disadvantages: Excessive mobility can lead to bone resorption, fibrous tissue ingrowth, and infection.

  • Functional Stability: Strong enough for active use during healing but not enough to prevent inter-fragmentary mobility.

  • Classic Example: Superior border or “Champy Method.”

LOAD-BEARING FIXATION

  • Characteristics: High-strength, rigid plates and screws that bear the entire load of the mandible during function.

  • Characteristics: No load sharing between bone fragments, and no buttressing is required.

  • Indications:

    • Comminuted segments.

    • Atrophic mandible fractures.

    • Minimal bone contact.

    • Total bone loss.

  • Common sizes: 2.3, 2.4, or 2.7 mm, placing three bone screws on either side of fractures.

LOAD-SHARING FIXATION

  • Any form of internal fixation insufficiently stable to bear all functional load across the fracture.

  • Common application: 2.0 mm mini-plate systems.

  • Indications: Simple fractures in which fragments are articulated well during healing and function, sharing functional loads with bone on each side of the fracture due to anatomic reduction.

FINAL DECISION CRITERIA FOR OPEN OR CLOSED TREATMENT

  • In absence of absolute contraindications, severity of fracture and positive medical findings lead to contributing postoperative complications.