Open Treatment of Mandible Fractures



Open Treatment of Mandible Fractures


Joseph Baylan

H. Peter Lorenz





ANATOMY2,3



  • The mandible is a U-shaped bone composed of thick buccal and lingual cortices with a thin medullary canal.


  • The mandible is divided into paired condyle, coronoid, ramus, angle, body, parasymphysis areas with a single midline symphysis, and tooth-bearing alveolus (FIG 1).


  • Blood supply to the mandible comes from the inferior alveolar artery and direct muscular attachments.


  • The inferior alveolar nerve traverses the mandible in the medullary canal, exiting at the mental foramen which is located inferior to the second premolar.


  • Muscles inserting on the mandible (FIG 2):



    • Muscles of mastication



      • Masseter


      • Temporalis


      • Medial pterygoid


      • Lateral pterygoid:


    • Suprahyoid muscles



      • Digastric






        FIG 1 • Bony anatomy of the mandible.


      • Stylohyoid


      • Mylohyoid


      • Geniohyoid


PATHOGENESIS



  • Two most common causes of mandible fractures are assault and motor vehicle collisions.


  • Additional causes include gunshot wounds, falls, and sports injuries.


  • Most common location of fractures2,3:



    • Condylar (36%)


    • Body (21%)


    • Angle (20%)


    • Symphysis (14%)


    • Alveolar ridge (3%)


    • Ramus (3%)


    • Coronoid fractures (2%)


  • Displacement of fracture segments commonly occurs from differing forces of inserting muscles3:



    • Muscles of mastication displace posterior segments superiorly.


    • Suprahyoid muscles displace anterior segment inferiorly.


    • The lateral pterygoid displaces condylar head medially.


  • Favorable mandible fractures3:



    • Nondisplaced by muscular pull.


    • Most rami fractures.







      FIG 2 • Muscle attachments of the mandible.


  • Unfavorable mandible fractures3:



    • Horizontal angle fractures that extend posteriorly and downward tend to be displaced by muscles of mastication.


    • Vertical symphyseal and parasymphyseal fractures are displaced downward by suprahyoid muscles.


    • High condylar fractures are displaced medially by the lateral pterygoid muscle.


PATIENT HISTORY AND PHYSICAL FINDINGS



  • Focused history and physical exam:



    • Mechanism of injury.


    • Full intraoral and dental examination.



      • Evaluate for anterior or posterior open bite in centric occlusion.


      • Evaluate for deviation of the mandible upon opening.


      • Palpate condyles in preauricular area and external auditory canal during opening to assess translation and tenderness.


    • Evaluate for mental nerve paresthesias.


    • Tips.



      • Use tongue blade intraorally for complete soft tissue evaluation.


      • Gingival lacerations are typically present at fracture sites.


      • Ecchymosis on the floor of the mouth is indicative of mandible fracture.


      • Chin deviation suggests condylar fracture.


    • Concomitant injury evaluation:



      • 2.6% of patients with facial fractures will have cervical spine injury.3


IMAGING



  • Panorex plain films may be used to diagnose mandible fractures.


  • CT imaging is superior to plain films for diagnosing and evaluating mandibular fractures.


  • Noncontrast maxillofacial CT, with three-dimensional (3D) reconstruction if available, is useful for determining fracture patterns, identifying concomitant injuries, and planning repair.2,3


NONOPERATIVE MANAGEMENT



  • The majority of mandible fractures will require operative intervention.


  • Nondisplaced, stable fractures with normal occlusion can be treated with soft diet and close follow-up.


  • Greenstick-type fractures or minimally displaced fractures in children with normal occlusion can also be treated nonsurgically.3,4


  • In the case of edentulous mandibles, minimally displaced fractures can be treated nonoperatively.3


SURGICAL MANAGEMENT



  • The main goal of operative intervention for mandible fractures is to restore preinjury occlusion and restore mandibular form and function.2


  • Timing of surgery has no correlation to complication rates.2,5


  • Antibiotics:



    • All patients with mandible fractures should receive prophylactic antibiotics from the time of injury until the fracture is treated.



      • This practice has been shown to reduce postoperative infection from 50% to 6%.2


      • Penicillin-based antibiotic is preferred or clindamycin for patients with penicillin allergy.


    • Postoperative antibiotics have been shown to have no effect on infection rates.2


  • Fracture patterns to consider:



    • Symphysis and parasymphysis: fracture is located in the anterior mandibular portion between the canine teeth.


    • Body: fracture is located between canine and distal last molar.


    • Angle or ramus: fracture is located posterior to the second molar and triangle between the horizontal and ascending ramus and often involving the third molar.


    • Condylar and subcondylar fracture: fracture is located superior to the ramus and is classified according to levels.


  • Indications for open reduction and internal fixation (ORIF):



    • Severely displaced fractures


    • Bilateral fractures


    • Open fractures


    • Comminuted fractures



    • Multiple fracture sites


    • Panfacial fractures


    • Infected fractures


    • Uncooperative patients


    • Patients with relative contraindication to MMF secondary to medical conditions (seizures, malnutrition, etc.)


  • Indications for external fixation6:



    • Bridge until ORIF


    • Large segmental defect


    • Severe comminution


    • Infection present


  • Indications for removal of the teeth:



    • Grossly mobile teeth with periapical pathology or advanced periodontal disease


    • Teeth preventing fracture reduction


    • Fractured tooth root


    • Exposed root apices


Preoperative Planning

Nov 24, 2019 | Posted by in Craniofacial surgery | Comments Off on Open Treatment of Mandible Fractures

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