ISSN 2398-2950      

Jaw: fracture

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Synonym(s): Mandible fracture


Introduction

  • Cause: motor-vehicle trauma, fall/jumping from a height, animal bite, hit by an object, iatrogenic, pathologic.
  • Signs: pain, oral bleeding, serosanguineous oral and/or nasal discharge, crepitus, malocclusion, difficulty opening or closing the mouth, soft tissue bruising, swelling, laceration, or avulsion.
  • Diagnosis: history of trauma; clinical signs; diagnostic imaging showing fracture of bones of the lower jaw, upper jaw, face, palate, bones of the temporomandibular joint (TMJ) or associated structures (ie zygomatic arch, coronoid process, etc).
  • Treatment: conservative treatment (monitoring if occlusion is good with minimal displacement); non-invasive or minimally invasive fixation (maxillomandibular fixation with muzzling, labial reverse sutures or interarch splinting; interdental wiring with intraoral splinting); invasive fixation (intraosseous wiring; external skeletal fixation; bone plating; partial mandibulectomy/maxillectomy, commissuroplasty).
  • Prognosis: greatly depending on the location and extent of jaw fracture, quality and amount of bone in the injured site, and whether teeth are in or near the bone fracture lines.
  • Definitions:
    • Mandibular fracture: fracture of the lower jaw (mandible); canine and premolar/molar region often affected in dogs; mandibular symphysis (separation and parasymphyseal fracture) or ramus more affected in cats.
    • Maxillary fracture: fracture of the upper jaw (maxilla and other facial bones); often multiple; life-threatening airway obstruction possible due to displaced bones, swelling, or blood.

Pathogenesis

Etiology

  • Motor-vehicle trauma, fall/jump from a height, animal bite, hit by an object; sometimes, minor trauma (eg hitting chin during walking down the stairs) may cause pathologic mandibular fracture when jaw bone has a pre-existing condition that resulted in severe bone loss.

Predisposing factors

General

  • Pre-existing bone loss.
  • Outdoor status (cats).

Pathophysiology

  • Favorable mandibular body fracture: fracture line running in a rostroventral direction, resulting in a more stable compression of the fracture segments upon contraction of the masticatory muscles that close the mouth.
  • Unfavorable mandibular body fracture: fracture runing in a caudoventral direction, resulting in a more unstable separation of the fracture segments upon contraction of the masticatory muscles that close the mouth.
  • Unilateral mandibular fracture: often resulting in deviation of the lower jaw toward the side of injury causing malocclusion.
  • Bilateral mandibular fractures: causing a ‘dropped-lower jaw’ appearance.
  • Traumatic cleft palate: acute midline defect of the hard palate usually seen in cats when falling from a height (high-rise syndrome).
  • Zygomatic arch fracture and separation of the temporal bone from the parietal bone: sometimes seen in cats.
  • Teeth in or near jaw fracture lines: if healthy, they can contribute to proper alignment of fracture segments and provide anchorage for fracture repair devices. If unhealthy (eg periodontally and/or endodontically compromised), they should be extracted.

Timecourse

  • Acute - signs develop immediately after injury.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

Other sources of information

  • Reiter A M, Soltero-Rivera M M (2018) Dentistry for the surgeon. In: Johnston SA, Tobias KM. Veterinary Surgery: Small Animal, 2nd edn. St. Louis, Elsevier, pp 1224-1240.
  • Reiter A M (2016) Oral surgical emergencies. In: Aronson LR (ed) Surgical Emergencies. Ames, Wiley-Blackwell, pp 511-519.
  • Reiter A M, Lewis J R (2011) Trauma-associated musculoskeletal injuries of the head. In: Drobatz K, Beal MW, Syring RS (eds) Manual of Trauma Management in the Dog and Cat. Ames, Wiley-Blackwell, pp 255-278.

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