Jaw: 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.
Presenting signs
- Pain.
- Oral bleeding and/or epistaxis.
- Serosanguineous oral and/or nasal discharge.
- Crepitus.
- Asymmetry, malocclusion.
- Difficulty opening or closing the mouth.
- Oral bruising and facial swelling.
- Subcutaneous emphysema.
- Lip/cheek laceration, avulsion.
Acute presentation
- Recumbent if in shock or if spinal/orthopedic injuries present.
- Dyspneic if partial airway obstruction or pulmonary contusions/pneumothorax present.
Breed/Species predisposition
- Small breed dogs are at greater risk of iatrogenic (caused examination or treatment) or pathologic jaw fracture (bone loss due to periodontal disease, metabolic conditions or neoplasia).
Cost considerations
- Diagnostic and treatment procedures requiring general anesthesia and surgical techniques are associated with increased cost.
Special risks
- Anesthesia-related risks.
- Trauma to teeth, bone and soft tissues during more invasive treatment.
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.
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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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
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.