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MANDIBLE FRACTURE Short Notes for Rapid Review
Sarang Suresh Hotchandani
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INTRODUCTION Occurs more frequently than any other fracture of
facial skeleton Sometimes can be complication of tooth
extraction Fracture of the mandible may be broadly divided
into two main groups; o Fractures with no gross comminution of
the bone and without significant loss of hard or soft tissues. Most Common type
o Fractures with gross comminution of the bone and with extensive loss of both hard & soft tissues May result from;
Missile injuries in war
Major road accidents Management of these both types is different.
AETIOLOGY Road traffic accident (RTA)
INCIDENCE The most common facial fractures are in the
mandible, followed by the maxilla, the Zygoma & then in last nasal bones.
Fracture of mandibular CONDYLE IS THE COMMONEST SITE
Fracture of mandibular ANGLE IS THE FREQUENT SITE
CLASSIFICATION 01) Based on TYPE OF FRACTURE 02) Based on SITE OF FRACTURE 03) Based on CAUSE OF FRACTURE
TYPE OF FRACTURE Simple Fracture Closed linear fracture of mandible Greenstick is variant of simple fracture found in
children. Minimal fragmentation of bone Non-external communication
Compound Fracture Aka OPEN FRACTURES In this, communication of margin of fractured bone
occurs with external environment; o Fracture of tooth bearing portion of
mandible are always compound into the mouth via periodontal membrane
o Some compound fractures of mandible open through overlying skin.
Comminuted In this, fractured bone is compound and is in
multiple segments with other hard and soft tissue loss.
Usually caused by; o Penetrating sharp objects o Missiles
Pathological Fracture When fracture of jaws occurs with minimal trauma
because of already weakened by any pathological condition, they are said to be pathological fracture.
Example of Conditions; o Osteomyelitis o Neoplasms o Generalized skeletal disease o Severe alveolar resorption
SITE OF FRACTURE Treatment and signs & symptoms are different for different locations of fracture of mandible.
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FAVORABLE vs UNFAVORABLE FRACTURES It depends on ANGULATION OF FRACTURE LINE &
FORCE OF THE MUSCLE PULL proximal or distal to the fracture line.
In favorable fracture, fracture line and muscle pull resist displacement of the fracture.
In unfavorable fracture, muscle pull results in displacement of fractured segments.
BASED ON CAUSES OF FRACTURE Direction and type of force determines the pattern
of mandibular fracture.
DIRECT & INDIRECT VIOLENCE Due to shape of mandible, any direct violence to one area may produce indirect force/violence of lesser severity in another usually opposite part of mandible which can produce multiple fracture. So keeping this
concept in mind, direct & indirect violence is again divided into;
01) Unilateral fracture mandible 02) Bilateral fracture mandible 03) Multiple fracture mandible 04) Comminuted fracture mandible
Unilateral fracture mandible Single or multiple fracture on one side of mandible. Frequently caused by direct violence, but
sometimes; o can be caused by indirect violence in which
site at which direct violence has occurred remain intact.
Bilateral fracture mandible more frequently caused by combination of direct &
indirect violence. o Direct force on angle may also fracture
condylar neck of opposite side OR o Direct force on canine of one side may
fracture angle of mandible of other side.
Multiple fracture mandible More than two fractures of mandible Caused by combination of direct & indirect force.
o Force on chin may fracture both condyles along with chin.
Usually occur in; o Epileptics o Elderly patients o Soldiers
GUARDSMAN fracture; soldiers who faint on parade from which fracture combination derives its name.
Comminuted Fracture mandible Always result from direct violence
FRACTURE DUE TO EXCESSIVE MUSCULAR CONTRACTION Fracture of condylar neck or coronoid process due
to sudden contraction of temporalis muscle.
SURGICAL ANATOMY OF MANDIBLE Mandible is strongest and most rigid component of
facial skeleton. However, it is more commonly fractured due to;
o Its prominent & exposed situation
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Mid facial skeleton is match box like and provide cushion effect to underlying structure. WHILE
o Forces applied to mandible are transmitted directly to base of skull through TMJ
Fracture of mandible may constitute a threat to airway due to its association with head injury. Cause of airway obstruction in mandibular fracture are;
o Depressed consciousness due to head injury o Broken teeth and displaced dentures
obstructing airway. o Bleeding into floor of mouth and base of
tongue causes swelling which obstructs the oro pharynx.
Mandibular fracture sites The minimum force which cause fracture of
mandible as observed from Nahums Cadaver experiment was found to be;
o 425 pounds for mandible when applied from front.
Fracture of neck of the condyle is regarded as safety mechanism which protects the patient from damage to middle cranial fossa.
Nahum also observed that a frontal force of 800 900 pounds was required to produce fracture of the symphysis & both condylar necks.
Mandible is much more SENSITIVE TO LATERAL FORCES than frontal forces.
Alveolar resorption weakens the mandible & fracture of edentulous of body of mandible results from much smaller force.
The Teeth Produce line of weakness in mandible
o Teeth determines where fracture will occur.
o long canine tooth, partially erupted wisdom tooth & impacted 2nd premolars represent the line of weakness in mandible.
Source of infection in fracture
Muscle attachments and displacement of fractures The periosteum of the mandible is thick & inflexible
in structure. o However, it may become flexible due to
accumulation of blood from rupture cancellous bone.
Displacement of bone during mandible fracture does not occur if the periosteum is attached to underlying bone.
o It means for displacement of bone fragments during fracture, the periosteum must be stripped out.
FRACTURE AT ANGLE OF MANDIBLE AND DISPLACEMENT Fracture at angle of mandible are influenced by
both medial pterygoid & masseter muscles. o But, medial pterygoid is strong
component involved in displacement. Fracture in this region have been classified as;
(figure 2.6 &2.7 in Killey) o Vertically favorable o Vertically unfavorable o Horizontally favorable o Horizontally unfavorable
FRACTURE & DISPLACEMENT AT SYMPHYSIS & PARASYMPHYSIS In this area, following muscles play the role;
o Mylohyoid muscle o Genio hyoid muscle o Genio glossus muscle
In transverse midline fracture of mandible, Genio hyoid and mylohyoid muscles act as stabilizing force and prevent the displacement.
But, if the fracture occurs lateral to the midline in the incisor area, the fragment which contains genial tubercles will be displaced lingually by the pull of geniohyoid & mylohyoid muscles
When bilateral parasymphyseal fracture occurs the anterior fragment is displaced backward by the pull of genioglossus muscles (figure 2.10 in Killey)
o Threat to airway in this condition occur only when voluntary tongue control is lost during loss of consciousness of patient. For explanation read passage on page # 18 in Killey.
FRACTURE & DISPLACEMENT OF CONDYLAR PROCESS When condylar neck is fractured, condylar head is
displaced and dislocates from the articular fossa. o Displacement of condylar head occurs in
forward & medial direction due to pull from lateral pterygoid muscles.
FRACTURE & DISPLACEMENT OF CORONOID PROCESS It is rare caused by reflex muscular contraction of
temporalis muscles, which displaces the coronoid process upward into infra temporal fossa.
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COMMINUTED FRACTURES & DISPLACEMENTS The amount of displacement in comminuted
fractures is very little. o It is because of fragmentation at the site of
muscle attachments which pulls the small fragments leaving the bulk of bone un-displaced.
FRACTURE & DISPLACEMENT OF EDENTULOUS MANDIBLE Bucket handle displacement
o In this anterior part of mandible is displaced backwards due to pull of digastric and mylohyoid muscles, which can compromise airway.
BLOOD SUPPLY OF THE MANDIBLE The mandible receives an endosteal supply via the
inferior dental artery. The other blood supply which mandible receive is
from the periosteum Inferior dental artery slowly diminishes and
disappear with aging, so thats why blood supply from periosteum is important
o So, thats why open reduction with elevation of periosteum is not a best treatment approach in older patients.
Other vessels which can be damaged during fracture of mandible are;
o Dorsal lingual veins causing sub lingual hematoma
o Facial vessels which cross the lower border of mandible anterior to angle.
OTHER IMPORTANT RELATED ANATOMICAL STRUCTURES