Executive Editor: Marcelo Figari, Gregorio Sánchez Aniceto General Editor: Daniel Buchbinder

Authors: Ricardo Cienfuegos, Carl-Peter Cornelius, Edward Ellis III, George Kushner

Mandible - Special considerations

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Glossary

1 General considerations top

The mandible is the only facial bone that is movable. The results of mandibular fracture treatments are easily measurable. Unfortunately, there is a relatively high complication rate when dealing with mandible fractures.

2 Nonunion top

Nonunion enlarge

General considerations

A nonunion occurs when the mandible does not heal in an appropriate time frame. The result is mobility of the fracture segments present after an adequate healing phase. Patients may also demonstrate malocclusion and infection at the site of fracture.

Note: no bony union is visible in fracture gap.


Nonunion enlarge

Clinical photograph reveals lack of bone at the fracture site.


Etiology

Nonunions are usually the result of one or more of the following factors:

  • Fracture instability (mobility)
  • Infection
  • Inaccurate reduction
  • No contact between fragments

Treatment

Treatment will consist of:

  • Identifying the cause
  • Controlling infection
  • Surgical reconstruction: removing the existing hardware, debridement of devital bone and/or soft tissues, decortication of bone fragments at the fracture ends, reestablishing occlusion, stabilizing segments using a locking reconstruction plate 2.4, and autogenous bone graft to this area.

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Case example

Panoramic x-ray 6 weeks after treatment of left angle fracture with single miniplate. The fracture is grossly mobile, infected, and the plate has become loose.


Nonunion enlarge

The fracture was debrided, the plate removed, the infection drained, and the patient placed on antibiotics to control infection.


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Once infection has subsided, the patient was taken to surgery and the fracture exposed through a submandibular approach. The fibrous tissue between the fragments was debrided and the fragments decorticated.


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Postoperative panoramic and ...


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... PA x-rays showing relationship of bone fragments and internal fixation hardware.


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The occlusion was reestablished with MMF and a miniplate placed along the superior border to maintain the position of the proximal segment after pushing it posteriorly and superiorly to see the condyle. A reconstruction plate was then adapted and secured to provide load-bearing fixation across the fracture gap. Once the occlusion was verified by releasing MMF, the miniplate was removed.


Nonunion enlarge

Particulate autogenous bone was placed into the fracture gap and the incision closed in layers.


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Photograph taken 10 months later showing reestablishment of normal occlusal relationship.


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Panoramic x-ray taken 10 months postoperatively showing bone filling fracture gap.

3 Malunion/malocclusion top

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Etiology

Malunions occur for at least one of several reasons:

  • Inadequate occlusal reduction during surgery
  • Inadequate osseous reduction during surgery
  • No osseous reduction (eg, condyle fractures)
  • Imprecise application of internal fixation devices
  • Inadequate stability (lack of rigidity)

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Treatment

The treatment of a malunion must involve:

  • Identification of the cause
  • Orthodontic/orthopedic treatment if possible
  • Osteotomies as necessary (re-fracture, standard osteotomies, combinations)

Malunion/malocclusion enlarge

Case example

Frontal photograph of a patient who sustained right angle and left symphysis fractures but was never treated. Note a deviation of his chin to the left.


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Intraoral photograph showing significant malocclusion resulting from malunion of fractures.


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Panoramic x-ray showing malunion of right angle and left parasymphyseal fractures.


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Photograph of dental models mounted on an articulator.


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Photographs ...


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... of obtainable occlusion.


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Interocclusal splint fabricated to be used during surgery to help position occlusal segments.


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Intraoperative photograph showing malunion of right angle fracture.


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Intraoperative photograph showing malunion of left parasymphyseal fracture.


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Intraoperative photograph taken after right angle osteotomy and fixation with two miniplates.


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Intraoperative photograph taken after left parasymphyseal osteotomy and fixation with a reconstruction plate.


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Postoperative panoramic x-ray shows osteotomies and fixation devices.


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Postoperative photograph showing that the facial asymmetry has been eliminated.


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Postoperative occlusion showing elimination of the malocclusion.

4 Infection top

Infection enlarge

Diagnosis

Infected fractures will usually demonstrate one or more of the following signs/symptoms:

  • Swelling
  • Erythema
  • Rrismus
  • Pain
  • Purulent discharge

Etiology

Infection occurring in fractures usually results from one or more of the following:

  • Microorganisms
  • Fracture instability
  • Devital tissues (teeth, bone, etc)

Treatment

The treatment of infected fractures involves:

  • Incision and drainage of abscesses,
  • Irrigations of the wounds as necessary
  • Systemic antibiotics
  • Removal of devital teeth/bone
  • Removal of any loose internal fixation devices
  • Re-stabilization of fracture

Infection enlarge

Case example

ORIF of posterior body and condyle fractures of the right mandible.

Note the consolidation at the body fracture and signs of bone resorption at the condylar fracture site.


Infection enlarge

Obvious infection of surgical site with wound dehiscence and purulent drainage.


Infection enlarge

The patient was taken to surgery and the internal fixation devices were removed along with loose bony fragments. The right mandibular condyle was found to be avascular and was therefore removed.


Infection enlarge

Panoramic x-ray showing removal of right mandibular condyle and mandibular body plates to treat infection of this surgical site. Good consolidation of the right mandibular body is evident.

The infection subsequently subsided and the soft tissues healed.

Patient will require secondary reconstruction of right mandibular condyle.

5 Ankylosis top

Ankylosis enlarge

Ankylosis is a process where the mandibular condyle fuses to the glenoid fossa. This generally occurs after prolonged immobilization (MMF) of a condylar fracture.

Patient demonstrating their maximum interincisal opening after treatment of multiple mandibular fractures and prolonged period of MMF.


Ankylosis enlarge

Panoramic x-ray showing bilateral condyle fractures and a symphyseal fracture.

Note: lack of joint space in bilateral TMJ region.


Ankylosis enlarge

CT scan showing bilateral TMJ ankylosis with bony fusion of mandibular condyle to the glenoid fossa on the left side.

The only option to remedy ankylosis in this case is additional surgery in the form of a gap arthroplasty or total alloplastic joint replacement.

6 Fixation failure top

Fixation failure enlarge

General consideration

Fixation failure results in fracture mobility that can subsequently lead to infection, nonunion and/or malunion.

Fixation fails by a number of mechanisms which include:

  • Insufficient amount of fixation
  • Fracture of the plate
  • Loosening of the screws
  • Devitalization of bone around screws

Fixation failure enlarge

Insufficient amount of fixation

Left mandibular angle fracture was treated using a malleable miniplate 2.0 at the inferior border of the mandible. This is insufficient fixation for this fracture.


Fixation failure enlarge

Illustration demonstrating biomechanics of an angle fracture. A small plate applied at the inferior border provides insufficient stability in such a fracture. It cannot prevent a gap from opening at the superior surface of the mandible under function.


Fixation failure enlarge

The patient developed infection of left angle fracture site 2 weeks later. They were taken back to the operation room and stable fixation was applied. Subsequently, the fracture healed.


Fixation failure enlarge

Fracture of the plate

X-ray shows a superior border miniplate.

It is obvious, that this clinical situation (edentulous mandible at fracture site, impacted third molar) is biomechanically demanding and not suitable for one miniplate osteosynthesis.


Fixation failure enlarge

X-ray shows plate fractured. Segments were mobile which required treatment consisting of ORIF with locking reconstruction plate 2.4.


Fixation failure enlarge

Loosening of screws

Four weeks after two miniplate fixation of a right angle fracture, the patient presents with a draining sinus tract through the skin.


Fixation failure enlarge

X-ray shows at least one loose screw and loss of fixation.

The patient was taken back to surgery where a reconstruction plate was applied.


Fixation failure enlarge

Devitalization of bone around screws

6 weeks after treatment of right angle fracture and left body fracture with two compression plates, the patient presents with swelling. Panoramic x-ray shows loose hardware in the right side.


Fixation failure enlarge

The fracture was opened and the hardware was found to be still attached to portions of the buccal cortex which had become devitalized and sequestered.


Fixation failure enlarge

Fortunately, the lingual cortex had healed and the occlusion was normal. Thus, no further treatment was necessary.

v1.0 2008-12-01