1 Special considerations topenlarge
Following special considerations may need to be taken into account:
- Multiple fractures
- Edentulous atrophic fractures
- Teeth in the line of fractures
- Involvement of alveolar area
- Infected fracture with or without bone loss
Click on any subject for further detail.
For simple fractures of the mandibular angle, an intraoral approach can be selected by those surgeons experienced in the technique of placing a large plate at the inferior border of the mandible using transbuccal trocar instrumentation. However, an extraoral approach is often chosen because this access provides a superior view.
2 Choice of implant top
Locking versus nonlocking plates
There are several advantages to a locking plate/screw system:
- Conventional plate/screw systems require precise adaptation of the plate to the underlying bone. Without this intimate contact, tightening of the screws will draw the bone segments toward the plate, resulting in alterations in the position of the osseous segments and the occlusal relationship. Locking plate/screw systems offer certain advantages over other plates in this regard; the most significant being that it becomes unnecessary for the plate to intimately contact the underlying bone in all areas. As the screws are tightened, they "lock" to the plate, thus stabilizing the segments without the need to compress the bone to the plate. This makes it impossible for the screw insertion to alter the reduction.
- Another potential advantage in locking plate/screw systems is that they do not disrupt the underlying cortical bone perfusion as much as conventional plates, which compress the undersurface of the plate to the cortical bone.
- A third advantage to the use of locking plate/screw systems is that the screws are unlikely to loosen from the plate. This means that even if a screw is inserted into a fracture gap, loosening of the screw will not occur. Similarly, if a bone graft is screwed to the plate, a locking head screw will not loosen during the phase of graft incorporation and healing. The possible advantage to this property of a locking plate/screw system is a decreased incidence of inflammatory complications due to loosening of the hardware.
- Locking plate/screw systems have been shown to provide more stable fixation than conventional nonlocking plate/screw systems.
Click here for a description of locking plate principles versus conventional plating.
One of the following plates should be chosen for fixation at the inferior border:
- 6- to 8- hole large profile locking plate 2.0
- 6- to 8- hole extra-large profile locking plate 2.0
- 6- to 8- hole locking reconstruction plate 2.4.
With the use of conventional screws, locking plates can be converted into conventional nonlocking plating systems using friction between the plate and the bony surface.
Screw application is bicortical.
3 Reduction topenlarge
Rigid fixation of a mandibular fracture in the dentate patients begins with fixation of the occlusion. The surgeon has the choice of using arch bars, MMF screws, or local wiring techniques.
Considerations of which MMF technique to be used will depend on fracture morphology, associated injuries, and personal preference.
Click here for further details on methods for applying MMF.
Using an extraoral approach, forceps can be used to manipulate the mandibular fragments into proper reduction.
4 Fixation topenlarge
For a true load bearing fixation, a reconstruction plate 2.4 should be used. The plate must be long enough so that there can be a minimum of three screws on each side of the fracture. The screws adjacent to the fracture should be at least 7 mm away from the fracture line. Most commonly there will be one or two holes without screws located over the fracture. There are advantages to using a locking reconstruction plate system. Click here for a description of the locking plate principle.
The plate must be contoured to the lateral surface of the mandible, flush
with the inferior border to avoid injuring the inferior alveolar nerve. In the
anterior body region the branches of the mental nerve must be spared during
plate introduction and adaption.
Click here to see a step-by-step description of plate bending using locking reconstruction plate.
Securing the plate to the bone with bone clamps
Insert the properly contoured plate onto the lateral surface of the mandible and hold it there using ball pointed reduction forceps. Ideally, one set of forceps is applied anterior and one set posterior to the fracture.
The sequence of screw insertion is not important if the plate is securely
clamped to the bone. Drill guides should always be used to center the screw
within the plate hole.
For step-by-step description follow this link.
Illustration shows the completed osteosynthesis.
Clinical image of the completed osteosynthesis.
Completed osteosynthesis using a large locking plate 2.0
X-ray shows the completed osteosynthesis with a large locking plate 2.0 in
the anterior body region as well as in the contralateral angle.
In this case, the large plate was used because of a mandibular prognathism.
Screws were inserted bicortically as shown in this "worm’s eye view".
One should then release the MMF and check the occlusion for accuracy before proceeding with closure.