1 Principles top
Keys to success
The keys to a successful result are:
- Fracture simplification with adequate three-dimensional fragment reduction and fixation
- Proper alignment of the alveolar segments to restore preoperative occlusion
- Well-adapted reconstruction plate, bridging unstable segments
Comminuted fractures should have load-bearing fixation applied across the area of comminution. The bone fragments within the area of comminution will provide no buttressing to help stabilize the fracture. A reconstruction plate with at least three and preferably four screws on each side of the comminuted area is the optimal way load bearing fixation is provided.
Click here for a detailed discussion of load-bearing versus load-sharing fixation.
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.
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.
For load-bearing fixation, a locking reconstruction plate 2.4 should be used. The plate must be long enough so that there can be a minimum of three or preferably four 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.
3 Reduction topenlarge
Open reduction and stable internal fixation in the dentate patient begins with fixation of the occlusion. Prior to placing the patient into MMF, the fracture should be exposed and any extractions deemed necessary performed. The bones should also be reduced prior to placing the patient into occlusion and securing the MMF.
Click here for further details on methods for applying MMF.
Clinical view of a comminuted symphyseal fracture before reduction.
Once the fracture has been exposed, forceps can be used to manipulate the
mandibular fragments into proper reduction.
The comminuted fragments can be positioned using bone screws as a handle on them.
Pearl: simplifying the fracture
Temporary/initial fixation of mandibular fragments can be accomplished using small plates and screws applied in locations that do not interfere with the placement of the reconstruction plate.
The small plate(s) may be left in place or may be removed after the placement of the reconstruction plate.
Note that the patient is in MMF and small plates now replace the bone clamps that were initially used to obtain reduction of the fragments. Also note that debridement of some bone was necessary, leaving an area of osseous defect.
4 Fixation topenlarge
The plate must be contoured to the surface of the mandible flush with the inferior border to avoid injuring the mental and inferior alveolar nerves.
The use of a malleable template is strongly advocated for accurate plate contouring. The risk of mental nerve injury is reduced because the plate will have to be reintroduced multiple times during the bending procedure.
Click here to see a step-by-step description of bending locking reconstruction plates.
Threaded drill guides should always be used to center the screw within the
locking reconstruction plate.
For a step-by-step description click here.
Large fragments (like the triangular one in this photograph) can be secured to the plate to hold them in position.
Removing small plates
The small plates used to simplify the fracture may be removed after the reconstruction plate has been attached to the mandible. They can also be left in position if they will not interfere with future prosthetic appliances.
Management of bone defects
Bone defects may be managed primarily or secondarily, depending on individual circumstances. If there is good soft tissue available for water-tight closure, one may primarily bone graft osseous defects. Otherwise, secondary reconstruction is advisable.
In this instance, adequate soft-tissue was available so the bone defect was filled with allogenic bone putty.
One should then release the MMF and check the occlusion for accuracy before proceeding with closure.
X-ray shows the completed osteosynthesis 12 weeks postoperatively.