ORIF, two plates (basal triangle)

The basal triangle decreases the bone buttressing and the interfragmentary support. This condition demands a degree of stability beyond pure load sharing.

Basal triangle fractures through the mandibular angle therefore should be considered as comminuted fractures requiring load-bearing fixation across the basal triangle via an extraoral approach. This can be provided one of two ways:

Using a reconstruction plate or ...

... using two plates , but the one along the inferior border must be a heavy mandible plate.

Sequence of plate insertion
The superior plate is inserted first in order to achieve preliminary fixation. This will prevent inadvertent displacement of the fragments during subsequent contouring and the insertion of the inferior border plate.

Locking versus nonlocking plates
There are several advantages to a locking plate/screw system:

1. 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.
2. 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.
3. 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.

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
• Complications

Click on any subject for further detail.

The below aditional reading may be useful:

• Biomechanics of the mandible
• Plate types
• Locking plate principles
• Trimming and bending of large-profile plates
• Transbuccal system
• Angulated screw driver
• Emergency screws/system

The intraoral approach to the angle can be selected by those surgeons experienced in the technique of plating the inferior border of the mandible using transbuccal trocar instrumentation.

However, an extraoral approach ( the submandibular approach) is often chosen because this access provides a superior view. Existing lacerations may also be used.

Open reduction and stable internal fixation in dentate patients 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 superior border of the fracture through the angle should also be reduced prior to placing them into MMF.

Click here for further details on methods for applying MMF.

It is not necessary to have the basal triangle reduced at this stage.

A miniplate 2.0 is applied along the superior border of the fracture to maintain the alignment and reduction of the major fragments while the inferior border plate is adapted and applied.

The miniplate can be placed either on the lateral surface of the mandible or along the inside of the external oblique ridge similar to the treatment of a simple mandibular angle fracture.

Hold the plate with an appropriate instrument (eg, periosteal elevator or forceps).

Use a 1.5 mm drill bit to drill through the plate hole next to the fracture line in the anterior fragment.

Insert a 2.0 mm screw of appropriate length. Do not fully tighten it until the final reduction and plate position are confirmed.

Insert a second screw in the hole next to the fracture line in the posterior fragment. The periosteal elevator is used now to keep the far end of the plate at the correct vertical level.
Tighten both screws.

Fill the remaining plate holes with screws.

The basal triangle itself must be repositioned by pushing and dragging it with an appropriate instrument. Bone screws inserted into the basal triangle function well as a handle on the fragment and are useful for reduction. Using a transoral approach, a small bone hook can be used to help position this fragment.

To keep the basal triangle in place it can be compressed between the greater fragments. An alternative is the preliminary fixation with a miniplate that will not interfere with the planned position of the inferior border plate.

Only large profile plates meet the biomechanical requirements of basal triangle fractures.

One of the following plates should be considered for fixation at the inferior border. The chosen plate should allow for fixation of the basal triangle to the plate if large enough. This prevents the use of plates with a center space.

• 6- to 8-hole medium profile locking plate 2.0
• 6- to 8-hole large profile locking plate 2.0 (straight or prebent)
• 6- to 8-hole extra large profile locking plate 2.0

The stability of universal fracture plates 2.4 is equal to the large profile plate from the locking plate 2.0 family.

Screw application is commonly bicortical.

Insert the properly contoured plate onto the lateral surface of the mandible and hold it there using forceps.

The sequence of screw insertion is not important if the plate is securely clamped to the bone. Drill guides should be used to center the screw within the plate hole.
For a step-by-step description follow this link.

Large fragments (like the triangular one in this illustration) can be secured to the plate to hold them in position. A locking head screw is a better choice for this purpose.

Release the MMF and check the occlusion for accuracy and the bony surfaces for precise anatomic reduction.

The incision is then closed in layers.

If arch bars or MMF screws are used intraoperatively, they are usually removed at the conclusion of surgery if proper fracture reduction and fixation have been achieved. Arch bars may be maintained postoperatively if functional therapy is required or if required as part of the fixation.

Postoperative x-rays are taken within the first days after surgery. In an uneventful course, follow-up x-rays are taken after 4–6 weeks.

The patient is examined approximately 1 week postoperatively and periodically thereafter to assess the stability of the occlusion and to check for infection of the surgical wound. During each visit, the surgeon must evaluate the patients ability to perform adequate oral hygiene and wound care, and provide additional instructions if necessary.

Adequate dental care is required in most patients having suffered a mandibular fracture.

If a malocclusion is detected, the surgeon must ascertain its etiology (with appropriate imaging technique). If the malocclusion is secondary to surgical edema or muscle splinting, training elastics may be beneficial. The lightest elastics as possible are used for guidance, because active motion of the mandible is desirable. Patients should be shown how to place and remove the elastics using a hand mirror.

If the malocclusion is secondary to a bony problem due to inadequate reduction or hardware failure or displacement, elastic training will be of no benefit. The patient must return to the operating room for revision surgery.

Follow-up appointments are at the discretion of the surgeon, and depend on the stability of the occlusion on the first visit. If a malocclusion is noted and treatable with training elastics, weekly appointments are recommended.

Postoperatively, patients will have to follow three basic instructions:

1. Diet
Depending upon the stability of the internal fixation, the diet can vary between liquid and semi-liquid to “as tolerated”, at the discretion of the surgeon. Any elastics are removed during eating.

2. Oral hygiene
Patients having only extraoral approaches are not compromised in their routine oral hygiene measures and should continue with their daily schedule.
Patients with intraoral wounds must be instructed in appropriate oral hygiene procedures. The presence of the arch-bars and any elastics makes this a more difficult procedure than normal. A soft toothbrush (dipping in warm water makes it softer) should be used to clean the surfaces of the teeth and arch-bars. Any elastics are removed for oral hygiene procedures. Chlorhexidine oral rinses should be prescribed and used at least three times each day to help sanitize the mouth. For larger debris, a 1:1 mixture of hydrogen peroxide/chlorhexidine can be used. The bubbling action of the hydrogen peroxide helps remove debris. A Waterpik® is a very useful tool to help remove debris from the wires. If a Waterpik is used, care should be taken not to direct the jet stream directly over intraoral incisions as this may lead to wound dehiscence.

3. Physiotherapy
Physiotherapy can be prescribed at the first visit and opening and excursive exercises begun as soon as possible. Goals should be set, and, typically, 40 mm of maximum interincisal jaw opening should be attained by 4 weeks postoperatively. If the patient cannot fully open his mouth, additional passive physical therapy may be required such as Therabite or tongue-blade training.