Authors of section

Authors

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

Executive Editors

Marcelo Figari, Gregorio Sánchez Aniceto

General Editor

Daniel Buchbinder

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ORIF, two miniplates

1. Principles

Biomechanics

All biomechanical models developed to date have shown that two points of fixation (ie, two plates) provide much more stability than a single one. Therefore, when more stability is deemed necessary the addition of a second plate provides more stable fixation.

Biomechanics of the mandible.

Two points of fixation provide much more stability

Special considerations

2. Approach

For this procedure the intraoral approach to the angle is normally used.

revision orif

3. Choice of implant

The factor to determine whether a 4- or 6-hole miniplate should be used is the condition of the labial plate of bone. If the bone where the third molar is/was very thin and/or the third molar is positioned laterally within the alveolus, a 6-hole plate may be needed to span the area of the third molar where screws may not be possible to safely and securely placed. In such instances, it is not necessary to use six screws, and a hole can be left empty in the area where the third molar is positioned. It is only necessary to place two secure screws on each side of the fracture.

Some surgeons prefer to use a thicker plate for the lower position (below the mandibular nerve) such as a medium or large profile 2.0 locking plate with bicortical screw for additional stability in specific clinical situations. Plate adaptation is more difficult when using large profile plates.

Superior border plate

The surgeon must choose whether to use a 4- or 6-hole miniplate along the oblique ridge in the angle region. Very often a 4-hole titanium miniplate can be adapted quite nicely to this area. However, if a third molar is present or recently extracted, the bone in this area may be absent. The surgeon may choose to use a longer 6-hole plate to span the defect. Obviously, there may be empty screw holes over the region where bone is missing.

The surgeon has several options when choosing a plate for this region. The minimum size would be a mandible miniplate 2.0. However, some surgeons prefer a more rigid plate such as the locking plate 2.0 which comes in incremental profiles. The small profile and medium profile plates are applicable to the oblique ridge.

The surgeon must choose whether to use a 4- or 6-hole miniplate along the oblique ridge in the angle region

Lower plate

The profile and type of the inferior border plate can range from a conventional miniplate to locking plates of incremental size.

The following varieties will yield sufficient stability:

  • 4- or 6-hole mandibular plate 2.0 with or without center space
  • 4- or 6-hole locking small profile plate 2.0
  • 4- or 6-hole locking medium profile plate 2.0
  • 4- or 6-hole locking large profile plate 2.0
Choice of implant

4. Reduction

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 determined necessary be 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.

Fixation of the occlusion

5. Plate adaption

Twist the plate approximately 90° to facilitate adaptation to the superior border of mandible in the angle region.

Twist the plate approximately 90°

Twist the plate approximately 90° to facilitate adaptation to the superior border of mandible in the angle region.

Twist the plate approximately 90°

6. Fixation of superior border plate

Application of first screw

Apply the screw just posterior to the fracture first. Use a 1.5 mm drill to make a mono cortical hole.

Apply the screw just posterior to the fracture first

Insert a 6 mm screw but tighten loosely, allowing the anterior portion of the plate to be rotated upwards or downwards as necessary to better adapt it to the bone.

Apply the screw just posterior to the fracture first

Placement of second screw

Drag the plate anteriorly with a point of a periosteal elevator and move it up or down until it is seating flush with the buccal cortex. Drill the hole just anterior to the fracture.

Drill the hole just anterior to the fracture.

Insert the second screw and tighten it as well as the first screw.

Insert the second screw and tighten it

Placement of third screw

Drill a hole through the most anterior plate hole. Insert and tighten the screw.

Insert and tighten the screw

Note that the posterior hole is not accessible for screw placement. Therefore, the last screw will be placed after the lower border miniplate has been applied by opening the mouth and instrumentation underneath the maxillary dentition.

Note that the inferior borders are not well aligned. The addition of a second plate is thought necessary.

The last screw will be placed after the lower border miniplate has been applied

7. Fixation of lower border plate

Fixation of lower border plate - Drilling first screw hole

Using transbuccal trocar instrumentation the first hole is drilled 4-5 mm posterior to the fracture line and 3-4 mm above the inferior border.

Click here for a detailed description of the use of the transbuccal system.

The first hole is drilled 4-5 mm posterior to the fracture line

The hole can be drilled monocortically or bicortically if it is certain that the inferior alveolar canal is located above this area.

The first hole is drilled 4-5 mm posterior to the fracture line

Pearl: plate placement
Once the first hole has been drilled, overbend a 4-hole malleable miniplate and insert it into the surgical site. To facilitate locating the hole in the bone, use a stylette inside the trocar to drag the second-to-last hole in the plate into position and to locate the first drill hole. The trocar is then pushed to hold the plate to the bone and the stylette is withdrawn.

Overbend a 4-hole malleable miniplate and insert it into the surgical site

The screw is then immediately inserted and tightened while ensuring that the anterior portion of the plate is positioned properly above the inferior border.

The screw is then immediately inserted and tightened

Placement of second screw

Drill the hole through the plate hole located just in front of the fracture. The plate should be pulled anteriorly during this maneuver to help close the fracture gap. The drill should be placed anteriorly within the hole of the plate to produce slight compression of the fracture when tightening the screw.

Drill the hole through the plate hole located just in front of the fracture

Once the hole has been drilled, the screw is placed and tightened fully.

Note that the inferior borders are now aligned.

Once the hole has been drilled, the screw is placed and tightened fully

Additional screw placement

The holes on the terminal ends of the plate are then drilled and the screws are inserted.

Drill the hole through the plate hole located just in front of the fracture

8. Completion of osteosynthesis

Fine tuning of superior border plate

If the most superior/posterior part of the upper plate is not well adapted to the underlying bone, one may very readily do so by …

Fine tuning of superior border plate

… placing one beak of a wire twister lateral to the ramus and the other against the plate. By squeezing the wire twister, the plate is pressed to the bone-in this case because of the malleability of the grade II titanium miniplate used.

Once the hole has been drilled, the screw is placed and tightened fully

Placement of final screw

If it is not possible to drill and place the most posterior screw because of inadequate access, ...

Once the hole has been drilled, the screw is placed and tightened fully

... the mandible can be opened at this point and instrumentation can proceed from underneath the maxillary dentition.

Once the hole has been drilled, the screw is placed and tightened fully

Final check

One should then release the MMF and check the occlusion for accuracy before proceeding with closure.

Check the occlusion for accuracy before proceeding with closure

Completed osteosynthesis

X-ray shows the completed osteosynthesis.

Completed osteosynthesis

X-ray shows the completed osteosynthesis.

Completed osteosynthesis

9. Aftercare following ORIF of mandibular symphysis, body, angle and ramus fractures

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.