ORIF, one miniplate

The ideal line of osteosynthesis in the body region runs at the vertical height of the tooth apices from the canine region to the oblique line. This carries into the oblique ridge which turns into the anterior outer rim of the ramus.

This line is located directly underneath the mucogingival sulcus that can be exposed with ease. The bone thickness of the lateral cortex varies between 6 and 8 mm approximately. To avoid injury of the tooth roots, monocortical screws less than 6 mm long should be used for plate fixation along this section of the ideal osteosynthesis line.

This single plate fixation method is contraindicated in the anterior mandibular body because of the existing rotational forces in that area that have to be neutralized. Two miniplates should be applied to neutralize those forces.

In the posterior transition to the angle and ramus, a second plate just below the oblique ridge may be advantageous in case of reduced bone stock (eg, an impacted wisdom tooth) or significant fracture displacement.

Biomechanics of the mandible

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.

These fractures can often be approached and treated through the intraoral approach.

However, depending on the difficulty or severity of the fracture, and/or the presence of a laceration suitable, an extraoral approach via the submandibular route may be indicated.

In the isolated mandible body fracture, preferably, an arch bar is applied for MMF. The arch bar provides additional stability by tension banding. This equates to a second line of resistance in particular with biting load anterior to the fracture line. The arch bar should include at least all teeth in the affected quadrant of the jaw. It is not necessary to encompass the whole dental arch.

MMF bone screws provide temporary fixation only during surgery and do not contribute postoperatively to stabilization.

Reduction is done manually. Since the indication for single miniplate fixation is limited only to minimally displaced fractures, there will be no major discrepancies to be overcome.

The maintenance of the reduction with a conventional clamp becomes more difficult the further posterior the fracture is located. The clamps can be applied into tiny predrilled holes in the outer cortex that do not interfere with later plate placement.

In the midbody and posterior body, the reduction can alternatively be held by the intermaxillary ligatures, or manually by the assistant using an instrument, eg, a periosteal elevator.

A variety of implants can be used. In the original Champy version a 4-hole miniplate without center space was used.

Today, the same type of plate is still applicable. The following alternatives provide similar or incrementally higher stability:

• 4- or 6-hole mandible plate 2.0 with or without center space
• 4- or 6-hole small profile locking plates 2.0
• 4- or 6-hole medium profile locking plates 2.0

The plate of greater strength is used for additional stability and safety.

Further information on:

• plate types
• locking plate principles
• Compression plating
• Emergency screws/systems

Contour the plate according to the surface anatomy adjacent to the fracture line on both sides using bending pliers. Longer adaptation plates should be bent starting at one end and successively proceeding towards the other end. Intermediate steps can be checked on the bony surface for correct seating.

Finally check the plate for precise fitting in-situ.

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

Use a 1.5 mm drill bit with 6 mm stop to drill monocortically through the plate hole next to the fracture line in the anterior fragment.

The surgeon must be aware that a cortical plate may be very thin in this region and damage to the tooth roots is still possible even when using a 6 mm drill bit with stop.

Insert a 2.0 mm screw, 6 mm in length. Do not fully tighten it until the final reduction and plate position are confirmed.

Screw insertion into locking plates

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.

The clamp can be removed afterwards.

Fill the remaining plate holes with screws in an orderly fashion continuing from the plate holes next to the fracture to the outer plate holes.

A splaying of the inferior border of the mandible can be ruled out by further soft-tissue exposure intraoperatively. In minimally displaced fractures this should not be necessary.

Prior to wound closure confirm adequate reduction along the exposed fracture line. The fracture alignment at the lower border can be palpated giving indication of major gapping.

Furthermore, a control of the fracture line in transverse plane is possible only indirectly by checking the occlusion and articulation. Prior to this, the MMF ligatures must be removed.

Midbody fracture line at the level between the second premolar and the first molar. Ernst ligatures were applied for temporary immobilization of the lower jaw until surgical treatment.

If arch bars are used, the incision is made more laterally in the vestibule.

However, in this case, since there is an open wound between the second premolar and the first molar, an alternative surgical approach is used. A mucogingival incision in the vestibular sulcus is chosen anteriorly to the wound. In the posterior vestibulum the gingiva of the molars is included in the mucoperiosteal flap after marginal incision.

The longitudinal exposure reaches from the lateral symphysis into the angle region. Two MMF screws are inserted into the maxillary alveolar ridge as anchor points for the wire ligatures. In this case no arch bars are used as they would interfere with surgical access and closure.

The MMF screws in the lower jaw are applied after exposure of the bony surface.

Note the additional fixation of the fracture using an interdental wire loop.

MMF is applied using MMF screws with wire loops bilaterally.

A 6-hole medium profile locking plate 2.0 was selected in this case to provide additional stability. The plate exactly contoured to the bone surface is shown in place.

Drill for the first screw hole next to the fracture line in the anterior fragment using a drill bit with drill stop.

Insert the first screw.

After drilling, insert the second screw next to the fracture line posteriorly.

The posterior end of the plate is accessible through lip retraction and does not necessitate an external incision.

Pearl: proper retraction of lips
Retractor tips parallel to instrumentation (not at angles) facilitate exposure with reduced retraction forces on the lips.

Clinical photograph shows all screws inserted.

After checking for correct occlusion, the MMF screws are removed and the wound is closed.

X-rays show the ...

... completed osteosynthesis.

A nondisplaced vertically running midbody fracture in a fully dentate and compliant patient can be treated straightforwardly using arch bars and a single plate applied on the ideal line of osteosynthesis according to Champy.

In this case, a 6-hole small profile locking plate 2.0 was used for stabilization.

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.