Debridement and internal fixation

The treatment of the nonunion consists of the removal of the etiological factors.

Control of acute infection must take place prior to the definitive treatment.

Mandibular fixation in both dentate and edentulous patients is best achieved with the use of a load bearing locking mandibular reconstruction plate.

A wide variety of options are currently available:

• 2.4 uni-lock reconstruction plates
• Matrix mandible reconstruction module, with different plate thicknesses (2.0, 2.5, 2.8), and screw diameters
• Preformed mandibular reconstruction plates

For illustration purposes we will here show the use of a 2.4 reconstruction locking plate in a dentate patient.

More information on mandibular plates can be found here.

The locking plate system tolerates bending imperfections (ie. bone-plate gaps) and provides rigid load bearing fixation.

Information on load bearing vs load sharing can be found here.

In persisting bone gaps after secondary osetosynthesis, bone grafting should be considered.

The optimal approaches for treating non-union fractures are transcutaneous as they provide ample and direct visualization of the fracture site. Good visualization of the surgical site allows for better debridement.

In addition a transcutaneous approach minimizes the risk of oral contamination or dehiscence of any added bone graft.

For symphyseal and parasymphyseal fractures the trans oral approach usually offers sufficient access.

However, if this is not the case, a transcutaneous approach such as the submental approach may be selected.

For most body and angle fractures a transoral approach usually offers sufficient access.

However, if this is not the case, the submandibular approach may be selected.

For the ramus and the lower part of the condylar neck, the retromandibular approach or...

...the submandibular approach may be selected.

Nonunion may have occurred due to a wrong choice of or improper insertion of plates and screws. The osteosynthesis material is removed before debridement.

Fibrous tissues tend to form around the unstable fracture site as a consequence of persistent mobility.

If the fragments are well aligned, the application of stable internal fixation will allow undisturbed osseous healing. However, if the fibrous tissue will not allow for proper fragment realignment, debridement of fibrous tissue will be necessary.

Poorly vascularized and necrotic bone is debrided to ensure the presence of healthy bone (normally bleeding bone) in all fracture lines.

The debridement is performed using rongeurs, saws, or burs.

Any devital teeth adjacent to the defect should also be managed.

Infected tissues are debrided, culture of purulent drainage should be sent for gram stain culture and sensitivity. The wound is then copiously irrigated with saline solution.

MMF is established to ensure that the patients achieve their pre traumatic occlusion.

For step-by-step description of how to establish MMF, follow this link.

The fragments are aligned and a template is contoured to the mandible, staying just superior to the inferior border. The plate is then bent to match the template. The plate is placed on the mandible and final adjustments are made to produce a near perfect fit.

For step-by-step description of how to bend the plate, follow this link.

A locking reconstruction-type plate with 3-4 bicortical screws on each side of the gap are inserted. Screws should not be placed closer than 7-10 mm to the fracture area.

For step-by-step description of how to insert the screws, follow this link.

The transbuccal system or an angulated screw driver may be useful.

If inadequate bone contact persists after alignment and fixation, the gap is grafted.

Small quantities of cancellous bone can be obtained through the use of bone scraping instruments or trephines.

It is then chopped or ground into tiny pieces and compressed into the bone gap and applied around the fracture site.

When indicated, a corticocancellous block shaped to fit the defect can be used. Gaps between the graft and the native mandible should be filled with cancellous bone to facilitate bony union.

After completion of the grafting, but prior to any closure, MMF is released and the occlusion is verified.

Prior to wound closure, Penrose or suction drains may be used to prevent dead space and the formation of hematoma.

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 site. During each visit, the surgeon must evaluate the patient's ability to perform adequate oral hygiene and wound care, and provide additional instructions if necessary.

The treatment of infected nonunions normally involves longer than the typical hospital stay, allowing daily examinations and intravenous antibiotics until the signs and symptoms of infection resolve.

Adequate dental care is required in most patients having undergone mandibular surgery.

If a malocclusion persists, 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 malreduction or hardware failure or displacement, elastic training will be of no benefit. The patient must return to the operating room for revision surgery. A slight malocclusion can be corrected by by orthodontics or dental adjustments with the help of a dentist.

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® or similar device 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. The assistance of a dental hygienist may be helpful.

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, as well as assistance from a physiotherapist if required.