lassification

General considerationsControversy has surrounded all aspects of fractures of the condylar process. There have been several proposed classification methods of these types of fractures.Following, the AO classification is presented along with a simplified version. The AO classification allows for better communication between radiologists and surgeons. On the other hand, the simplified version better reflects the clinical treatment implications.

AO ClassificationThe condylar process and head is a subunit of the mandible and is defined by an oblique line running backward from the sigmoid notch to the upper masseteric tuberosity. The condylar process is differed into three subregions: Head Neck Subcondylar (caudal) areaAd by JoniCoupon|Close This Ad

Frontal view.

Three lines are used to define these subregions:1. The first line parallels the posterior border of the mandible2. The sigmoid notch line runs perpendicular to the first line at the deepest portion of the sigmoid notch3. A line below the lateral pole of the condylar head that is also perpendicular to the first line.Clinical pearl: the neck region can be divided into high and low halves by equally dividing the distance between the sigmoid notch line and the lateral pole line.Ad by JoniCoupon|Close This Ad

Treatment implications simplified classificationIn contrast to the descriptive, previously defined anatomical classification, a more simplified one is outlined and used in the Surgery Reference.The surgeon decides to treat condylar process fractures in an open or closed method. To perform an open reduction and internal fixation, there must be room in the superior fragment for at least two screws fixing the same plate.Clinically, this equates to open treatment of condylar neck fractures or subcondylar (caudal) fractures (A). The surgeon may elect to place one or two plates depending on the location and configuration of the fracture.Fractures at a level where there is inadequate space for two holes to be drilled for the plate (B) require special techniques of osteosynthesis. For that reason, among others, most surgeons choose closed treatment for these joint fractures.General considerationsAd by JoniCoupon|Close This Ad

Fractures of the condylar process (unilateral or bilateral) can occur in isolation. They are more often combined with other mandibular fractures.Imaging

Routine diagnosis of this type of fracture should include radiographs taken in two planes at 90 to each other; the minimum requirement is a PA view and a panoramic view.CT or digital volume tomography (DVT) imaging may be used as an alternative.Panoramic view showing left condylar process fracture in association with an anterior body fracture.

Townes (oblique PA) view of the above patient. X-ray taken at 90 to show displacement of left condylar process fracture. Vertical shortening of the left mandible is noted along with the right anterior body fracture.

CT scans give the surgeon the best information with regard to fracture location, morphology, fragmentation, and associated injuries.CT scan 3-D reconstruction illustrates right condylar process fracture.

Coronal view of the above patient shows angulation and luxation of the condylar process fracture.Clinical findings

The dental occlusion can give orientation about the fracture location. With a unilateral condylar process fracture and subsequent reduction of height in the ramus region, the clinician will see an ipsilateral premature occlusion and contralateral open bite. The dental midline will shift toward the side of fracture.The occlusion shows premature contact on the right with the deviation of the jaw to the affected side that is commonly seen with a right mandibular condyle fracture.

Bilateral fractures with shortening and dislocation result in anterior open bite with minimal deviation of the midline.

Pitfall: widening of the lower faceBilateral condyle fractures associated with fractures of the symphysis and body region often produce a widening of the mandible and subsequent malocclusion. These fractures are very difficult to treat. Great care must be taken when performing the open reduction and internal fixation of the body fractures to assure the mandible is narrowed to its pre-injury status. Failure to recognize and/or correct the widening of the body fractures will prevent anatomic reduction of the condylar fractures and subsequent occlusal and functional complications.Bilateral condylar process fracture

CT and/or digital volume tomography (DVT) is extremely useful especially in cases of high and/or intracapsular fractures of the condyle.This coronal view demonstrates bilateral condylar process fracture with displacement. On the patients right side there is a condylar neck fracture with angulation and on the left side there is sagittal condylar head fracture medial to the lateral pole. On the right side, the height of the mandible is not reduced.The increased width of the mandible in ramus/condyle region may indicate that there is an associated fracture in the anterior mandibular arch.Subcondylar fracture

Detail of a panoramic x-ray showing a subcondylar fracture.Neck fracture

Example of (low) neck fracturePlain x-ray taken at 90 to demonstrate displacement of condylar process fracture.Townes

and panoramic views of a (low) neck fracture.

Example of a (high) neck fracture3-D reconstructions are useful in identifying fracture height, direction and severity of displacement.This 3-D reconstruction illustrates a (high) neck fracture with displacement. Note the associated anterior body fracture of the contralateral side.Nondisplaced, nondislocated fracture

Nondisplaced, nondislocated fractures suggest the presence of periosteal support for stability and may not require open treatment.X-ray in the PA plane shows no vertical shortening.

X-ray shows that no displacement occurred.BiomechanicsHunting bow conceptThe mandible is similar to a hunting bow in shape, strongest in the midline (symphysis) and weakest at both ends (condyles). The most common area of fracture in the mandible is therefore the condylar region.A blow to the anterior mandibular body is the most common reason for condylar fracture. The force is transmitted from the body of the mandible to the condyle. The condyle is trapped in the glenoid fossa. Commonly, a blow to the ipsilateral mandible causes a contralateral fracture in the condylar region. If the impact is in the midline of the mandible, fractures of the bilateral condylar region are very common.

Clinical findingsDirect trauma to the TMJ area is unusual but may be associated with fractures of the zygomatic complex.With a condylar fracture, there is very often shortening of the ramus on the affected side. This will result in an ipsilateral premature contact of the teeth. In case of bilateral fractures, the patient may present an anterior open bite. The condylar fragment may be displaced (most often laterally) based on the angulation of the fracture and predominant muscle pull.Plating considerations

At the time of surgery, the decision is made whether to place one or two plates. This decision is based on fracture morphology, the amount of bone available to hold plates and screws, and on surgeon preference.Ideally, two miniplates should be applied in a triangular fashion with one plate below the sigmoid notch and one plate along the posterior border.Ad by JoniCoupon|Close This Ad

As an alternative way of achieving the same stability, a single heavier plate can be used where there is limited bone available for plating. This plate is placed along the long axis of the condylar process.General considerationsWith plate and screw systems, micromovement of condylar fracture fragments is minimized. Correct application along with good fracture reduction will lead to primary bone healing and subsequent bone formation along the fracture surface.Depending on the fracture location in the condylar region, one or two plates are used. In high condylar fractures, due to bony limitations, only one plate can be placed. In most cases, a mandibular plate 2.0 with two screws on each side of the fracture line is sufficient.Adequate mechanical stability is gained by use of two adaptation plates or one stronger plate.Plate and screw fixation used in condylar fractures allows immediate postoperative function.AnesthesiaIn condylar fractures, muscle relaxation is crucial.Several extraoral surgical approaches to the condylar region can involve the facial nerve. During the soft-tissue dissection, a nerve stimulator may be used to identify the facial nerve. Chemical muscle relaxation will interfere with the use of a nerve stimulator. However, once the bony fracture has been reached, muscle relaxation may help the surgeon reduce and stabilize the fracture.Therefore, a sufficient dose of muscle relaxant is administered before the reduction maneuvers.Use of MMFWhen treating condylar fractures, the surgeon may use arch bars or another form of mandibulomaxillary fixation (MMF). However, reduction and manipulation of the fracture may be best accomplished with the jaw open. At some point during the plate and screw fixation, the patient should be placed into occlusion. This may be accomplished by an assistant holding the patient into occlusion while the fracture is being plated. This minimizes the risk of postoperative malocclusion.Additionally, many surgeons prefer the use of training elastics in the postoperative period.Alternative: endoscopically assisted ORIFThe endoscopic technique is an alternative treatment technique for condylar fractures.The two most important advantages of the endoscopic technique are the avoidance of face scars and minimizing the risk of facial nerve injury. The disadvantages are the necessity of endoscopic/special equipment and the specialized training and experience required for this surgical technique.Special considerationsFollowing special considerations may need to be taken into account: Multiple fractures Edentulous atrophic fractures ComplicationsClick on any subject for further detail.2.Choice of implant and plate position one plateChoice of implant for one plate fixationAd by JoniCoupon|Close This Ad

If only one plate can be used, the surgeon should opt for a thicker plate and bicortical screws if possible.The plate used can either be a mandible plate 2.0or preferably a small/medium locking plate 2.0. A DCP 2.0 can also be used (for its strength but not for its compression) as well as a large profile locking plate 2.0 because of their increased rigidity.In each side of the fracture line, a minimum of two screws have to be inserted. Plates with or without a center space can be used.Plate position and order of screw insertionAd by JoniCoupon|Close This Ad

The plate should be positioned in the center of the condylar region or close to the posterior border. The numbers indicate the order of screw insertion.3.Choice of implant two platesChoice of implants for two plate fixation

There are several options of plates that can be used with condylar fractures:1. Two mandible plates 2.0 (2-hole and 4-hole, or 4-hole and 4-hole)2. Combination of a mandible plate on the anterior border of the condyle and a compression plate 2.0 (4- or 5-hole DCP) without using the compression effect (screws in neutral position)3. Two locking plates 2.0 (small and small/medium profile).Thicker plates are usually best fixed with bicortical screws.Lastly, mandible and locking plates 2.0 are preferred over compression plates by many surgeons.In the following procedure, a combination of a 2-hole with a 4-hole mandible plate 2.0 is shown.4.ReductionReduction strategy

It is advantageous if the condylar fragment is already displaced laterally (lateral override). However, the most common displacement of the condylar fragment is medial, by pull of the lateral pterygoid muscle. If the fragment is displaced medially, the surgeon must manipulate it and convert it into a lateral override situation.Then the plate can be applied and fixed with one screw to the condylar fragment while it is supported by the underlying mandibular ramus. Using the plate as a handle, the condylar fragment can be reduced anatomically.Intraoperative image shows angulation and lateral displacement of the condylar fragment.One plateIf the use of only one plate is possible, the plate should be centered over the long axis of the condylar process.Two platesIf two plates are being used, the anterior plate is used to reduce and initially stabilize the condylar fragment. The second plate is placed parallel to the posterior border of the ramus.5.Reduction one plateDrill hole for the first screw in condylar fracture fragment

Drill a hole in the midaxis of the condylar fragment through the plate hole closest to the fracture line using the 1.5 mm diameter drill. The use of the drill guide is recommended to avoid injuries in the soft tissues.Plate placement

Place the plate and insert the screw manually without complete tightening. The aim of not tightening the screw completely is to be able to apply traction to the fragments later in the procedure.Manual traction

Reduction of the fracture is done under direct vision by aligning the posterior border of the ramus.Pull the mandible inferior and anterior in order to restore the posterior height of the ramus and achieve reduction.The lower end of the plate prevents the medial displacement of the condylar fragment during reduction.

Clinical image shows the reduced fracture. The plate acts as stop during the reduction and prevents medial displacement of the condylar fragment.In this clinical example a 5-hole locking plate without center space is used. The center hole is placed directly over the fracture line and left empty.Pearl: use of bite block

To keep the jaw open and aid fracture reduction, a bite block is placed in the molar region after placement of the first screw in the plate.This results in posterior vertical distraction and rotation of the mandible.Alignment of posterior border

In order to align the posterior border, pull traction on most distal hole of the plate with a clamp.6.Reduction two platesDrill hole for the first screw in condylar fragment

The first plate to be applied will simplify the fracture. In this case the anterior plate is applied first.Drill a hole in the proximal fragment with the 6 mm drill stop drill bit of 1.5 mm diameter. The use of the drill guide is recommended to avoid injuries in the soft tissues.Plate placement

Place the plate and insert the screw manually without complete tightening. The aim of not tightening the screw completely is to be able to apply traction to the fragments later in the procedure.Manual traction

Reduction of the fracture is done under direct vision by aligning the posterior border of the ramus.Pull the mandible inferior and anterior in order to restore the posterior height of the ramus and achieve reduction.The lower end of the plate prevents medial displacement of the condylar fragment during reduction.Pearl: use of bite block

To keep the jaw open and aid fracture reduction, a bite block is placed in the molar region after placement of the first screw in the anterior 2-hole plateThis results in posterior vertical distraction and rotation of the mandible.Alignment of posterior border

In order to align the posterior border, pull traction on the small plate with a clamp (illustrated) or an angled hook.7.Fixation one plateFixation of the plate

Place the inferior screw of the plate while the patient is in occlusion.Completely tighten both screws at this time.Insertion of additional screws

Fill the remaining screw holes in the order shown in the illustration with additional screws and fully tighten them.

Completed osteosynthesis.

3-D CT reconstruction shows a one plate fixation using a large profile locking plate 2.0.

Case example.

Another case example.8.Fixation two platesFixation of anterior plate

Place the inferior screw of the anterior plate while the patient is in occlusion.Completely tighten both screws at this time.Templating

Check the proper alignment of the posterior border. If it is properly aligned, adapt the plate. Sometimes, a template can be beneficial if the lateral pole of the condylar head is approached. However, use of a template is not always possible due to the size of the surgical approach and fracture morphology.Plate bending

In the condylar neck and subcondylar region, the plate does not require much bending. Bending is done using bending pliers.Posterior plate application

Drill the first screw hole in the condylar fragment close to the posterior border. It is recommended to drill the first hole without the plate applied.Apply the plate and insert the first screw but do not completely tighten it.

Place the plate parallel to the posterior border of the ramus.Apply the second screw which is placed in the plate hole next to the fracture line and fully tighten it. Then fully tighten the first screw.Additional screw insertion

Fill the remaining screw holes with additional screws and fully tighten them.Completed osteosynthesis

Clinical image shows the completed osteosynthesis.Option: plate without center spaceAs an option for the anterior plate, a 3-hole plate with empty center hole over the fracture is used.

X-ray of the completed osteosynthesis.AppendixNoteThe surgeons personal expertise is the most important factor influencing the decision-making process. Always choose the strongest possible osteosynthesis.