If you don't remember your password, you can reset it by entering your email address and clicking the Reset Password button. You will then receive an email that contains a secure link for resetting your password
If the address matches a valid account an email will be sent to __email__ with instructions for resetting your password
Address reprint requests and correspondence: Andrew H. Murr, MD, FACS, Department of Otolaryngology–Head & Neck Surgery, University of California, San Francisco, Box 0342, 400 Parnassus Ave, UC Clinics 730, University of California, San Francisco, San Francisco, CA 94143-0342
Fractures of the angle of the mandible are prone to complications including malocclusion and non-union. Although a standard rigid fixation technique allowing immediate load bearing using large plates and tension bands has a long track record, the non-rigid mono-cortical plate technique using load sharing engineering principles popularized by Champy has gained the confidence of many surgeons. This article describes the Champy technique in detail in contrast to the technique of load bearing fixation.
There are several unique properties of the mandibular angle that pertain to fracture management. The cross-section of bone at the angle is less than that in more anterior locations, providing less surface contact area to allow stabilization between fragments. The angle is less surgically accessible than parasymphyseal or body fractures via a transoral approach. Fractures are generally posterior to the molar dentition, which prevents optimal stabilization by maxillomandibular fixation. Also, the presence of a third molar has been linked to an increased risk of angle fractures,
The angle fracture can be further complicated by distraction and rotation by opposing forces of the elevator muscles (masseter, medial and lateral pterygoids, temporalis) and the depressor muscles (geniohyoid, genioglossus, mylohyoid, digastric). The angle is subject to forces up to 60 DN during mastication, which any successful fixation method must be able to withstand.
The standard options for treatment of angle fractures include maxillomandibular fixation (MMF) for 4 to 6 weeks versus open reduction and internal fixation with or without MMF. The application of MMF creates several well-known and significant problems for both patient and surgeon. The patient's inability to open the mouth leads to nutritional deficits, suboptimal wound healing, and weight loss. The MMF hardware often creates painful abrasions and ulcers in the oral mucosa. Also, prolonged immobilization of the temporomandibular joint leads to ankylosis and bone resorption. MMF can even lead to life-threatening complications, as when patients with nausea and/or substance abuse aspirate gastric contents during episodes of emesis.
Because of such problems, the use of rigid fixation is appealing as it allows early recovery of mandible function with limited or no need for postoperative maxillomandibular fixation. In the 1960s, the Schenk studies illustrated how bone healing could be accelerated with compression of the fragments.
For decades, the AO/ASIF (Arbeitgemeinshaft fur Osteosynthesefragen/Association for the Study of Internal Fixation) has stressed the need of rigid fixation with fragment compression to promote primary bone healing and has provided guidelines for its application at the mandibular angle.
The AO recommends placement of internal fixation plates in such a fashion that avoids injury to the underlying mandibular canal and tooth roots. This can be accomplished with a 6-hole compression plate or reconstruction plate with bicortical screws inserted along the inferior border of the mandible. Alternatively, a 2-plate technique can be employed with a bicortical compression plate or reconstruction plate along the inferior border and a four-hole monocortical tension band just inferior to the tooth roots (see Figure 1). The tension band may be substituted with a set of arch bars to counteract tension along the alveolar ridge.
In practice, however, the AO technique is challenging to perform correctly at the mandibular angle. Surgical accessibility through a transoral route may be challenging and many surgeons prefer an external transbuccal approach, which carries the risk of damaging the marginal branch of the facial nerve and the possibility of infection and prominent scarring. Furthermore, when bending the compression plate, failure to precisely coapt the plate to the outer cortex of the mandible will create a gap on the lingual surface of the fracture. Also, a fracture that is oriented in a sagittal direction cannot be effectively compressed and may actually be distracted by applying a compression plate. In fact, compression at the angle is not currently recommended at the angle because of this factor. Finally, the thinness of the bone at the inferior border of the angle leads to less available surface area for fragment approximation and somewhat less toleration of fracture compression.
In the late 1970s and early 1980s, Champy and colleagues developed an internal fixation technique using only 1 or 2 monocortical plates inserted along the superior ridge of the mandibular angle.
This method was born from the realization, through a series of elegant experiments, that there existed “ideal lines of osteosynthesis” across the mandibular angle where the compressive and tensile forces from mastication could be countered with only monocortical fixation. The plates can be applied via a transoral approach. Maxillomandibular fixation may be applied for a short period after fixation or forgone completely.
The Champy technique offers advantages over the AO standard method of internal fixation and is a viable option for appropriate patients. A recent survey of the practices of 110 AO faculty members revealed that 51% usually use the Champy technique for a simple fracture of the angle, and it is used more commonly by more experienced surgeons.
By precise application of these low-profile monocortical plates, the surgeon uses only the minimal amount of hardware necessary to fixate the fracture against predictable force patterns. The thin plates can be easily coapted to the surface of the bone. Monocortical screws pose very little risk to the mandibular canal and inferior alveolar nerve. By using a transoral approach, the surgeon can avoid a large external skin incision and minimize risk to the facial nerve. The transoral approach is also technically easier than an external approach, can be swiftly performed, and requires minimal tissue dissection with less tissue devitalization.
Although the Champy technique forgoes fragment compression and primary bone healing, its success rate for treating angle fractures has been proven through many clinical studies with complication rates as low as 3.8%.
The successful clinical experience is seemingly at odds with the results of numerous in vitro studies on the biomechanics of angle fracture fixation, all of which conclude that monocortical miniplates offer insufficient resistance to the displacing forces of mastication.
This may be partly explained by the fact that patients' bite forces are subnormal for many weeks after sustaining a fracture, so that a less rigid form of fixation is adequate for fragment stability during the healing phase.
The Champy technique does have its limitations in practice and is not well-suited for all angle fractures. Because the use of monocortical plates does not allow primary bone healing, it is critical to follow patients in the outpatient setting to ensure that secondary bone healing occurs. This may be challenging or impossible in the setting of homelessness, substance abuse, and other socioeconomic barriers. Reduction of a displaced or unfavorable fracture can be challenging via a transoral approach. These fractures are better visualized and reduced via an external approach and using reduction forceps. Similarly, a comminuted fracture should be adequately exposed and fixated with a reconstruction plate via a transcervical approach.
There are current topics of discussion regarding the details of the Champy technique, especially whether it is preferable to use one or two miniplates along the superior mandible border. In 1996, Ellis and Walker
noted that the use of a single 2-mm monocortical plate was associated with a low complication rate (16%), most frequently local infection that was treated with outpatient incision and drainage and later removal of the miniplate under local anesthesia. In contrast, these authors reported a much higher complication rate of 29% when paired miniplates were employed.
Ellis speculates that using one miniplate avoids unnecessary dissection and preserves blood supply to the fracture site. However, other studies would indicate that two miniplates lead to better stability and lower complication rates. Fox and Kellman found a low 18% complication rate in 68 patients treated with paired 2-mm miniplates.
found a very low complication rate of 3% in fractures treated with paired miniplates compared with a 26% complication rate in fractures fixed with a single miniplate.
The patient is brought to the operating room and intubated with a nasal RAE tube. The patient's occlusion is first placed into MMF. This can be achieved using either arch bars and intermaxillary wires or four-hole fixation with screws placed into the mandible and the maxilla at the nasal maxillary buttress (see Figure 2).
Care must be taken to avoid drilling into the tooth roots. Premorbid occlusion is thus restored and attention can be turned to exposing the angle fracture. The gingivo-buccal sulcus over the angle and along the ipsilateral alveolar ridge is infiltrated with 1% lidocaine with 1:100,000 epinephrine for hemostasis. The planned incision is marked at intervals with pinpoint marks using needle-point electrocautery. At least 5 mm of gingiva should be left attached to the alveolar ridge to allow adequate tissue for closure at the end of the case. The electrocautery is then used to incise the mucosa and dissect down the periosteum of the mandible. The dissection proceeds with a Freer or Cottle elevator to expose the fracture and the surrounding periosteum. The use of Sewall or Obwegeser toe-in retractors can greatly aid in adequate exposure. In Champy's model of mandible biomechanics, the ideal lines of fixation are located along the alveolar portion of the angle of the mandible posterior to the third molar (see Figure 3).
With the fracture adequately exposed and reduced, a 4-hole 2-mm monocortical miniplate is positioned spanning the fracture line over the superior ridge of the mandible angle. Miniplates are now available that are prebent in a 90° orientation to aid in optimal coaptation to the mandible angle (Figure 4). Otherwise, bending of the miniplate should be performed to allow two screw holes on either side of the fracture.
The drill hole must be performed absolutely perpendicular to the periosteum and should only proceed through the outer cortex. A drill guide can be screwed into the hole of the plate to ensure correct drilling orientation (Figure 5).
A 6-mm screw is used to secure the plate. The remaining 3 holes are drilled with the plate in situ. A transbuccal trochar may be necessary to drill the holes into the distal fracture segment in a true perpendicular fashion and secure the bone screws (Figure 6).
This is performed by making a 5-mm incision through the skin overlying the mandible angle with a scalpel. Then, focused blunt dissection proceeds through the soft tissues with a clamp until the tips protrude through the buccal mucosa. The clamp is removed and the trochar can be inserted into the wound, so that the tip is lined up with the plate holes of interest. The drill guide is then threaded through the trochar and screwed into the miniplate screw hole, allowing drilling to take place in the correct perpendicular trajectory. The drill guide is then removed and the screwdriver, with 6 mm screw attached, is threaded through the trochar to secure the screw into the newly drilled hole (Figure 7). A second 4-hole miniplate can then be secured, if desired, along the superior lateral border of the angle (Figure 8).
The surgical wound is irrigated with Bacitracin irrigation. The wound is closed with 0-chromic in a running locking fashion. No surgical drain is necessary. The IMF wires are removed with the arch bars left in place to allow placement of guiding elastic bands if deemed necessary in the postoperative period. Postoperative plain films of the mandible will demonstrate placement of the hardware and reduction of the fracture line (Figure 9).
Early recovery of mandibular function is a clear benefit in the treatment of mandible fractures. Both the AO/ASIF and the Champy technique are acceptable options for internal fixation of an angle fracture and offer different profiles of advantages and disadvantages. For fractures that are distracted or comminuted, and for patients in whom weekly follow-up is not likely, the AO/ASIF compression technique is preferred for its superior exposure, fragment reduction, and rigid stability. However, for simple angle fractures, the Champy technique is an elegant and effective method of internal fixation that reduces surgical time and dissection, minimizes risk to the facial and inferior alveolar nerves, and allows early return of function with acceptable complication rates.
One- or two-plate fixation of mandibular angle fractures?.