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Murr has provided an excellent discussion of the fundamental concepts of treating fractures of the angle of the mandible as well as discussing arguments in favor of and against several commonly used techniques. His comments are well-founded.
Kris S. Moe, MD
The decision algorithm used in the treatment of craniofacial fractures is quite complex. The first consideration is whether any treatment is required. If so, one must decide whether the reduction should be performed in an open or closed approach. A decision on what type of repair to undertake must be made, considering external vs internal fixation and fracture immobilization vs rigid fixation. If rigid fixation is chosen, one must choose between lag screws and compression and noncompression plating.
Alisha West, MS
Fractures of the angle of the mandible are located posterior to the second molar in the triangle of bone between the horizontal and ascending rami. As Murr points out, fractures of the angle are technically challenging. Because the bone is thin, there is little contact between the fracture fragments in the axial plane; transoral access to this area of the mandible can be difficult; and the fracture may be located behind the third molar so that placement of an arch bar will not hold the fragments in apposition. Given this complexity, it is not surprising that there are many areas of controversy in the subject of mandibular angle fracture repair.
The Swiss Arbeitsgemeinschaft fur Osteosynthesefragen (“Association for the Study of Internal Fixation,” or AO) was founded in 1958 to examine some of these controversies. Among the main principles emphasized early on by this group were the concepts of accurate anatomic reduction and adequate fracture stabilization. Ongoing research, including that by Bagby and James,1 demonstrated that compression applied uniformly to a fracture site accelerated healing. Spiessl2 later noted that this effect is due to an increased rate of angiogenic ossification (“primary” or “direct” bone healing), which is more rapid than when healing occurs through formation of a callus and remodeling (“secondary” or “indirect” healing). To provide the desired compression at the fracture site, the AO developed a system of dynamic compression plates (DCP) that create linear compression of the fracture beneath the plate. However, the physiologic forces acting on the mandible result in compression at the inferior border and distraction at the superior border (alveolus). To counteract this uneven loading along the fracture site, the AO developed eccentric DCPs (EDCPs) that redistribute the load with equal and opposite uniform compression along the entire length of the fracture to allow primary bone healing. For repair of mandibular angle fractures, the DCP or EDCP is placed at the inferior border of the mandible, taking care to avoid the inferior alveolar nerve. A 4- or 6-hole plate is used, with at least 2 bicortical screws on each side of the fracture. A miniplate is then placed at the superior border with monocortical screws to prevent distraction in this area.
While the AO compression technique may theoretically offer the best chance of rapid, primary bone healing,3 numerous caveats must be observed to ensure a favorable outcome. If the fragments of a fracture are not properly reduced, application of a compression plate can actually cause increased fracture displacement. Patients with a comminuted fracture can also sustain worse fragment alignment when compression is used. Furthermore, a compression plate must be precisely bent to coapt with the underlying bone along its entire length, which can be difficult to achieve at the mandibular angle. A locking screw compression plate is scheduled to be on the market soon; while this may decrease somewhat the need for exact plate adaptation to the bone, it will not eliminate the problems intrinsic to suboptimally reduced or comminuted fractures. Compression plating is thus indicated for use by experienced surgeons for selected fractures in which proper reduction and alignment can be assured.
Another compression technique that is used for the repair of mandibular angle fractures is the use of lag screws. This method causes direct compression across the fracture site. The same disadvantages apply to this as discussed in the use of compression plates. In addition, this may be more difficult to perform through a transoral approach, and lag screws can only be used in the areas of thicker bone.
For cases that are not suitable for repair by the methods mentioned herein, there are 2 other options: rigid noncompression plating and “semi-rigid” plating (the Champy technique).4 For comminuted fractures, rigid fixation is indicated. A larger noncompression fracture plate is placed along the inferior border of the mandible using bicortical screws, and a tension band is placed along the superior border using monocortical screws. Locking screw fracture plates that provide adequate fixation, even with a moderate gap between the plate and the bone, may be used.
For ideal fractures (ie, nondisplaced, noncomminuted) in patients who will adhere to a soft diet and follow-up as directed postoperatively, the placement of a miniplate along the oblique line (Champy’s technique) is a satisfactory approach, with or without a tension band fixed with monocortical screws at the occlusal border. This technique does not fully immobilize the fracture, however, and as a result, healing is likely to occur through indirect union with the formation of callus. This does not compromise the outcome in most cases.
When considering the appropriate surgical approach to use, there are again several options. For a displaced, comminuted fracture, an open approach will provide the best exposure, allowing the greatest ease in realigning the fragments and bending and attaching the plate. The downside to this approach is that it creates a significant scar in a highly noticeable area, and few patients prefer to have a scar added to the suffering that they have gone through with the injury and repair. Furthermore, the open approach puts the marginal mandibular branch of the facial nerve at unnecessary risk. We thus use the transoral approach for the repair of these fractures, unless there are other associated fractures that necessitate an open approach. In those cases where Champy’s technique can be used, the transoral approach also provides excellent exposure.
Patient characteristics influence decision making a great deal in the management of craniofacial trauma. One has to consider whether the patient is likely to appear for postoperative follow-up and whether it is necessary to make the patient “bomb proof” using a technique that is battle-ready at the time of patient discharge. This is a serious consideration for jailed and homeless patients. Whether a patient is going to follow postoperative dietary instructions is also important.
In conclusion, compression plating is likely to provide the most rapid direct bone healing possible, but its use is limited to fractures that are well reduced without fragmentation. The Champy technique is easy to use through a transoral approach and uses the least amount of plating material. However, it, too, has limitations similar to those of compression plating and requires a responsible patient who is able to protect the mandible during the healing phase and adhere to dietary restrictions. The surgeon must therefore tailor the method of repair to each patient individually based on the factors described herein and should maintain an armamentarium of options for use in these complex cases. Though there is a growing trend in the literature toward using the smallest possible amount of fixation material possible, the most reliable method of fracture repair for the typical surgeon will be the use of standard noncompression rigid fixation.
Correspondence: Dr Moe, Department of Surgery, University of California San Diego School of Medicine, 350 Dickinson St, Suite 211, San Diego, CA 92103 (email@example.com).
Moe KS, West A. Compression Plating of Mandibular Angle Fractures. Arch Otolaryngol Head Neck Surg. 2005;131(2):170–171. doi:10.1001/archotol.131.2.170
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