Mandibular angle fractures and noncompression plating techniques.

Fractures of the mandibular angle are a common occurrence in the emergency departments of any inner-city hospital. In the year 2002, more than 100 mandible fractures were repaired at San Francisco General Hospital, about one third of which involved the angle of the mandible. The angle of the mandible has some unique properties. Fractures in this area are less surgically accessible than parasymphyseal or body fractures via a transoral approach. The crosssection of the bone in this area is less than that in more anterior locations, creating less surface contact area to allow stabilization. In addition, fractures in the angle are often posterior to occluding molar teeth, and, therefore, slight differences in reduction can be tolerated with regard to dental occlusion. Nevertheless, the force generated by the muscles of mastication can reach 60 DN or more at the angle, and any fracture fixation technique must be strong enough to counteract this force. Prior to the development of internal fixation plating systems, a variety of different techniques could be used to stabilize fractures to allow healing. Intermaxillary fixation using Ernst ligatures or arch bars for 6 weeks was a traditional method of stabilization, allowing secondary bone healing to occur. If the fracture was displaced and unfavorable, open reduction using stainless steel wire or perhaps a K-wire could be employed. Yet the open techniques did not allow for immediate function and could not counteract the forces of mastication at the angle. In the 1950s and 1960s, internal fixation plating systems that used bone fragment compression were developed for a variety of different types of bone fractures. The advantage of these systems was the promise of more immediate function and the possibility of primary bone healing rather than secondary healing via callous formation. The problem in this era was that the metallurgy of the plating systems was not refined from the standpoint of biocompatibility, and infected hardware was a relatively common occurrence requiring urgent removal and external fixation, which was dire from the standpoint of the goal of obtaining early function. In the early 1980s, Branemark and colleagues discovered the biocompatibility of titanium with regard to bone healing. The remarkable properties of titanium allowed the use of plating systems even in contaminated wounds, ie, almost all mandibular angle fractures. Suddenly, the potential to create primary bone healing and early function without prolonged periods of intermaxillary fixation became a potential reality. In addition, studies examining the physiology of bone healing existed and identified that compression and close anatomic approximation across a fracture line could allow for primary healing of fractures without the need to remodel a callous formation that is required in secondary healing. The Arbeitsgemeinshaft fur Osteosynthesefragen (AO) and the Association for the Study of Internal Fixation (ASIF) published guidelines that were considered standards to allow internal fixation that was routinely adequate to counteract distraction forces at various fracture sites. For the angle, a basic principle of internal fixation dictated that a 6-hole bicortical dynamic compression plate on the inferior edge of the fracture or a 4-hole bicortical dynamic compression plate on the inferior edge with a 4-hole monocortical tension band on the superior edge was enough to counteract the forces of mastication at the angle of the mandible. In the late 1970s and early 1980s, a French surgeon challenged the basic concept of how plating systems needed to be designed to counteract the forces of mastication. After Andrew H. Murr, MD