62.10 Fractures of the angle or body of the mandible

The angle of the mandible is one of its weak points, and is the next most common site for fractures after the condyles. The fragments may or may not be displaced, depending on the severity of the injury and the direction of the fracture line (E, or F, in Fig. 62-15). If the fragments are displaced, the anterior one is pulled downwards by the muscles attached to it, while the posterior one is pulled upwards by the patient’s masseter (F). Sometimes there is a tooth on the posterior fragment.

If the fragments are not displaced, as in A, Fig. 62-15, you can bandage the patient’s jaws together, and need not wire them, although it is good practice to do so.

Figure 62.15: A FRACTURE OF THE ANGLE OF THE MANDIBLE. A, shows the fracture after interdental wiring and before interosseous wiring. B, shows it before wiring. This is the patient whose mandible is being wired in Fig. 62-19. John Maina’s patient.

If the fragments are displaced, you will have to reduce and fix them. If they have enough teeth in them, you can use the patient’s upper jaw as a splint and wire the teeth of both his jaws together (interdental eyelet wiring or intermaxillary fixation, IMF), or you can use an arch bar. Fortunately, most patients are young and have enough teeth to let you do this. Interdental eyelet wiring (occasionally with an arch bar) is thus all that is necessary in most cases. If you don’t have an arch bar, you can use Risdon wiring, as in Fig. 62-19, which is as good if not better. Or you can make an improvised arch bar with paper clips or fencing wire. If you don’t have the right kind of stainless steel wire, you can use ordinary brass wire, but it is not so strong.

If a patient does not have suitable teeth for interdental wiring, you can drill holes in the fragments and wire them together (interosseous wiring). Or, you can combine interdental and interosseous wiring. For example, if the anterior fragment has enough teeth to wire it to the maxilla, but the posterior fragment has not, you may be able to wire it to the anterior one. Interosseous wiring is never enough by itsef and is only an adjunct to interdental wiring.

Interosseous wiring is the most practical way of fixing those fractures in which there is no other way of controlling the posterior fragment. The inferior alveolar nerve runs through the centre of the mandible, so always wire the mandible through its edges. You may need to wire it anywhere along its length. Wiring is easiest on the front of a patient’s chin. There are two approaches: (1) You can wire the lower border of his mandible from outside his mouth. (2) It is possible to wire the upper border from inside it, but this is more difficult, so avoid it if you can. The patient is likely to be elderly and will probably tolerate his malocclusion.

If a patient wears a denture, you may be able to use this as a splint, You can wire a lower denture to his mandible by circumferential wiring, or you can suspend an upper denture from his zygomatic arches by an adaptation of method B, in Fig. 62-8.

Fractures of the ramus are open, and are easily infected by bacteria from the mouth. Osteomyelitis, sometimes with extensive fistulae, is thus an important complication, and may follow interosseous wiring. Fortunately, prophylactic antibiotics will usually prevent it.

If for any reason you cannot fix these fractures, remodelling will occur in those which involve the angle with upward and forward displacement of the posterior fragment, and in most comminuted fractures. It will not occur in fractures near the genial tubercles.

Anaesthesia is critical. If neither you nor your assistant is an anaesthetic expert, the patient is probably safest under local anaesthesia. The alternative is to give him a general anaesthetic, pass a nasotracheal tube, and pack his throat. The dangerous moment comes when you remove the pack before you finally close his jaws. While you are doing this, blood and saliva can collect in his pharynx. You cannot suck this out through wired jaws. So, when you do finally pull the tube out, he may inhale the collected blod and saliva, perhaps fatally, or he may have a severe inhalation pneumonia. Another moment of danger occurs as he recovers from the anaesthetic, when he may try to cough or vomit through closed jaws, so that you have to open them urgently. Local anaesthesia also reduces this risk. You can use ketamine, but it is not ideal.