Positioning a patient with a mandibular fracture for optimal access to the oral cavity, ensuring proper reduction/dental occlusion, and placing implants easily can be challenging. Uncomplicated scenarios, such as unilateral, linear (non-comminuted), mid-body mandibular fractures can be repaired via a lateral approach. Most other fracture patterns are more readily addressed by positioning the animal in either dorsal or ventral recumbency. Both positions have advantages and disadvantages.
Dorsal recumbency offers excellent access to the ventral and lateral aspects of the mandibular bodies for bone plating or placement of external skeletal fixator pins but limits oral cavity access for repair of lacerations often associated with mandibular fractures.
Ventral/sternal recumbency offers excellent access to the oral cavity and rostral mandible for placement of external fixation pins or intraoral splinting but becomes challenging for bone plating of mid-body or more caudal fractures of the mandible.
Repairing a mandibular fracture with the dog in dorsal recumbency is fairly straightforward. The dog is placed on its back and a vacuum positioner bag or V-trough is used to maintain position. The thoracic limbs can be extended caudally and, if desired, clipped, prepped and draped for harvesting of cancellous bone graft. This dorsal position allows the mandible to naturally close, facilitating interdigitation of the maxillary and mandibular arcades for proper fracture reduction (Figure 1).
Figure 1 - Dorsal recumbency, reduction and alignment facilitated via occlusion
To repair a mandibular fracture with the dog in ventral recumbency, the oral cavity and mandible are prepped and draped with the patient positioned on its sternum (on a padded surface – e.g. positioner bag) with the thoracic limbs abducted. The maxilla is suspended between two IV poles. One inch adhesive tape or gauze is attached to the poles and passed underneath the maxilla immediately caudal to the canine teeth or punctured through by the maxillary canine teeth for added security. Thicker materials (e.g., rope) may interfere with attempts to check dental occlusion, even if passed through the space immediately caudal to the canine teeth. The pole height is adjusted to align the maxilla parallel to the table or slightly elevated while preventing tilting to either side. The mandible is allowed to hang freely (Figure 2).
If external skeletal fixation is the intended fixation method, the entire mandible is clipped, surgically prepped and draped to isolate the surgical field. This is optional when applying an intraoral splint to stabilize the fracture. To determine proper reduction of the fracture, the external fixator is applied with the clamps loose while closing the mandible against the maxilla to define reduction. Clamps are then tightened after obtaining proper reduction. The same principle is frequently utilized when applying acrylic-and-pin fixators.
Figure 2 - Ventral/sternal recumbency and pharyngostomy intubation
Endotracheal Tube Placement/Removal
Complete closure of the mouth and interdigitation of the upper and lower arcades facilitates accurate reduction and alignment especially with a highly comminuted fracture. Optimally, the endotracheal tube can be placed through a pharyngostomy approach to simplify this process.
After placement of the endotracheal tube, the pharyngostomy exit site is draped out of the operative field and the surgical repair begun. When the procedure is completed, the endotracheal tube is removed and replaced in a standard per os fashion until anesthetic recovery occurs and the patient is extubated.
Tip submitted by Mark Rochat, DVM, Diplomate ACVS - Oklahoma State University