Intraoral wiring is not sufficient to achieve stable fixation in bilateral rostral fractures, because there is no stable element which acts as a splint. When only dorsal cerclage is used, the fragment is displaced dorsally. Therefore, additional ventral wiring is required.
The fragment gap is thoroughly cleaned and all debris removed followed by reduction of the fragments to their anatomically correct position.
4. Intraoral wire fixation
In the horse 1.2 mm (18 gauge) orthopedic stainless steel wire is most commonly used for cerclage. For rostral fractures that result in loosening of the incisors, an interdental continuous wire-loop splint described by Obwegeser (1952) can be used. It allows the application of uniform tension between all the teeth that are engaged in the splint. The wires need to be anchored around the cheek teeth. One end of the wire is guided around the cheek teeth and then back and forth between all incisors to form small loops in front of the incisor teeth starting on one side of the arcade. The other end of the wire is then threaded through the loops, followed by tightening of the wire ends. Care is taken to avoid placement of any loops through the fractured alveoli. The wire should always be tight and care must be taken that it is not weakened by repeated bending and kinks during insertion.
Anchoring the wire
Cheek teeth provide very good stability for tension wires, usually placed between the 06 and 07 teeth (the second and third premolar). To achieve this, the skin is clipped, surgically prepared and a short arthroscopy sleeve with a trocar or obturator is advanced into the mouth via a stab incision. This technique minimizes hemorrhage, which can be a problem when the tissue is cut with a scalpel. A drill bit is then introduced through a protective drill guide and a hole is prepared between the two cheek teeth on both sides of the mandible.
Pearl: For insertion of the wire, a sharp end can be created by cutting the wire at an angle. This facilitates penetration of the gingiva. Alternatively a 2 mm (14 gauge) hypodermic needle can be used to penetrate the tissue between two adjacent teeth and to allow passage of the wire, or small holes (2.0 or 2.5mm diameter) may be prepared using a Steinman pin or a small drill bit. This is usually required for passing a wire between the incisors and almost always for placing the wire between cheek teeth.
Tightening the loops
Subsequently each wire loop previously created in front of the incisor teeth is tightened in a uniform fashion using pliers or needle drivers. This must be completed in an even fashion, alternating between multiple loops, and under careful monitoring of the fracture site to avoid displacement after reduction.
After the wires are tightened, the twisted ends are shortened and bent flat so that they do not irritate or injure the gingiva. If they are sharp, they should be protected.
5. Ventral wire fixation
One stab incision is made ventral on the horizontal ramus of the mandible on each side. The soft tissues are removed from the axial and abaxial side of the bone. A 2.0 mm hole is drilled across both rami and used as an anchor for the wire.
One end of the wire is guided through the hole and then both ends of the wire are advanced subcutaneously to the incisor teeth. The wire is guided around the incisors in figure-of-8 fashion and both ends are tightened together. The same procedure is repeated using the hole on the other side.
6. Final tightening
The dorsal wiring and the ventral wiring are tightened together to get good compression and no ventral or dorsal dislocation.
At the end of the surgery, the teeth of the upper jaw are shortened to reduce pressure during eating.
During the post-surgical period, the horse is confined to stall rest for one week and fed with soft fiber feed stuff; firm feed such as hay cubes, apples or carrots should not be fed. Antibiotics and anti-inflammatory drugs are administered for 3 to 5 days or longer, if required. Intraoral cerclage and tension wires are cleaned once daily until their removal. After 6-8 weeks the wire can be removed under sedation and local anesthesia.