Fractures of the interdental space and horizontal ramus are almost always open fractures. Wound debridement and flushing is extremely important. Nevertheless, infections of soft tissues as well as the bone are common. Therefore establishment of ventral drainage is important.
Aluminum splints can easily be bent into a U-shape and attached to the labial aspect of the incisors and the buccal aspect of the cheek teeth using wire sutures. However, attachment of the splint to the caudal cheek teeth is difficult, time consuming, and presents a major limitation of this technique.
In older or infected fractures, wound débridement is important. All infected bone must be removed with a curette or rongeur. Additional flushing is indicated.
The fracture is reduced manually.
Application of the U-shaped splint
The pre-bent U-shaped splint is most often made of a malleable brass or of an aluminum rod. The bar has holes at different locations to allow for insertion of the wires. It is placed on the labial surface of the incisors and spans the interdental space and most of the length of the dental arcade bilaterally.
Stab incisions are prepared through the cheek (as described of the interdental wiring technique) and a drill bit is then introduced through a protective drill guide. Holes are prepared between the cheek teeth at the gum line.
Holes are also prepared between the incisors, either with a cannula or with a drill bit.
To increase stability, first intraoral wire fixation is applied in addition to the U-bar. For more details please see "Wire fixation".
These wires have to be placed prior to application of the U-bar.
First the wires are introduced between the incisors and the cheek teeth and followed by insertion of the bar.
The bar is fixed to the incisors and cheek teeth at multiple sites by cerclage wires encircling the teeth and passing through the holes in the bar.
The wires are guided through the bar and tightened by twisting.
Pearl: Leaving the wires between the cheek teeth very long and exiting them through the mouth helps guiding them through the holes in the bars. The two wires encircling one cheek tooth are identified and twisted together. The corresponding wires are untwisted and one by one guided through the respective holes under visual control and twisted together again. Once all are placed through the intended holes the bar is placed in its final position and the corresponding wires exited through a stab incision, followed by tightening.
The stab incisions are closed routinely. In old, infected or open fractures, a drainage should be placed.
The image shows the interdental wiring applied initially to achieve reduction and the U bar that was added to the incisor and premolar teeth to increase stability.
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 given for 3 to 5 days or longer, if required, especially in open fractures. Intraoral cerclage and tension wires are cleaned once daily until their removal. The drainage sites are cleaned and flushed daily with antiseptic solutions. After the fracture has healed the U-bar and wires can be removed under sedation and local anesthesia.