Anatomic reduction is imperative for a successful outcome. Without load sharing of the bone-plate construct, implant failure is likely. Reduction can be difficult and is aided by large bone-holding forceps and external traction devices.
Like with all comminuted fractures, reduction and fixation of the fracture fragments into two larger segments is the goal. Application of bone holding forceps and strategic cortex screw placement in lag fashion are used to accomplish this.
One of the bone plates should span the entire diaphyseal length of the tibia to avoid a stress riser at the ends of the plate. Typically the medial plate is the longest.
The tension side of the tibia is the cranial lateral surface and one of the plates should be placed at or near this location. The plates should be placed approximately 90 degrees to each other. Since double-plating is typically required, staggering of the bone plates (especially when using LCP) is imperative to get bicortical purchase of the bone screws.
In comminuted fractures as many cortex screws in lag fashion should be placed through the plate as possible.
2. Choice of approach
Three surgical approaches are available: the medial approach directly over the tibia without muscle cover; the lateral approach between the long digital extensor and the cranial tibial muscles, and the cranial approach, in which the incision is made over the cranial tibial muscle. The cranial approach over the muscle is the most versatile. Implants can be placed on the medial and lateral aspects of the bone through this incision, eliminating the need for two incisions, as are required with the medial and lateral approaches. The choice of approach is also dependent upon the fracture configuration. The principle that the most distal part of the proximal fragment should be covered by a plate should always be followed. Therefore, if the most distal aspect of the proximal fragment is located laterally, a lateral plate should be applied through the corresponding approach.
Reduction is accomplished using a combination of tenting of the fracture ends, distal retraction and application of bone-holding forceps.
In this case, the butterfly segment is first reduced and fixed with a cortex screw placed in lag fashion to one of the larger fragments to create a two-part fracture.
In the next step, the two remaining fragments are reduced and fixed in the same manner.
4. Plate application
Plate selection and preparation
Either a broad DCP, LC-DCP or LCP is contoured to the entire medial diaphyseal length of the tibia. The proximal and distal physis of the tibia should not be bridged by the plate or any screws.
Application of the first plate
A single 4.5 mm bicortical bone screw is placed in neutral position in a proximal screw hole of the plate above the length of the fracture.
4.5 mm cortex screws are placed in lag fashion across fracture lines where possible in the mid-portion of the plate.
The remaining screws in the plate are bicortical and are placed using the 3.2 mm neutral plate drill guide.
Alternatively, only two bicortical screws in the medial plate can be placed and the second cranial lateral plate attached prior to placement of all the screws in the medial plate.
Application of the second plate
The second, shorter broad DCP, LC-DCP or LCP is contoured to the cranial or craniolateral aspect of the tibia. Prior to application consideration is given to the location of the screws in the medial plate to avoid interference with the screws of the second plate. Hohmann retractors are very useful to retract the cranialis tibialis muscle laterally for application of the second plate. The distal limb should be elevated by an assistant during application of the second plate.
The plate is attached using 4.5 or 5.5 mm cortex screws or 5.0 mm locking screws using a combination of bicortical plate screws and screws inserted in lag fashion where possible in a matter similar to the application of the first plate. If possible, all holes in both plates should be filled with bone screws. If necessary, unicortical screws can be placed and overdrilling of fracture lines to place additional screws is recommended.
Complete stall confinement for 6-8 weeks is recommended. Further exercise instructions are based upon follow-up radiography at 6 weeks postoperatively. If plate removal is elected, staggered removal of the plates is recommended. At least 30 days of pasture exercise is recommended prior to removal of each plate. Plate removal is not required in horses intended for breed or pasture activity.