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.
1) 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. 2) One of the plates should bridge the distal leading edge of the proximal fragment. 3) The tension side of the tibia is the craniolateral surface and one of the plates should be placed at or near this location. The plates should be placed approximately 90 degrees relative 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.
Lag screws through plate
In long oblique 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 traction and application of bone-holding forceps.
Once reduction is achieved, it can be maintained with bone-reduction forceps although application of two 4.5 mm cortex screws in lag fashion will make plate application easiest. Consideration of plate placement is necessary prior to application of the screws. The screws used for reduction may be removed later if necessary for plate and screw application. Another option is the use of 3.5 mm cortex screws which are countersunk such that the entire screw head, which is flatter and smaller than the one of the 4.5 mm screw, comes to lie within the cortex of the tibia.
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.
Applying the first plate
A single 4.5 mm bicortical screw is placed in neutral position in a proximal screw hole of the plate above the fracture site.
Placing screws in lag fashion
4.5 mm cortex screws are placed in lag fashion across the oblique fracture line where possible in the mid-portion of the plate.
Placing the remaining screws
The remaining screws in the plate are bicortical and are placed using the 3.2 mm neutral plate drill guide. As a rule, all the screws should be placed perpendicular to the long axis of the plate to facilitate insertion of the screws of the second plate.
Alternatively, only two bicortical screws in the medial plate can be placed in addition to a distal screw followed by the application of the second craniolateral plate. This is especially important with the use of an LCP, where the locking head screws must be inserted perpendicularly relative to the long axis of the plate.
Application of the second plate
A second, shorter broad DCP, LC-DCP or LCP is contoured to the cranial or craniolateral aspect of the tibia. Prior to application consideration is giving 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 head 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 screws. If necessary, unicortical screws can be placed and overdrilling of fracture lines to place additional screws is recommended.
Diaphyseal fracture of the tibia in a foal repaired with 2 DCP’s.
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 breeding or pasture activity.
Immediate postoperative radiographic views of a fracture repair in a 2 week old Thoroughbred foal. In the proximal aspect of the medial DCP cancellous screws were used. In general it is best to use cortex bone screws even in metaphyseal bone in the foal.
2-week follow up radiographs show widening of the fracture lines proximally.
The 4-week follow up radiographs show progressive fracture healing with some callus formation in the caudal cortex.
At 5 months postoperatively the fracture is completely healed. Staggered late removal was implemented. The medial plate was removed at that time followed by 2 weeks stall rest and subsequent 30 day pasture exercise. The lateral plate was then removed with a slightly longer reconvalescent period.
17-months follow up radiographs at the time the colt entered race training. The colt had a successful racing career with two wins.