Dependent on the fracture configuration displaced fracture fragments are reduced one after the other and fixed with cortex screws in lag fashion to create a two-part fracture.
Plate selection and preparation
Depending on the fracture configuration an appropriate length plate is chosen. Most likely, a 12-14 hole plate is appropriate. Although a single narrow plate may be adequate, a broad plate may be more appropriate in some cases because it provides additional stability. Two narrow plates are needed in some cases (one caudally and one laterally) because of the degree of comminution and need for increased purchase in the proximal fracture fragment. LCP, LC-DCP or DCP have all been used successfully in this location. A soft aluminum template is contoured for application over the proximal olecranon extending distally onto the ulna. The plate is bent to match the previously contoured aluminum template.
When possible, fracture fragments are compressed using a combination of screws placed in lag fashion and the dynamic compression attribute of the plate.
Once the fracture is reduced and the plate applied to the fracture an intraoperative radiograph should be taken to confirm reduction and plate position. In addition, radiographs taken at this time allow the surgeon to assess and, if needed, modify the preoperative plan.
If fluoroscopy is available, it is very useful to identify implant positioning and feedback on the quality of fracture reduction intraoperatively.
Placement of the remainig screws
The remaining screws are inserted, with the cortex screws being placed prior to insertion of any locking head screws if an LCP is employed. Because of the comminuted nature of the fracture it is important to avoid inadvertently placing screws into fracture lines. The proximal screws should gain purchase in the dense cortical bone of the cranial metaphysis of the olecranon. Take care that the screws adjacent to the trochlear notch do not penetrate into the joint.
1-2 locking head screws are usually placed proximal and distal to the area of comminution one at or near the ends of the plate.
Engaging the radius
In horses over a year of age the screws distal to the articular surface of the radius should engage the caudal cortex of the radius to strengthen the fixation. It is not necessary to engage the cranial cortex of the radius, which could predispose to a radial fracture. In addition, it is important to direct the distal plate screws medially, into the medullary cavity of the radius, to avoid the lateral cortex of the radius which can also predispose to fracture of the radius.
Alternative: placing a second plate
If single plate fixation is inadequate the second plate is placed on the lateral cortex with care taken to avoid screw interference with the screws of the first plate.
Antibiotic impregnated polymethylmethacrylate beads are placed along the plate prior to surgical wound closure. The wounds are closed routinely and are covered and protected with a bandage until the skin staples or sutures are removed. Some surgeons prefer to use suction drains, but the author does not use them.
6. Overview of rehabilitation
The stent bandage is removed after 72 hours post operatively. Postoperative treatment depends on the age of the horse. Foals are kept in stall rest for a minimum of 60 days, adult horses for approximately 90 days. The first half of the period hand-grazing only is advised, followed hand-walking exercises in the second half of the period. Follow up radiographs are taken at 60 resp. 90 days. If healing appears to be progressing without complications the horse is gradually transitioned to free paddock exercise.
The implants are left in place unless complications appear. More information about plate removal can be found here.
Plate removal after the ulna fracture has healed is strongly discouraged because of potential re-fracture of the ulna during recovery along empty screw holes. Therefore, whenever possible plate removal is performed in the sedated, standing horse. For more information please see additional material "Implant removal and complications".
Occasionally specific situations (explicit wish of the owner, etc.) may lead to implant removal and rarely selected screws have to be removed but the plate is left in place.
The only real indication of implant removal is chronic, non-resolving infection.
Chronic infection is usually diagnosed because intermittent lameness and subsequent opening of a fistulous tract at the surgical wound draining purulent material. Through cleaning of the fistulous tract and repeated flushing with physiologic saline and mild antiseptica the tract eventually clears up and the skin closes. As soon as the tract opens lameness disappears. With time, however, another pocket containing purulent material accumulates at the same spot associated with increasing lameness and the whole cycle repeats itself.