Usually an 8-10 hole narrow plate is appropriate. LCP, LC-DCP or DCP have all been used successfully in this location. A soft aluminum template is centered over the fracture and contoured to fit the bone. This may require additional bending at the proximal end to overlie part of the apophysis and assure adequate purchase in the proximal fragment. The plate is bent to match the previously contoured aluminum template.
A screw is inserted in the proximal aspect of the plate in neutral position to fix the plate to the bone. The fracture is usually reduced using the dynamic compression attribute of the plate or, if a wide gap exists, with an Articulated Tension Device (ATD) as shown here.
Once the fracture is reduced and the plate applied to each side of 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.
Insertion of the remaining screws
The remaining screws are inserted. If an LCP is used for the fixation it is important to place all cortex screws prior to insertion of any locking head screws. 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. Whenever possible one plate screw should be inserted as interfragmentary screw. Such a screw increases rotational stability significantly. This screw can be inserted either in lag fashion or as regular plate screws.
1-2 locking screws are usually placed adjacent to the fracture in each fracture fragment and one at or near the ends of the plate.
Left: The oblique fracture line was initially repaired with a 3.5 mm cortex screw inserted in lag fashion followed by application of the plate with exclusively locking head screws. The plate was previously pressed onto the bone surface with the help of push-pull devices.
Pitfall: Care must be taken to avoid screw penetration into the caudal radius in individuals less than 7 months of age as this may lead to incongruity of the elbow joint. This is caused by the inability of the transfixed ulna to slide proximally to maintain elbow congruity as the proximal radial epiphysis grows proximally.
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 routinely use them.
4. Overview of rehabilitation
The stent bandage is removed after 72 hours post operatively and the horse is kept in stall rest for a minimum of 60 days. The first 30 days hand-grazing only is advised, followed by 30 days of hand-walking.
Follow up radiographs are taken at 60 days. If healing appears to be progressing without complications the foal 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.