Plate fixation

The author has treated a limited number of minimally displaced fractures conservatively with good success. The foals were managed with stall confinement and a splint bandage. The foal whose radiographs are shown here, with a minimally displaced Type 1a fracture, had a good outcome. The radiograph on the right was taken approximately 4 months after the one on the left.

However, if there is significant instability and/or marked displacement, nonsurgical treatment is contraindicated and open reduction and internal fixation is warranted. In the radiographs pictured here, the foal was managed conservatively. The fracture was markedly displaced, and after an extended period of confinement and splint application, the result was a non-union and an unacceptable clinical outcome at 7 months post injury.

Note: If a foal does not bear good weight on one limb, the opposite limb will in most cases acquire a bowed (varus) deviation because of the prolonged “tripod-stance”.

Prior to surgery, splinting the carpus in extension will allow the foal to support weight on the affected limb. Because of the tendency for young foals to develop laxity of their flexor support structures, the splint should not incorporate the digit or be left in place for an extended time. A splint applied to the caudal aspect of a well-padded bandage, extending from just proximal to the fetlock to just distal to the elbow, will suffice.

This procedure is performed with the patient placed in lateral recumbency through the caudolateral approach.

Because of the cartilaginous nature and small mineralized ossification center of the apophysis it is difficult to obtain satisfactory screw purchase in the proximal fracture segment. Therefore the fixation is supplemented with cerclage wires placed in figure-of-8 configuration to supplement plate fixation in an effort to prevent the apophysis from splitting through screw holes and the fixation failing.

The apophysis of the olecranon is carefully grasped with pointed reduction forceps seated medially and laterally. The limb is extended and distal traction is applied to the pointed reduction forceps, to bring the fracture into reduction.

Note: to prevent trauma potentially splitting the fragile ossified apophyseal separate ossification center, traction can also be applied to the triceps fibers just proximal to the displaced apophysis using the reduction forceps.

A soft aluminum template of appropriate length is contoured for application over the proximal olecranon extending distally onto the ulna.

Usually a 8-10 hole narrow plate is appropriate. LCP, LC-DCP or DCP have all been used successfully in this location.

The plate is bent to match the previously contoured aluminum template.

With an assistant holding the fracture in reduction using the pointed reduction forceps, the plate is applied with either a short screw in the separate ossification center of the apophysis of the olecranon or a long screw just cranial to it and another screw distal to the fracture.

Note: It is optional to insert the cerclage wires around the most proxinal screw in the apophysis already at this time. For this reason the illustrations show the wires already. Wire placement will be described later on in the procedure.

If possible, an intraoperative lateral to medial radiograph is taken to assess implant position and fracture reduction.
Left: a long cortex screw was placed cranial to the ossification center of the apophysis. Additionally two pieces of cerclage wires were placed around the circumference of the apophysis.

The remainder of the screws are then placed in the appropriate holes. It is not necessary to fill all the holes overlying the apophysis and the fracture line, because doing so may further weaken the apophysis and predisposes to failure of the apophysis through the screw holes.

If LCP implants and instrumentation are available, then locking head screws are used as appropriate to increase the strength of fixation in the soft bone of the foal. Remember that cortex screws are placed prior to insertion of any locking head screws.

Pitfall: Care must be taken to avoid screw penetration into the caudal radius. If these screws engage the radius in individuals less than 7 months of incongruity of the elbow joint is likely to develop and cause lameness. Screw fixation into the radius prevents the ulna from sliding proximally to maintain elbow congruity as the proximal radius elongates with growth.

Ensure that the screws adjacent to the trochlear notch of the olecranon do not penetrate cranially into the articulation.

A 2 mm drill bit is used to drill two transverse holes cranial to the most proximal plate screw in the apophysis for the placement of two,1.25 mm figure-of-8 wires.
Two additional holes are drilled from lateral to medial in the metaphysis.

1.25 mm wires are placed in figure-of-8 fashion through the holes and tightened. The ends are twisted and cut in an appropriate position and bent so they do not irritate the soft tissues.

Postoperative radiographs are taken to confirm the final configuration of the fixation.

Antibiotic impregnated polymethylmethacrylate beads are placed along the plate prior to closure of the surgical wound.
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.

The patient 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 patient is gradually transitioned to free paddock exercise.
The implants are left in place unless complications develop.

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.

More information about plate removal can be found here.

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.