Routinely the fracture is anatomically reduced and repaired with two plates spanning the entire bone and applied at 90° relative to each other (left) It is very important to insert some interfragmentary screws to assure that not only the plate(s) bridge the fracture. Care must be taken in foals to avoid bridging the distal physis of the bone with the plate or screws.
In selected cases, such as a young foals or ponies, single plate fixation is possible. Occasionally external coaptation of a full-limb splint bandage or cast is applied during anesthetic recovery the immediate post operative period.
The repair can be carried out with Dynamic Compression Plates (DCPs), Limited Contact Dynamic Compression Plates (LC-DCPs), or Locking Compression Plates (LCPs), among which the LCPs are presently the first choice. Dependent upon the size of the animal and the fracture configuration, either 2 broad plates or one broad and one narrow plate may be applied.
The plates are attached to the bone either with cortex- or locking head screws; the latter only in the LCPs. Dependent upon the size and/or age of the animal either 3.5 mm (in ponies and small foals), 4.5 mm or 5.5mm cortex screws are used. Usually cancellous screws are avoided. 3.5 mm cortex screws can be used in lag fashion even in adult animals to initially repair the fracture. This is routinely followed by the application of larger plates.
One of the fracture planes is anatomically reduced using traction, tenting and rotating movements, followed by the application of a pointed reduction forceps.
In cases with multiple larger fragments, fracture reduction is achieved one fragment at a time until the entire bone is reconstructed. Small fragments void of any blood supply are discarded.
A broad 10-hole LCP with the drill guide mounted in the most distal hole, is positioned on the dorsal aspect of the bone, so that one locking head screw can be placed in the butterfly fragment.
While an assistant holds the plate in position, the surgeon drills the first push-pull reduction device monocortically through the most proximal hole. Rotating the collet clockwise pushes the plate onto the bone.
The second push-pull device is applied through the most distal hole and tightened applying the plate tightly on the bone surface.
A 4.5 mm cortex screw is inserted in neutral position at a 90° angle relative to the long axis of the plate through the second plate hole from the bottom and the top. Both screws are solidly tightened.
Additional cortex screws are implanted in neutral position through the DCU portions of the plate holes immediately proximal and distal of the butterfly fragment. All screws are firmly tightened and the push-pull devices removed.
The carefully contoured narrow 12 hole LCP is applied to the lateral aspect of the bone using two push-pull devices.
A 4.5mm cortex screw is positioned in lag fashion across the distal fracture plane and another one across the proximal fracture plane.
Cortex screws are implanted in neutral plate-screw fashion through each of the two adjacent holes to the butterfly fragment and one more screw is inserted next to each push-pull devices. All he screws are solidly tightened and the push-pull devices are removed.
The 4.3 LCP drill sleeve is applied to the threaded portion of the dorsal plate hole that is positioned over the butterfly fragment and the 4.3mm screw hole is prepared.
After the drill sleeve is removed, the depth of the hole measured, the 5 mm locking head screw of predetermined length is connected to the 4Nm torque limiting device and inserted.
Locking head screws are subsequently inserted through the remaining plate holes of the dorsal plate. In places where a screw has to be implanted in a non-orthogonal direction, a cortex screw is used.
The same is repeated in the lateral plate.
Note: In hybrid LCP-technique at least two locking head screws should be inserted in the proximal and distal main fragments. Also, the procedure can be performed using LCPs and only cortex screws if financial constraints demand it.
All screws are checked for tightness prior to closing the incision. The longitudinally split common digital extensor tendon provides adequate resistance to allow coverage of the soft tissues over the fracture fixation despite the additional tension encountered through the additional space occupying bone plates applied to the bone.
Skin closure is routine.
One-day postoperative radiographs of a multifragment MtIII fracture repaired with a braod LCP applied dorsally and a narrow LCP applied laterally.
5. Regional intravenous perfusion
At the end of the procedure it is advisable to perform regional intravenous perfusion with broad spectrum antibiotic of the surgeon’s choice. A tourniquet is applied at the distal third of the radius/tibia followed by insertion of an indwelling catheter into the corresponding vein distal to the tourniquet (Cephalic vein in the forelimb, saphenous vein in the hind limb).
About 40 ml of blood is withdrawn from the vein followed by by slow injection of the same amount if antibiotic. The antibiotic is maintained in the fracture region for 20 to 30 minutes.
6. Recovery from anesthesia
The limb is covered by a tight full-limb bandage and recovered from anesthesia.
A full-limb splint is added to the bandage for recovery.
The patient is kept in a box stall for one month with some hand grazing after two weeks. The bandage is maintained for 2-3 weeks and changes at 4-day intervals. At the end of the first month the patient is allowed some exercise in a small paddock for one additional month.
Follow up radiographs are taken 2 months postoperatively. The remaining postoperative period is managed dependent upon the result of the follow up radiographs. Right: A marked callus bridges the fracture gab at the plantaromedial aspect of MtIII.
More information about implant removal can be found here.