Fixation with lag screw

Incomplete proximal metaphyseal fractures are best treated surgically to achieve rapid fracture healing. Usually cortex screws are inserted in lag fashion perpendicular to the fracture plane, in association with a full limb cast for the recovery from anesthesia and the immediate postoperative period.

This procedure is performed with the patient in dorsal recumbency or in lateral recumbency, through a stab incision.

The incision edges are parted and the 5.5 mm drill protected by the corresponding drill guide is placed prependicularly on the bone followed by preparation of the glide hole into the medullary cavity.

Note: Crossing of the fracture plane can rarely be appreciated during drilling, therefore propagation of thecdrill bit is stopped after the dorsal cortex has been crossed.

The drill bit is removed and exchanged with the 4.0 mm drill bit, the corresponding drill guide is inserted into the glide hole, followed by preparation of the thread hole across the remainder of the bone

Note: Dependent upon the orientation of the fracture plane, care has to be taken to avoid drilling across the vestigial metacarpal/metatarsal bone.

Following countersinking, determining the depth of the hole with the depth gauge and tapping of the hole, the screw of predetermined length is inserted and tightened.

Additional screws are inserted using identical technique at the remaining marked locations.

It is advisable to take immediate post operative radiographs with the horse still on the table.
In this case two screws were not fully inserted. Because the horse was still on the table the correction was easy to accomplish.

The skin sutures are closed with simple interrupted sutures.

The repair was again radiographed and the horse was recovered.

It is prudent to apply a full limb cast for recovery because one can never be completely sure about the fracture configuration, except if CT imaging was performed preoperatively. Also some faint fracture line may not be visible on radiographs and potentially with CT imaging.
The cast can be removed with the horse standing 3-5 days postoperatively. At that time a tight bandage is applied to the limb for two weeks. The bandage is changed at 4-5 day intervals.

The patient is kept in a box stall for weeks. After that it can be hand grazed or walked.
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. This animal showed good progression of fracture healing and light exercise was initiated.