Lag-screw fixation

The goal of surgery is to reconstruct the joint, and to ensure joint stability and medial column length.

The timing of surgery is influenced by the soft tissue injury and the patient's physiologic status. 

For the procedure, a range of screws can be utilized:

• Cannulated screws
• Non-cannulated screws
• Headless compression screws

We will here demonstrate the use of cannulated and non-cannulated screws.

The procedure is performed with the patient placed supine with the knee flexed 90°.

A limited dorsomedial approach is made directly over the fracture without peripheral dissection and undermining, maintaining the blood supply.

The fracture is entered directly and dealt with as necessary.

Use a K-wire or small clamp to reduce the avulsed fragment to the main fragment. Verify the reduction fluoroscopically.

Take care not to place the clamp (or K-wire) where the lag screw will be inserted.

When cannulated screws are used, insert the guidewire perpendicular to the fracture line under image intensification to temporarily secure the fixation.

Care must be taken to avoid tarsonavicular joint penetration.

Insert a cannulated lag screw according to the standard technique. A washer is typically used.

A headless screw can also be inserted following the standard technique of headless screw insertion.

In contrast to lag screws inserted in the diaphysis, these lag screws will typically not penetrate the far cortex, as this would damage the opposite articular surface.

A K-wire may be inserted to fix the fragment temporarily.

Insert a lag screw with a washer according to the standard technique.

• Cortical lag screw insertion 

Remove the K-wire.

The non-adherent antibacterial dressing is applied as a first layer. Sterile undercast padding is placed from toes to knee. Extra side and posterior cushion padding are added.

The foot should be immobilized for the first two weeks, which can be achieved using a three-sided plaster splint. The anterior area is left free of plaster to allow for swelling. Ensure that the splint’s medial and lateral vertical portions do not overlap anteriorly and that the splint does not compress the popliteal space or the calf.

The patient should be counseled to keep the leg on a cushion and elevated. Remember not to elevate the leg too much as it may impede the inflow. The foot’s ideal position is halfway between the waist and the heart when the patient is sitting. While seated, the foot should be on a cushion and elevated, but if badly swollen, the patient must be supine since elevating the foot while seated decreases swelling less effectively.

Avoid direct pressure against the heel during recumbency to prevent decubiti.

The OR dressing is usually left in place and not changed until the first postoperative visit at two weeks when x-rays are obtained once the dressing is removed. If any complication is suspected (eg, infection or compartment syndrome), the dressing must be split and, if necessary, removed to allow full inspection.

The strict non-weight bearing should be maintained until there is evidence of healing and any transfixion K-wires (6–12 weeks) or bridging devices (min 12 weeks) are removed.

Daily toe movement is encouraged.

Formal physical therapy should not begin in the early postoperative period.

A gastrocnemius release may need to be performed in cases with postoperative gastrocnemius contracture. This occurs more typically in the mid and hind-foot.