Lag screw fixation

The screws are inserted in lag fashion. To achieve maximal interfragmentary compression, the screws should be directed as close to perpendicular to the fracture plane as is possible.

A glide hole (outer diameter of the screw) is first drilled through the cis- (near) cortex, followed by the thread hole (core diameter of the screw) in the trans- (far) cortex using the appropriate drill bits and drill sleeves. The drill sleeve for the thread hole must be inserted through the cis cortex down to the trans cortex to ensure proper screw placement and effective compression.

The hole is slightly countersunk to enlarge the contact area of the screw head to the bone.

The screw length is measured with a depth gauge. The longer measurement is used.

The thread hole is tapped, and a screw of appropriate length is inserted. The screw should exit the trans cortex by 2 mm.

Depending on fracture configuration, 1–2 additional screws are inserted in the same fashion.

Note: Care must be taken not to place the screws too close to each other. A safe distance is at least one screw diameter away from any fracture line, and two times their diameter should separate two screws.