Locking plates allow for the insertion of two different types of screws
- Locking head screws
- Nonlocking screws
Generally, locking screws are preferred as there is less chance of the screw loosening.
Further advantages of locking screws vs nonlocking screws can be found here.
Depending on the producer, locking head screws may need to be placed at a right angle to the plate and centered to allow the locking head to engage.
Different locking plate shapes and sizes are available.
When inserting a nonlocking screw in a locking plate, up to 30° angulation is possible. The need for angled screw insertion can depend on fracture anatomy and the requirements for screw fixation.
Generally, locking head screws and conventional screws are self-tapping. On rare occasions, tapping may be desirable when the surgeon encounters unusually dense or sclerotic cortical bone, such as in the atrophic edentulous mandible.
Tapping is accomplished using the bone-tap instrument discussed here.