Since the introduction of Locking Screws into veterinary orthopaedics we have had the feedback that the self tapping feature works well in relatively soft bone (e.g. proximal tibia for TPLO) but it is less effective in dense cortical bone where getting the screw started can be a challenge. Starting the screw at any angle other than 90 degrees to the plate will have serious consequences when the locking threads meet the plate. In addition if the screw does not tap the trans cortex efficiently a disc of bone may be punched from the bone surface as the screw exits.