Which of these is true regarding lag screw fixation?

Any threaded screw may be used as a lag screw if the width of the drill hole in proximal and distal segments of fractures bone is made correctly. The hole in the proximal (segment nearer to screw insertion and screw head) has the gliding hole that does not ehgage the screw threads. The screw glides through that hole. The distal segment (segment away from the screw head) has the threaded hole that engages the screw threads and as the ascrew is tightened, the threads pull the distal segment towards the proximal segment, hence creating compression. Lag screws are always places perpendicular to the fracture line, not the bone segments.