Screw　loosening　remains　a　prominent　problem　for　osteoporotic　patients　undergoing　pedicle　screw　fixation　surgeries　and　is　affected　by　screw　parameters　(e.g.,　diameter,　pitch,　and　thread　angle).　However,　the　individual　and　interactive　effects　of　these　parameters　on　screw　fixation　are　not　fully　understood.　Furthermore,　the　current　finite　element　modeling　of　a　threaded　screw　is　less　computationally　efficient.　To　address　these　issues,　we　(1)　explored　a　novel　＂simulated　threaded　screw＂　approach　(virtual　threads　assigned　to　the　contact　elements　of　a　simplified　screw)　and　compared　its　performance　with　threaded　and　simplified　screws,　and　(2)　examined　this　approach　the　individual　and　interactive　effects　of　altering　screw　diameter　(5.5-6.5　mm),　pitch　(1-2　mm)　and　half-thread　angle　(20-30　deg)　on　pullout　strength　of　normal　vertebrae.　Results　demonstrated　that　the　＂simulated　threaded　screw＂　approach　equivalently　predicted　pullout　strength　compared　to　the　＂threaded　screw＂　approach　(R-2　=　0.99,　slope　=　1).　We　further　found　that　the　pullout　strength　was　most　sensitive　to　the　change　in　screw　diameter,　followed　by　thread　angle,　pitch,　and　interactions　of　diameter*pitch　or　diameter*angle.　In　conclusion,　the　＂simulated　threaded　screw＂　approach　can　achieve　the　same　predictive　capability　compared　to　threaded　modeling　of　the　screw.　The　current　findings　may　serve　as　useful　references　for　planning　of　screw　parameters,　so　as　to　improve　the　complication　of　screw　loosening.