title: Evaluation of cruciate and slot auxiliary screw head design modifications for extracting stripped screw heads.
abstract: Slotted and cruciate auxiliary screw head design modifications for "salvaging" a stripped hexagonal head screw were studied. Thirty screws were divided into 3 groups: Group 1 = control without modification, Group 2 = auxiliary cruciate design modification and Group 3 = auxiliary slot design modification. Screws were inserted into adhesive filled high-density synthetic bone tunnels using a hexagonal driver. Group 1 screws were removed using a hexagonal driver. Group 2 and group 3 screws were removed using drivers that matched their respective auxiliary design modifications. All group 1 and group 3 screws (100%) were effectively extracted. Three of 10 (30%) group 2 screws could not be effectively extracted. Group 2 screws displayed greater stripping and deformation than the other groups. The auxiliary slot design modification withstood comparable extraction torques as control screws without significant deformation. Screws with a cruciate design modification displayed more frequent failure, greater stripping and deformation.
authors.affiliation: Department of Orthopaedic Surgery, University of Louisville, Louisville, Kentucky 40202, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Klein
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Kenney
authors.forename: John A
authors.initials: JA
authors.lastname: Nyland
authors.forename: David
authors.initials: D
authors.lastname: Seligson
mesh_terms: D001863:Bone Screws; D020878:Device Removal; D004867:Equipment Design; D005593:Fracture Fixation, Internal; D006801:Humans; D010147:Pain Measurement