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.