title: Cannulated screw with solid core insert: stronger than cannulated screws.
abstract: We conducted a study to determine if there is a significant difference in ultimate load, yield strength, and fatigue strength between solid core screws and cannulated screws and if a solid core insert placed inside a cannulated screw would have biomechanical effects similar to those of a solid core screw. Five screw designs were tested: Synthes 4.5-mm solid core and 4.5-mm cannulated and our prototype 4.0-mm solid core, 4.0-mm cannulated, and 4.0-mm cannulated with solid core insert. Biomechanical testing with 3-point bending was used to determine ultimate load, yield strength, and cycles to failure for 6 screws of each design. Ultimate load, yield strength, and cycles to failure were significantly (P < .05) lower in the Synthes 4.5-mm cannulated screws than in the Synthes solid core screws and significantly lower in the prototype cannulated screws than in the prototype solid core screws (P < .05) and prototype cannulated screws with solid core inserts (P < .05). There was no significant difference (P > .05) in ultimate load, yield strength, or cycles to failure between the prototype cannulated screws with solid core inserts and the prototype solid core screws.
authors.affiliation: Department of Orthopaedic Surgery, Sports Medicine, and Rehabilition, Boonshoft School of Medicine, Wright State University, Dayton, OH. dundon.3@wright.edu.
authors.forename: John M
authors.initials: JM
authors.lastname: Dundon
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Gould
authors.forename: Michael A
authors.initials: MA
authors.lastname: Herbenick
authors.forename: J Adam
authors.initials: JA
authors.lastname: Hamilton
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D005592:Fracture Fixation / Q000295:instrumentation*; D006801:Humans; D008422:Materials Testing