title: Biomechanical Evaluation of 6.5-mm Cannulated Screws.
abstract: Although biomechanical and clinical evidence exists regarding smaller compression screws, biomechanical data regarding the larger headless screws are not currently available. Headed and headless 6.5-mm cannulated compression screws were examined, with analysis of interfragmentary compression, insertion torque, and resistance of the construct to a shear force. No significant differences were seen between the maximum insertion torque of the headless or headed screws. Maximum and steady-state compression forces were also not significantly different between groups. Countersinking the headless model 2 mm led to a 77.01% decrease in steady-state compression levels. Shear testing did not reveal any significant differences in peak load at ultimate failure, specimen stiffness, or final block displacement, although a trend to increased peak load and stiffness was seen with the headless specimens.
authors.affiliation: Department of Orthopaedic Surgery, Grant Medical Center, Columbus, Ohio. drbentaylor@gmail.com.
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: Taylor
authors.forename: Alan S
authors.initials: AS
authors.lastname: Litsky
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Pugh
authors.forename: T Ty
authors.initials: TT
authors.lastname: Fowler
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D004867:Equipment Design; D005593:Fracture Fixation, Internal / Q000295:instrumentation; D006801:Humans; D008422:Materials Testing; D033081:Shear Strength; D019415:Torque