title: Syndesmosis fixation: analysis of shear stress via axial load on 3.5-mm and 4.5-mm quadricortical syndesmotic screws.
abstract: The effect of shear stress on a fixated distal syndesmosis of the ankle was evaluated with a servohydraulic materials-testing machine. Eighteen syndesmoses were fixated in a quadricortical technique using 3.5-mm cortical and 4.5-mm cortical stainless steel screws. A shear stress was applied via an axial load in an attempt to simulate weightbearing. The 4.5-mm quadricortical screws produced a higher yield load and peak load (484.3 +/- 93.8 N and 597.7 +/- 81.4 N) when compared with the 3.5-mm quadricortical syndesmotic screws (412.8 +/- 55 N, P = .033 and 511.2 +/- 64.4 N). These findings suggest that a larger diameter screw provides greater resistance to an applied shear stress at the distal syndesmosis.
authors.affiliation: St. John North Shores Hospital, 26755 Ballard Road, Harrison Township, MI 48045, USA. mphansen43@hotmail.com
authors.forename: Matthew
authors.initials: M
authors.lastname: Hansen
authors.forename: Long
authors.initials: L
authors.lastname: Le
authors.forename: Stuart
authors.initials: S
authors.lastname: Wertheimer
authors.forename: Eric
authors.initials: E
authors.lastname: Meyer
authors.forename: Roger
authors.initials: R
authors.lastname: Haut
mesh_terms: D016512:Ankle Injuries / Q000601:surgery*; D001863:Bone Screws; D002102:Cadaver; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D008422:Materials Testing; D011474:Prosthesis Design; D013314:Stress, Mechanical; D016474:Weight-Bearing