title: A comparison of bicortical and intramedullary screw fixations of Jones' fractures.
abstract: Two different fixations for treatment of Jones' fracture were tested in bone models and cadaveric specimens to determine the differences in the stability of the constructs. A bicortical 3.5-mm cannulated cortical screw and an intramedullary 4.0-mm partially threaded cancellous screw were tested using physiologic loads with an Instron 8500 servohydraulic tensiometer (Instron Corporation, Canton, MA). In bone models, the bicortical construct (n = 5, 87+/-23 N) showed superior fixation strength (p = .0009) when compared to the intramedullary screw fixation (n = 5, 25+/-13 N). Cadaveric testing showed similar statistical significance (p = .0124) with the bicortical construct (n = 5, 152+/-71 N) having greater load resistance than the intramedullary screw fixation (n = 4, 29+/-20 N). In bone models, the bicortical constructs (23+/-9 N/mm) showed over twice the elastic modulus than the intramedullary screw fixations (9+/-4 N/mm) with statistical significance (p = .0115). The elastic modulus in the cadaveric group showed a similar pattern between the bicortical (19+/-17 N/mm) and intramedullary (9+/-6 N/mm) screw constructs. Analysis of the bicortical screw failure patterns revealed that screw orientation had a critical impact on fixation stability. The more distal the exit site of the bicortical screw was from the fracture site, the greater the load needed to displace the fixation.
authors.affiliation: Department of Medicine and Surgery, Dr. William M. Scholl College of Podiatric Medicine, Chicago, IL 60610, USA.
authors.forename: Zeeshan S
authors.initials: ZS
authors.lastname: Husain
authors.forename: Donna J
authors.initials: DJ
authors.lastname: DeFronzo
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D002102:Cadaver; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D008682:Metatarsal Bones / Q000293:injuries*; D008954:Models, Biological; D016474:Weight-Bearing