Mechanical Properties of Small Fragment Screws
- 1 April 2000
- journal article
- research article
- Published by Ovid Technologies (Wolters Kluwer Health) in Clinical Orthopaedics and Related Research
- Vol. 373 (373), 277-284
- https://doi.org/10.1097/00003086-200004000-00034
Abstract
For many years, stainless steel small fragment screws have been produced by one manufacturer. Recently, other implant makers have begun offering similar stainless steel screws. In addition, screw geometry and material composition have been modified in an attempt to produce screws for a wide range of clinical situations. This study compared the mechanical properties of several commonly used small fragment screws. Seven sets of screws were tested mechanically, including three brands of geometrically identical standard stainless steel cortical screws and one brand each of cannulated stainless steel cortical screws, titanium cortical screws, stainless steel cancellous screws, and bioabsorbable polylactic acid screws. Screws from each group were tested for pullout strength, torque to failure, and three-point bending to failure. There were no differences in the mechanical properties of the identical 3.5-mm standard stainless steel cortical screws. No difference in pullout strength was found between the five sets of cortical screws. However, the cancellous screws had 4% to 24% less pullout strength. Torsion tests showed that cannulated stainless steel cortical, titanium cortical screws, stainless steel cancellous screws, and polylactic acid screws failed at significantly less torque than did standard stainless steel cortical screws. Standard stainless steel cortical screws had the highest mean yield point and maximal load at failure of all screws in three-point bending. Other metal screws had lower yield strength and maximal load at failure than did the standard stainless steel cortical screws, and polylactic acid screws had the least bending strength.Keywords
This publication has 22 references indexed in Scilit:
- Metallic or Absorbable Fracture Fixation DevicesClinical Orthopaedics and Related Research, 1996
- Factors Affecting the Pullout Strength of Cancellous Bone ScrewsJournal of Biomechanical Engineering, 1996
- EFFECT OF CYCLICAL LOADING ON THE HOLDING POWER OF SURGICAL SCREWSOrthopedics, 1994
- Correlations Between Screw Hole Preparation, Torque of Insertion, and Pullout Strength for Spinal ScrewsJournal of SPINAL DISORDERS, 1994
- Optimizing Bone Screw Pullout ForceJournal of Orthopaedic Trauma, 1990
- Pull-Out Strengths of Bone Screws at Various Sites About the Pelvis—A Preliminary StudyJournal of Orthopaedic Trauma, 1988
- Compact bone fatigue damage—I. Residual strength and stiffnessJournal of Biomechanics, 1977
- Metallurgical aspects of surgical implant materialsInjury, 1971
- A metallurgical examination of surgical implants which have failed in serviceInjury, 1970
- A study of some factors which affect the strength of screws and their insertion and holding power in boneJournal of Biomechanics, 1968