STUDY DESIGN: In vitro biomechanical evaluation of rod stress during physiologic loading of anterior scoliosis instrumentation. OBJECTIVES: To determine effects of material properties and rod diameter on rod stresses in anterior scoliosis instrumentation. SUMMARY OF BACKGROUND DATA: Relationships between instrumentation dimensions, materials, and potential rod failure in anterior scoliosis instrumentation remain unclear. METHODS: Eighteen immature bovine spines were randomized to 3 groups: 1) 4.0-mm stainless steel, 2) 5.0-mm stainless steel, and 3) 4.75-mm titanium alloy. Spines underwent physiologic tests in flexion-extension, lateral bending, and torsion. Rod surface strains were converted to rod stress and normalized to each material's yield stress. Construct stiffness and the normalized rod stresses were compared with a one-way ANOVA (P < 0.05). RESULTS: The 4.0-mm steel and 4.75-mm titanium construct stiffness was similar across all tests. The 5.0-mm steel system was significantly stiffer than 4.0-mm steel (lateral bending/torsion) and 4.75-mm titanium (torsion/flexion) constructs. Rod surface stress was significantly lower for the 4.75-mm titanium rod compared with 4.0-mm and 5.0-mm steel rods for all tests. CONCLUSIONS: The percentage of yield stress was lowest for the 4.75-mm Ti rod for all tests due to titanium's greater yield stress. This suggests the 4.75-mm rod has a lower fatigue failure risk than either steel construct.
STUDY DESIGN: In vitro biomechanical evaluation of rod stress during physiologic loading of anterior scoliosis instrumentation. OBJECTIVES: To determine effects of material properties and rod diameter on rod stresses in anterior scoliosis instrumentation. SUMMARY OF BACKGROUND DATA: Relationships between instrumentation dimensions, materials, and potential rod failure in anterior scoliosis instrumentation remain unclear. METHODS: Eighteen immature bovine spines were randomized to 3 groups: 1) 4.0-mm stainless steel, 2) 5.0-mm stainless steel, and 3) 4.75-mm titanium alloy. Spines underwent physiologic tests in flexion-extension, lateral bending, and torsion. Rod surface strains were converted to rod stress and normalized to each material's yield stress. Construct stiffness and the normalized rod stresses were compared with a one-way ANOVA (P < 0.05). RESULTS: The 4.0-mm steel and 4.75-mm titanium construct stiffness was similar across all tests. The 5.0-mm steel system was significantly stiffer than 4.0-mm steel (lateral bending/torsion) and 4.75-mm titanium (torsion/flexion) constructs. Rod surface stress was significantly lower for the 4.75-mm titanium rod compared with 4.0-mm and 5.0-mm steel rods for all tests. CONCLUSIONS: The percentage of yield stress was lowest for the 4.75-mm Ti rod for all tests due to titanium's greater yield stress. This suggests the 4.75-mm rod has a lower fatigue failure risk than either steel construct.
Authors: Hak Sun Kim; Jin Oh Park; Ankur Nanda; Phillip Anthony Kho; Jin Young Kim; Hwan Mo Lee; Seong Hwan Moon; Jung Won Ha; Eun Kyoung Ahn; Dong Eun Shin; Sung Jun Kim; Eun Su Moon Journal: Yonsei Med J Date: 2010-09 Impact factor: 2.759
Authors: William J Cundy; Annika R Mascarenhas; Georgia Antoniou; Brian J C Freeman; Peter J Cundy Journal: J Child Orthop Date: 2015-01-15 Impact factor: 1.548
Authors: Jacob Januszewski; Joshua M Beckman; Jeffrey E Harris; Alexander W Turner; Chun Po Yen; Juan S Uribe Journal: Surg Neurol Int Date: 2017-09-06