scholarly journals Patient-Specific Variations in Local Strain Patterns on the Surface of a Trussed Titanium Interbody Cage

2022 ◽  
Vol 9 ◽  
Author(s):  
Arjan C. Y. Loenen ◽  
Jérôme Noailly ◽  
Keita Ito ◽  
Paul C. Willems ◽  
Jacobus J. Arts ◽  
...  
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Local Strain ◽  
Patient Specific ◽  
Finite Element Models ◽  
Bone Homeostasis ◽  
Interbody Cage ◽  
Functional Dynamics ◽  
Specific Factors ◽  
Contact Pressures

Introduction: 3D printed trussed titanium interbody cages may deliver bone stimulating mechanobiological strains to cells attached at their surface. The exact size and distribution of these strains may depend on patient-specific factors, but the influence of these factors remains unknown. Therefore, this study aimed to determine patient-specific variations in local strain patterns on the surface of a trussed titanium interbody fusion cage.Materials and Methods: Four patients eligible for spinal fusion surgery with the same cage size were selected from a larger database. For these cases, patient-specific finite element models of the lumbar spine including the same trussed titanium cage were made. Functional dynamics of the non-operated lumbar spinal segments, as well as local cage strains and caudal endplate stresses at the operated segment, were evaluated under physiological extension/flexion movement of the lumbar spine.Results: All patient-specific models revealed physiologically realistic functional dynamics of the operated spine. In all patients, approximately 30% of the total cage surface experienced strain values relevant for preserving bone homeostasis and stimulating bone formation. Mean caudal endplate contact pressures varied up to 10 MPa. Both surface strains and endplate contact pressures varied more between loading conditions than between patients.Conclusions: This study demonstrates the applicability of patient-specific finite element models to quantify the impact of patient-specific factors such as bone density, degenerative state of the spine, and spinal curvature on interbody cage loading. In the future, the same framework might be further developed in order to establish a pipeline for interbody cage design optimizations.

Modeling the HSK Toolholder-Spindle Interface

2002 ◽  
Vol 124 (3) ◽  
pp. 734-744 ◽  
Author(s):  
Ihab M. Hanna ◽  
John S. Agapiou ◽  
David A. Stephenson
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
System Reliability ◽  
High Volume ◽  
Finite Element Models ◽  
Operational Experience ◽  
Bending Load ◽  
Load Carrying ◽  
Detailed Evaluation ◽  
Contact Pressures

The HSK toolholder-spindle connection was developed to overcome shortcomings of the 7/24 steep-taper interface, especially at higher speeds. However, the HSK system was standardized quickly, without detailed evaluation based on operational experience. Several issues concerning the reliability, maintainability, and safety of the interface have been raised within the international engineering community. This study was undertaken to analytically investigate factors which influence the performance and limitations of the HSK toolholder system. Finite Element Models were created to analyze the effects of varying toolholder and spindle taper geometry, axial spindle taper length, drawbar/clamping load, spindle speed, applied bending load, and applied torsional load on HSK toolholders. Outputs considered include taper-to-taper contact pressures, taper-to-taper clearances, minimum drawbar forces, interface stiffnesses, and stresses in the toolholder. Static deflections at the end of the holder predicted by the models agreed well with measured values. The results showed that the interface stiffness and load-carrying capability are significantly affected by taper mismatch and dimensional variations, and that stresses in the toolholder near the drive slots can be quite high, leading to potential fatigue issues for smaller toolholders subjected to frequent clamping-unclamping cycles (e.g., in high volume applications). The results can be used to specify minimum toolholder material properties for critical applications, as well as drawbar design and spindle/toolholder gaging guidelines to increase system reliability and maintainability.

Modeling the HSK (Hollow Shank Taper 1/10 Tapered Joint) Toolholder-Spindle Interface

2000 ◽  
Author(s):  
Ihab M. Hanna ◽  
John S. Agapiou ◽  
David A. Stephenson
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
System Reliability ◽  
High Volume ◽  
Finite Element Models ◽  
Operational Experience ◽  
Bending Load ◽  
Load Carrying ◽  
Detailed Evaluation ◽  
Contact Pressures

Abstract The HSK toolholder-spindle connection was developed to overcome shortcomings of the 7/24 steep-taper interface, especially at higher speeds. However, the HSK system was standardized quickly, without detailed evaluation based on operational experience. Several issues concerning the reliability, maintainability, and safety of the interface have been raised within the international engineering community. This study was undertaken to analytically investigate factors which influence the performance and limitations of the HSK toolholder system. Finite Element Models were created to analyze the effects of varying toolholder and spindle taper geometry, axial spindle taper length, drawbar/clamping load, spindle speed, applied bending load, and applied torsional load on HSK toolholders. Outputs considered include taper-to-taper contact pressures, taper-to-taper clearances, minimum drawbar forces, interface stiffnesses, and stresses in the toolholder. Static deflections at the end of the holder predicted by the models agreed well with measured values. The results showed that the interface stiffness and load-carrying capability are significantly affected by taper mismatch and dimensional variations, and that stresses in the toolholder near the drive slots can be quite high, leading to potential fatigue issues for smaller toolholders subjected to frequent clamping-unclamping cycles (e.g., in high volume applications). The results can be used to specify minimum toolholder material properties for critical applications, as well as drawbar design and spindle/toolholder gaging guidelines to increase system reliability and maintainability.

Predisposing Factors for Orthodontic Mini-Implant Failure Defined by Bone Strains in Patient-Specific Finite Element Models

2016 ◽  
Vol 44 (10) ◽  
pp. 2948-2956 ◽  
Author(s):  
Mhd Hassan Albogha ◽  
Toru Kitahara ◽  
Mitsugu Todo ◽  
Hiroto Hyakutake ◽  
Ichiro Takahashi
Keyword(s):  
Finite Element ◽  
Predisposing Factors ◽  
Implant Failure ◽  
Patient Specific ◽  
Finite Element Models ◽  
Bone Strains

scholarly journals The mechanical response of the lumbar spine to different combinations of disc degenerative changes investigated using randomized poroelastic finite element models

2010 ◽  
Vol 20 (4) ◽  
pp. 563-571 ◽  
Author(s):  
Fabio Galbusera ◽  
Hendrik Schmidt ◽  
Cornelia Neidlinger-Wilke ◽  
Andreas Gottschalk ◽  
Hans-Joachim Wilke
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Mechanical Response ◽  
Degenerative Changes ◽  
Finite Element Models

An efficient tissue classifier for building patient-specific finite element models from X-ray CT images

1996 ◽  
Vol 43 (3) ◽  
pp. 333-337 ◽  
Author(s):  
N. Shrinidhi ◽  
D.R. Haynor ◽  
Yanqun Wang ◽  
D.B. Jorgenson ◽  
G.H. Bardy ◽  
...  
Keyword(s):  
Finite Element ◽  
Ct Images ◽  
Patient Specific ◽  
Finite Element Models ◽  
X Ray
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