Meshing the Human Lumbar Spine2015 Americas Altair Technology Conference

May 5-7, 2015

Jeff HarrisSundar Gopalan

ABOUT NUVASIVE®

#3 in the global spine industry

A pure play

spine company

Specializing in minimally

disruptive surgical procedures

Driving the shift toward minimally

invasive spine surgery

Pioneered lateral access spine

surgery with eXtreme Lateral

Interbody Fusion (XLIF®)

NuVasive, Inc.

ABOUT NUVASIVE®The NuVasive® approach to

Minimally Invasive Surgery (MIS) is

a surgical platform considered to be

Maximum Access Surgery (MAS®).

MAS procedures deliver the benefits

of less invasive surgery through safe

and reproducible techniques.

HISTORY OF

EXPLOSIVE

GROWTH

REVENUE IN MILLIONS

Source: NuVasive Company Financial

Statements

• From start-up to #3 in the U.S. Spine Industry in less

than 10 years

• Growth fueled by innovation and by the shift

from traditional to MAS/MIS spine procedures

$12 $23 $38 $63$98

$154

$250

$370

$478$540

$620

$685

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

SPEED OF INNOVATION

Source: Idata Research Inc.

All percentages are estimates.

NUVASIVE® IS

DRIVING THE SHIFT

TOWARD MINIMALLY

DISRUPTIVE SURGERY

Within 10 years, MAS/MIS procedures are

expected to represent 80% of all spine surgeries.

Others

23%

Medtronic

24%

NuVasive

19%Depuy Synthes

18%

Stryker

8%

Zimmer

4%

Globus

4%

Minimally Invasive Spinal

Implant Market in 2012

NuVasive® offers more than

90 products in its portfolio.

Our products have been

used in tens of thousands

of cases worldwide.

®

Affix®2008

ABOUT NUVASIVE

• Biomechanical functions of the spine

– Transfer weight & bending moments

from the head, trunk, and external loads

to the pelvis

– Allow physiologic motion between head,

trunk, and pelvis

– Protect the spinal cord

INTRODUCTION

• Complex geometry requires a robust meshing tool.

LUMBAR SPINE ANATOMY

Spinous Process

Vertebral Body

Transverse Process

Superior Facet

Inferior Facet

Pedicle

Interior Region

PosteriorRegion

• Cadaveric testing typically performed to evaluate the biomechanics of

medical devices in a more clinically relevant setting.

• FEA offers significant advantages in repeatability and direct

comparison

• Simulate cadaveric testing with a computer model:

– Eliminates specimen variability.

– Less cost/time (once base model is created).

– Can evaluate multiple designs under the same anatomical and

biomechanical conditions.

• Stress analysis of bone, soft tissue and implants.

• Requires complex anatomical model + complex anisotropic, non-linear

materials.

FEA IN BIOMECHANICS

REGULATORY APPLICATIONS

• Anatomic geometry obtained using thresholded CT

Segmentation

– CT scan produces “virtual slices” from many different

angles

– Slices can be stacked together to create a 3D rendering.

• Mesh generation

• Apply appropriate material models

GEOMETRY

1. Import STL and partition the vertebral

body elements away from the

posterior elements.

2. Create circular line and circular

mesh.

3. Create shell elements inside line and

morph to create oblong shape to

capture the body profile.

METHODS

4. Duplicate morph those shells to

the top and bottom surfaces of

the vertebral body.

5. Solid Map mesh between the

shells to create the core solid

elements.

6. Create faces (i.e. shells) to create

elements around solid elements

METHODS

7. Then duplicate morph those shells

outward to the original body

geometry

8. Solid Map mesh between those

transverse shells

9. Using same Solid Map technique,

solid mesh around the remaining top

and bottom areas

METHODS

10.Connect the shell elements to the body and tetramesh using node

merging. This will create a volume that can be meshed and create the

hybrid meshed vertebrae

METHODS

12.Use same process to mesh the other vertebrae.

13.Connect the vertebrae by solid map meshing

between the faces defining the intervertebral

discs

METHODS

14.Use morphing to add any needed shaping

METHODS

• HyperMesh was critical in meshing the complex STL file and Moments

from the neck and pelvis were applied to the meshed model

• Large Displacement simulation was carried out to predict the

deformation and stress in the test experiment before the surgical

procedure

• To the existing FEA model an implant was introduced between the

discs with the corresponding material and properties

• This study helped NuVasive predict stresses induced in the Human

Lumbar Spine before and after the surgical procedure

CONCLUSION

• Jeff Harris – Senior Engineer, Computational Biomechanics

NuVasive, Inc.

7475 Lusk Blvd. San Diego, CA 92121

jharris@nuvasive.com

(858)909-1939

CONTACT

NuVasive, Inc. 7475 Lusk Blvd., San Diego, CA 92121 • phone: 800-475-9131 fax: 800-475-9134

NuVasive UK Ltd. Ste. B, Ground Floor, Caspian House, The Waterfront, Elstree, Herts WD6 3BS UK

phone: +44 (0) 208-238-7850 fax: +44 (0) 207-998-7818

www.nuvasive.com

© 2013. NuVasive, Inc. All rights reserved. , , NuVasive, Speed of Innovation, ILIF, MAS, NVJJB, NVM5, PCM, SOLAS, The Better Way Back, and XLIF are registered trademarks of NuVasive, inc. NuVasive Spine

Foundation is a common law trademark of NuVasive, Inc. 13-NUVA-451