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Creatingbiomechanicallyaccuratebone models.

2Creating biomechanicallyaccurate bone models.
To create realistic synthetic musculoskeletal
models for medical device development,
physician training, surgical demonstration andprocedural planning, synthetic bones must
replicate the density properties and mechanicalbehavior of human bone.

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The J750 Digital Anatomy™ printer gives
clinicians and engineers the power to create
the most lifelike anatomical models available.
Combinations of unique materials that vary insoftness, flexibility and density, and more than
100 clinically-validated preset anatomy options,help to mimic human bone like never before.

3THE POWER TO CREATE

Accurate cortical and cancellous bones:
Testing screw pull out force and driving torqueIn 2020, researchers at the Computational
Mechanics and Experimental Biomechanics Lab
evaluated the characteristics of bone models 3D
printed on the J750 Digital Anatomy printer andhow accurately they replicate screw pull out forceand driving torque.
Method3D printed models of cortical and cancellous
bone were created using Digital Anatomy printersoftware. Pilot holes were drilled into each model,
and tapped with the appropriate tap. The mostcommonly-used cortical and cancellous screws
were inserted to the ASTM standard depth fortesting bone substitutes.
Pullout tests were performed until the screw was
released from the bone model, and measured tocompare force and displacement. Driving torqueand pullout measurements were then compared tovalues found in literature and to ASTM standards.
Results
Screw pull out force during screw insertion
corresponded to those found in literature for thecortex of a cadaver bone, demonstrating that the3D printed model accurately replicates cortex
thickness.
Conclusion

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Orthopedic screws have a similar haptic response
in human bone and 3D printed bone models.
The J750 Digital Anatomy printer allows cliniciansand engineers to control density properties ofbone models with physician-tested anatomicalpresets. 3D printed models accurately mimic bonedensity characteristics and behave like native bonewhen force is applied such as drilling, reaming, orsawing.

4THE POWER TO CREATE

Accurate lumbar spine models:Testing mechanical performance
In 2020, researchers from the Technion Instituteof Technology Materials Science and Engineering
Laboratory performed mechanical lab tests tomeasure the mechanical accuracy of 3D printed
synthetic spine models compared to cadaverspine.
MethodUsing Digital Anatomy printer software, researchers
constructed four lumbar spine models using
3D printed lumbar vertebrae (S1-L3), ligaments,
sacrum, facet joints, and intervertebral discs. Eachmodel was created using unique pre-set material
combinations that varied in flexibility, stiffness anddensity to mimic a range of native musculoskeletal
characteristics.
Mechanical tests were performed to simulate thenatural axes of movement of the human spine
as force is applied: disc compression, extension,flexion, lateral bending, and axial tension. Forcevalues were then compared to those found inliterature for human cadaver lumbar spines.
Results
Mechanical disc compression, displacement,and elasticity values for the 3D printed model
corresponded to those found in literature forcadaver lumbar spines, demonstrating thatthe synthetic model accurately replicatesbiomechanical behavior of human bone.
Conclusion

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3D printed L3-S1 models accurately represent therange of motion of human and cadaver spines.
Digital Anatomy printer technology uniquely allows
clinicians and engineers to control the range oflumbar disc stiffness to accurately mimic thedisease pathologies and anatomy variations of thehuman spine.

5Unlock the power to mimic
native bone structures.
• Highly-realistic, low-risk training• High repeatability between samples• Clinically-relevant benchtop testing• Most consistent, accurate representation of bone
• Cost reduction of up to 70%

Learn more about theJ750 Digital Anatomy
printer, materials andsoftware at Stratasys.com.
Questions? Contact us atmedical@stratasys.com.
References
Dahan, Gal et al., “Screw Pull-Out and Driving Torque Experiments,” Computational Mechanics and Experimental Biomechanics Lab, Final Report(2020).
ASTM F1839 – 08, Standard Specification for Rigid Polyurethane Foam for Use as a Standard Material for Testing Orthopaedic Devices andInstruments, ASTM International, West Conshohocken, PA, USA, (2016).
Barak, Yaron, “Biomechanical Evaluation of a Printed Digital Anatomy Lumbar (L3-S1 Spine Model), Technion Institute of Technology Materials
Science and Engineering Laboratory, Final Report (2020).

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