ASTM F2267-03

Standard Test Method for Measuring Load Induced Subsidence of an Intervertebral Body Fusion Device Under Static Axial Compression

SCOPE
1.1 This test method specifies the materials and methods for the axial compressive subsidence testing of non-biologic intervertebral body fusion devices, spinal implants designed to promote arthrodesis at a given spinal motion segment.
1.2 This test method is intended to provide a basis for the mechanical comparison among past, present, and future non-biologic intervertebral body fusion devices. This test method allows comparison of intervertebral body fusion devices with different intended spinal locations and methods of application to the intradiscal spaces. This test method is intended to enable the user to mechanically compare intervertebral body fusion devices and does not purport to provide performance standards for intervertebral body fusion devices.
1.3 This test method describes a static test method by specifying a load type and a specific method of applying this load. This test is designed to allow for the comparative evaluation of intervertebral body fusion devices.
1.4 Guidelines are established for measuring test block deformation and determining the subsidence of intervertebral body fusion devices.
1.5 Units—The values stated in SI units are to be regarded as the standard with the exception of angular measurements, which may be reported in terms of either degrees or radians.
1.6 Since some intervertebral body fusion devices require the use of additional implants for stabilization, the testing of these types of implants may not be in accordance with the manufacturer's recommended usage.
1.7 The use of this standard may involve the operation of potentially hazardous equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-Aug-2003
• ICS: 11.040.40 - Implants for surgery, prosthetics and orthotics
• Technical Committee: F04 - Medical and Surgical Materials and Devices
• Drafting Committee: F04.25 - Spinal Devices

Relations

• Replaced By: ASTM F2267-04 - Standard Test Method for Measuring Load Induced Subsidence of an Intervertebral Body Fusion Device Under Static Axial Compression
• Effective Date: 01-Apr-2004
• Referred By: ASTM F3292-19 - Standard Practice for Inspection of Spinal Implants Undergoing Testing
• Effective Date: 10-Aug-2003
• Referred By: ASTM F2789-10(2020) - Standard Guide for Mechanical and Functional Characterization of Nucleus Devices
• Effective Date: 10-Aug-2003

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: F 2267 – 03
Standard Test Method for
Measuring Load Induced Subsidence of an Intervertebral
Body Fusion Device Under Static Axial Compression
This standard is issued under the fixed designation F 2267; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method specifies the materials and methods for 2.1 ASTM Standards:
the axial compressive subsidence testing of non-biologic inter- E 4 Practices for Force Verification of Testing Machines
vertebral body fusion devices, spinal implants designed to F 1582 Terminology Related to Spinal Implants
promote arthrodesis at a given spinal motion segment. F 1839 Specification for Rigid Polyurethane Foam for Use
1.2 This test method is intended to provide a basis for the as a Standard Material for Testing Orthopaedic Devices
mechanical comparison among past, present, and future non- and Instruments
biologic intervertebral body fusion devices. This test method F 2077 Test Methods for Intervertebral Body Fusion De-
allows comparison of intervertebral body fusion devices with vices
different intended spinal locations and methods of application
3. Terminology
to the intradiscal spaces. This test method is intended to enable
the user to mechanically compare intervertebral body fusion 3.1 All subsidence testing terminology is consistent with the
referenced standards above, unless otherwise stated.
devices and does not purport to provide performance standards
for intervertebral body fusion devices. 3.2 Definitions:
3.2.1 coordinate system/axes—three orthogonal axes are
1.3 This test method describes a static test method by
specifying a load type and a specific method of applying this defined by Terminology F 1582 as seen in Fig. 4. The center of
the coordinate system is located at the geometric center of the
load. This test is designed to allow for the comparative
evaluation of intervertebral body fusion devices. intervertebral body fusion device assembly. The X-axis is along
the longitudinal axis of the implant, with positive X in the
1.4 Guidelines are established for measuring test block
anterior direction, Y is lateral and Z is cephalic.
deformation and determining the subsidence of intervertebral
body fusion devices. 3.2.2 ideal insertion location—the implant location with
respect to the simulated inferior and superior vertebral bodies
1.5 Units—The values stated in SI units are to be regarded
as the standard with the exception of angular measurements, (polyurethane) dictated by the type, design, and manufacturer’s
surgical installation instructions.
which may be reported in terms of either degrees or radians.
1.6 Since some intervertebral body fusion devices require 3.2.3 intended method of application—intervertebral body
fusion devices may contain different types of stabilizing
the use of additional implants for stabilization, the testing of
these types of implants may not be in accordance with the features such as threads, spikes, and knurled surfaces. Each
type of feature has an intended method of application or
manufacturer’s recommended usage.
1.7 The use of this standard may involve the operation of attachment to the spine.
3.2.4 intended spinal location—the anatomic region of the
potentially hazardous equipment. This standard does not pur-
port to address all of the safety concerns, if any, associated spine intended for the intervertebral body fusion device.
Intervertebral body fusion devices may be designed and
with its use. It is the responsibility of the user of this standard
to establish appropriate safety and health practices and developed for specific regions of the spine such as the lumbar,
thoracic, and cervical spine. Also, there potentially exist
determine the applicability of regulatory limitations prior to
use. different anatomical surgical approaches, which will result in
different implant orientation at different levels of the spine.
This test method is under the jurisdiction of ASTM Committee F04 on Medical
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.25 on Spinal Devices. Annual Book of ASTM Standards, Vol 03.01.
Annual Book of ASTM Standards, Vol 13.01.
Current edition approved Aug. 10, 2003. Published October 2003.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F2267–03
FIG. 1 Intradiscal Height Diagram
FIG. 2 Typical Load-Displacement Curve with 1.5 mm (Thoracic Device) Offset for Polyurethane Foam Test Blocks
3.2.5 intervertebral subsidence—the process of a vertebral 3.2.6 intradiscal height—the straight-line distance along the
body cavitating or sinking around an implanted intervertebral Z-axis between the unaltered simulated vertebral bodies. See
body fusion device resulting in the loss of intradiscal height. Fig. 1.
F2267–03
FIG. 3 Typical Load-Displacement Plot Comparison for Test Specimens in Metallic and Polyurethane Test Blocks
3.2.7 load point—the point through which the resultant deformation equal to the offset displacement found by plotting
force on the intervertebral device passes (that is, the geometric line BC with stiffness, K, originating at point B (see Point D in
Fig. 2).
center of the superior fixture’s sphere) (Fig. 4).
3.2.8 offset displacement—offset on the displacement axis
4. Summary of Test Method
equal to 1 mm for cervical disc devices, 1.5 mm for thoracic
4.1 To measure load induced subsidence, a test method is
devices, and 2 mm for lumbar devices (see distance AB in Fig.
proposed for the axial compression of intervertebral body
2)
fusion devices specific to the lumbar, thoracic, and cervical
3.2.9 simulated vertebral bodies—the component of the test
spine.
apparatus for mounting the intervertebral body fusion device.
4.2 The axial compressive subsidence testing of the inter-
3.2.10 stiffness, (N/mm)—the slope of the initial linear
vertebral body fusion device will be conducted in a simulated
portion of the load-displacement curve (see the slope of line
motion segment via a gap between two polyurethane foam
AE in Fig. 2).
blocks.
3.2.11 test block height—the linear distance along the
4.3 Grade 15 foam shall be employed conforming to Speci-
Z-axis from the top surface of the superior simulated vertebral
fication F 1839.
body to the bottom surface of the inferior simulated vertebral
body with the intervertebral body fusion device in position. 5. Significance and Use
The block heights shall be 70 mm, 60 mm, and 40 mm for
5.1 Intervertebral body fusion devices are generally simple
lumbar, thoracic, and cervical intervertebral disc devices re-
geometric shaped devices, which are often porous or hollow in
spectively. See Fig. 4.
nature. Their function is to support the anterior column of the
3.2.12 yield load—the applied load, F, transmitted by the spine to facilitate arthrodesis of the motion segment. This test
pushrod (assumed equal to force component parallel to and
method outlines materials and methods for the characterization
indicated by load cell), required to produce a permanent and evaluation of the mechanical performance of different
F2267–03
FIG. 4 Subsidence Test Fixture
intervertebral body fusion devices so that comparison can be 5. Two pieces of polyurethane foam or rigid metal are rigidly
made between different designs. mounted inside the test fixture. The testing machine is then
5.2 This test method is designed to quantify the subsidence
directly attached to the test fixture. The user of this test method
characteristics of different designs of intervertebral body fusion
may choose to use an alternate method for achieving this same
devices since this is a potential clinical failure mode. These
result. The actuator of the testing machine is connected to the
tests are conducted in vitro in order to simplify the comparison
pushrod by a minimal friction ball and socket joint or universal
of simulated vertebral body subsidence induced by the inter-
joint (that is, unconstrained in bending). The pushrod is
vertebral body fusion devices.
connected to the superior fixture by a minimal friction sphere
5.3 The static axial compressive loads that will be applied to
joint (that is, unconstrained in bending and torsion). The
the intervertebral body fusion devices and test blocks will
inferior sphere portion firmly holds the inferior polyurethane
differ from the complex loading seen in vivo, and therefore, the
block and is rigidly fixed within the base socket so that no
results from this test method may not be used to directly predict
rotation occurs. The test apparatus shall apply a load in the (0,
in vivo performance. The results, however, can be used to
0, Z) direction. The hollow pushrod and superior sphere should
compare the varying degrees of subsidence between different
be of minimal weight so as to be considered a “two force”
intervertebral body fusion device designs.
member. It thus applies to the intervertebral device a resultant
5.4 The location within the simulated vertebral bodies and
force directed along the
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