ISO 18192-3:2025
(Main)Implants for surgery — Wear of total intervertebral spinal disc prostheses — Part 3: Impingement-wear testing and corresponding environmental conditions for test of lumbar and cervical prostheses
Implants for surgery — Wear of total intervertebral spinal disc prostheses — Part 3: Impingement-wear testing and corresponding environmental conditions for test of lumbar and cervical prostheses
This document specifies a test procedure to simulate and to evaluate lumbar and cervical spinal disc prostheses wear under adverse impingement conditions.
Titre manque — Partie 3: Titre manque
General Information
Relations
Standards Content (Sample)
International
Standard
ISO 18192-3
Second edition
Implants for surgery — Wear of
2025-11
total intervertebral spinal disc
prostheses —
Part 3:
Impingement-wear testing and
corresponding environmental
conditions for test of lumbar and
cervical prostheses
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Reagents and materials . 2
5.1 Fluid test medium .2
5.2 Test and control specimen .3
6 Apparatus . 3
7 Impingement wear testing methods . 5
7.1 General .5
7.2 Example of development of load and displacement profiles for extension impingement
protocol for a lumbar prosthesis .6
7.3 Procedure .7
8 Test report . 8
9 Disposal of test specimen . 9
Annex A (normative) Wear of spinal disc prostheses — Gravimetric measurement method .10
Annex B (informative) Justification of the test method .13
Bibliography . 14
iii
Foreword
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The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
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This document was prepared by Technical Committee ISO/TC 150, Implants for surgery, Subcommittee SC 5,
Osteosynthesis and spinal devices.
This second edition cancels and replaces the first edition (ISO 18192-3:2017), which has been technically
revised.
The main changes are as follows:
— the scope of this document has been extended to cervical prosthesis;
— values for the impingement testing of cervical prothesis have been integrated.
A list of all parts in the ISO 18192 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
International Standard ISO 18192-3:2025(en)
Implants for surgery — Wear of total intervertebral spinal
disc prostheses —
Part 3:
Impingement-wear testing and corresponding environmental
conditions for test of lumbar and cervical prostheses
1 Scope
This document specifies a test procedure to simulate and to evaluate lumbar and cervical spinal disc
prostheses wear under adverse impingement conditions.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 7500-1, Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Calibration and verification of the force-measuring system
ISO 18192-1, Implants for surgery — Wear of total intervertebral spinal disc prostheses — Part 1: Loading and
displacement parameters for wear testing and corresponding environmental conditions for test
ISO 23788, Metallic materials — Verification of the alignment of fatigue testing machines
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 18192-1 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
impingement
point at which two opposing components collide or restrict motion usually indicated by a sharp change in
force or moment
3.2
range of motion
ROM
amount of angular displacement that a total disk replacement prosthesis can undergo from the device
neutral position to the point at which impingement (3.1) occurs around a defined global axis
Note 1 to entry: If an implant impinges at 15° from the implant neutral position in flexion and 20° from the implant
neutral position in extension, the implant range of motion can be defined as +15°/-20° in flexion and extension.
3.3
distance between centre of rotation and point of impingement
DCI
distance between the point of impingement (3.1) and the nominal centre of rotation for the flexion, extension
or lateral bending motions
3.4
axial load during impingement
ALI
axial load applied to the device in newtons while the device is in an impinged condition
3.5
axial load minimum
ALM
minimum of the time-varying axial load applied to the device in newtons during the repeated test cycle
3.6
point of impingement
point of contact between two opposing components that results in impingement (3.1)
4 Principle
Based on current clinical evidence, lumbar and cervical spinal disc prostheses have experienced impingement
in extension/flexion, lateral bending, axial rotation and combinations thereof with extension being the most
commonly reported mode.
Adverse impingement testing conditions are determined based on available clinical data, engineering
analysis and other relevant information in the literature. This information is summarized in Annex B and a
justification for the test method is also given in Annex B.
An axial load and a time-varying angular displacement are applied to the test specimens to simulate repeated
contact between design features of the specimens.
Four possible individual impingement scenarios have been identified in the literature:
a) flexion;
b) extension;
c) lateral bending;
d) combined flexion and lateral bending.
In addition, combined axial rotation with any of the aforementioned motion modes should be considered, if
necessary to achieve either a clinically relevant impingement wear scar or worst case impingement scenario,
or both.
A load soak control specimen, if polymers are the object of investigation, is subjected to the same time-
varying force to determine either the creep of the test specimen or the amount of mass change, due to fluid
transfer or both. The test takes place in a controlled environment simulating physiological conditions.
5 Reagents and materials
5.1 Fluid test medium
The fluid test medium consisting of calf serum diluted with de-ionized water (balance) to a concentration of
20 g ± 2 g of protein per litre shall be prepared in accordance with ISO 18192-1. If routine monitoring of the
pH of the fluid test medium is undertaken, the values shall be included in the test report [see Clause 8 m) 7)]
[1]
as an increase in pH can indicate an increase in microbial activity .
5.2 Test and control specimen
Between the inferior and superior components shall be the articulating surface of the inferior and superior
components, attached by its normal immediate backing (e.g. bone cement or a machined replica of the inner
surface of the backing), unless this is impractical due to physical features of the implant system. If the
component forming the articulating surface is fixed to the backing by a rim/snap-fit system, the machined
replica shall provide the same fixation conditions.
If it is not practical to use the normal backing or cement fixation due to physical features of the implant
system, the support system for either the inferior component or the superior component, or both, should
represent normal design features and conditions of use but should allow removal of the component for
measurement of wear without destruction.
It is recommended that six specimens be tested for the impingement-wear test. If less than six specimens are
tested, appropriate justification shall be given.
NOTE The number of specimens tested can be the subject of national legislation.
If polymers are the object of investigation, a load soak control specimen is to be subjected to the same axial
load to determine either the creep of the test specimen or the amount of mass change due to fluid transfer,
or both. The test should take place in a controlled environment of test medium to simulate physiological
conditions (see 5.1).
In the test cases where surrounding fluid is not absorbed by the specimens, test specimens shall be weighed
prior to testing with an instrument having a precision of 0,1 mg.
The tested implant size should be selected by an engineering analysis including theoretical, computational
or experimental methods. If computational methods are used, experimental verification that considers the
point of impingement, the materials in contact and the range of motion of the specimens is recommended.
The point of impingemen
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