ISO 22926:2023
(Main)Implants for surgery — Specification and verification of synthetic anatomical bone models for testing
Implants for surgery — Specification and verification of synthetic anatomical bone models for testing
This document provides requirements and recommendations for specification and verification of synthetic anatomical bone models for use in testing of implants. The anatomical source of the synthetic model can be digital data from computed tomography (CT) scanning or any other sources such as from cadaveric specimens or statistically determined shape data. The specifications covered in this document are 3D shape and mechanical characteristics. Other characteristics, such as colour or cosmetic features, are not considered in this document.
Implants chirurgicaux — Spécification et vérification des modèles osseux anatomiques synthétiques pour les essais
Le présent document fournit des exigences et des recommandations pour la spécification et la vérification des modèles osseux anatomiques synthétiques pour une utilisation dans les essais d’implants. La source anatomique du modèle synthétique peut être les données numériques obtenues par tomodensitométrie, ou toute autre source telle que des échantillons cadavériques ou des données de forme déterminées statistiquement. Les spécifications abordées dans le présent document sont la forme 3D et les caractéristiques mécaniques. D’autres caractéristiques, telles que la couleur ou l’aspect esthétique, ne sont pas prises en compte dans le présent document.
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 22926
First edition
2023-07
Implants for surgery — Specification
and verification of synthetic
anatomical bone models for testing
Reference number
© ISO 2023
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Design and development of a synthetic model . 2
4.1 General . 2
4.2 Identification of physical model characteristics . 2
4.3 Model verification . 3
4.3.1 General . 3
4.3.2 Model geometrical verification . 3
4.3.3 Model material verification . 3
4.3.4 Model mechanical verification . 3
5 Specification report .4
Annex A (informative) Background, detailed scope and rationale . 5
Annex B (informative) Example of model geometrical verification methods .8
Annex C (informative) Example of a specification report .10
Bibliography .17
iii
Foreword
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electrotechnical standardization.
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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
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 150, Implants for surgery.
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
Introduction
Synthetic anatomical bone models can be useful to characterize mechanical performance of surgical
implants and instruments, such as those used in musculoskeletal fixation or reconstruction surgery. A
synthetic bone model is typically made by methods of casting, machining and/or recently by additive
manufacturing, all of which can leverage medical image-based modelling. To use a synthetic anatomical
bone model for mechanical testing of an implant, its similarity to natural bone in terms of shape and
mechanical behaviour is of paramount importance to bone model users.
This document provides a way to specify, verify and report characteristics of synthetic bone models
used for implant testing. The details of testing and the choice of a suitable bone model is outside the
scope of this document. A more detailed rationale for this document is provided in Annex A.
There are two related standards for synthetic materials that are used as mechanical models of bone
[1]
for implant testing. ASTM F1839 was first issued in 1997 and is a standard specification for rigid
polyurethane foam. Polyurethane foam is a cellular solid that exhibits certain aspects of mechanical
behaviour that are similar to bone such as the relationship between apparent density and its stress-
[2]
strain response to mechanical loading. A second relevant standard is ISO 19213 which was first
issued in 2017 and provides a list of test methods to describe synthetic material models of cortical bone.
The methods referenced in ISO 19213 report material properties from long standing test methods for
plastics, and include specialized tests to mimic certain orthopaedic surgical processes such as drilling,
milling (burring) and cutting. This document goes beyond materials, and includes shape and structure
of a synthetic bone model.
While the scope of this document is limited to bone models, it is intended to lay the framework for
future models of other biologic tissues.
v
INTERNATIONAL STANDARD ISO 22926:2023(E)
Implants for surgery — Specification and verification of
synthetic anatomical bone models for testing
1 Scope
This document provides requirements and recommendations for specification and verification of
synthetic anatomical bone models for use in testing of implants.
The anatomical source of the synthetic model can be digital data from computed tomography (CT)
scanning or any other sources such as from cadaveric specimens or statistically determined shape data.
The specifications covered in this document are 3D shape and mechanical characteristics. Other
characteristics, such as colour or cosmetic features, are not considered in this document.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
digital anatomical bone model
digital model
dataset to represent the shape and any other desired characteristics for target synthetic model (3.2)
Note 1 to entry: The procedure to produce digital model of the knee bone from computed tomography (CT) data
can be found in ISO 19233-1.
EXAMPLE STL, CAD STEP, voxel-based model.
Note 2 to entry: Examples of other desired characteristics are: density, hardness, porosity, Young’s modulus.
3.2
synthetic anatomical bone model
synthetic model
physical model resulting from the manufacturing process based on the digital model (3.1)
3.3
physical model characteristic
parameter or feature used to represent the physical anatomical bone in order to establish the design
requirements for the synthetic model (3.2)
Note 1 to entry: The physical model characteristics include both geometrical shape, material and mechanical
properties.
Note 2 to entry: Physical model characteristics can be specified by the bone model producer (3.4) and/or user.
3.4
bone model producer
model producer
organization or individual responsible for producing the synthetic model (3.2)
3.5
bone model user
model user
organization or individual that uses the synthetic model (3.2)
3.6
specification report
report which provides information of characteristics of the synthetic model (3.2) manufactured
according to the design requirements established in this document
Note 1 to entry: See Annex C for an example.
4 Design and development of a synthetic model
4.1 General
The applicable requirements for characterizing physical and digital anatomical bone models, and
verification after production are shown in 4.2 to 4.3.
The bone model producer shall establish appropriate system controls in order to ensure the traceability
of each synthetic anatomical bone model throughout the design and development process.
4.2 Identification of physical model characteristics
The required physical model characteristics shall be specified by either the bone model producer or the
bone model user. This specification shall include any of the following if required based on the intended
application of the model:
a) the overall shape described geometrically in any manner, such as surface model (e.g. an STL file),
solid vector model (e.g. CAD STEP file), or volumetric representation (e.g. voxel based model), as
input for an overall digital bone model;
b) the description of the 3D shapes of any segments within the overall shape [of list item a)], such as
cortical bone, cancellous bone and intramedullary canal;
c) the material and properties for the overall model or each segment, such as density, hardness,
porosity, surface roughness and Young’s modulus;
d) structural mechanical characteristics of the overall or part of the bone model, such as stiffness,
ultimate strength and fatigue strength, under certain loading conditions;
e) any other characteristics such as chemical or thermal resistance, residual stress levels and
dimensional stability due to manufacturing process, and fluid absorption in the intended working
environment of the model.
The bone model user should determine which of the above characteristics are critical for their
application and which verification model is needed.
NOTE Reference of material and mechanical characteristics for human bone segments can be collected from
the published literature, for examples, see References [3] to [11].
4.3 Model verification
4.3.1 General
To verify that the synthetic anatomical bone model fulfils the requirements of desired digital model,
this process shall be conducted by the bone model producer, and the results reported to the bone model
user. This verification includes model geometrical and model mechanical performance if required,
according to the following steps:
a) model geometrical verification (4.3.2),
b) model material verification (4.3.3), and
c) when necessary, model mechanical verification (4.3.4).
The bone model producer shall select and implement the processes for model geometrical, material and
mechanical verifications of the synthetic anatomical bone model as required or agreed with the bone
model users.
Results of verification shall be presented in specification report in accordance with Clause 5.
4.3.2 Model geometrical verification
Geometrical characteristics of the synthetic anatomical bone model shall be verified by examining the
agreement to the geometrical specifications established in 4.2 a) an
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