ISO TS 10993 19:2020 download.Biological evaluation of medical devices Part 19: Physico-chemical, morphological and topographical characterization of materials.
Introduction
Iso 14971 highlights the importance of taking into account the nature of the materials within a biological risk analysis.
ISO 10993-1 is to serve as a framework in which to plan a biological evaluation which, as scientific knowledge advances human understanding of the basic mechanisms of tissue responses, minimizes the number and exposure of test animals by giving preference to chemical constituent testing and in vitro models. In situations where these methods yield equally relevant information to that obtained from in vivo models, ISO 10993-1 states that, when selecting the materials to be used for device manufacture, fitness for purpose with regards to characteristics and properties of the material, which include chemical, toxicological, physical, electrical, morphological and mechanical properties, will be the first consideration. The identification and evaluation of the physico-chemical, morphological and topographical properties of materials used in a finished medical device are important in determining the biological evaluation of that device and its materials. Such information can be used in:
— assessing the overall biological evaluation of a medical device according to ISO 10993;
— screening of potential new materials and/or processes for suitability in a medical device for a proposed clinical application.
The compositional characteristics of the materials of manufacture are mainly under the control of the suppliers of these materials. However, other characteristics are chiefly influenced by the requirements to be met by the finished medical device as well as the production processes used by the medical device manufacturer.
1 Scope
ISO TS 10993 19 provides a compilation or parameters and test methods that can be useful for the identification and evaluation of the physical, i.e. physlco-chemlcal, morphological and topographical (PMT) properties of materials In finished medical devices. Such an assessment is limited to those properties that are relevant to biological evaluation and the medical devices intended use (clinical application and duration of use) even If such properties overlap with clinical effectiveness.
ISO TS 10993 19 does neither address the Identification or quantification of degradation products nor the evaluation of the physico-chemical properties of the degraded materials, which are covered in
ISO 10993-9, ISO 10993-13, ISO 10993-14 and ISO 10993-15,
Chemical characterization of materials is covered by ISO 10993-1K.
The ISO 10993 series Is not applicable when the material or device is not in contact with the body
directly or Indirectly.
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 ISO TS 10993 19. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 10993.1, BiologIcal evaluation of medical devices — Part 1: EvaluatIon and testing within a risk management process
ISO 10993-18. Biological evaluation of medical devices — PIn-I 18: Chemical characterization of medical device materials within a risk management process
3 Terms and deflnltlons
For the purposes of this document, the terms and definitions given in ISO 10993-1. ISO 10993-18 and the following apply.
ISO and IEC maintain terminological databases for use In standardization at the following addresses:
3.3
topographical
relating to the features or the surface (or materials)
4 General principles
Consideration of the PMT characterization of the materials from which a medical device is made, like chemical characterization of materials (addressed in ISO 10993-18), Is a necessary step In assessing the biological safety and clinical effectiveness of the device. Both types of characterization are also Important in ‘odging equivalence of
a) a proposed material to a clinically established material.
b) a prototype device to a final device.
C) a material or device after a process or manufacturing change, or
d) a real’tIrne and/or accelerated device and the non•aged device.
The rebtionship between PMT characteristics of medical device materLals and their biacompalibility and clinical effectiveness is still a developing area. However, there are several examples of where these relationships are becoming better understood, as listed below.
— The use otcertain PMT characteristics or porous materials as surfaces on orthopaedic implants can encourage tissue In-growth at the surface of the implant and thus result in better integration with the surrounding tissue.
— The use of material scaffolds and meshes, with certain PMT characteristics, as implants into inlured soft or hard tissue can facilitate the beneficial infiltration of certain types of cells which aid the healing process (see Reference 1491).
— The PMT characteristics of the surfaces of materials used as catheters have a major influence on the adherence of bacteria and proteins to the inner and outer surfaces, which in turn influences the risk of infections and blockages.
— Alterations to the micro•topography of surfaces, for example, producing microgrooves or other defined patterns, has been shown to influence the adhesion and direction of movement of certain types olcells on that surface (see References 142) and 145)).
— For certain medical devices, for example. orthopaedic implants and vascular prostheses, mechanical properties can influence biological responses such as tissue re-modelling.
— To characterize the P4T principally surface topography/morphology following a process change,
NOTE The shape and geometric form of medical devices and their components are known to ailed the biological response, for example. lie aspect ratio, thickness and form in relation to blood flow Information on specific devicei can be found in the applicable product standards.
ISO TS 10993 19 provides a range at examples of PMT characterization parameters and methods which can be usefully applied in the PMT characterization of materials utilized in medical devices.
Medical device manufacturers should select relevant PMT parameters and methods and ustify their selection. Manufacturers should document the level of characterization performed on their medical device and its component materials, appropriate to its clinical application.
The extent of characterization should reflect the nature and duration of the diniral exposure and can be useful for risk assessment of the biological safety of the device. The PMT characterization should also reflect the materials used and their physical form(s), for example, solid, liquid, gel, composite or biologically-sourced material. Characterization generally requires the dose collaboration of material scientists, analytical scientists and risk assessors.
5 Characterization procedure
5.1 General
The analytical methods should be selected to give the required information for the evaluation, Prior to new method development, existing standards, monographs, scientific artides or other relevant scientific documents should be consulted to check for existing appropriate test methods. Methods from the literature can need to be adapted and validated before use. If suitable methods cannot be identified, appropriate new methods should be developed.
The analytical methods used should be validated, justified and reported In line with Clauses 6 and Z The validation of an analytical method Is the process by which It Is established that the performance characteristics at the method meet the requirements for the Intended analytical applications. To verily the validity of the PMT method or instrument, the use of surrogate materials/surfaces and/or system suitability on analysis system may be used for PMT method used to ensure reliability of the data obtained.
At each step of the characterization procedure, a decision should be made on the adequacy of the data obtained, as a basis for the risk analysis. This procedure should consider each of the materials as they appear in the finished device.
NOTE The supplier can be a useful source of appropriate analytical meihods, In the absence of any initial data on material properties, a literature study Is recommended to assist In the selection of the mast appropriate methods of analysis for the material being evaluated.
5.2 Qualitative information
Describe the material/device and Us Intended purpose. A documented, qualitative description of the PMT characteristics of the finished device Is recommended, Including the physlco-chemlcal characteristics of each material used In the device (see ISO 10993-1:2018, Clause 4). The level of qualitative data provided should reflect the category of medical device In terms of degree of Invasiveness and clinical exposure duration, as well as the nature of the materials present. The qualitative description should include details of the batch or lot, the supplier and the material specification for each material.
Medical device manufacturers should obtain qualitative material characterization information. relevant to the final product. Such information can be obtained from the supplier of the starting material, the literature or additional testing. The PMT characteristics of materials should either be In accordance with applicable materials standards or should be specified by the manufacturer. It Is Important to obtain as much Information as possible at this early stage to be able to gain a thorough understanding of the hazards (potential risks) and potential benefits arising from the properties of the material, and to develop an Initial assessment of the fitness for the Intended purpose. This assessment will be further refined as additional Information Is gained during the product development process. Importantly. It should be assumed that PMT characteristics will change during manufacture. Therefore, PMT characterization should be performed on or otherwise represent the final product.
5.3 Material equivalence
As a part of material suitability assessment, a comparison of these data should be made to determine whether this material Is equivalent to that utilized in a device or prototype with the same clinical exposure/use and having had the same manufacturing and sterilization processes applied. e.g. established sale and effective use of materials In a product to be used on intact skin. AuaszA gives further guidance on judging material equivalency.
NOTE Discussion on nanomaterlals is presented In lSO/TR 10993.22. See also ISO 10993lH:2O20, Annex C for more on material equivalence.
Where qualitative material characterization data alone have riot provided sufficient data for a material suitabIlity assessment to be completed, quantitative material characterization data should be established, documented and sublected to assessment of suitability and risk.