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EN ISO 10993-6

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EN ISO 10993-6

EN ISO 10993-6 is a standard published by the International Organisation for Standardisation (ISO) and adopted by the European Committee for Standardisation (CEN), entitled ‘Biological evaluation of medical devices – Part 6: Tests for local effects following implantation”, i.e. “Biological evaluation of medical devices – Part 6: Tests for local effects following implantation”.

Regulatory status and version note: The base text of the standard is ISO 10993-6:2016 (third edition) and has been adopted at European level as EN ISO 10993-6:2016. The standard has been recognised as a harmonised standard under the EU Medical Devices Regulation (MDR 2017/745). The current consolidated version, as well as any amendments and the scope of recognition by the FDA, should be checked against the relevant official sources before submitting an application.

The basic principle of the standard is the macroscopic and histopathological assessment of the local tissue reaction that occurs at the implantation site when materials for medical devices or the finished product are implanted into living tissue. The evaluation is based on a comparison of the test material with a known and recognised control material; this makes it possible to distinguish whether the observed tissue reaction is attributable to the material or to the surgical procedure or trauma.

Duration of implantation

  • Short-term: Usually 1–4 weeks (e.g. 1, 2 or 4 weeks)
  • Long-term: Usually 12 weeks; in some cases, longer periods (e.g. 26 weeks or more) may also be analysed
  • The choice of duration depends on the product’s intended clinical use, the expected duration of implantation and the timeline of the biological response.

Laboratory animal and implantation site

The choice of animal species and implantation site depends on the size of the implant, the duration of implantation, the type of tissue and the intended clinical use. Common options:

  • Animal species: rats, rabbits, guinea pigs, dogs, sheep, pigs (taking into account implant size and tissue compatibility)
  • Site of administration: subcutaneous, intramuscular, bone (a specific assessment is required for orthopaedic and dental implants)
  • As a rule, a sufficient number of implants are assessed for each item and each group; the standard contains recommendations on the minimum sample size required for statistical significance.

Sample preparation and implant properties

  • Test and control implants shall be prepared in accordance with ISO 10993-12; they must reflect the final production and sterilisation conditions of the product.
  • The size and shape of the implants are chosen so that they remain stable within the tissue and elicit a measurable response (usually cylindrical in shape).
  • A material recognised in the relevant regulatory guidelines and whose biocompatibility is known is used as the control material.
  • In the case of resorbable (absorbable) materials, their degradation and resorption behaviour during the implantation period are also assessed.

Scope of the assessment

Macroscopic assessment (necropsy): The appearance of the implant site, capsule formation, changes in colour, fluid accumulation, necrosis and other local findings are documented.

Histopathological assessment: The implant and the surrounding tissue are fixed, sectioned and stained as appropriate (routinely with H&E; special stains where required). Typical assessment parameters include:

  • Capsule formation / fibrosis and capsule thickness
  • Inflammatory cell infiltration: polymorphonuclear leukocytes, lymphocytes, plasma cells, macrophages, giant cells
  • Necrosis
  • Neovascularisation
  • Fatty infiltration / degeneration
  • Where applicable, calcification, apoptosis, tissue integrity and foreign body reaction in the area around the implant

These parameters are usually assessed using a rating scale (e.g. 0 = absent, 1 = minimal, 2 = mild, 3 = moderate, 4 = severe). The ratings for the test and control implants are compared; the differences and the overall rating are reported.

The main parameters reported in the study are as follows:

    • Animal species used, number and implantation site
    • Duration of implantation and timing
    • Number and size

the test and control implants

  • Conditions for sample preparation and sterilisation (in accordance with ISO 10993-12)
  • Macroscopic findings
  • Histopathological assessments (by parameters) and comparison between the test and control groups
  • Differential scores and assessment of the general local tissue reaction
  • Findings on degradation/resorption in the case of resorbable materials
  • Data on measurement uncertainty and repeatability

What is the purpose of the examination?

EN ISO 10993-6 is carried out for the following scientific and regulatory purposes:

  • Assessment of local biocompatibility: determining whether the product or material elicits an acceptable tissue response at the implantation site
  • Ensuring patient safety: Evaluation of implanted products with regard to local inflammation, fibrosis, necrosis and other adverse tissue reactions
  • MDR compliance: Provision of the data required for the assessment of biological safety under the EU Medical Devices Regulation (2017/745)
  • Test-control comparison: Distinguishing between a material-specific tissue reaction and one caused by surgical trauma
  • Materials and Design Development: Assessment of the influence of surface properties, shape, porosity and coatings on the local tissue response
  • Evaluation of resorbable materials: investigation of the degradation process and the relationship between resorption and the tissue response
  • Support with the preparation of regulatory documentation: for use as part of the biocompatibility dossier in applications to the FDA, in accordance with the EU MDR and other regulatory authorities
  • Evidence-based approach: Chemical characterisation (ISO 10993-18), cytotoxicity (ISO 10993-5), sensitisation (ISO 10993-10), irritation (ISO 10993-23), genotoxicity (ISO 10993-3) and systemic toxicity (ISO 10993-11) as a contribution to the holistic assessment of the product

EN ISO 10993-6 assesses only local tissue effects; systemic toxicity, carcinogenicity, reproductive toxicity and haemocompatibility do not fall within the scope of this standard and must be assessed in accordance with the relevant ISO 10993 standards. The results should be interpreted in conjunction with the chemical characterisation, other biological tests and clinical data.

As part of our nano-testing services, we carry out implantation and local tissue reaction assessments in accordance with EN ISO 10993-6, applying scientific rigour within the framework of our accredited laboratory infrastructure and our quality management system. Our scope of services includes the following:

Study design and protocol development

    • Depending on the product’s intended clinical use, scientific justification for the animal species, the implantation site and the time periods
    • Statistical and scientific planning of the number and size of test and control implants
    • Auswahl und Begründung des geeigneten Kontrollmaterials
    • Establishment of a sample preparation and sterilisation strategy in accordance with ISO 10993-12

(so as to reflect the product’s actual operating conditions)

  • Planning the degradation assessment for resorbable materials
  • Compliance with requirements relating to ethical approval, animal welfare and surgical procedures

For information on study design, the selection of animal species and implantation sites, sample preparation, histopathological evaluation, the test schedule and reporting procedures in connection with your implantation and local tissue effect assessments in accordance with EN ISO 10993-6, please feel free to contact Nano-Test.

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