When this test applies
Required for devices that contact or are anchored in bone, under ISO 10993-1:2025. The bone route exists because the osseous response is a different biology from soft tissue: what matters is new bone formation against the implant, resorption at the interface, and whether a fibrous membrane forms between the two. A soft-tissue implantation result does not predict any of that. At twenty-six weeks the interface has reached something close to steady state, and this is the study regulators expect for a permanent osseous implant. It is where slow processes show up — progressive resorption, late particulate response, a fibrous membrane that thickened rather than resolved.
When to run it
Late, and only once the material, the surface finish and the manufacturing process are locked — surface topography drives the osseous response as much as chemistry does, so a finishing change after the implants go in means starting over. Your biological evaluation plan should settle which timepoints the device category requires before any of them are commissioned.
What a pass tells you
That the histological response at the test sites, scored against the control sites per ISO 10993-6 Annex E, produced an irritation ranking of 2.9 or less — classed as a non-irritant in bone over a 26 weeks implantation period.
What it does not tell you
Even a clean twenty-six-week result says nothing about the first fortnight, which the two-week study characterises and which some submissions ask for alongside this one. Nor does histology speak to fixation strength or to wear over a device lifetime measured in years. It also says nothing about systemic effects, genotoxicity or sensitization, each of which is a separate endpoint.
Method
Testing per ISO 10993-6:2016 in the rabbit. Solid samples are implanted directly — there is no extraction step — with sample geometry prepared to the dimensions ISO 10993-6 specifies for the bone route, and placed in prepared cortical sites alongside control implants in the contralateral position. After 26 weeks the sites are explanted and processed for bone histology, then reviewed by a pathologist and scored to derive an irritation ranking per Annex E.
Where it runs
This method is internationally sourced. The laboratory is ISO/IEC 17025 accredited and GLP certified, and the report is issued under Groenakker cover, in Groenakker’s report template or in your document template on request at no extra cost.
Usually ordered alongside
The two- and thirteen-week timepoints, which together with this one describe the whole trajectory rather than its endpoint. Cytotoxicity, sensitization and irritation as the baseline battery.
