Choosing the wrong tissue site in an implantation study is one of the fastest ways to derail your 510(k) submission.
We’ve seen FDA request repeat testing—adding months and tens of thousands of dollars—simply because the chosen implantation site didn’t match the device’s intended clinical use.

Why Tissue Site Selection Matters
Under ISO 10993-6, implantation studies must simulate the real-world environment in which a medical device will function.
This means your implantation site should:

Reflect the target tissue type (muscle, subcutaneous, bone, vascular, organ)

Mimic physiological conditions (vascularization, mechanical stress, immune environment)

Represent the intended duration of contact

The wrong site can:

Underestimate risks (e.g., smooth muscle site for a vascular stent)

Overestimate risks (e.g., highly reactive tissue for a device intended for skin contact)

Trigger FDA Additional Information (AI) requests

How to Match Tissue Site to Device Use
Think of the implantation site as a biological stand-in for where your device will actually live in the body.

If your device will be in blood vessels (like stents or catheters), select a site that matches the endothelial contact and blood flow environment.

For orthopedic implants, bone sites—either cortical or cancellous—are essential to capture load-bearing and integration behavior.

Devices intended for soft tissue or subcutaneous applications should be tested in muscle or under the skin, where immune response and vascularization patterns are similar.

If the product will contact the heart or valves, the implantation site must reflect the mechanical stress, perfusion, and tissue type found in the cardiac environment.
Common Mistakes in Tissue Site Selection

 Convenience over clinical relevance – Choosing muscle when device is meant for bone because it’s “easier to test.”

 Ignoring vascularization differences – Underestimating how blood supply affects healing and inflammation.

 One-size-fits-all – Using the same site for every device in a product family without risk justification.

Real 510(k) Case Study
A startup submitted a 510(k) for a permanent orthopedic implant but conducted their implantation study in muscle tissue.

FDA feedback:
“Muscle site does not adequately represent bone contact environment. Repeat implantation study in relevant tissue required.”

The repeat study in cancellous bone cleared the deficiency—but added 4+ months and $$$$ to the project.

Toxicologist’s Tip

 Build tissue site selection into your Biological Evaluation Plan (BEP) early.
Document your justification in the risk assessment—this makes FDA more likely to accept your approach without delays.

Key Takeaway
For 510(k) implantation studies, the correct tissue site isn’t just a lab decision—it’s a regulatory strategy.
When the site matches the real-world use, your data is stronger, your review is smoother, and your time to market is faster.

 Need help selecting the right implantation site for your 510(k)?

We help device developers design ISO 10993-6 compliant studies that align with FDA expectations—avoiding costly re-testing.
Contact us to get started.