How Is the Biological Evaluation of a Surgical Saw Performed? Step-by-Step Biological Safety from Manufacturing to Regulatory Approval

August 17, 2026

A surgical saw used for cutting bone in orthopedic surgeries undergoes a mandatory and highly rigorous safety assessment before it comes into contact with the patient. So, how exactly is the biological evaluation process carried out for a surgical saw? First of all, the general characteristics of the surgical saw product family and the detailed manufacturing process planning are defined as the foundation of the evaluation process.

The process begins with the raw materials used in surgical saw manufacturing. Potential toxicological risks throughout the production process are evaluated individually, starting from the alloy composition of our raw material, EN 1.4028 stainless steel (Chromium, Iron, Manganese, etc.), and extending to residues from machining, polishing, ultrasonic cleaning oils, and cleaning chemicals. How will the impact of these risks on human health and safety be tested step by step? This is where the ISO 10993 series of standards comes into play.

Biological Evaluation Process

First, chemical characterization (ISO 10993-18) and Toxicological Risk Assessment (ISO 10993-17) are performed on the surgical saw extracts. The primary objective here is to measure the amount of organic and inorganic substances that may leach from the device into the tissue. Critical details are included in the test methodology: In chemical analyses and irritation testing, dual solvents (two different extraction solvents), including polar solvents (such as purified water/isotonic solution) and non-polar solvents (such as n-hexane/sunflower oil), are used in order to simultaneously identify organic residues such as oils or hydrogen-derived compounds and water-soluble substances. On the other hand, a single solvent (cell culture medium) is sufficient for cell culture-based cytotoxicity testing (ISO 10993-5).

Chemical Characterization in Medical Devices: Biological Safety and Risk Management

The hierarchical monitoring and planning of test results are carried out in accordance with the 3R principles (Replacement, Reduction, Refinement). If volatile, semi-volatile compounds, or heavy metals detected in the extracts obtained from the surgical saw remain below the Analytical Evaluation Threshold (AET), instead of performing severe animal tests such as acute systemic toxicity and genotoxicity, the process is planned through Toxicological Risk Assessment (TRA) and scientific justification for waivers. In the following stage, in vitro and in vivo tests are performed, including cytotoxicity at the cellular level (ISO 10993-5), irritation at the tissue level (ISO 10993-23), and sensitization/GPMT at the immune response level (ISO 10993-10). Additionally, to prevent metal dissolution in such cutting instruments, the corrosion resistance of the passivation layer is experimentally verified according to ISO 9626 Annex D.

All of these experimental evidences are formalized under the framework of the Biological Evaluation Report (BER) prepared for the surgical saw. The evidence generated for the product is formalized by mapping it against the requirements of the European Medical Device Regulation (EU 2017/745 MDR Annex I – GSPR) and ISO 10993-1 standards. Thus, cellular reactivity, inflammatory responses, and allergenic endpoints are identified and evaluated through the conducted assessments.

As a result, initial risks anticipated for the surgical saw at the beginning of the manufacturing planning stage, such as chemical residues, metal ion release, and tissue reactions, are eliminated. By scientifically and legally demonstrating that the clinical benefit provided by the finished surgical saw product significantly outweighs the remaining biological risks, the device is safely introduced to the market.

European Medical Device Regulation (EU 2017/745)