Arne Carlson, the former governor of Minnesota, recently contributed an opinion column to the Minneapolis Star-Tribune, voicing concerns about increased Food & Drug Administration regulation of the medical device industry stifling innovation. The column came as Dr. Jeffrey Shuren, director of the FDA’s Center for Devices & Radiological Health, prepared to visit the state — one of the country’s biggest medical device hubs — for a town hall meeting to discuss CDRH’s 2010 Strategic Imperatives and hear feedback from industry officials.
Testing Talk
Planar biaxial testing system for biological tissue
Constitutive models are necessary to predict the mechanical behavior of biological tissues. However, biological materials present challenges in constitutive modeling due to their complex mechanical behavior. Their oriented fibrous structures often exhibit pronounced mechanical anisotropy. Due to anisotropy, stress strain data generated from uniaxial tests cannot be used to extrapolate to generalized three-dimensional constitutive equations.
Flexural fatigue
ASTM F1264 Annex 3 is a test method for bending fatigue testing of intramedullary fixation devices (IMFD). This cyclic, four-point bend test determines the fatigue life at a specified bending moment or estimates the fatigue strength for a specified number of cycles.
Have you hugged an auditor today?
In the life sciences industry, many companies have a heightened sensitivity to risk due to increased regulatory scrutiny and/or product quality issues. As a result, the concern around compliance has renewed many organizations’ focus on audit programs, which are being re-calibrated as a tool to identify the most vulnerable parts of the business.
How to perform an ASTM D412 rubber elastomer tensile strength test
ASTM D412 covers the tensile properties of thermoset rubbers and thermoplastic elastomers. The specification describes two test methods, A and B. Method A is common and can be performed on a universal testing machine (tensile testing machine). If you are going to perform this test, you should read the entire specification from ASTM. This is a quick summary to decide if this test is right for you and to point out what equipment you need to perform the test.
This video shows the basic steps necessary to perform the ASTM D412 test:
Suture tensile strength test
A suture is a medical device that doctors use to hold skin, internal organs, blood vessels and all other tissues of the human body together, after they have been severed by injury or surgery. They must be strong enough to hold the tissue and flexible enough to be easily tied into knots.
Suture tensile strength determines where the suture can be used inside or outside of the body and for how long it is intended to remain. Sutures are absorbable or non-absorbable and in some cases, have needles attached.
Below we describe a typical suture tensile test and what type of equipment is needed to perform this test.
Testing the force required to pull open a seam of a package
Examples of specimen set ups
Testing Talk: Tensile strengths
Typical points of interest when tensile testing a material include ultimate tensile strength or peak stress; modulus of elasticity, offset yield strength, which represents a point just beyond the onset of permanent deformation; and elongation at break.
The modulus of elasticity is calculated as the slope in the linear elastic region of the stress-strain curve. The linear elastic region is prior to the proportional limit (see point A – Figure 1). Beyond the proportional limit, the material undergoes permanent plastic deformation.
Testing bone screws
ASTM F543 Annex A2 is used to measure the torque required to drive a bone screw into a test block made of rigid, unicellular polyurethane foam. The results obtained from this test bear no direct correlation to the torque required to insert a bone screw in human or animal bone. This method is used as a quality control check for maintaining product uniformity.
The basic test procedure for determining the insertion and removal torque is as follows:
Torsion testing conical fittings and connectors for medical devices
Torque, also called moment or moment of force, is the tendency of a force to rotate an object about an axis or pivot. Torque is rotational force. Twisting the female to male fitting, to remove or replace the connection, is an example of applying torque. The amount of torque developed is proportional to the force applied and to how far from the center of the rotation the force is applied.
ASTM F382-99 Metallic Bone Plate Material 4-point Bend Test
Metallic bone plates need to undergo several tests before gaining approval as internal fixation devices for the skeletal system. One standard, ASTM F382-99, defines the test methods for single cycle bend testing (annex A1) and for determining the bending fatigue properties (annex A2) of metallic bone plates. A summary of the test methods for annex A1 and A2 follows. For a complete description of ASTM F382-99, refer to the specification from the ASTM International organization.
