The term Medical textile can be used to describe a wide range of products, including: gauze, bandages, medical clothing, and implantable biomaterials. This post refers specifically to the mechanical property testing of implantable mesh and sutures used in surgical applications.
All products to be used in medical applications should be accurately tested during product development and manufacturing processes. Doing so helps to ensure patient safety and comfort and enables practitioners to perform medical procedures correctly. The need for comprehensive product testing is even greater for products used in surgical applications because of an added consideration, the need to know how these materials will react and interact with the human body, a factor known as biocompatibility.
Sutures are used by doctors to stitch and hold together the structure of tissue. Sutures can be designed to biodegrade into the body or be removed after a certain period of time. Testing the tensile strength (measure of the average tensile load required to bring the material to a complete break) of sutures can help determine how likely the stitch is to break and the amount of stitch separation needed to hold tissue. Testing the elongation (average increase in length) of suture materials helps determine how likely the suture is to hold when stretched and the amount of pain the stitch can cause the patient when used in areas of high mobility. Planar biaxial (pulling of both axes simultaneously) and biaxial (tension plus torsion) tests can be conducted to further replicate the behavior of suture products in real world applications. To simulate how sutures will react inside the human body, these tests can be performed inside of temperature chambers and/or liquid baths. These tests can be performed on just the suture material (A) or on a sutured tissue sample (B).
Surgical mesh is used to secure inner tissue walls in applications such as hernia repair. Like sutures, there are absorbable and non absorbable types of surgical mesh. Unlike sutures, surgical mesh is normally not removed and is almost always applied inside the body. Tension and elongation testing of the woven fibers should be performed to ensure structural integrity and durability. Planar biaxial (pulling of both axes simultaneously) and biaxial (tension plus torsion) tests can be conducted to further replicate the behavior of surgical mesh in real world applications. To simulate how surgical mesh will react inside the human body, these tests can be performed inside of temperature chambers and/or liquid baths.
ADMET offers a full range of testing systems to help you test surgical mesh and sutures with certainty. The following equipment is required to perform the tests described above:
- A machine frame and load cell capable of applying the amount of tensile force needed to bring the specimen to a full break. The eXpert 7600 and 2600 series machines satisfy this requirement for tension and elongation tests. Biaxial (torsion and tension) and planar biaxial(pulling of both axes simultaneously) frames are also available.
eXpert 7600 single column frame with pneumatic thread grips and MTESTQuattro (left). eXpert 2600 short version with webbing grips (right).
- A testing controller capable of pulling the sample at a specified rate, identify peak load, and record test data. Both MTESTQuattro PC-based controller and eP2 Digital controlleroffer this capability. Specialized versions of these controllers are available for biaxial and planar biaxial tests.
MTESTQuattro (left) eP2 Digital Controller (Right).
- A pair of grips or fixture that is able to securely hold your specimen. Special rope/thread grips are recommended for sutures. Web/ribbon grips can be used for long samples of mesh. Vice grips, available in both manual and pneumatic configurations, can be used for mesh. Self-tightening eccentric roller grips can be used to secure certain types of sutures and mesh. Specialized fixtures are available for performing planar biaxial tests.
(From left to right) Pneumatic thread grip, webbing/ribbon grip, manual vice grip, eccentric roller grip.
- A heating/cooling chamber and/or bath to simulate in-body product performance.
Heating chamber (left) Testing bath (right).