How fatigue tests enhance medical product safety

Fatigue tests are an essential element in the development of durable, safe and reliable medical implants.

Prototypes undergo extensive testing before entering the validation process; Komet Medical, the surgical division of Gebr. Brasseler based in Lemgo, Germany, uses a Zwick testing machine with linear drive for these tests.

Komet Medical's core area of expertise lies in developing and manufacturing motor-powered precision tools for use in surgical drive systems. These include saw-blades, drills and high-speed milling cutters. This extensive know-how is now being channelled into Komet Medical's current implant development project.

Using a Zwick LTM linear testing machine (Fmax 5 kN), prototypes are checked in the Komet testing laboratory before moving on to the validation process. Dynamic tests are performed under cyclic loading and are used for determination of fatigue-limit values and for durability forecasts for the implants. Komet's testing requirements cover various standards. Tests carried out with the LTM include fatigue tests on spinal implants to ASTM F1717, dental implants to ISO 14801 and bone-screws to ASTM F1264.

The LTM is operated solely by electricity; no hydraulic or compressed air supplies are therefore needed in the laboratory. As well as dynamic tests, the testing machine can also be used for monotonic tests.

The Komet laboratory facility also features a zwickiLine materials testing machine (Fmax 5 kN) incorporating a torsion drive (Nmax 20 Nm). This allows the maximum fracture torques and insertion properties of bone-screws to be determined in accordance with ASTM F453. These two testing machines enable a wide range of relevant biomechanical and endoprosthetic test standards to be covered.