The Institute for Surgical Technology and Biomechanics (ISTB) consists of multi-disciplinary research groups which collaborate with clinicians from the university hospital, and with both Swiss and international research partners from outside the university. The Musculoskeletal Biomechanics research group is interested in the hierarchical mechanical properties of human bones which are responsible for an increased risk of fracture in an aging population, particularly with diseases such as osteoporosis.
The aims of this research are to achieve a better understanding of the relationships between the structure and function of bone tissue on multiple scales and to validate simulation models based on computer tomography. Models of this type can in turn quantify the effectiveness of anti-osteoporosis medications.
For the various mechanical tests performed on animal or human bone in the ISTB research laboratory the research group, headed by Philippe Zysset, uses a servo-hydraulic testing machine equipped with a compact ZwickRoell laser extensometer, providing non-contact, high-precision strain measurement at a resolution of 0.04 µm. This represents an indispensable addition to the Institute's state-of-the-art biomechanical testing environment.
Bone specimens are subjected to tensile, compression and torsion loads in order to localize strains and quantify plastic strains. Philippe Zysset emphasizes the fact that movements represent the greatest source of error in tests of this type; non-contact measurement using ZwickRoell's laserXtens provides the anticipated accuracy without damaging the specimen (Accuracy Class 0.5 according to EN ISO 9513). The signal from the extensometer can be used for strain-controlled tests on their existing testing machine, thereby satisfying one of the scientists' key requirements. With the optical extensometer attached to their testing system, test preparation is simple and time-saving, a clear demonstration that ZwickRoell possesses the necessary flexibility to achieve the optimum solution for its customers.
The first research results from the current ISTB projects at the University of Bern are eagerly awaited. We would like to thank Philippe Zysset of ISTB at the University of Bern for his contribution.