Hochdynamisches Prüfsystem zur biomechanischen Charakterisierung von Knorpel und seinen Regeneraten

Abstract

Articular cartilage repair methods, in particular scaffold-based autologous chondrocyte implantation, are already in clinical use. In the coming years, the European guidelines on human cell-based medicinal products by the European Medical Agency (EMA) will extend today's quality control mechanisms by additional structural analyses. As articular cartilage has complex biphasic and viscoelastic mechanical properties, a high-performance material test system is required and has already been implemented. To characterize the recovery of cartilage and cartilage replacement materials, it is necessary to measure the dynamic recovery profile. A measurement system for an application like this requires an axis acceleration of more then 50 m/s(2). Furthermore, the test system needs custom-made components to fix the biological specimen while testing. A software package consisting of a graphical user interface and an axis controller leads to highly reproducible tests. The software makes use of a position and velocity controller as well as a force controller at kilohertz speed. While using the high performance force controller it is possible to apply static and dynamic loading profiles that are independent from position or speed set points and signals.

Instruments for reproducible setting of defects in cartilage and harvesting of osteochondral plugs for standardisation of preclinical tests for articular cartilage regeneration

“…Samples for biomechanical and other tests have to be of a specific size, depending on the test procedure. Several biomechanical tests require samples of a size varying between 4 mm [ 24 ] and 6 mm [ 4 ] in diameter. Therefore, large animal models have an advantage over small ones in this context also for measuring the outcome in osteoarthritis (OA) research [ 25 ].…”

Biomechanical Properties of Repair Cartilage Tissue Are Superior Following Microdrilling Compared to Microfracturing in Critical Size Cartilage Defects

“…Biomechanical analysis. All biomechanical analyses were performed with a custom-built dynamic indentor test system with a cylindrical indentor (d=0.8 mm) and a measurement threshold of less than 5 mN, as previously published (14). Initially, specimens were thawed in phosphate buffered saline (PBS) at room temperature for 30 min and subsequently fixed in a test chamber on a freely tiltable table, which, in combination with a high resolution 2-camera video system, facilitated a perfect horizontal alignment of the region of interest within the defect.…”

“…Cartilage thickness can be measured either by optical determination, needle indentation or ultrasound (30). As the first two methods are destructive and the latter is dependent on the tide marker not necessarily present in regenerated cartilage (31), we established a protocol to measure the thickness via microindentation (14). With that, the measured thickness of native cartilage was in the expected range for sheep (26,32).…”

3D grating-based X-ray phase-contrast computed tomography for high-resolution quantitative assessment of cartilage: An experimental feasibility study with 3T MRI, 7T MRI and biomechanical correlation

“…Cartilage stiffness measurements were conducted to verify that healthy and degenerated specimens provide a different mechanical behavior. This experimental verification was performed using a custom-made micro-indentation system (Fig 1A) [21]. The samples were clamped at their bone part by a rigid holder and the cartilage surface was individually aligned perpendicular to the indentation axis.…”