title: Development and evaluation of a device for simultaneous uniaxial compression and optical imaging of cartilage samples in vitro.
abstract: In this paper, we present a system that allows imaging of cartilage tissue via optical coherence tomography (OCT) during controlled uniaxial unconfined compression of cylindrical osteochondral cores in vitro. We describe the system design and conduct a static and dynamic performance analysis. While reference measurements yield a full scale maximum deviation of 0.14% in displacement, force can be measured with a full scale standard deviation of 1.4%. The dynamic performance evaluation indicates a high accuracy in force controlled mode up to 25 Hz, but it also reveals a strong effect of variance of sample mechanical properties on the tracking performance under displacement control. In order to counterbalance these disturbances, an adaptive feed forward approach was applied which finally resulted in an improved displacement tracking accuracy up to 3 Hz. A built-in imaging probe allows on-line monitoring of the sample via OCT while being loaded in the cultivation chamber. We show that cartilage topology and defects in the tissue can be observed and demonstrate the visualization of the compression process during static mechanical loading.
authors.affiliation: Department of Experimental Orthopaedics and Biomechanics, Philipps University Marburg, Baldingerstr., 35043 Marburg, Germany.
authors.forename: Marian
authors.initials: M
authors.lastname: Steinert
authors.affiliation: Department of Experimental Orthopaedics and Biomechanics, Philipps University Marburg, Baldingerstr., 35043 Marburg, Germany.
authors.forename: Marita
authors.initials: M
authors.lastname: Kratz
authors.affiliation: Photonics and Terahertz Technology, Ruhr University Bochum, Universitätsstr. 150, 44801 Bochum, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Jaedicke
authors.affiliation: Photonics and Terahertz Technology, Ruhr University Bochum, Universitätsstr. 150, 44801 Bochum, Germany.
authors.forename: Martin R
authors.initials: MR
authors.lastname: Hofmann
authors.affiliation: Department of Experimental Orthopaedics and Biomechanics, Philipps University Marburg, Baldingerstr., 35043 Marburg, Germany.
authors.forename: David B
authors.initials: DB
authors.lastname: Jones
mesh_terms: D002356:Cartilage; D004867:Equipment Design; D005240:Feasibility Studies; D055595:Mechanical Phenomena; D041623:Tomography, Optical Coherence / Q000295:instrumentation*; D016474:Weight-Bearing