caa a22 4500 445834935 CHVBK 20190416140711.0 cr unu---uuuuu 170323e20110201xx s 000 0 eng 10.1007/s00586-010-1620-6 doi (NATIONALLICENCE)springer-10.1007/s00586-010-1620-6 The effect of design parameters of dynamic pedicle screw systems on kinematics and load bearing: an in vitro study [Elektronische Daten] [C. Schilling, S. Krüger, T. Grupp, G. Duda, W. Blömer, A. Rohlmann] As an alternative treatment for chronic back pain due to disc degeneration motion preserving techniques such as posterior dynamic stabilization (PDS) has been clinically introduced, with the intention to alter the load transfer and the kinematics at the affected level to delay degeneration. However, up to the present, it remains unclear when a PDS is clinically indicated and how the ideal PDS mechanism should be designed to achieve this goal. Therefore, the objective of this study was to compare different PDS devices against rigid fixation to investigate the biomechanical impact of PDS design on stabilization and load transfer in the treated and adjacent cranial segment. Six human lumbar spine specimens (L3-L5) were tested in a spine loading apparatus. In vitro flexibility testing was performed by applying pure bending moments of 7.5Nm without and with additional preload of 400N in the three principal motion planes. Four PDS devices, "DYN” (Dynesys®, Zimmer GmbH, Switzerland), "DSS™” (Paradigm Spine, Wurmlingen, Germany), and two prototypes of dynamic rods, "LSC” with a leaf spring, and "STC” with a spring tube (Aesculap AG, Tuttlingen, Germany), were tested in comparison to a rigid fixation device S4 (Aesculap AG, Tuttlingen, Germany) "RIG”, to the native situation "NAT” and to a defect situation "DEF” of the specimens. The instrumented level was L4-L5. The tested PDS devices comprising a stiffness range for axial stiffness of 10N/mm to 230N/mm and for bending stiffness of 3N/mm to 15N/mm. Range of motion (ROM), neutral zone (NZ), and intradiscal pressure (IDP) were analyzed for all instrumentation steps and load cases of the instrumented and non-instrumented level. In flexion, extension, and lateral bending, all systems, except STC, showed a significant reduction of ROM and NZ compared to the native situation (p<0.05). Furthermore, we found no significant difference between DYN and RIG (p>0.1). In axial rotation, only DSS and STC reduced the ROM significantly (p<0.005) compared to the native situation, whereas DYN and LSC stayed at the level of the native intersegmental rotation (p>0.05). A correlation was found between axial stiffness and intersegmental stabilization in the sagittal and frontal plane, but not in the transversal plane where intersegmental stabilization is mainly governed by the systems' ability to withstand shear loads. Furthermore, we observed the systems' capacity to reduce IDP in the treated segment. The adjacent segment does not seem to be affected by the stiffness of the fixation device under the described loading conditions. Springer-Verlag, 2010 Dynamic pedicle screw system nationallicence Kinematics nationallicence Intradiscal pressure nationallicence Biomechanics nationallicence Spine nationallicence Schilling C. Research and Development, Biomechanical Research, Aesculap AG, Am Aesculap Platz, 78532, Tuttlingen, Germany aut Krüger S. Research and Development, Biomechanical Research, Aesculap AG, Am Aesculap Platz, 78532, Tuttlingen, Germany aut Grupp T. Research and Development, Biomechanical Research, Aesculap AG, Am Aesculap Platz, 78532, Tuttlingen, Germany aut Duda G. Julius Wolff Institute and Berlin-Brandenburg Center for Regenerative Therapies, Charité, Universitätsmedizin Berlin, Berlin, Germany aut Blömer W. Research and Development, Biomechanical Research, Aesculap AG, Am Aesculap Platz, 78532, Tuttlingen, Germany aut Rohlmann A. Julius Wolff Institute and Berlin-Brandenburg Center for Regenerative Therapies, Charité, Universitätsmedizin Berlin, Berlin, Germany aut European Spine Journal Springer-Verlag 20/2(2011-02-01), 297-307 0940-6719 20:2<297 2011 20 586 https://doi.org/10.1007/s00586-010-1620-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00586-010-1620-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Schilling C. Research and Development, Biomechanical Research, Aesculap AG, Am Aesculap Platz, 78532, Tuttlingen, Germany aut NATIONALLICENCE 700 1- Krüger S. Research and Development, Biomechanical Research, Aesculap AG, Am Aesculap Platz, 78532, Tuttlingen, Germany aut NATIONALLICENCE 700 1- Grupp T. Research and Development, Biomechanical Research, Aesculap AG, Am Aesculap Platz, 78532, Tuttlingen, Germany aut NATIONALLICENCE 700 1- Duda G. Julius Wolff Institute and Berlin-Brandenburg Center for Regenerative Therapies, Charité, Universitätsmedizin Berlin, Berlin, Germany aut NATIONALLICENCE 700 1- Blömer W. Research and Development, Biomechanical Research, Aesculap AG, Am Aesculap Platz, 78532, Tuttlingen, Germany aut NATIONALLICENCE 700 1- Rohlmann A. Julius Wolff Institute and Berlin-Brandenburg Center for Regenerative Therapies, Charité, Universitätsmedizin Berlin, Berlin, Germany aut NATIONALLICENCE 773 0- European Spine Journal Springer-Verlag 20/2(2011-02-01), 297-307 0940-6719 20:2<297 2011 20 586 Metadata rights reserved Springer special CC-BY-NC licence nationallicence SWISSBIB 445834935 BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer