gms | German Medical Science

Deutscher Kongress für Orthopädie und Unfallchirurgie
74. Jahrestagung der Deutschen Gesellschaft für Unfallchirurgie
96. Tagung der Deutschen Gesellschaft für Orthopädie und Orthopädische Chirurgie
51. Tagung des Berufsverbandes der Fachärzte für Orthopädie und Unfallchirurgie

26. - 29.10.2010, Berlin

Biomechanical evaluation of a new non-fusion instrumentation of the lumbar spine

Meeting Abstract

Suche in Medline nach

  • W. Schmölz - Medizinische Universität Innsbruck, Universitätsklinik für Unfallchirurgie u. Sporttraumatologie, Innsbruck, Austria
  • S. Erhart - Medizinische Universität Innsbruck, Universitätsklinik für Unfallchirurgie u. Sporttraumatologie, Innsbruck, Austria
  • S. Unger - Medizinische Universität Innsbruck, Universitätsklinik für Unfallchirurgie u. Sporttraumatologie, Innsbruck, Austria
  • H.-J. Leu - Privatklinikum Bethanien, Spine base, Zürich, Switzerland

Deutscher Kongress für Orthopädie und Unfallchirurgie. 74. Jahrestagung der Deutschen Gesellschaft für Unfallchirurgie, 96. Tagung der Deutschen Gesellschaft für Orthopädie und Orthopädische Chirurgie, 51. Tagung des Berufsverbandes der Fachärzte für Orthopädie. Berlin, 26.-29.10.2010. Düsseldorf: German Medical Science GMS Publishing House; 2010. DocIN16-167

DOI: 10.3205/10dkou091, URN: urn:nbn:de:0183-10dkou0915

Veröffentlicht: 21. Oktober 2010

© 2010 Schmölz et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielfältigt, verbreitet und öffentlich zugänglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Objective: Since the introduction of the Dynesys system as posterior dynamic instrumentation of the lumbar spine numerous new non-fusion or dynamic instrumentation systems were developed. In this study the biomechanically investigated implant system, called Elaspine (Spinelab AG, Winterthur, Switzerland), is compromised of pedicle screws and a clip mechanism connecting to a PCU rod with a 360° form-fit. Hence, the relatively rigid PET cord to transmit tensile loads through the implant is not required. Therefore, the device is expected to be more flexible and to allow more motion. The aim of the study was to evaluate the range of motion (RoM) of Elaspine in the three main motion planes and compare it to published data of the Dynesys system.

Methods: Six fresh frozen lumbar spine specimens (L2-5, age 62.2±12.7) were loaded in a spine tester with pure moments of 7.5 Nm in lateral bending, flexion/extension and axial rotation. The tested states of the specimens were: intact (a), instrumentation of L3-4 with Elaspine (Spinelab AG, Winterthur, Switzerland) (b), nucleotomy L3-4 (c) and instrumentation of L3-4 with Elaspine after nucleotomy (d). The segmental RoM in each of the three motion planes was evaluated.

Results and conclusions: The instrumentation of the intact segment (b) significantly reduced the RoM (p<0.002) in flexion, extension and lateral bending to 37.7, 44.6 and 53% of the intact state, respectively. In axial rotation the instrumentation resulted in a non significant RoM reduction to 95% of the intact state. The nucleotomy (c) caused a significant instability compared to the intact state in all motion planes (128–143% of intact, p<0.05). Compared to the intact segment, instrumentation of the defect (d) significantly (p>0.05) reduced the RoM to 69.8, 62.3 and 79.1% in flexion, extension and lateral bending, respectively. In axial rotation the instrumented segment showed a significantly higher RoM than the intact segment (137.6% of the intact state (p<0.01)).

The tested non-fusion implant reduced the RoM in all motion planes except in axial rotation. Compared to data published about the Dynesys system, the Elaspine implant allowed more motion in flexion/extension and lateral bending while still limiting the RoM compared to the intact state. However, in axial rotation both implants did not reduce the increased RoM caused by a nucleotomy back to the range of the intact motion segment.