gms | German Medical Science

Deutscher Kongress für Orthopädie und Unfallchirurgie
70. Jahrestagung der Deutschen Gesellschaft für Unfallchirurgie
92. Tagung der Deutschen Gesellschaft für Orthopädie und Orthopädische Chirurgie und
47. Tagung des Berufsverbandes der Fachärzte für Orthopädie

02. - 06.10.2006, Berlin

Pure Beta TCP for press fit fixation of the ACL-graft - biomechanical results of a sheep trial

Meeting Abstract

  • H.O. Mayr - Orthopädie, OCM-Clinic, München, Germany
  • A. Bernstein - Universitätsklinik für Orthopädie, Medizinische Fakultät der Martin-Luther-Universität Halle-W, Halle, Germany
  • M. Dietrich - Universitätsklinik für Orthopädie, Medizinische Fakultät der Martin-Luther-Universität Halle-W, Halle, Germany
  • F. Fraedrich - Universitätsklinik für Orthopädie, Medizinische Fakultät der Martin-Luther-Universität Halle-W, Halle, Germany
  • W. Hein - Universitätsklinik für Orthopädie, Medizinische Fakultät der Martin-Luther-Universität Halle-W, Halle, Germany

Deutscher Kongress für Orthopädie und Unfallchirurgie. 70. Jahrestagung der Deutschen Gesellschaft für Unfallchirurgie, 92. Tagung der Deutschen Gesellschaft für Orthopädie und Orthopädische Chirurgie und 47. Tagung des Berufsverbandes der Fachärzte für Orthopädie. Berlin, 02.-06.10.2006. Düsseldorf, Köln: German Medical Science; 2006. DocW.4.1.5-384

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/dgu2006/06dgu0576.shtml

Veröffentlicht: 28. September 2006

© 2006 Mayr 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 vervielf&aauml;ltigt, verbreitet und &oauml;ffentlich zug&aauml;nglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

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Purpose: To develop an osteoconductive dowel system made of micro porous pure beta-tricalcium phosphate (beta-TCP) cylinders for a press fit fixation of ACL-grafts with and without bone blocks. The purpose of this study was to investigate the biomechanical properties of ACL reconstruction using bone-to-bone and tendon-to-bone press fit fixation with TCP cylinders in a sheep trial.

Material and methods: 42 mature female merino sheep underwent ACL reconstruction using pure beta TCP cylinders for press fit fixation of the ACL-graft. They were divided into two equal groups. Animals with bone-tendon-bone (BTB) Patellar tendon graft and with tendon of superficial digital flexor M. (=Achilles tendon split graft). After 6, 12 and 24 weeks 7 animals of each group were euthanized. The anterior drawer test of the knees was performed at 50N. After removal of all soft tissue except the ACL the system was loaded until failure (single cycle loading test) in a tensiometer with a preload of 1 N and at a crosshead speed of 50mm/min. Failure mode, linear load, peak load, energy to failure and stiffness were recorded. The contralateral knees served for a control group. Results were analyzed by mean value, standard deviation, Mann-Whitney-U-test and T-test. Differences with p≤0.05 are significant.

Results: Time zero failure modes at BTB and Achilles tendon split graft were partial pull-out from the tibial tunnel combined with rupture of the transplant. At 6, 12 and 24 weeks all systems failed by rupture of the graft. None of the systems failed by pull out of the graft. The anterior drawer displacement of the contralateral knee was 0.97±0.58mm, of the BTB reconstruction 2.36±1.41mm at time zero, 3.99±0.56mm after 6 weeks, 1.74±0.79mm after 12 weeks and 1.27±0.56mm after 24 weeks, of the Achilles tendon split graft knee 2.25±0.88mm at time zero, 4.21±1.91mm after 6 weeks, 2.55±0.64mm after 12 weeks and 2.04±0.63mm after 24 weeks. The load to failure of the contralateral knee was 1935±264N, of the BTB reconstruction 373±87N at time zero, 244±58N after 6 weeks, 438±322N after 12 weeks and 505±146N after 24 weeks, of the Achilles tendon split graft knee 364±94N at time zero, 180±95N after 6 weeks, 238±133N after 12 weeks and 308±89N after 24 weeks. A significant difference between both systems was not seen at any time.

Conclusions: Press fit fixation with micro porous pure beta tricalcium phosphate cylinders of bone-tendon-bone (BTB) graft or Achilles tendon split graft for ACL reconstruction does not fail in the biomechanical testing after 6, 12 and 24 weeks. The weakest link of the reconstructed ACL is the transplant.

Prospect: The probability is that pure Beta TCP implants of 7 mm diameter will be replaced by bone. A radiological, histological und immunohistochemical analysis will follow.