Alexandra Neddermann

Publications (2)6.63 Total impact

• Article: The relation between tunnel widening and bone mineral density after anterior cruciate ligament reconstruction: an experimental study in sheep.

  Rupert Meller, Alexandra Neddermann, Elmar Willbold, Eric Hesse, Carl Haasper, Anshu Singh, Karsten Knobloch, Christian Krettek, Stefan Hankemeier
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  ABSTRACT: The aim of this study was to analyze the relation between bone mineral density (BMD) and femoral tunnel enlargement (TE) in a previously validated sheep model of soft-tissue anterior cruciate ligament (ACL) reconstruction. Thirty sheep underwent ACL reconstruction by use of a soft-tissue graft at the age of 4 months. Graft fixation was achieved with the EndoButton (Smith & Nephew Endoscopy, Andover, MA) and Suture Washer (Smith & Nephew Endoscopy). Six animals were killed at 0, 3, 6, 12, and 24 weeks postoperatively. Each ACL-reconstructed knee was examined both by computed tomography to analyze the bone tunnel cross-sectional area and by dual-energy x-ray absorptiometry to analyze BMD. There was a significant increase in tunnel cross-sectional area. BMD decreased significantly within the first 3 weeks after surgery and increased thereafter. A positive correlation between TE and BMD was found. However, a subgroup analysis showed that there is no influence of BMD on the development of a tunnel widening. The hypothesis that a TE would be associated with a loss in BMD was not confirmed. Tunnel widening during the first 6 months after ACL reconstruction is not affected by the transient changes in BMD. There is no correlation between TE and BMD in an experimental sheep model of ACL reconstruction. Translational investigations will determine whether this is also true in humans.
  Arthroscopy The Journal of Arthroscopic and Related Surgery 04/2010; 26(4):481-7. · 3.02 Impact Factor
• Article: Tunnel widening after anterior cruciate ligament reconstruction: an experimental study in sheep.

  Alexandra Neddermann, Elmar Willbold, Frank Witte, Christof Hurschler, Stefan Hankemeier, Timo Stübig, Eric Hesse, Michael Fehr, Christian Krettek, Rupert Meller
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  ABSTRACT: A common clinical concern after anterior cruciate ligament reconstruction is the expansion of the bone tunnels as seen radiographically. The etiology and clinical relevance of this phenomenon remain unclear. Tunnel widening results in an increased anteroposterior translation, and there are specific histologic changes due to osteoclastic bone resorption associated with this phenomenon. Controlled laboratory study. Thirty sheep (age, 4 months) underwent an anterior cruciate ligament reconstruction using a soft tissue graft. Graft fixation was achieved using the EndoButton and Suture Washer. Six animals each were sacrificed at 0, 3, 6, 12, and 24 weeks after surgery. Each anterior cruciate ligament-reconstructed knee was examined by computed tomography. Anteroposterior translation was determined using a universal force-moment sensor robot. The bone surrounding the tunnel was evaluated histologically. RESULTS The prevalence of tunnel enlargement on the femoral side was 77.3%. Animals with tunnel widening did not demonstrate increased anteroposterior translation. Widening of the femoral tunnel was significantly associated with a higher stiffness of the graft (P < .05) and hypertrophy of the graft throughout the remodeling process. The histologic evaluation of the bone tunnel walls demonstrated an increase of bone volume in animals with tunnel enlargement. No statistically significant correlation could be found between the number of osteoclasts and the presence of tunnel widening. In this large animal model of anterior cruciate ligament reconstruction, animals with significant tunnel widening did not suffer increased anteroposterior translation. Tunnel widening was associated with a high stiffness of the graft, graft hypertrophy, and an increase in bone volume of the tunnel wall. The present data correspond to the current opinion in humans that tunnel widening is not associated with knee instability. Further research is needed to understand the role of graft stiffness, graft hypertrophy, and the increase in bone volume in this phenomenon.
  The American journal of sports medicine 04/2009; 37(8):1609-17. · 3.61 Impact Factor