David Grevenstein1, Carolin Meyer2, Kilian Wegmann3, Michael Hackl4, Jan Bredow5, Peer Eysel6, Andreas Prescher7, Max J Scheyerer8. 1. Department for Orthopaedic and Trauma Surgery, Faculty of Medicine, University Hospital of Cologne, Joseph-Stelzmann Strasse 24, 50931 Cologne, Germany. Electronic address: david.grevenstein@uk-koeln.de. 2. Department for Orthopaedic and Trauma Surgery, Faculty of Medicine, University Hospital of Cologne, Joseph-Stelzmann Strasse 24, 50931 Cologne, Germany. Electronic address: carolin.meyer@uk-koeln.de. 3. Department for Orthopaedic and Trauma Surgery, Faculty of Medicine, University Hospital of Cologne, Joseph-Stelzmann Strasse 24, 50931 Cologne, Germany. Electronic address: kilian.wegmann@uk-koeln.de. 4. Department for Orthopaedic and Trauma Surgery, Faculty of Medicine, University Hospital of Cologne, Joseph-Stelzmann Strasse 24, 50931 Cologne, Germany. Electronic address: michael.hackl@uk-koeln.de. 5. Department for Orthopaedic and Trauma Surgery, Faculty of Medicine, University Hospital of Cologne, Joseph-Stelzmann Strasse 24, 50931 Cologne, Germany. Electronic address: jan.bredow@uk-koeln.de. 6. Department for Orthopaedic and Trauma Surgery, Faculty of Medicine, University Hospital of Cologne, Joseph-Stelzmann Strasse 24, 50931 Cologne, Germany. Electronic address: peer.eysel@uk-koeln.de. 7. Institute of Molecular and Cellular Anatomy, University Hospital Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany. Electronic address: aprescher@ukaachen.de. 8. Department for Orthopaedic and Trauma Surgery, Faculty of Medicine, University Hospital of Cologne, Joseph-Stelzmann Strasse 24, 50931 Cologne, Germany. Electronic address: max.scheyerer@uk-koeln.de.
Abstract
BACKGROUND: Bicortical screw fixation is an established technique to increase screw strength in vertebral bodies, although it is associated with several complications, for example screw-loosening. Cement augmentation can increase stability of screw-fixation but can also cause various complications, such as cement-leakage or cement embolism. In this study, we tested a new, multicortical screw fixation technique in the sacrum. METHODS: Four fresh-frozen sacrums were used. In group 1, standard screw insertion, with sagittal parallel and axial convergent screw-drive was performed. In group 2, the screw-drive of the first screw was similar to the screw-drive in group 1. In addition, a second screw was inserted descending into the intended hole in the head of the screw and at a stable angle. Therefore, the screws of the multiloc humerus nail-system (Synthes) were used. The specimens were connected to a testing-machine and underwent cyclic axial loading with an increase in the load after each completed stage. FINDINGS: Multicortical screw fixation leads to a significant increase in the number of completed cycles and a significantly increased load until failure. INTERPRETATION: Multicortical screw fixation in the sacrum offers a stronger attachment of the screws. In the future, multicortical implants, which fulfil the criteria demanded in spine surgery, can offer higher stability and may decrease the loosening rates of the implanted screws.
BACKGROUND: Bicortical screw fixation is an established technique to increase screw strength in vertebral bodies, although it is associated with several complications, for example screw-loosening. Cement augmentation can increase stability of screw-fixation but can also cause various complications, such as cement-leakage or cement embolism. In this study, we tested a new, multicortical screw fixation technique in the sacrum. METHODS: Four fresh-frozen sacrums were used. In group 1, standard screw insertion, with sagittal parallel and axial convergent screw-drive was performed. In group 2, the screw-drive of the first screw was similar to the screw-drive in group 1. In addition, a second screw was inserted descending into the intended hole in the head of the screw and at a stable angle. Therefore, the screws of the multiloc humerus nail-system (Synthes) were used. The specimens were connected to a testing-machine and underwent cyclic axial loading with an increase in the load after each completed stage. FINDINGS: Multicortical screw fixation leads to a significant increase in the number of completed cycles and a significantly increased load until failure. INTERPRETATION: Multicortical screw fixation in the sacrum offers a stronger attachment of the screws. In the future, multicortical implants, which fulfil the criteria demanded in spine surgery, can offer higher stability and may decrease the loosening rates of the implanted screws.