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Article: A stronger bicortical sacral pedicle screw fixation through the S1 endplate: An in vitro cyclic loading and pull-out force evaluation

TitleA stronger bicortical sacral pedicle screw fixation through the S1 endplate: An in vitro cyclic loading and pull-out force evaluation
Authors
KeywordsBicortical sacral screw fixation
Cyclic loading
Pull-out strength
Vertebral endplate
Issue Date2005
PublisherLippincott, Williams & Wilkins. The Journal's web site is located at http://www.spinejournal.com
Citation
Spine, 2005, v. 30 n. 5, p. 525-529 How to Cite?
AbstractStudy Design. The insertion torque and pull-out force after cyclic loading of the bicortical sacral pedicle screw through the S1 endplate were tested using human cadaveric specimens. Objectives. The purpose of this study was to (1) evaluate the effect of cyclic loading on the pull-out force of two different techniques of bicortical sacral pedicle screw fixation and (2) to correlate the pull-out force after cyclic loading with the screw insertion torque. Summary of Background Data. Biomechanical studies using conventional sacral pedicle screw fixation techniques have demonstrated reduction in stiffness and strength after cyclic loading. Technical difficulties with anterior sacral cortex penetration and frequent screw loosening have been reported in clinical studies. In the authors' center, a new method of sacral pedicle screw fixation bicortically through the S1 endplate has been used successfully in the clinical setting. However, the mechanical stability of this new technique after undergoing cyclic loading has not been documented in the literature. Methods. Seven-millimeter compact Cotrel-Dubousset sacral screws were randomly assigned by side (left vs. right) and inserted bicortically either anteromedially through the anterior sacral cortex or superiorly through the S1 endplate of 17 fresh frozen human sacrum. The tk;4maximum insertion torque for each screw was measured. Cyclic loading from 40 N to 400 N was applied to each screw at a frequency of 2 Hz for 20,000 cycles. Pull-out tests were conducted after completion of the cyclic tests. Results. The mean maximum insertion torque and mean pull-out force following cyclic loading were significantly higher for bicortical fixation through the S1 endplate (mean 3.17 N·m and 1457 N) than bicortical fixation through the anterior sacral cortex (mean 1.98 N·m and 1122 N). Both S1 endplate and anterior cortical fixation techniques demonstrated significant correlations between insertion torque and pull-out force following cyclic loading. Conclusions. In sacral pedicle screw fixation, screw trajectory through the S1 endplate was significantly stronger than screws penetrating the anterior sacral cortex. Insertion torque was a good intraoperative indicator of screw pull-out force after cyclic loading. © 2005, Lippincott Williams & Wilkins, Inc.
Persistent Identifierhttp://hdl.handle.net/10722/79316
ISSN
2015 Impact Factor: 2.439
2015 SCImago Journal Rankings: 1.459
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorLuk, KDKen_HK
dc.contributor.authorChen, Len_HK
dc.contributor.authorLu, WWen_HK
dc.date.accessioned2010-09-06T07:53:17Z-
dc.date.available2010-09-06T07:53:17Z-
dc.date.issued2005en_HK
dc.identifier.citationSpine, 2005, v. 30 n. 5, p. 525-529en_HK
dc.identifier.issn0362-2436en_HK
dc.identifier.urihttp://hdl.handle.net/10722/79316-
dc.description.abstractStudy Design. The insertion torque and pull-out force after cyclic loading of the bicortical sacral pedicle screw through the S1 endplate were tested using human cadaveric specimens. Objectives. The purpose of this study was to (1) evaluate the effect of cyclic loading on the pull-out force of two different techniques of bicortical sacral pedicle screw fixation and (2) to correlate the pull-out force after cyclic loading with the screw insertion torque. Summary of Background Data. Biomechanical studies using conventional sacral pedicle screw fixation techniques have demonstrated reduction in stiffness and strength after cyclic loading. Technical difficulties with anterior sacral cortex penetration and frequent screw loosening have been reported in clinical studies. In the authors' center, a new method of sacral pedicle screw fixation bicortically through the S1 endplate has been used successfully in the clinical setting. However, the mechanical stability of this new technique after undergoing cyclic loading has not been documented in the literature. Methods. Seven-millimeter compact Cotrel-Dubousset sacral screws were randomly assigned by side (left vs. right) and inserted bicortically either anteromedially through the anterior sacral cortex or superiorly through the S1 endplate of 17 fresh frozen human sacrum. The tk;4maximum insertion torque for each screw was measured. Cyclic loading from 40 N to 400 N was applied to each screw at a frequency of 2 Hz for 20,000 cycles. Pull-out tests were conducted after completion of the cyclic tests. Results. The mean maximum insertion torque and mean pull-out force following cyclic loading were significantly higher for bicortical fixation through the S1 endplate (mean 3.17 N·m and 1457 N) than bicortical fixation through the anterior sacral cortex (mean 1.98 N·m and 1122 N). Both S1 endplate and anterior cortical fixation techniques demonstrated significant correlations between insertion torque and pull-out force following cyclic loading. Conclusions. In sacral pedicle screw fixation, screw trajectory through the S1 endplate was significantly stronger than screws penetrating the anterior sacral cortex. Insertion torque was a good intraoperative indicator of screw pull-out force after cyclic loading. © 2005, Lippincott Williams & Wilkins, Inc.en_HK
dc.languageengen_HK
dc.publisherLippincott, Williams & Wilkins. The Journal's web site is located at http://www.spinejournal.comen_HK
dc.relation.ispartofSpineen_HK
dc.rightsThis is a non-final version of an article published in final form in (provide complete journal citation)-
dc.subjectBicortical sacral screw fixationen_HK
dc.subjectCyclic loadingen_HK
dc.subjectPull-out strengthen_HK
dc.subjectVertebral endplateen_HK
dc.subject.meshAdult-
dc.subject.meshBone Screws-
dc.subject.meshInternal Fixators-
dc.subject.meshSacrum - physiology-
dc.subject.meshSpinal Fusion - instrumentation - methods-
dc.titleA stronger bicortical sacral pedicle screw fixation through the S1 endplate: An in vitro cyclic loading and pull-out force evaluationen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0362-2436&volume=30&issue=5&spage=525&epage=529&date=2005&atitle=A+stronger+bicortical+sacral+pedicle+screw+fixation+through+the+s1+endplate:+an+in-vitro+cyclic+loading+and+pull-out+force+evaluationen_HK
dc.identifier.emailLuk, KDK:hcm21000@hku.hken_HK
dc.identifier.emailLu, WW:wwlu@hku.hken_HK
dc.identifier.authorityLuk, KDK=rp00333en_HK
dc.identifier.authorityLu, WW=rp00411en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1097/01.brs.0000154649.55589.bfen_HK
dc.identifier.pmid15738784-
dc.identifier.scopuseid_2-s2.0-14344261941en_HK
dc.identifier.hkuros101723en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-14344261941&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume30en_HK
dc.identifier.issue5en_HK
dc.identifier.spage525en_HK
dc.identifier.epage529en_HK
dc.identifier.isiWOS:000227323000007-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridLuk, KDK=7201921573en_HK
dc.identifier.scopusauthoridChen, L=8299798100en_HK
dc.identifier.scopusauthoridLu, WW=7404215221en_HK

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