File Download

There are no files associated with this item.

  Links for fulltext
     (May Require Subscription)
Supplementary

Article: The effects of cyclic loading on pull-out strength of sacral screw fixation: An in vitro biomechanical study

TitleThe effects of cyclic loading on pull-out strength of sacral screw fixation: An in vitro biomechanical study
Authors
KeywordsCyclic loading
Pull-out strength
Sacral screw fixation
Issue Date2000
PublisherLippincott, Williams & Wilkins. The Journal's web site is located at http://www.spinejournal.com
Citation
Spine, 2000, v. 25 n. 9, p. 1065-1069 How to Cite?
AbstractStudy Design. The pull-out strength of sacral screw fixation after cyclic loading was tested using young human cadaveric specimens. Objectives. To evaluate the effects of fatigue loading on the pull-out strength of medial and lateral unicortical and bicortical sacral screws and to correlate the pull-out strength with sacral bone density and the screw insertion torque. Summary of Background Data. The immediate biomechanical effects of depth of penetration, screw orientation, and bone density on sacral screw fixation have been studied in aged cadaveric specimens. The effect of cyclic loading on the pull-out strength of sacral screw fixation is unknown, however, and data from young specimens is rare. Methods. Eleven fresh specimens of human sacrum were used in this study. Bone mineral density at the vertebral body and the ala were determined by peripheral quantitative computed tomography. Seven-millimeter compact Cotrel-Dubousset sacral screws were inserted into the sacrum anteromedially and anterolaterally, both unicortically and bicortically, and the insertion torque for each screw was measured. Cyclic loading from 40 to 400 N was applied to each screw at a frequency of 2 Hz up to 20,000 cycles. Pull-out tests were conducted after completion of the fatigue tests. Results. The average bone density was 0.38 ± 0.08 g/mL at the S1 body and 0.24 ± 0 05 g/mL at the S1 ala. The insertion torque and average pull-out force after cyclic loading were significantly higher for bicortical fixation than for unicortical fixation for a particular screw alignment. The pull-out strength and insertion torque of medially oriented fixation was always higher than that for lateral fixation, however, regardless of whether the insertion was unicortical or bicortical. The pull-out force of unicortical and bicortical medial screw fixations after cyclic loading showed significant linear correlations with both the insertion torque and the bone mineral density of the S1 body. Conclusions. In a young population, screw orientation (anterolateral or anteromedial) was more important in determining pull-out strength than screw depth (unicortical or bicortical) after fatigue loading, anteromedially directed screws being significantly stronger than laterally placed screws. Bone mineral density of the S1 body andinsertion torque were good preoperative and intraoperative indicators of screw pull-out strength.
Persistent Identifierhttp://hdl.handle.net/10722/79390
ISSN
2015 Impact Factor: 2.439
2015 SCImago Journal Rankings: 1.459
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorZhu, Qen_HK
dc.contributor.authorLu, WWen_HK
dc.contributor.authorHolmes, ADen_HK
dc.contributor.authorZheng, Yen_HK
dc.contributor.authorZhong, Sen_HK
dc.contributor.authorLeong, JCYen_HK
dc.date.accessioned2010-09-06T07:54:09Z-
dc.date.available2010-09-06T07:54:09Z-
dc.date.issued2000en_HK
dc.identifier.citationSpine, 2000, v. 25 n. 9, p. 1065-1069en_HK
dc.identifier.issn0362-2436en_HK
dc.identifier.urihttp://hdl.handle.net/10722/79390-
dc.description.abstractStudy Design. The pull-out strength of sacral screw fixation after cyclic loading was tested using young human cadaveric specimens. Objectives. To evaluate the effects of fatigue loading on the pull-out strength of medial and lateral unicortical and bicortical sacral screws and to correlate the pull-out strength with sacral bone density and the screw insertion torque. Summary of Background Data. The immediate biomechanical effects of depth of penetration, screw orientation, and bone density on sacral screw fixation have been studied in aged cadaveric specimens. The effect of cyclic loading on the pull-out strength of sacral screw fixation is unknown, however, and data from young specimens is rare. Methods. Eleven fresh specimens of human sacrum were used in this study. Bone mineral density at the vertebral body and the ala were determined by peripheral quantitative computed tomography. Seven-millimeter compact Cotrel-Dubousset sacral screws were inserted into the sacrum anteromedially and anterolaterally, both unicortically and bicortically, and the insertion torque for each screw was measured. Cyclic loading from 40 to 400 N was applied to each screw at a frequency of 2 Hz up to 20,000 cycles. Pull-out tests were conducted after completion of the fatigue tests. Results. The average bone density was 0.38 ± 0.08 g/mL at the S1 body and 0.24 ± 0 05 g/mL at the S1 ala. The insertion torque and average pull-out force after cyclic loading were significantly higher for bicortical fixation than for unicortical fixation for a particular screw alignment. The pull-out strength and insertion torque of medially oriented fixation was always higher than that for lateral fixation, however, regardless of whether the insertion was unicortical or bicortical. The pull-out force of unicortical and bicortical medial screw fixations after cyclic loading showed significant linear correlations with both the insertion torque and the bone mineral density of the S1 body. Conclusions. In a young population, screw orientation (anterolateral or anteromedial) was more important in determining pull-out strength than screw depth (unicortical or bicortical) after fatigue loading, anteromedially directed screws being significantly stronger than laterally placed screws. Bone mineral density of the S1 body andinsertion torque were good preoperative and intraoperative indicators of screw pull-out strength.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.subjectCyclic loadingen_HK
dc.subjectPull-out strengthen_HK
dc.subjectSacral screw fixationen_HK
dc.titleThe effects of cyclic loading on pull-out strength of sacral screw fixation: An in vitro biomechanical studyen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0887-9869&volume=25&issue=9&spage=1065&epage=1069&date=2000&atitle=The+effects+of+cyclic+loading+on+pull-out+strength+of+sacral+screw+fixation:+an+in+vitro+biomechanical+studyen_HK
dc.identifier.emailLu, WW:wwlu@hku.hken_HK
dc.identifier.authorityLu, WW=rp00411en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1097/00007632-200005010-00005en_HK
dc.identifier.pmid10788849-
dc.identifier.scopuseid_2-s2.0-0034194437en_HK
dc.identifier.hkuros50179en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0034194437&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume25en_HK
dc.identifier.issue9en_HK
dc.identifier.spage1065en_HK
dc.identifier.epage1069en_HK
dc.identifier.isiWOS:000086978200004-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridZhu, Q=7403313141en_HK
dc.identifier.scopusauthoridLu, WW=7404215221en_HK
dc.identifier.scopusauthoridHolmes, AD=7401687268en_HK
dc.identifier.scopusauthoridZheng, Y=7404836971en_HK
dc.identifier.scopusauthoridZhong, S=8243008000en_HK
dc.identifier.scopusauthoridLeong, JCY=35560782200en_HK

Export via OAI-PMH Interface in XML Formats


OR


Export to Other Non-XML Formats