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Article: Comparison of the strengths of lumbosacral fixation achieved with techniques using one and two triangulated sacral screws

TitleComparison of the strengths of lumbosacral fixation achieved with techniques using one and two triangulated sacral screws
Authors
KeywordsBiomechanics
Lumbosacral fixation
Pedicle screw
Sacrum
Issue Date1998
PublisherLippincott, Williams & Wilkins. The Journal's web site is located at http://www.spinejournal.com
Citation
Spine, 1998, v. 23 n. 21, p. 2289-2294 How to Cite?
AbstractStudy Design. The strength of sacral screw fixation achieved with techniques using one sacral screw and two triangulated sacral screws with Chopin block was tested on 10 fresh human sacrum specimens. Objectives. To compare the stiffness and the failure strength of single sacral screw fixation and those of two divergent triangulated sacral screw fixation under different loading conditions. Summary of Background Data. Weak sacral screw fixation is the major cause of failure in instrumented lumbosacral fusion. Although previous studies have evaluated the strength of anteromedially and anterolaterally inserted sacral screws, the strength of two divergent triangulated sacral screws has not been evaluated biomechanically. It is assumed that increasing the number of sacral screws and using a triangulated insertion technique may increase the strength of purchase for lumbosacral fixation. Methods. Ten fresh human sacrum specimens were used in this study. Six specimens were from donors less than 30 years of age (younger group), and the other four were from donors more than 60 years of age (aged group). The specimens were assigned randomly to either one side with one S1 pedicle screw inserted anteromedially or to the other side with two screws directed anteromedially and anterolaterally. All specimens were tested with an Instron material testing machine (Instron Limited, High Wycombe, England). The average stiffness under compression, tension, and torsion were calculated from the average slopes of the load deformation curves. The failure load was applied for the final testing. Results. The results showed significant differences in stiffness between fixation with one screw and fixation with two divergent triangulated screws. With one S1 pedicle screw fixation, the average stiffness was 203 N/mm for compression, 147 N/mm for tension, and 2 Nm/°for torsion. With two-screw fixation, the average stiffness increased to 255 N/mm (126%), 185 N/mm (126%) and 2.4 Nm/°(120%), respectively. The average failure strength under tension loads was found to be 1450 N in the younger specimens and was reduced to 980 N in the aged specimens. Conclusion. This study showed that fixation with two divergent triangulated screws to the sacrum was significantly stronger than one-screw fixation for lumbosacral fusion. The strength of fixation seems to have a negative correlation with aging.
Persistent Identifierhttp://hdl.handle.net/10722/79579
ISSN
2015 Impact Factor: 2.439
2015 SCImago Journal Rankings: 1.459
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorLeong, JCYen_HK
dc.contributor.authorLu, WWen_HK
dc.contributor.authorZheng, Yen_HK
dc.contributor.authorZhu, Qen_HK
dc.contributor.authorZhong, Sen_HK
dc.date.accessioned2010-09-06T07:56:15Z-
dc.date.available2010-09-06T07:56:15Z-
dc.date.issued1998en_HK
dc.identifier.citationSpine, 1998, v. 23 n. 21, p. 2289-2294en_HK
dc.identifier.issn0362-2436en_HK
dc.identifier.urihttp://hdl.handle.net/10722/79579-
dc.description.abstractStudy Design. The strength of sacral screw fixation achieved with techniques using one sacral screw and two triangulated sacral screws with Chopin block was tested on 10 fresh human sacrum specimens. Objectives. To compare the stiffness and the failure strength of single sacral screw fixation and those of two divergent triangulated sacral screw fixation under different loading conditions. Summary of Background Data. Weak sacral screw fixation is the major cause of failure in instrumented lumbosacral fusion. Although previous studies have evaluated the strength of anteromedially and anterolaterally inserted sacral screws, the strength of two divergent triangulated sacral screws has not been evaluated biomechanically. It is assumed that increasing the number of sacral screws and using a triangulated insertion technique may increase the strength of purchase for lumbosacral fixation. Methods. Ten fresh human sacrum specimens were used in this study. Six specimens were from donors less than 30 years of age (younger group), and the other four were from donors more than 60 years of age (aged group). The specimens were assigned randomly to either one side with one S1 pedicle screw inserted anteromedially or to the other side with two screws directed anteromedially and anterolaterally. All specimens were tested with an Instron material testing machine (Instron Limited, High Wycombe, England). The average stiffness under compression, tension, and torsion were calculated from the average slopes of the load deformation curves. The failure load was applied for the final testing. Results. The results showed significant differences in stiffness between fixation with one screw and fixation with two divergent triangulated screws. With one S1 pedicle screw fixation, the average stiffness was 203 N/mm for compression, 147 N/mm for tension, and 2 Nm/°for torsion. With two-screw fixation, the average stiffness increased to 255 N/mm (126%), 185 N/mm (126%) and 2.4 Nm/°(120%), respectively. The average failure strength under tension loads was found to be 1450 N in the younger specimens and was reduced to 980 N in the aged specimens. Conclusion. This study showed that fixation with two divergent triangulated screws to the sacrum was significantly stronger than one-screw fixation for lumbosacral fusion. The strength of fixation seems to have a negative correlation with aging.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.subjectBiomechanicsen_HK
dc.subjectLumbosacral fixationen_HK
dc.subjectPedicle screwen_HK
dc.subjectSacrumen_HK
dc.titleComparison of the strengths of lumbosacral fixation achieved with techniques using one and two triangulated sacral screwsen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0887-9869&volume=23&issue=21&spage=2289&epage=2294&date=1998&atitle=Comparison+of+the+strengths+of+lumbosacral+fixation+achieved+with+techniques+using+one+and+two+triangulated+sacral+screwsen_HK
dc.identifier.emailLu, WW:wwlu@hku.hken_HK
dc.identifier.authorityLu, WW=rp00411en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1097/00007632-199811010-00008en_HK
dc.identifier.pmid9820908-
dc.identifier.scopuseid_2-s2.0-0032213850en_HK
dc.identifier.hkuros42235en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0032213850&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume23en_HK
dc.identifier.issue21en_HK
dc.identifier.spage2289en_HK
dc.identifier.epage2294en_HK
dc.identifier.isiWOS:000076828300007-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridLeong, JCY=35560782200en_HK
dc.identifier.scopusauthoridLu, WW=7404215221en_HK
dc.identifier.scopusauthoridZheng, Y=7404836971en_HK
dc.identifier.scopusauthoridZhu, Q=7403313141en_HK
dc.identifier.scopusauthoridZhong, S=8243008000en_HK

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