人体颈椎椎弓根钉与侧块钉轴向和切线方向生物力学研究以及与椎体骨密度相关性分析英文
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人体颈椎椎弓根钉与侧块钉轴向和切线方向生物力学研究以及与椎体骨密度相关性分析
第一军医大学珠江医院脊柱骨病科(广州510282) 吴广森 靳安民 袁岱军 于 博
第一军医大学解剖学教研室、生物力学实验室(510515) 吴玉鹏
[摘要]目的 研究中下颈椎椎弓根钉和侧块钉的固定强度与骨密度的相关性。方法 解离C3～C7骨块120个随机分为两组,测量每个椎体骨的松质骨密度,同一节段椎体随机配对置入椎弓根和侧块螺钉,在位移控制下分别测量位移控制下的平均最大拔出阻力和压力控制下的切向弹性与永久位移。结果 椎弓根钉的轴向平均最大拔出阻力明显高于侧块钉,切向弹性和固定位移则刚好相反(均P<0.01),在椎体松质骨密度<120mgHA/ml时椎弓根钉和侧块钉的轴向拔出阻力与其呈显著正相关(P<0.01),骨密度>120mg/ml2
HA时二者无相关性,而切线方向的永久位移和弹性位移与骨密度始终呈负相关。结论 椎弓根钉内固定较侧块钉具有更为优越的生物力学强度,二者与椎体松质骨密度有显著相关性。关键词 颈椎 椎弓根钉 侧块钉 生物力学 骨密度分类号 R318.01
BIOMECHANICALSTUDYOFPEDICLESCREWSVERSUSLATERALMASS
SEREWSINTHEMIDDLEANDLOWERCERVICALSPINE
WuGuangsen,YuanDaijun,YuBo,etal.
DepartmentofOthopaedicsinZhujiangHospitalofTheFirstMillitaryMedicalUniversity,510282
WuYupeng
DepartmentofAnatomyAndTheInsituteofBromecharucsoftheFirst
MillitaryMedicalUniversity,510515
[Abstract]Objective:Toanalyzethefixationstrengthofpediclescrewsversuslateralmassscrewsinthemilddleandlowercervicalspineandthecorrelationtovertebralbonemineraldensity.Methods:Onehundredandsixdisartic2ulatedhumanverebrae(C3～C7)wereevaluatedwithcomputedtomographytodeterminevertebralbonemineralden2sity.Pediclescrewsandlateralmassscrewswereinsertedtotheleftandrightatrandom.Screwswereloadedeitheraxiallystrictlylongitudinaltofailureorinacoronalplanestrictlyperpendiculartothelogitudinalaxis,thestrengthsanddisplacementswererecorded.Theclinicalapplicationwasalsoestimated.Results:Cervicalpediclescrewsdemon2stratedasignificantlyhigherresistancetopull-outforcethandidlateralmassscrews(P<0.01),buttheaveragetangentialelasticandpermanentdisplacementwasadverse(P<0.01).Ifbonemineraldensitywas<120mghy2droxyapatite/ml,thecorrelationwassignificant(P<0.01).Theclinicalpracticeswerenice.Conclusions:Pediclescrewswerebeneficialforinstrumentationofthecervicalspine,butthemoreaccurateskillsaretoneed.Keywords:CervicalSpine;PedicleScrew;LateralMassScrew;BiomechanicsClassificationNo:R318.01
TheuseofLateralmassscrewinternalfixation
instrumentsintreatingunstableanddisplacedcervical
spineisprevalent,especiallyinexpandingandshap2
ingofvertebralcanal,multi-segmentlaminectomy,
andintreatingprocessofthedamageorabsentof
spinousprocess,laminaofvertebra,articularpro2
cess.Thepracticeofpediclescrewinternalfixationisfewerbecauseoftherelativecomplexityofanatomic
structureinpedicleofcervicalvertebra.Wecan
browsesomereportsaboutthestrengthoflateral
massscrewsandpediclescrewsrespectively,butthe
studycomparingbiomechanicsbetweenthemis
scarce,especiallyintangentline.Thistestdeter2
minedthebiomechanicalstrengthsofcervicallateral
・5・第13卷第20期2003年10月 中国现代医学杂志ChinaJournalofModernMedicine Vol.13 No.20Oct.2003massscrewsandpediclescrews,didthecorrelated
analysestothebonemineraldensity,andevaluated
theclinicalapplicationofthem.
1 Trials
1.1 Materialsandmethods
24freezingfreshhumancadavericcervicalspines
(C3～C7)wereselectedfromtheanatomicresearch
instituteofthefirstmilitarymedicaluniversity,ex2
ceptforthatoffractures,tumorsordeformingbytakingphotosinanteroposterior,lateralandbi-slope
position.120freshdisarticulatedhumanvertebrae
wereharvestedafterpickingsofttissueandthemid2
dleofvertebraeswithstandardenergycomputerto2
mographyandcalculatedthevertebralbonemineral
density(unit:mgHA/ml)withinarectangularbox
(1mm×1.5mm)whichonlycontainscancellous
bone.Byaprincipleofpair-matchingatrandom,a
qualifiedtechnicianinsertedapediclescrewandalat2
eralmassscrew(Φ3.5mm,Sofamor-Danek,Mem2
phis,TN)onthetwosideofeveryvertebraeusing
techniqueofRoy-camilleandAbumirespectively.
Intheoperation,thestructuresof5pedicleofverte2
bra(C3×2,C4,C5,C7×1)and2lateralmasses(C7×2)weredestroyed,sothenumberoftestinggroups
wasset53.WithPhoenixMTIRoswellGAmaterial
testmachine,wepulledthescrewswiththeconstant
velocityof5mm/mininaxiallineandloadedwith
500Ninorthogonaltangentlineoftheinserted
screws,thecurvesofstrength-displacementwere
recordedandanalyzed.
1.2 Statistics
Thedatawasprocessedwiththesoftwareof
SPSS11.0,thebiomechanicalparameterwasevalu2
atedbyOne-wayANOVandLSD-tTest,andthe
correlationbetweenthevertebralbonemineraldensity
andthestrengthofthescrewawasanalyzedandesti2
matedwithlogisticregression.
2 Result
2.1 Theaverageofpulled-outpeakstrengthand
correspondingdisplacementinaxialline (Table1).
Wefoundthattheaverageofpulled-out
strengthofpediclescrews(617.1N)ishigherthan
lateralmassscrews(370.0N),thecorrespondingdis2
placementisthesame(P<0.01).Atsamesegment,thedifferencesofthepulled-outstrengthandthe
correspondingdisplacementbetweenpediclescrews
andlateralmassscrewsareallsignificant(P<
0.01).
Table1 Theaverageofpulled-outpeakstrengthandcorre2spondingdisplacementinaxialline (x±s)
SegmentNumberofvertebraePulled-outstrength(N)
PediclescrewlateralmassscrewMaximumofdisplacement(mm)PediclescrewlateralmassscrewC310550.9±175.2292.8±174.12)1.72±0.191.34±0.223)C411627.4±224.1393.0±198.51)1.73±0.101.36±0.243)C511696.0±151.4448.4±173.02)1.73±0.141.35±0.193)C612620.1±185.9393.9±160.72)1.74±0.141.34±0.183)C79577.6±198.8299.9±121.02)1.76±0.201.33±0.213)total53617.1±187.7370.0±172.72)1.73±0.151.35±0.203)
