The Design And Related Study Of Adjustable Hollow Titanium Artificial Vertebral Body

Objective: A adjustabIe hollow ntanium artificial vertebral body(AHT-AV8) were designed to enhance the abiIity of AVB inreconstruCtion of vertebral body shape, reStoration of spinaIsegment height and possibiIity of Ione4erm bone fusion, as welI asto decrease the difficulty of procedure when impIanting theprosthesis. The biomechanics, hiStoIogy and clinical application ofthe AHT-AVB were inveStigated.Methods: AHT-AVB for cervical, thoracic and lumbar spine fOrChinese human being were designed and manufaCtured, theirbiomechanics, histoIogics and clinicaI appIication were studied.This study was divided into fOur parts. Part one; The design ofAHTMB. On basis of Iiterature, the size of AHTMB fOr Chinesewas obtained and protOtype of AHT-AVB was manufaCtured withTitanium aIloy. The materiaI and funCtionaI charaCteriStic Of AHT-AVB were also described. Part tWo is fOr biomechanical study ofAHTWB. This part consists of two experiments. One was forevaIuating spinaI Stability of bovine spine construCt using differentimpIants. 27 bovine thorathic-Iumbar spine were randomIy dividedinto three groups, which were controI group, iIiac bone graff groupand AHT-AVB group. The Stress, dispIacement, Strength, Stiffnessand uItimate Strength of the spinal construCt were t6sted under flex,eXtension, left and right bending, torsion respeCtively. The resuItswere statisticalIy anaIyzed. Experiments tWo was for evaIuation ofdiff6rent implanting position of AHT-AVB to the spinaI construCtbiomechanical behavior. The AHT-AVB were impIanted in theneutraI, IateraI, anterioF, posterior and obIique position, their Stress,strength, and uItimate Strength were teSted in nex, ertension, leffand right bending and torsion. Part three; HistoIogical experiment.12 dogs were randomIy divided into controI groups (n=3) andexperimental group (n=10). After corpeCtomy the dog's iIiac wereharveSted and impIant6d into the controI group and AHT-AVB thatwere impaCted by the canceIIous bone were impfanted in theexperimentaI group. The migration of the impIants and bone fusionwas observed during 3-6 months follow-up. Part four was for clinicaIapplication. The AHT-AVB was used for 26 cases of spinal tumor,fraCture and deformity The reconStruCtion eff6Ct, spinaI Stabilityand bone fUsion was observed at an average 18-month foIIow-up.ResuItS: The AHT-AVB is of stable in physical and chemical quaIityand rational in morphology for Chinese human spine. TheBiomenchanicaI study shows the stress and dispIacementmeasurements in AHT-AVB group was Iess than in iIiac group andcontroI group in various modeIs such as flex, eXtension, leff andright bending (P<0.01). The torsion Stress in both iIiac and AHT-AVB groups were greater than in control group which indicated adeficiency of anti4orsion ability of AHT-AVB. With additionalanterior pIate or pedicle screw, their stabiIity in varies modeIsjncluding torsion all increased and greater than in control group.UItimate strength test shows the materiaI maintained normaI inshape after the bovine bone has damaged, but the threads of AHT-AVB didn't work. When AHTAVB were impIanted in diff6rentposition the stability were decreased especiaIly in oblique andIateraI position comparing with the neutraI position (P<0.01).HistOIogicaI experiment shows that there were fibrous cell andchondroCyte around the AHT-AVB affer 3 month of operation.Mature chondrocyte and osteoCyte was fOund around the AHT-AVB6 months lateL The resuIts of clinicaI appIication show that nomigration or breakage of implants was found. The AHTAVB canreStore the height of spinal segment eff6CtiveIy and bone fusion canbe reached after one year.ConcIusions: The AHT-AV8 has an ideal adjuStabIe ability andrationaI biomechanicaI stabiIity it can be used aIone in spinal deficitthat the segment was not severally destroyed. With additional inter-fixation, the construct has an effective biomechanical sta...