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Linda M. Mcgrady - One of the best experts on this subject based on the ideXlab platform.
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biomechanical evaluation of contemporary posterior spinal internal fixation configurations in an unstable burst fracture calf Spine Model special references of hook configurations and pedicle screws
Spine, 2004Co-Authors: Kern Singh, Jason C. Eck, Linda M. Mcgrady, Alexander R Vaccaro, G Wang, Hiroyuki Yoshida, Tae-hong LimAbstract:Study Design. This study attempts to determine the most biomechanically rigid posterior spinal instrumentation configuration in a burst-fracture calf Spine Model. Objectives. To compare the biomechanical stability of contemporary posterior spinal instrumentation in various hook and screw configurations in an unstable calf Spine Model. Summary of Background Data. Burst-fractures are relatively common injuries seen in the setting of spinal trauma. The use of posterior-only configurations in the treatment of this deformity has become a much more popular approach because of the relative ease of applying the instrumentation. Methods. Fresh frozen in vitro study using 10 calf Spines involving the T11-S1 vertebral segments. Pure moment forces including flexion, extension, axial rotation, and lateral bending were applied to the top of the spinal column at T11. Testing was first performed on all intact specimens. A corpectomy was then performed at L2. Testing was then repeated on each of the ten specimens after internal fixation with different posterior spinal configurations using ISOLA instrumentation (DePuy AcroMed Inc., Raynham, MA) Results. With regards to fiexion-extension and lateral bending, all configurations except for distraction hook-rod construct provided stability greater than the intact Spine. The distraction hook-rod configuration failed to control extension (P > 0.05) above the intact specimen. All pedicie screw constructs were more rigid than the hook-rod constructs in axial rotation at the ievei of injury (P < 0.001}. Conclusions. The motion segment at the corpectomy site is adequately stabilized by contemporary spinal internal fixation configurations tested except for the distraction-hook stabilization. Axial rotation is generally poorly controlled by posterior-only internal fixation. Pedicle screw instrumentation was the most rigid compared with other forms of stabilization in stabilizing a burst-corpectomy defect. Based on this study, pedicle screw configurations are preferred over hook-rod strategies in the posterior stabilization of a burst-corpectomy anterior defect, Among hook-rod configurations, the distraction hook-rod strategy provided the least stability.
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Biomechanical evaluation of anterior and posterior fixations in an unstable calf Spine Model
Spine, 1997Co-Authors: Tae-hong Lim, Jung Hwa Hong, Jae Yong Ahn, Jae Won You, Jason C. Eck, Linda M. McgradyAbstract:Study design Fresh calf lumbar Spines were used to perform flexibility tests in multiple loading directions to compare the stabilizing effects of anterior and posterior rigid instrumentations. Objective To compare the biomechanical flexibility of anterior and posterior instrumentation constructs using an unstable calf Spine Model. Summary of background data Unstable burst fractures of the thoracolumbar Spine can be managed anteriorly or posteriorly. Controversy persists, however, on the merit of anterior fixation versus that of posterior fixation in terms of how much stability can be achieved. Methods Fifteen fresh calf Spines (L2-L5) were loaded with pure unconstrained moments in flexion, extension, axial rotation, and lateral bending directions. After removal of L3-L4 disc and endplates to create an 1.5-cm anterior and middle column defect, testing was performed on five specimens after anterior Kaneda rod fixation, anterior University Plate fixation, or posterior ISOLA pedicle screw fixation (AcroMed, Cleveland, OH). Testing was repeated after inserting a polymethylmethacrylate block to stimulate an interbody anterior graft with instrumentation. Results All fixation devices provided a significant stabilizing effect in flexion and lateral bending. In extension, all constructs except ISOLA (AcroMed) without graft were stiffer than the intact specimen. In axial rotation with no graft, only the Kaneda device significantly reduced the flexibility from that of the intact specimen. The interbody graft provided additional rigidity to the ISOLA (AcroMed) instrumentation construct in flexion and extension and to the Kaneda construct in lateral bending. There was no significant effect of grafting in axial rotation. Conclusions A short, transpedicular instrumentation, such as ISOLA (AcroMed), provided less rigid fixation in flexion and extension without the anterior structural graft. The Kaneda rod and University plate with grafting provided a significant stabilizing effect in all directions compared with the intact specimen. When no graft was inserted, the Kaneda device was more effective in preventing axial rotation than the other devices. In lateral bending, the University plate provided more rigid fixation than the Kaneda device without grafting.
Tae-hong Lim - One of the best experts on this subject based on the ideXlab platform.
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Hydroxyapatite-coating of pedicle screws improves resistance against pull-out force in the osteoporotic canine lumbar Spine Model: a pilot study.
The spine journal : official journal of the North American Spine Society, 2005Co-Authors: Toru Hasegawa, Akihiko Inufusa, Yoshiyuki Imai, Yoshihiro Mikawa, Tae-hong LimAbstract:Abstract Background context In patients with spinal osteoporosis, the early achievement and maintenance of a biological bond between the pedicle screw and bone is important to avoid screw loosening complications. There are few reports of in vivo investigations involving biomechanical and histological evaluations in the osteoporotic Spine. Purpose To evaluate the effect of hydroxyapatite (HA)-coating on the pedicle screw in the osteoporotic lumbar Spine and to investigate the relationship between resistance against the screw pull-out force and bone mineral density (BMD) of the vertebral body. Study design/setting Mechanical and pathological investigations in the lumbar Spine. Methods Two 24-month-old female beagle dogs were fed a calcium-free dog chow for 6 months after ovariectomy (OVX). BMD (in g/cm 2 ) was measured by dual energy X-ray absorptiometry at pre-OVX and 6 months after OVX. Pedicle screws were placed from L1 to L6 at 6 months after OVX. Twenty-four pure titanium cortical screws (Synthes, #401-114) were used as pedicle screws (Ti-PS). Of these, 12 screws had HA-coating (HA-PS). The HA-PS screws were inserted into the right pedicles and the Ti-PS were inserted into the left pedicles. Ten days after this procedure, the lumbar Spines were removed en bloc for screw pull-out testing and histological evaluation. Results The mean BMD value of the lumbar vertebrae 6 months after the OVX was 0.549±0.087 g/cm 2 , which was significantly less than the pre-OVX mean BMD of 0.603±0.092 g/cm 2 (p Conclusions The results of this study showed that the resistance to the pull-out force of HA-PS is 1.6 times that of Ti-PS. Furthermore, HA-PS has superior biological bonding to the surrounding bone, as early as 10 days after surgery in this osteoporotic Spine Model. Thus, in patients with osteoporosis, coating of the pedicle screw with HA may provide better stability and bonding between the pedicle screw and bone in the early postoperative period.
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biomechanical evaluation of contemporary posterior spinal internal fixation configurations in an unstable burst fracture calf Spine Model special references of hook configurations and pedicle screws
Spine, 2004Co-Authors: Kern Singh, Jason C. Eck, Linda M. Mcgrady, Alexander R Vaccaro, G Wang, Hiroyuki Yoshida, Tae-hong LimAbstract:Study Design. This study attempts to determine the most biomechanically rigid posterior spinal instrumentation configuration in a burst-fracture calf Spine Model. Objectives. To compare the biomechanical stability of contemporary posterior spinal instrumentation in various hook and screw configurations in an unstable calf Spine Model. Summary of Background Data. Burst-fractures are relatively common injuries seen in the setting of spinal trauma. The use of posterior-only configurations in the treatment of this deformity has become a much more popular approach because of the relative ease of applying the instrumentation. Methods. Fresh frozen in vitro study using 10 calf Spines involving the T11-S1 vertebral segments. Pure moment forces including flexion, extension, axial rotation, and lateral bending were applied to the top of the spinal column at T11. Testing was first performed on all intact specimens. A corpectomy was then performed at L2. Testing was then repeated on each of the ten specimens after internal fixation with different posterior spinal configurations using ISOLA instrumentation (DePuy AcroMed Inc., Raynham, MA) Results. With regards to fiexion-extension and lateral bending, all configurations except for distraction hook-rod construct provided stability greater than the intact Spine. The distraction hook-rod configuration failed to control extension (P > 0.05) above the intact specimen. All pedicie screw constructs were more rigid than the hook-rod constructs in axial rotation at the ievei of injury (P < 0.001}. Conclusions. The motion segment at the corpectomy site is adequately stabilized by contemporary spinal internal fixation configurations tested except for the distraction-hook stabilization. Axial rotation is generally poorly controlled by posterior-only internal fixation. Pedicle screw instrumentation was the most rigid compared with other forms of stabilization in stabilizing a burst-corpectomy defect. Based on this study, pedicle screw configurations are preferred over hook-rod strategies in the posterior stabilization of a burst-corpectomy anterior defect, Among hook-rod configurations, the distraction hook-rod strategy provided the least stability.
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Biomechanical evaluation of anterior and posterior fixations in an unstable calf Spine Model
Spine, 1997Co-Authors: Tae-hong Lim, Jung Hwa Hong, Jae Yong Ahn, Jae Won You, Jason C. Eck, Linda M. McgradyAbstract:Study design Fresh calf lumbar Spines were used to perform flexibility tests in multiple loading directions to compare the stabilizing effects of anterior and posterior rigid instrumentations. Objective To compare the biomechanical flexibility of anterior and posterior instrumentation constructs using an unstable calf Spine Model. Summary of background data Unstable burst fractures of the thoracolumbar Spine can be managed anteriorly or posteriorly. Controversy persists, however, on the merit of anterior fixation versus that of posterior fixation in terms of how much stability can be achieved. Methods Fifteen fresh calf Spines (L2-L5) were loaded with pure unconstrained moments in flexion, extension, axial rotation, and lateral bending directions. After removal of L3-L4 disc and endplates to create an 1.5-cm anterior and middle column defect, testing was performed on five specimens after anterior Kaneda rod fixation, anterior University Plate fixation, or posterior ISOLA pedicle screw fixation (AcroMed, Cleveland, OH). Testing was repeated after inserting a polymethylmethacrylate block to stimulate an interbody anterior graft with instrumentation. Results All fixation devices provided a significant stabilizing effect in flexion and lateral bending. In extension, all constructs except ISOLA (AcroMed) without graft were stiffer than the intact specimen. In axial rotation with no graft, only the Kaneda device significantly reduced the flexibility from that of the intact specimen. The interbody graft provided additional rigidity to the ISOLA (AcroMed) instrumentation construct in flexion and extension and to the Kaneda construct in lateral bending. There was no significant effect of grafting in axial rotation. Conclusions A short, transpedicular instrumentation, such as ISOLA (AcroMed), provided less rigid fixation in flexion and extension without the anterior structural graft. The Kaneda rod and University plate with grafting provided a significant stabilizing effect in all directions compared with the intact specimen. When no graft was inserted, the Kaneda device was more effective in preventing axial rotation than the other devices. In lateral bending, the University plate provided more rigid fixation than the Kaneda device without grafting.
Kwang-bok Lee - One of the best experts on this subject based on the ideXlab platform.
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An Anesthesia, Surgery, and Harvest Method for the Evaluation of Transpedicular Screws Using an In Vivo Porcine Lumbar Spine Model.
Journal of visualized experiments : JoVE, 2017Co-Authors: Young Jae Moon, Jong-kil Kim, Ji-hun Kang, Gun-joo Park, Kwang-bok LeeAbstract:Pedicle screw fixation is the gold standard for the treatment of spinal diseases. However, many studies have reported the issue of loosening pedicle screws after spinal surgery, which is a serious concern. To address this problem, diverse types of pedicle screws have been examined to identify those with good fixation strength and osseointegration in Spine bone. The porcine Spine is a good alternative for the human Spine in the evaluation of pedicle screws due to the anatomical size, mechanical characteristics, and cost. Although several studies have reported that pedicle screws are efficient in the porcine Model, no study has described detailed protocols for the evaluation of a pedicle screw using the porcine Model. Here, we describe a detailed method for evaluating transpedicular screws using an in vivo porcine lumbar Spine Model. The technical details for anesthesia, Spine surgery, and harvest provided here will facilitate with the evaluation of the transpedicular screw fixation Model.
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Evaluation of Titanium-Coated Pedicle Screws: In Vivo Porcine Lumbar Spine Model
World neurosurgery, 2016Co-Authors: Do-yeon Kim, Jung-ryul Kim, Kyu Yun Jang, Min Gu Kim, Kwang-bok LeeAbstract:Objective Many studies have addressed the problem of loosening pedicle screws in spinal surgery, which is a serious concern. Titanium coating of medical implants (arthroplasty) is common, but few studies involving in vivo Spine Models have been reported. We evaluated the radiological, mechanical, and histological characteristics of titanium-coated pedicle screws compared with uncoated or hydroxyapatite-coated pedicle screws. Methods Three different types of pedicle screws, i.e., uncoated, hydroxyapatite-coated, and titanium-coated, were implanted into the lumbar 3-4-5 levels of 9 mature miniature pigs. Radiological evaluation of loosening of pedicle screws was performed. Peak torsional extraction torque was tested in the 42 screws from 7 miniature pigs at 12 weeks postoperatively. The implant–bone interface of the remaining 12 pedicle screws from 2 miniature pigs in each group was assessed by micro-computed tomography and histologic studies. Results The incidence of loosening at 12 weeks postoperatively was not significantly different between the titanium-coated pedicle screw group and the other groups. The titanium-coated pedicle screw group exhibited the greatest mean extraction torsional peak torque at 12 weeks postoperatively (P Conclusions Fixation strength was greatest in the titanium-coated pedicle screw group. Osteointegration at the interface between the titanium-coated implant and bone produced prominent and firm bonding. The titanium-coated pedicle screw is a promising device for application in spinal surgery.
Jason C. Eck - One of the best experts on this subject based on the ideXlab platform.
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biomechanical evaluation of contemporary posterior spinal internal fixation configurations in an unstable burst fracture calf Spine Model special references of hook configurations and pedicle screws
Spine, 2004Co-Authors: Kern Singh, Jason C. Eck, Linda M. Mcgrady, Alexander R Vaccaro, G Wang, Hiroyuki Yoshida, Tae-hong LimAbstract:Study Design. This study attempts to determine the most biomechanically rigid posterior spinal instrumentation configuration in a burst-fracture calf Spine Model. Objectives. To compare the biomechanical stability of contemporary posterior spinal instrumentation in various hook and screw configurations in an unstable calf Spine Model. Summary of Background Data. Burst-fractures are relatively common injuries seen in the setting of spinal trauma. The use of posterior-only configurations in the treatment of this deformity has become a much more popular approach because of the relative ease of applying the instrumentation. Methods. Fresh frozen in vitro study using 10 calf Spines involving the T11-S1 vertebral segments. Pure moment forces including flexion, extension, axial rotation, and lateral bending were applied to the top of the spinal column at T11. Testing was first performed on all intact specimens. A corpectomy was then performed at L2. Testing was then repeated on each of the ten specimens after internal fixation with different posterior spinal configurations using ISOLA instrumentation (DePuy AcroMed Inc., Raynham, MA) Results. With regards to fiexion-extension and lateral bending, all configurations except for distraction hook-rod construct provided stability greater than the intact Spine. The distraction hook-rod configuration failed to control extension (P > 0.05) above the intact specimen. All pedicie screw constructs were more rigid than the hook-rod constructs in axial rotation at the ievei of injury (P < 0.001}. Conclusions. The motion segment at the corpectomy site is adequately stabilized by contemporary spinal internal fixation configurations tested except for the distraction-hook stabilization. Axial rotation is generally poorly controlled by posterior-only internal fixation. Pedicle screw instrumentation was the most rigid compared with other forms of stabilization in stabilizing a burst-corpectomy defect. Based on this study, pedicle screw configurations are preferred over hook-rod strategies in the posterior stabilization of a burst-corpectomy anterior defect, Among hook-rod configurations, the distraction hook-rod strategy provided the least stability.
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Biomechanical evaluation of anterior and posterior fixations in an unstable calf Spine Model
Spine, 1997Co-Authors: Tae-hong Lim, Jung Hwa Hong, Jae Yong Ahn, Jae Won You, Jason C. Eck, Linda M. McgradyAbstract:Study design Fresh calf lumbar Spines were used to perform flexibility tests in multiple loading directions to compare the stabilizing effects of anterior and posterior rigid instrumentations. Objective To compare the biomechanical flexibility of anterior and posterior instrumentation constructs using an unstable calf Spine Model. Summary of background data Unstable burst fractures of the thoracolumbar Spine can be managed anteriorly or posteriorly. Controversy persists, however, on the merit of anterior fixation versus that of posterior fixation in terms of how much stability can be achieved. Methods Fifteen fresh calf Spines (L2-L5) were loaded with pure unconstrained moments in flexion, extension, axial rotation, and lateral bending directions. After removal of L3-L4 disc and endplates to create an 1.5-cm anterior and middle column defect, testing was performed on five specimens after anterior Kaneda rod fixation, anterior University Plate fixation, or posterior ISOLA pedicle screw fixation (AcroMed, Cleveland, OH). Testing was repeated after inserting a polymethylmethacrylate block to stimulate an interbody anterior graft with instrumentation. Results All fixation devices provided a significant stabilizing effect in flexion and lateral bending. In extension, all constructs except ISOLA (AcroMed) without graft were stiffer than the intact specimen. In axial rotation with no graft, only the Kaneda device significantly reduced the flexibility from that of the intact specimen. The interbody graft provided additional rigidity to the ISOLA (AcroMed) instrumentation construct in flexion and extension and to the Kaneda construct in lateral bending. There was no significant effect of grafting in axial rotation. Conclusions A short, transpedicular instrumentation, such as ISOLA (AcroMed), provided less rigid fixation in flexion and extension without the anterior structural graft. The Kaneda rod and University plate with grafting provided a significant stabilizing effect in all directions compared with the intact specimen. When no graft was inserted, the Kaneda device was more effective in preventing axial rotation than the other devices. In lateral bending, the University plate provided more rigid fixation than the Kaneda device without grafting.
Akio Minami - One of the best experts on this subject based on the ideXlab platform.
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Multidirectional flexibility analysis of anterior and posterior lumbar artificial disc reconstruction: in vitro human cadaveric Spine Model
European spine journal : official publication of the European Spine Society the European Spinal Deformity Society and the European Section of the Cerv, 2006Co-Authors: Yoshihisa Kotani, Paul C. Mcafee, Bryan W. Cunningham, Kuniyoshi Abumi, Anton E. Dmitriev, Manabu Ito, Yasuo Shikinami, Akio MinamiAbstract:The in vitro multidirectional flexibility analysis was conducted to investigate the initial biomechanical effect of biomimetic artificial intervertebral disc replacement from either anterior or posterior approach in a cadaveric lumbosacral Spine Model. Two designs of anterior total and posterior subtotal artificial discs were developed using bioactive three-dimensional fabric and bioresorbable hydroxyapatite/poly-l-lactide material (3DF disc). Both Models were designed to obtain the stable interface bonding to vertebral endplates with maximum surface area occupation. Using seven cadaveric lumbosacral Spines, the following three anterior reconstruction methods were sequentially performed at L4–5 level: anterior 3DF disc replacement; anterior BAK cages (BAK); and posterior pedicle screw fixation and anterior BAK cages combined (BAK + PS). The L2–3 level received two methods of posterior reconstructions: subtotal 3DF disc replacement (two implants), and posterior interbody cages and pedicle screw fixation (PLIF). Six unconstrained pure moments were applied and three-dimensional segmental motions were measured with an optoelectronic motion measurement system. The center of rotation (COR) calculation was conducted radiographically using flexion-extension films. Both anterior and posterior 3DF replacements statistically demonstrated equivalent range of motions (ROMs) in all loading modes compared to intact segment. Anterior BAK, BAK + PS, and PLIF demonstrated significantly lower ROMs when compared to intact and 3DF groups (P
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Multidirectional flexibility analysis of cervical artificial disc reconstruction: in vitro human cadaveric Spine Model.
Journal of neurosurgery. Spine, 2005Co-Authors: Yoshihisa Kotani, Paul C. Mcafee, Bryan W. Cunningham, Kuniyoshi Abumi, Anton E. Dmitriev, Manabu Ito, Yasuo Shikinami, Akio MinamiAbstract:Object. This in vitro experimental study was conducted to investigate the initial biomechanical effect of artificial intervertebral disc replacement in the cervical Spine. The multidirectional flexibility of replaced and adjacent spinal segments were analyzed using a cadaveric cervical Spine Model. Methods. The following three cervical reconstructions were sequentially performed at the C5–6 level after anterior discectomy in seven human cadaveric occipitocervical Spines: anterior artificial disc replacement with a bioactive three-dimensional (3D) fabric disc (FD); anterior iliac bone graft; and anterior plate fixation with iliac bone graft. Six unconstrained pure moments were applied with a 6-df Spine simulator, and 3D segmental motions at the operative and adjacent segments were measured with an optoelectronic motion measurement system. The 3D FD group demonstrated statistically equivalent ranges of motion (ROMs) when compared with intact values in axial rotation and lateral bending. The 45% increase in ...