ABSTRACT
BACKGROUND: Cervical spondylotic radiculopathy could be effectively treated by cervical rotatory manipulation, but the symptoms may be exacerbated when rotated to the wrong direction. OBJECTIVE: To simulate the cervical rotatory manipulation in left/right rotation by three-dimensional finite element, and then investigate the effect of this manipulation on the displacement of cervical disc and the volume of intervertebral foramen so as to provide a basis for effectiveness and safety of cervical rotatory manipulation in treating cervical spondylotic radiculopathy. METHODS: With Mimics10.01, Geomagic Studio and Solidworks 14.0 software, a three-dimensional geometric CAD model of C5-6was developed from the CT scan images of a 25-year-old normal adult female. The model was imported into Ansys Workbench 14.5, and a three-dimensional finite element model was verified and simulated the cervical rotatory manipulation. The cervical rotatory manipulation was decomposed by principium of manipulation in left lateral flexion and rotated to the left/right side. The parameter of mechanics was analyzed with the finite element system. The change of displacement in cervical disc and volume in intervertebral foramen simultaneously were displayed during simulating the manipulation. RESULTS AND CONCLUSION: In left lateral flexion and rotated to the left side, the posterior part of the left side of annulus fibers was expanded 0.46 mm into posterior, and the posterior part of the right side of annulus fibers was retracted 0.77 mm. The volume of left intervertebral foramen became small and the right side became large. However, in left lateral flexion and rotated to the right side, the posterior part of the left side of annulus fibers was retracted 0.71 mm, and the posterior part of the right side of annulus fibers was expanded 0.43 mm into posterior. The volume of left intervertebral foramen became large and the right side became small. Therefore, the posterior part of the rotated side of cervical disc was expanded into posterior, while the posterior part of the contralateral side of cervical disc was retracted. The volume of intervertebral foramen in rotated side became small, while the volume of intervertebral foramen in contralateral side became large. We should rotate to the contralateral side when cervical spondylotic radiculopathy was treated with cervical rotatory manipulation.
ABSTRACT
Objective To compare biomechanical properties of pedicle screw with different axial angles and interbody cage with different positions for unilateral transforaminal lumbar interbody fusion (TLIF) surgery. Methods The normal L3-5 finite element (FE) model was established and validated. Then one bilateral TILF reconstruction FE model and four unilateral TILF reconstruction FE models with different pedicle screw-cage combination types at L4-5 level were constructed, respectively. Namely, Model A (a small axial angle-implanted screw and an ipsilaterally-placed cage), Model B (a small axial angle-implanted screw and a contralaterally-placed cage), Model C (a large axial angle-implanted screw and an ipsilaterally-placed cage), Model D (a large axial angle-implanted screw and a contralaterally-placed cage). The range of motion (ROM) of 4 reconstruction models under various physiological stresses as well as the maximum Von Mises stresses on pedicle screw, cage-L4 inferior endplate were compared. Results The ROMs at fusion segment (L4-5) in 4 unilateral TLIF reconstruction models were significantly decreased compared with the normal model, but they were still larger than bilateral TLIF reconstruction model. For 4 unilateral TLIF reconstruction models, Model C showed the largest decrease in stability, and the ROM of Model C was 50.7%, 89.9%, 90.3% of the normal model in flexion-extension, lateral bending, axial rotation, respectively. When comparing the maximum Von Mises stress of posterior pedicle screw and cage-L4 inferior endplate in 4 unilateral TLIF reconstruction models, Model C could bear relatively smaller stress under most loading modes, except in ipsilateral lateral bending and axial rotation. Conclusions The unilateral TLIF reconstruction model with a large axial angle-implanted screw and an ipsilaterally placed-cage can achieve the optimal stability. By narrowing the difference in stability with the bilateral TILF model, the unilateral TLIF reconstruction model can reduce the risk of screw failure and cage subsidence, which is worth of clinical application.
ABSTRACT
Objective To compare biomechanical properties of pedicle screw with different axial angles and interbody cage with different positions for unilateral transforaminal lumbar interbody fusion (TLIF) surgery.Methods The normal L3-5 finite element (FE) model was established and validated.Then one bilateral TILF reconstruction FE model and four unilateral TILF reconstruction FE models with different pedicle screw-cage combination types at L4-5 level were constructed,respectively.Namely,Model A (a small axial angle-implanted screw and an ipsilaterally-placed cage),Model B (a small axial angle-implanted screw and a contralaterally-placed cage),Model C (a large axial angle-implanted screw and an ipsilaterally-placed cage),Model D (a large axial angle-implanted screw and a contralaterally-placed cage).The range of motion (ROM) of 4 reconstruction models under various physiological stresses as well as the maximum Von Mises stresses on pedicle screw,cage-L4 inferior endplate were compared.Results The ROMs at fusion segment (L4-5) in 4 unilateral TLIF reconstruction models were significantly decreased compared with the normal model,but they were still larger than bilateral TLIF reconstruc-tion model.For 4 unilateral TLIF reconstruction models,Model C showed the largest decrease in stability,and the ROM of Model C was 50.7％,89.9％,90.3％ of the normal model in flexion-extension,lateral bending,axial rotation,respectively.When comparing the maximum Von Mises stress of posterior pedicle screw and cage-L4 inferior endplate in 4 unilateral TLIF reconstruction models,Model C could bear relatively smaller stress under most loading modes,except in ipsilateral lateral bending and axial rotation.Conclusions The unilateral TLIF reconstruction model with a large axial angle-implanted screw and an ipsilaterally placed-cage can achieve the optimal stability.By narrowing the difference in stability with the bilateral TILF model,the unilateral TLIF reconstruction model can reduce the risk of screw failure and cage subsidence,which is worth of clinical application.
ABSTRACT
Objective To compare the biomechanical differences in 3 posterior fixation methods with or without crosslink for treatment of thoracolumbar fractures, so as to find the optimal posterior fixation methods. Methods On the basis of the validated finite element model of T12-L2 segments to simulate L1 vertebra burst fracture, the superior 1/2 cortical bone of T12 segment was removed and the superior 1/2 cancellous bone was assigned with the material damage property of cancellous bone. Then 6 thoracolumbar fracture models by intermediate unilateral pedicle screw fixation without or with crosslink (Model A1, A2), traditional short-segment pedicle screw fixation without or with crosslink (Model B1, B2), intermediate bilateral pedicle screw fixation without or with crosslink (Model C1,C2) were established, respectively. The range of motion (ROM) as well as the maximum Von Mises stress of the pedicle screw and rod for 6 models under various physiological loading conditions were compared. Results The ROM under flexion-extension and lateral bending in Model A and Model C was obviously smaller than that of Model B. Under flexion-extension, no significant difference was found in ROM between Model A and Model C; under lateral bending, the ROM of Model C was smaller than that of Model A. The stress was concentrated in the root of upper screw and the rob located between upper screw and intermediate screw; the maximum stress of upper screw in Model C was smaller than that in Model A and Model B. The crosslink could increase the stability of all fixation groups under axial rotation stress condition, and decrease the maximum stress on upper screw and rod under axial rotation stress condition, but no significant difference was found under flexion-extension and lateral bending. Conclusions Additional pedicle screws at the level of fracture vertebra can achieve the better biochemical stability. The additional crosslink not only increases the torsional rigidity, but also decreases the maximum torsional stress of the screw and rod, which is a better choice as the treatment of thoracolumbar fractures.
ABSTRACT
In this study, a rapid and sensitive analytical method was developed for the determination of 10 major compounds (procyanidin B1, catechin, procyanidin B2, rutin, isoquercitrin, kaempferol-3-O-rutinoside, astragalin, quercitrin, quercetin, and kaempferol) in Tetrastigma hemsleyanum by using ultra-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UPLC-MS/MS) in multiple-reaction monitoring (MRM) mode. UPLC-MS/MS assay with negative ion mode was performed on a Waters CORTECS C18 (2.1 mm x 100 mm, 1.6 μm) with the mobile phase consisting of acetonitrile (A) and 0.1% aqueous formic acid (B) in gradient elution at a flow rate of 0.25 mL · min(-1) and the column temperature was set at 45 °C. Under the optimized chromatographic conditions, good separation for 10 target compounds were obtained including chiral isomer procyanidins B1 and B2 were completely separated within 8.5 min. Satisfactory linearity was achieved with wide linear range and fine determination coefficient (r > 0.996 6), the overall recoveries were ranged from 95.44%-110.40% with the RSD ranging from 2.37%-8.69%. It is the first report about simultaneous analysis of 10 major flavonoids components in Tetrastigma hemsleyanum by using UPLC-MS/MS method, which affords highly sensitive, specific, speedy and efficient method for quality control of Tetrastigma hemsleyanum
Subject(s)
Acetonitriles , Chromatography, High Pressure Liquid , Flavonoids , Chemistry , Kaempferols , Quercetin , Rutin , Tandem Mass Spectrometry , Vitaceae , ChemistryABSTRACT
Objective To observe the effect of cervical rotatory manipulation on tensile mechanical properties of atherosclerotic carotid artery in rabbits, so as to provide safety references for such manipulation. Methods Twenty male New Zealand rabbits were randomly divided into control group (n=10) and experimental group (n=10), then all fed with high-cholesterol diet for 12 weeks. The rabbits in experimental group were then applied with cervical rotatory manipulation (rotating on each side once a day during a total of 4 weeks), while no manipulation for rabbits in control group. The bilateral carotid arteries were obtained after all the rabbits were executed, and measured for the maximum load, the maximum displacement, the average load, the elastic modulus, elongation at break and stress-strain by the material testing machine. Results The maximum tension, the maximum displacement, the average tension, the elastic modulus and elongation at break in experimental group were (1.36±0.35) N, (6.84±2.08) mm, (0.44±0.30) N, (4.30±2.66) MPa and (83.08±51.32)%, respectively, while the corresponding data in control group were (2.92±0.65) N, (9.23±2.62) mm, (1.17±0.63) N, (3.71±0.60) MPa and (154.19±34.32)%. The maximum load, the average load and elongation at break in experimental group were obviously smaller than those in control group (P0.05). Conclusions The tensile mechanical properties of atherosclerotic carotid artery after cervical rotatory manipulation were declined; thus, intensity and magnitude of cervical rotatory manipulation should be proper so as to avoid harm to carotid artery.
ABSTRACT
A qualitative analytical method of liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (HPLC-Q-TOF-MS) was developed for identification of multi-constituents and an analytical method was developed for simultaneously determining 4 major compounds (rutin, isoquercitrin, kaempferol-3-0-rutinoside, and astragalin) in Tetrastigma hemsleyanum Diels et Gilg. The HPLC-Q-TOF-MS assay was performed on a Welch Ultimate XB-C18 column (4.6 mm x 150 mm, 5 microm) with the mobile phase consisting of acetonitrile (A) and water containing 0.1% Formic acid (B) in gradient mode at a flow rate of 0.8 mL x min(-1). The column temperature was at 30 degrees C, and negative ion mode was used for TOF-MS. The UPLC-QqQ-MS assay was performed on a Waters CORTECS C18 (2.1 mm x 100 mm, 1.6 microm) with the mobile phase consisting of acetonitrile (A) and water containing 0.1% formic acid (B) in gradient mode at a flow rate of 0.25 mL x min(-1). The column temperature was at 45 degrees C, and MRM mode was used for QqQ-MS. Based on the retention time and MS spectra, 24 compounds were identified or tentatively characterized by comparing with reference substances or literatures. For quantitative the linear range of 4 detected compounds were good (r > 0.9966), and the overall recoveries ranged from 98.27% to 101.58%, with the RSD ranging from 3.15% to 5.88%. The results indicated that new approach conbined HPLC-Q-TOF-MS and UPLC-QqQ-MS was applicable in qualitative and quantitative quality control of Tetrastigma hemsleyanum.