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Find video protocols related to scientific articles indexed in Pubmed.
How does Free Rod-Sliding affect the Posterior Instrumentation for a Dynamic Stabilization Utilizing a Bovine Calf Model?
Spine
PUBLISHED: 11-11-2014
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Study Design. A biomechanical cadaveric study in lumbar calf spine.Objective. Evaluation of the effects of selected degrees of freedom (DoF) on the dynamic stabilization of the spine in terms of segmental range of motion (RoM), center of rotation (CoR) and implant loadings.Summary of Background Data. For dorsal stabilization, rigid implant systems are becoming increasingly complemented by numerous dynamic systems based on pedicle screws and varying degrees of freedom. However, it is still unclear which degree of freedom is most suitable to accomplish a physiologically related dynamic stabilization, and which loadings are induced to the implants. Human and calf specimens are reported to show certain similarities in their biomechanics. Young healthy calves are not degenerated and show less interindividual differences than elderly human specimens. However, the existing differences between species limit the conclusions in a preclinical setting.Methods. Six Calf-specimens from level L3-4 were analyzed in flexion and extension with a six degree of freedom robotic spine simulator. A clinical functional radiologic examination tool was utilized and parameters such as RoM, CoR and implant loadings were determined for six configurations: 1. intact, 2. defect, 3. rigid fixation, 4. free cranio caudal rod-sliding, 5. free polyaxiality, and 6. combined free rod-sliding and free polyaxiality. The location of the CoR was determined relative to vertebral body dimensions. A CoR repositioning was defined as sufficient when its median differed less than 5% of the vertebral body dimensions.Results. Free rod-sliding in the cranio-caudal direction restored the center of rotation from the defect back to the intact condition. The range of motion could be significantly reduced to ?1/2 of the intact condition. Compared to the rigid condition, the implant bending moments increased from 0.3/-0.8 Nm (flexion/extension) to 1.3/-1.2 Nm for the free cranio caudal rod-sliding condition.Conclusion. Free cranio-caudal rod-sliding restores the intact conditions of the tested kinematic parameters most suitably and at the same time reduces the range of motion. Stabilization towards the intact condition could decrease the risk of stress shielding and the progress of segment degeneration.
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Biomechanical evaluation of the Facet Wedge: a refined technique for facet fixation.
Eur Spine J
PUBLISHED: 08-26-2014
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Purpose of this paper is to evaluate the primary stability of a new approach for facet fixation the so-called Facet Wedge (FW) in comparison with established posterior fixation techniques like pedicle screws (PS) and translaminar facet screws (TLS) with and without anterior cage interposition.
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Cationic synthetic peptides: assessment of their antimicrobial potency in liquid preserved boar semen.
PLoS ONE
PUBLISHED: 08-22-2014
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Various semen extender formulas are in use to maintain sperm longevity and quality whilst acting against bacterial contamination in liquid sperm preservation. Aminoglycosides are commonly supplemented to aid in the control of bacteria. As bacterial resistance is increasing worldwide, antimicrobial peptides (AMPs) received lively interest as alternatives to overcome multi-drug resistant bacteria. We investigated, whether synthetic cationic AMPs might be a suitable alternative for conventional antibiotics in liquid boar sperm preservation. The antibacterial activity of two cyclic AMPs (c-WWW, c-WFW) and a helical magainin II amide analog (MK5E) was studied in vitro against two Gram-positive and eleven Gram-negative bacteria. Isolates included ATCC reference strains, multi-resistant E. coli and bacteria cultured from boar semen. Using broth microdilution, minimum inhibitory concentrations were determined for all AMPs. All AMPs revealed activity towards the majority of bacteria but not against Proteus spp. (all AMPs) and Staphylococcus aureus ATCC 29213 (MK5E). We could also demonstrate that c-WWW and c-WFW were effective against bacterial growth in liquid preserved boar semen in situ, especially when combined with a small amount of gentamicin. Our results suggest that albeit not offering a complete alternative to traditional antibiotics, the use of AMPs offers a promising solution to decrease the use of conventional antibiotics and thereby limit the selection of multi-resistant strains.
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Influences on semen traits used for selection of young AI boars.
Anim. Reprod. Sci.
PUBLISHED: 04-08-2014
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The ability to produce high-quality semen in sufficient quantity is a crucial trait of artificial insemination (AI) boars in the pig industry. Therefore, the selection process of young boars at AI centers, apart from their genetic value, should specifically take into account the quality of collected semen. The aim of the current study was to analyze factors influencing semen quality in boars ranging from 4.5 to 16.8 months of age and to demonstrate the impact of these factors on selection of AI boars. The present multi-factorial analysis includes a complete standard spermatology data set of 4611 semen samples from 3633 young boars of five different breeds. Data were obtained from one reference laboratory during the years 2002-2012. Approximately one-half of the boars were excluded from use for AI due to below-threshold values of semen quality. In this group of excluded boars was a noticeably high number of boars less than 8 months of age. Boar age and breed were identified as significant (P<0.001) factors influencing semen quality. The influence of season was marginal. Therefore, a minimum age is proposed for young boars to qualify for selection, or alternatively, age-related semen quality thresholds in young boars should be established.
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Phenotype and frequency of STUB1 mutations: next-generation screenings in Caucasian ataxia and spastic paraplegia cohorts.
Orphanet J Rare Dis
PUBLISHED: 02-18-2014
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Mutations in the gene STUB1, encoding the protein CHIP (C-terminus of HSC70-interacting protein), have recently been suggested as a cause of recessive ataxia based on the findings in few Chinese families. Here we aimed to investigate the phenotypic and genotypic spectrum of STUB1 mutations, and to assess their frequency in different Caucasian disease cohorts.
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Biomechanical comparison of stability of tibiotalocalcaneal arthrodesis with two different intramedullary retrograde nails.
Foot Ankle Surg
PUBLISHED: 02-01-2014
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The aim of the study was to compare the initial construct stability of two retrograde intramedullary nail systems for tibiotalocalcaneal arthrodesis (TTCF) (A3, Small Bone Innovations; HAN, Synthes) in a biomechanical cadaver study.
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Effects of cationic antimicrobial peptides on liquid-preserved boar spermatozoa.
PLoS ONE
PUBLISHED: 01-01-2014
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Antibiotics are mandatory additives in semen extenders to control bacterial contamination. The worldwide increase in resistance to conventional antibiotics requires the search for alternatives not only for animal artificial insemination industries, but also for veterinary and human medicine. Cationic antimicrobial peptides are of interest as a novel class of antimicrobial additives for boar semen preservation. The present study investigated effects of two synthetic cyclic hexapeptides (c-WFW, c-WWW) and a synthetic helical magainin II amide derivative (MK5E) on boar sperm during semen storage at 16 °C for 4 days. The standard extender, Beltsville Thawing Solution (BTS) containing 250 µg/mL gentamicin (standard), was compared to combinations of BTS with each of the peptides in a split-sample procedure. Examination revealed peptide- and concentration-dependent effects on sperm integrity and motility. Negative effects were more pronounced for MK5E than in hexapeptide-supplemented samples. The cyclic hexapeptides were partly able to stimulate a linear progressive sperm movement. When using low concentrations of cyclic hexapeptides (4 µM c-WFW, 2 µM c-WWW) sperm quality was comparable to the standard extender over the course of preservation. C-WFW-supplemented boar semen resulted in normal fertility rates after AI. In order to investigate the interaction of peptides with the membrane, electron spin resonance spectroscopic measurements were performed using spin-labeled lipids. C-WWW and c-WFW reversibly immobilized an analog of phosphatidylcholine (PC), whereas MK5E caused an irreversible increase of PC mobility. These results suggest testing the antimicrobial efficiency of non-toxic concentrations of selected cyclic hexapeptides as potential candidates to supplement/replace common antibiotics in semen preservation.
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Single-Bundle Anterior Cruciate Ligament Reconstruction: A Biomechanical Cadaveric Study of a Rectangular Quadriceps and Bone-Patellar Tendon-Bone Graft Configuration Versus a Round Hamstring Graft.
Arthroscopy
PUBLISHED: 08-25-2013
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The purposes of this study were to investigate anterior tibial translation under loading conditions after single-bundle (SB) anterior cruciate ligament (ACL) reconstruction using a rectangular tunnel placement strategy with quadriceps and bone-patellar tendon-bone (BPTB) graft and to compare these data with a SB hamstring reconstruction with a round tunnel design.
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Biomechanical comparison of two angular stable plate constructions for periprosthetic femur fracture fixation.
Int Orthop
PUBLISHED: 07-18-2013
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Fractures of the femur associated with total hip arthroplasty are a significant concern in orthopaedic and trauma surgery. However, little is known about the different biomechanical properties of internal fixation systems in combination with periprosthetic fractures. In this study two new internal fixation systems for periprosthetic fractures are investigated using a cadaver fracture model simulating a Vancouver B1 periprosthetic femur fracture.
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Healing of the goat anterior cruciate ligament after a new suture repair technique and bioscaffold treatment.
Tissue Eng Part A
PUBLISHED: 07-10-2013
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Primary suture repair of the anterior cruciate ligament (ACL) has been used clinically in an attempt to heal the ruptured ACL. The results, however, were not satisfactory, which in retrospect can be attributed to the used suturing technique and the suboptimal healing conditions. These constraining conditions can be improved by introducing a new suturing technique and by using small intestinal submucosa (SIS) as a bioscaffold. It is hypothesized that the suturing technique keep the torn ends together and that SIS enhance and promote the healing of the ACL. The goat was used as the study model. In the Suture group, the left ACL was transected and suture repaired with a new locking suture repair technique (n=5) allowing approximation and fixation under tension. The Suture-SIS group underwent the same procedure with the addition of SIS (n=5). The right ACL served as control. After 12 weeks of healing, anterior-posterior translation and in situ force of the healing ACL were measured, followed by the measurement of the cross-sectional area and structural stiffness. Routine histology was performed on tissue samples. Gross morphology showed that the healing ACL was continuous with collagenous tissue in both groups. The cross-sectional area of the Suture and the Suture-SIS group was 35% and 50% of the intact control, respectively. The anterior-posterior translations at different flexion angles were statistically not different between the Suture group and the Suture-SIS group. Only the in situ force at 30° in the Suture-SIS group was higher than in the Suture group. Tensile tests showed that the stiffness for the Suture group was not different from the Suture-SIS group (31.1±8.1?N/mm vs. 41.9±18.0?N/mm [p>0.05]). Histology showed longitudinally aligned collagen fibers from origo to insertion. More fibroblasts were present in the healing tissue than in the control intact tissue. The study demonstrated the proof of concept of ACL repair in a goat model with a new suture technique and SIS. The mechanical outcome is not worse than previously reported for ACL reconstruction. In conclusion, the approach of using a new suture technique, with or without a bioscaffold to heal the ACL is promising.
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Biomechanical evaluation of combined short segment fixation and augmentation of incomplete osteoporotic burst fractures.
BMC Musculoskelet Disord
PUBLISHED: 06-24-2013
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Treating traumatic fractures in osteoporosis is challenging. Multiple clinical treatment options are found in literature. Augmentation techniques are promising to reduce treatment-related morbidity. In recent years, there have been an increasing number of reports about extended indication for augmentation techniques. However, biomechanical evaluations of these techniques are limited.
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Metabolic incorporation of unsaturated fatty acids into boar spermatozoa lipids and de novo formation of diacylglycerols.
Chem. Phys. Lipids
PUBLISHED: 06-10-2013
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Lipids play an important role in the maturation, viability and function of sperm cells. In this study, we examined the neutral and polar lipid composition of boar spermatozoa by thin-layer chromatography/mass spectrometry. Main representatives of the neutral lipid classes were diacylglycerols containing saturated (myristoyl, palmitoyl and stearoyl) fatty acyl residues. Glycerophosphatidylcholine and glycerophosphatidylethanolamine with alk(en)yl ether residues in the sn-1 position and unsaturated long chained fatty acyl residues in sn-2 position were identified as the most prominent polar lipids. The only glycoglycerolipid was sulfogalactosylglycerolipid carrying 16:0-alkyl- and 16:0-acyl chains. Using stable isotope-labelling, the metabolic incorporation of exogenously supplied fatty acids was analysed. Boar spermatozoa incorporated hexadecenoic (16:1), octadecenoic (18:1), octadecadienoic (18:2) and octadecatrienoic (18:3) acids primarily in the diacylglycerols and glycerophosphatidylcholines. In contrast, incorporation of eicosapentaenoic acid (20:5) was not detected. The analysis of molecular species composition subsequent to the incorporation of exogenous [(14)C]-octadecadienoic acid suggests two pathways for incorporation of exogenous fatty acids into glycerophosphatidylcholine: (1) de novo synthesis of glycerophosphatidylcholine via the CDP-choline pathway and (2) reacylation of lysophosphatidylcholine via an acyltransferase.
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Biomechanical consequences of a posterior root tear of the lateral meniscus: stabilizing effect of the meniscofemoral ligament.
Arch Orthop Trauma Surg
PUBLISHED: 03-31-2013
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The purpose of this study was to evaluate the effects of different types of lateral meniscus root tears in terms of tibiofemoral contact stress.
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Effects on boar semen quality after infection with porcine reproductive and respiratory syndrome virus: a case report.
Acta Vet. Scand.
PUBLISHED: 02-21-2013
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The effect of porcine reproductive and respiratory syndrome virus (PRRSV) on semen quality was examined in a group of 11 spontaneously infected boars in a commercial boar stud. Semen samples were collected 4 weeks prior to 4 weeks post-infection (wpi). Infection with PRRSV of the European genotype subtype 1 (EU-1) was verified by specific quantitative real-time polymerase chain reaction (RT-PCR) in 36% of the serum samples. All boars seroconverted before 4 wpi and remained in normal condition throughout the study. Comparison of the percentage of morphologically intact spermatozoa revealed an increase of acrosome-defective spermatozoa (P = 0.012) between -4 and 4 wpi. Significant deleterious effects on semen quality were detected for membrane integrity when semen had been stored for 2 days after sampling. Analysis of sperm subpopulations in a thermoresistance test on day 7 after sampling revealed alterations in the percentage of circular, progressively motile spermatozoa (P = 0.013), in the percentage of non-linear, progressively motile spermatozoa (P = 0.01), and on the amplitude of lateral sperm head displacement (P = 0.047). There was no difference in the incidence of mitochondrially active spermatozoa (P = 0.075). Investigation of routine production data between pre- and post-infection status showed no differences on ejaculate volume (P = 0.417), sperm concentration (P = 0.788), and percentage of motile spermatozoa (P = 0.321). This case report provides insights into a potential control strategy for PRRSV outbreaks in boar studs.
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Medial patellofemoral ligament reconstruction: fixation strength of 5 different techniques for graft fixation at the patella.
Arthroscopy
PUBLISHED: 02-08-2013
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To compare the structural properties of 5 different fixation strategies for a free tendon graft at the patella in medial patellofemoral ligament (MPFL) reconstruction under cyclic loading and load to failure testing.
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A method to perform spinal motion analysis from functional X-ray images.
J Biomech
PUBLISHED: 03-31-2011
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Identifying spinal instability is an important aim for proper surgical treatment. Analysis of functional X-ray images delivers measurements of the range of motion (RoM) and the center of rotation (CoR). In todays practice, CoR determination is often omitted, due to the lack of accurate methods. The aim of this work was to investigate the accuracy of a new analysis software (FXA™) based on an in vitro experiment. Six bovine spinal specimens (L3-4) were mounted in a robot (KR125, Kuka). CoRs were predefined by locking the robot actuator tool center point to the estimated position of the physiologic CoR and taking a baseline X-ray. Specimens were deflected to various RoM(preset) flexion/extension angles about the CoR(preset). Lateral functional radiographs were acquired and specimen movements were recorded using an optical motion tracking system (Optotrak Certus). RoM and CoR errors were calculated from presets for both methods. Prior to the experiment, the FXA™ software was verified with artificially generated images. For the artificial images, FXA™ yielded a mean RoM-error of 0.01 ± 0.03° (bias ± standard deviation). In the experiment, RoM-error of the FXA™-software (deviation from presets) was 0.04 ± 0.13°, and 0.10 ± 0.16° for the Optotrak, respectively. Both correlated with 0.998 (p < 0.001). For RoM < 1.0°, FXA™ determined CoR positions with a bias>20mm. This bias progressively decreased from RoM = 1° (bias = 6.0mm) to RoM = 9° (bias<1.5mm). Under the assumption that CoR location variances <5mm are clinically irrelevant on the lumbar spine, the FXA™ method can accurately determine CoRs for RoMs > 1°. Utilizing FXA™, polysegmental RoMs, CoRs and implant migration measurements could be performed in daily practice.
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Pentaplexed quantitative real-time PCR assay for the simultaneous detection and quantification of botulinum neurotoxin-producing clostridia in food and clinical samples.
Appl. Environ. Microbiol.
PUBLISHED: 04-30-2010
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Botulinum neurotoxins are produced by the anaerobic bacterium Clostridium botulinum and are divided into seven distinct serotypes (A to G) known to cause botulism in animals and humans. In this study, a multiplexed quantitative real-time PCR assay for the simultaneous detection of the human pathogenic C. botulinum serotypes A, B, E, and F was developed. Based on the TaqMan chemistry, we used five individual primer-probe sets within one PCR, combining both minor groove binder- and locked nucleic acid-containing probes. Each hydrolysis probe was individually labeled with distinguishable fluorochromes, thus enabling discrimination between the serotypes A, B, E, and F. To avoid false-negative results, we designed an internal amplification control, which was simultaneously amplified with the four target genes, thus yielding a pentaplexed PCR approach with 95% detection probabilities between 7 and 287 genome equivalents per PCR. In addition, we developed six individual singleplex real-time PCR assays based on the TaqMan chemistry for the detection of the C. botulinum serotypes A, B, C, D, E, and F. Upon analysis of 42 C. botulinum and 57 non-C. botulinum strains, the singleplex and multiplex PCR assays showed an excellent specificity. Using spiked food samples we were able to detect between 10(3) and 10(5) CFU/ml, respectively. Furthermore, we were able to detect C. botulinum in samples from several cases of botulism in Germany. Overall, the pentaplexed assay showed high sensitivity and specificity and allowed for the simultaneous screening and differentiation of specimens for C. botulinum A, B, E, and F.
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Diagnostic approach for the differentiation of the pandemic influenza A(H1N1)v virus from recent human influenza viruses by real-time PCR.
PLoS ONE
PUBLISHED: 02-04-2010
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The current spread of pandemic influenza A(H1N1)v virus necessitates an intensified surveillance of influenza virus infections worldwide. So far, in many laboratories routine diagnostics were limited to generic influenza virus detection only. To provide interested laboratories with real-time PCR assays for type and subtype identification, we present a bundle of PCR assays with which any human influenza A and B virus can be easily identified, including assays for the detection of the pandemic A(H1N1)v virus.
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Anteroposterior and rotational stability in fixed and mobile bearing unicondylar knee arthroplasty: a cadaveric study using the robotic force sensor system.
Knee Surg Sports Traumatol Arthrosc
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Different bearing designs in unicondylar knee arthroplasty (UKA) have been developed in order to influence the rate of polyethylene wear. Increased anteroposterior translation and rotation after UKA has been hypothesized due to changes in joint surface geometry. The mobile bearing design was expected to show increased anteroposterior translation compared to the fixed bearing and biconcave bearing design.
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Experimentally induced incomplete burst fractures - a novel technique for calf and human specimens.
BMC Musculoskelet Disord
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Fracture morphology is crucial for the clinical decision-making process preceding spinal fracture treatment. The presented experimental approach was designed in order to ensure reproducibility of induced fracture morphology.
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Evaluation of a robot-assisted testing system for multisegmental spine specimens.
J Biomech
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Mono- and multi-segmental testing methods are required to identify segmental motion patterns and evaluate the biomechanical behaviour of the spine. This study aimed to evaluate a new testing system for multisegmental specimens using a robot combined with an optical motion analysis system. After validation of the robotic system for accuracy, two groups of calf specimens (six monosegmental vs. six multisegmental) were mounted and the functional unit L3-4 was observed. Using rigid body markers, range of motion (ROM), elastic zone (EZ) and neutral zone (NZ), as well as stiffness properties of each functional spine unit (FSU) was acquired by an optical motion capture system. Finite helical axes (FHA) were calculated to analyse segmental movements. Both groups were tested in flexion and extension. A pure torque of 7.5 Nm was applied. Statistical analyses were performed using the Mann-Whitney U-test. Repeatability of robot positioning was -0.001±0.018 mm and -0.025±0.023° for translations and rotations, respectively. The accuracy of the optical system for the proposed set-up was 0.001±0.034 mm for translations and 0.075±0.12° for rotations. No significant differences in mean values and standard deviations of ROM for L3-4 compared to literature data were found. A robot-based facility for testing multisegmental spine units combined with a motion analysis system was proposed and the reliability and reproducibility of all system components were evaluated and validated. The proposed set-up delivered ROM results for mono- and multi-segmental testing that agreed with those reported in the literature. Representing the FHA via piercing points determined from ROM was the first attempt showing a relationship between ROM and FHA, which could facilitate the interpretation of spine motion patterns in the future.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.