Human Cervical Specimens Research Articles

The move-C cervical artificial disc can restore intact range of motion and 3-D kinematics

BACKGROUND CONTEXTIn contrast to cervical discectomy and fusion, total disc replacement (TDR) aims at preserving the motion at the treated vertebral level. Spinal motion is commonly evaluated with the range of motion (ROM). However, more qualitative information about cervical kinematics before and after TDR is still lacking. PURPOSEThe aim of this in vitro study was to investigate the influence of cervical TDR on ROM, instantaneous centers of rotation (ICR) and three-dimensional helical axes. STUDY DESIGNAn in vitro study with human spine specimens under pure moment loading was conducted to evaluate the kinematics of the intact cervical spine and compare it to cervical TDR. METHODSSix fresh frozen human cervical specimens (C4–5, median age 28 years, range 19–47 years, two female and four male) were biomechanically characterized in the intact state and after implantation of a cervical disc prosthesis (MOVE-C, NGMedical, Germany). To mimic in vivo conditions regarding temperature and humidity, water steam was used to create a warm and humid test environment with 37°C. Each specimen was quasistatically loaded with pure moments up to ±2.5 Nm in flexion/extension (FE), lateral bending (LB) and axial rotation (AR) in a universal spine tester for 3.5 cycles at 1 °/s. For each third cycle of motion the ROM was evaluated and an established method was used to determine the helical axis and COR and to project them into three planar X-rays. Statistical analysis was conducted using a Friedman-test and post hoc correction with Dunn-Bonferroni-tests (p<.05). RESULTSAfter TDR, total ROM was increased in FE from 19.1° to 20.1°, decreased in LB from 14.6° to 12.6° and decreased in AR from 17.7° to 15.5°. No statistical differences between the primary ROM in the intact condition and ROM after TDR were detected. Coupled rotation between LB and AR were also maintained. The position and orientation of the helical axes after cervical TDR was in good agreement with the results of the intact specimens in all three motion directions. The ICR in FE and AR before and after TDR closely matched, while in LB the ICR after TDR were more caudal. The intact in vitro kinematics we found also resembled in vivo results of healthy individuals. CONCLUSIONThe results of this in vitro study highlight the potential of artificial cervical disc implants to replicate the quantity as well as the quality of motion of the intact cervical spine. CLINICAL SIGNIFICANCEPhysiological motion preservation was a driving factor in the development of cervical TDR. Our results demonstrate the potential of cervical TDR to replicate in vivo kinematics in all three motion directions.

Range of motion of the mid-cervical spine: human versus goat

BackgroundThe goat cervical spine represents a promising alternative for human specimen in spinal implant testing, but the range of motion (ROM) of the spine is lacking. We aimed to evaluate and compare the ROMs of fresh goat and human mid-cervical spine specimens.MethodsTen fresh adult healthy male goat cervical spine specimens (G group) and ten fresh frozen adult healthy human cervical spine specimens (average age: 49.5 ± 12.1 years; 6 males, 4 females) (H group) were included. The ROMs of each specimen were biomechanically tested at the C2–3, C3–4, C4–5 and C2–5 levels at 1.5 Nm and 2.5 Nm torque and recorded. The ROMs of different levels of goat cervical samples were compared to those of human cervical samples using an independent sample t test. Significance was defined as a P value of less than 0.05.ResultsAt the C2–3, C3–4 and C4–5 levels, the ROMs of the goat cervical spine were significantly larger than those of the human cervical spine in all directions except extension under 1.5 Nm torque; under 2.5 Nm torque, the ROMs of the goat cervical spine at the C2–3 and C3–4 levels were significantly larger than those of humans in the pure movement of flexion, lateral bending and axial rotation, and the ROMs for axial rotation of the goat specimens and human specimens were comparable. Under both 1.5 Nm and 2.5 Nm torque, the goat cervical spine displayed a much greater ROM in all directions at the C2–5 level.ConclusionsSeveral segmental ROMs of fresh goat and human cervical spine specimens were recorded in this investigation. We recommend using goat cervical specimens as an alternative to fresh human cervical specimens in future studies when focusing only on the ROMs of C2–3, C3–4 and C4–5 in flexion under a torque of 1.5 Nm or the ROMs of C2–3 and C3–4 in flexion and rotation under a torque of 2.5 Nm.

Reduction in immune cell number and loss of 5hmC are associated with lesion grade in cervical carcinogenesis.

Tumor genome methylation is closely related to tumor immunosuppression. In the present study, we evaluated the fluctuations in DNA methylation levels, and the numbers of infiltrating T cells and their cytokines in different-grade cervical lesions. A total of 154 human cervical specimens that included LSIL (43 cases), HSIL (48 cases), and cervical squamous cancer (63 cases) were used for this study. Immunohistochemistry for 5-hydroxymethylcytosine (5hmC) and T-cell-attracting chemokines was performed, and multiplex immunofluorescence labeling was used to identify different T-cell subtypes. We found that the proportions of samples that immunostained weakly or negatively for 5hmC were increased commensurately with elevations in the severity of cervical lesions. The expression of T-cell-attracting chemokines-including CXCL9, CXCL10, and CXCL11-was positively associated with 5hmC levels, and CXCL9 was the cytokine that was most pronounced. With the progression of cervical lesions, the numbers of total T cells, CTL, and NK cells in the cervical tissues all gradually decreased. During the occurrence and development of cervical squamous carcinoma, 5hmC was gradually lost, and immunosuppression occurred in precancerous cervical lesions.

Analysis of three-dimensional facet joint displacement during two passive upper cervical mobilizations

BackgroundUnderstanding the 3D-kinematics of the upper cervical spine during manual mobilization is essential for clinical examination and therapy. Some information about rotational motion is available in literature but translational components are often ignored, complicating the understanding of the complex inter-segmental motions. ObjectivesThis study aims to describe the amount, trajectories and reproducibility of atlanto-occipital facet joints’ displacement during a flexion-extension mobilization and of the atlanto-axial facet joints during an axial rotation mobilization. DesignOriginal research using quantitative data. Methods20 fresh frozen human cervical specimens were examined with a Zebris® CMS20 ultrasound-based motion tracking system. Two physiotherapists performed regionalmobilizations in flexion-extension and axial rotation. The amount of displacement and the trajectories were calculated along the XYZ axes. Difference between measurements was evaluated with the Friedman two-way ANOVA test. Intra- and inter-rater reliability were estimated through ICC scores. Results3D-displacement (2.6–23.4 mm) was larger at C1–C2 during axial rotation, Atlanto-occipital flexion displayed the greatest variability in the C0 trajectory. During a right rotation, the left C1 facet moved mainly forward, and the right C1 facet moved backward. During a left rotation, the left C1 facet moved backward, while the right C1 facet moved forward. Intra-tester and Inter-tester ICCs varied between 0.5 and 0.90 (p < 0.005). ConclusionsDuring passive spinal motion, there is an important variability in magnitude and trajectory of joints’ displacement. Nevertheless, different clinicians may be able to achieve the same position at the end of the mobilization.

Effect of Dome-Shaped Titanium Mesh Cages on Cervical Endplate Under Cyclic Loading: An In Vitro Biomechanics Study.

BackgroundThis study aimed to verify the anti-subsidence ability of dome-shaped titanium mesh cage (TMC) used in anterior cervical corpectomy and fusion (ACCF).Material/MethodsThirty fresh human cervical vertebrae specimens were collected and randomly harvested into 2 groups: the traditional TMC group and the dome-shaped TMC group. The bone mineral density (BMD) of the specimens was recorded. Each group was biomechanically tested in axial compression with a cyclically loading range from 60 to 300 N at 0.5Hz for 10 000 cycles. The displacement data of the 2 groups were recorded every 10 cycles.ResultsThere was no significant difference in bone mineral density between the 2 groups of cervical specimens. The traditional TMC group stabilized at 535±35 cycles while the dome-shaped TMC group stabilized at 1203±57 cycles, which showed that the rate of subsidence of the dome-shaped TMC group was significantly slower than that of the traditional TMC group (p<0.05). After reaching stability, both groups had a more gradual and sustained growth. The peak displacement during fatigue testing was −2.064±0.150mm in the traditional TMC group and −0.934±0.086mm in the dome-shaped TMC group, which showed a significant difference (p<0.05).ConclusionsThe dome-shaped TMC showed a smaller subsidence displacement and a gentler subsidence tendency following the same cyclic loading (compared to the traditional TMC). From a biomechanical point of view, the dome-shaped TMC has stronger anti-subsidence ability due to its unique structural design that closely matches the vertebral endplate.

Influence of follower load application on moment-rotation parameters and intradiscal pressure in the cervical spine

The objective of this study was to implement a follower load (FL) device within a robotic (universal force-moment sensor) testing system and utilize the system to explore the effect of FL on multi-segment cervical spine moment-rotation parameters and intradiscal pressure (IDP) at C45 and C56. Twelve fresh-frozen human cervical specimens (C3-C7) were biomechanically tested in a robotic testing system to a pure moment target of 2.0 Nm for flexion and extension (FE) with no compression and with 100 N of FL. Application of FL was accomplished by loading the specimens with bilateral cables passing through cable guides inserted into the vertebral bodies and attached to load controlled linear actuators. FL significantly increased neutral zone (NZ) stiffness and NZ width but resulted in no change in the range of motion (ROM) or elastic zone stiffness. C45 and C56 IDP measured in the neutral position were significantly increased with application of FL. The change in IDP with increasing flexion rotation was not significantly affected by the application of FL, whereas the change in IDP with increasing extension rotation was significantly reduced by the application of FL. Application of FL did not appear to affect the specimen’s quantity of motion (ROM) but did affect the quality (the shape of the curve). Regarding IDP, the effects of adding FL compression approximates the effect of the patient going from supine to a seated position (FL compression increased the IDP in the neutral position). The change in IDP with increasing flexion rotation was not affected by the application of FL, but the change in IDP with increasing extension rotation was, however, significantly reduced by the application of FL.

Biomechanics of open-door laminoplasty with and without preservation of posterior structures.

OBJECTIVE Cervical open-door laminoplasty (ODL) is designed to decompress the spinal cord, maintain motion, and prevent postlaminectomy kyphosis. Many traditional laminoplasty techniques involve disruption of the posterior ligamentous structures, most notably the C7-T1 supraspinous ligament and interspinales muscle complex (intraspinous and supraspinous ligaments [ISLs]). METHODS Eight human cervical cadaveric specimens (C2-T1) were used to investigate the subaxial kinematics following ODL with varying degrees of posterior element disruption. Ligamentous integrity was preserved and specimens were tested utilizing force control in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) in the native state, and following 1) C3-7 ODL, 2) ODL with terminal ISL resection, 3) ODL with C3-7 spinous process resection, and 4) C3-7 laminectomy. Range of motion (ROM) was measured across C2-T1, "global," and at the segmental level. RESULTS Compared with ODL, sectioning the terminal ISLs resulted in global ROM increases by 7.9% in FE, 2.4% in LB, and 5.6% in AR (p > 0.05), whereas laminectomy increased global ROM by 36.0% in FE (p = 0.002) and a 26.3% increase in AR ROM (p = 0.01). When considering segmental ROM, resection of the terminal ISLs increased ROM in FE by 36.5% at C2-3 (p = 0.019) and 25.4% at C7-T1 (p > 0.05). Segmental increases following C3-7 spinous process resection averaged less than 3% per level, compared with up to 40% increases in ROM per level after laminectomy. CONCLUSIONS Laminectomy resulted in the greatest increase in global cervical ROM. Resection of the ISLs at C2-3 and C7-T1 increased segmental ROM at these specific levels to a similar extent that laminectomy increased ROM at each cervical level. This segmental ROM may contribute to pain or postprocedural deformity and highlights the importance of the ISLs at the terminal ends of the ODL.

MicroRNA-106b is involved in transforming growth factor β1-induced cell migration by targeting disabled homolog 2 in cervical carcinoma.

BackgroundMicroRNA-106b (miR-106b) was recently identified as an oncogene participating in cancer progression. Transforming growth factor β1(TGF-β1) is an indispensable cytokine regulating the local microenvironment, thereby promoting cervical cancer progression. However, the roles of miR-106b in cervical carcinoma progression and TGF-β1-involvement in the tumorigenesis of cervical cancer remain unknown.MethodsThe expression of miR-106b in human cervical specimens was detected by real-time PCR analysis and in situ hybridization assay. The effect of miR-106b on cell migration was analyzed by scratch and transwell assays. TGF-β1 was used to induce cell migration. The expression of the miR-106b target gene DAB2 in human cervical tissues and cell lines were measured by qRT-PCR, western blot and immunohistochemistry. Dual-luciferase reporter assay was used to identify DAB2 as a miR-106b-directed target gene.ResultsmiR-106b was frequently up-regulated in human cervical carcinoma specimens and cervical cancer cell lines. Over-expression of miR-106b significantly promoted HeLa and SiHa cells migration. Likewise, inhibition of miR-106b decreased HeLa and SiHa cells migration. The multifunctional cytokine TGF-β facilitates metastasis in cervical carcinoma. miR-106b inhibitor treatment decreased the TGF-β1-stimulated migration of HeLa and SiHa cells. DAB2, a predicted target gene of miR-106b, was inhibited by TGF-β1 partly through miR-106b and was involved in TGF-β1-induced cervical cancer cell migration. The expression of DAB2 was low in cervical cancer tissues, and negatively correlated with miR-106b expression. Finally, DAB2 was identified as a miR-106b-directed target gene by dual-luciferase reporter assay.ConclusionOur data suggest that the TGF-β1/miR-106b/DAB2 axis may be involved in the pathogenesis of cervical carcinoma.

Unilateral laminoplasty with lateral mass screw fixation for less invasive decompression of the cervical spine: a biomechanical investigation.

To compare the stabilization behavior of additional unilateral mass screw fixation with current standard procedures in patients with cervical spondylotic myelopathy (CSM) in a biomechanical study. Ten human C2-C7 cervical specimens were tested under various segment conditions: native (NAT), laminoplasty (LP), laminoplasty with unilateral (LPU) or bilateral (LPB) stabilization, laminectomy with bilateral stabilization (LCB), and laminectomy. The instrumented level was from C3 to C6. For each segment condition, in vitro flexibility tests were performed using a spinal simulator and an applied load of ±2.5 Nm. The three-dimensional kinematics of the entire cervical segment in three main loading directions [flexion-extension (FE), lateral bending (LB), and axial rotation (AR)] was measured with an ultrasonic motion analysis system. Analysis of variance followed by a post hoc test was used to determine differences under the specific segment conditions to assess the parameters range of motion (ROM) and neutral zone (NZ). For FE, the total ROM of laminoplasty (-6.3% difference to NAT) and laminectomy (+6.4%) remained at the level of native (p > 0.56), whereas the instrumentations LPU (-37.1%), LPB (-44%), and LCB (-43.2%) lead to significant reductions (p < 0.01) without significant differences in LPU to LPB and LCB (p > 0.38). The same results were found with LB. For AR, the stabilization of all instrumentations was less pronounced, but had the same tendency seen for FE and AR. The results for the NZ showed equivalent values as that for ROM. The degree of stabilization was as expected for LC and LCB; namely, no stabilization for LC and maximal stabilization for LCB. LPU exhibited almost the same degree of stabilization as LCB. LPU could be a new treatment option for less invasive decompression for multilevel CSM.

In vitro evaluation of translating and rotating plates using a robot testing system under follower load.

Various modifications to standard "rigid" anterior cervical plate designs (constrained plate) have been developed that allow for some degree of axial translation and/or rotation of the plate (semi-constrained plate)-theoretically promoting proper load sharing with the graft and improved fusion rates. However, previous studies about rigid and dynamic plates have not examined the influence of simulated muscle loading. The objective of this study was to compare rigid, translating, and rotating plates for single-level corpectomy procedures using a robot testing system with follower load. In-vitro biomechanical test. N=15 fresh-frozen human (C3-7) cervical specimens were biomechanically tested. The follower load was applied to the specimens at the neutral position from 0 to 100N. Specimens were randomized into a rigid plate group, a translating plate group and a rotating plate group and then tested in flexion, extension, lateral bending and axial rotation to a pure moment target of 2.0Nm under 100N of follower load. Range of motion, load sharing, and adjacent level effects were analyzed using a repeated measures analysis of variance (ANOVA). No significant differences were observed between the translating plate and the rigid plate on load sharing at neutral position and C4-6 ROM, but the translating plate was able to maintain load through the graft at a desired level during flexion. The rotating plate shared less load than rigid and translating plates in the neutral position, but cannot maintain the graft load during flexion. This study demonstrated that, in the presence of simulated muscle loading (follower load), the translating plate demonstrated superior performance for load sharing compared to the rigid and rotating plates.

Artificial disc and vertebra system: a novel motion preservation device for cervical spinal disease after vertebral corpectomy

OBJECTIVE:To determine the range of motion and stability of the human cadaveric cervical spine after the implantation of a novel artificial disc and vertebra system by comparing an intact group and a fusion group.METHODS:Biomechanical tests were conducted on 18 human cadaveric cervical specimens. The range of motion and the stability index range of motion were measured to study the function and stability of the artificial disc and vertebra system of the intact group compared with the fusion group.RESULTS:In all cases, the artificial disc and vertebra system maintained intervertebral motion and reestablished vertebral height at the operative level. After its implantation, there was no significant difference in the range of motion (ROM) of C3–7 in all directions in the non-fusion group compared with the intact group (p>0.05), but significant differences were detected in flexion, extension and axial rotation compared with the fusion group (p<0.05). The ROM of adjacent segments (C3−4, C6−7) of the non-fusion group decreased significantly in some directions compared with the fusion group (p<0.05). Significant differences in the C4-6 ROM in some directions were detected between the non-fusion group and the intact group. In the fusion group, the C4−6 ROM in all directions decreased significantly compared with the intact and non-fusion groups (p<0.01). The stability index ROM (SI-ROM) of some directions was negative in the non-fusion group, and a significant difference in SI-ROM was only found in the C4−6 segment of the non-fusion group compared with the fusion group.CONCLUSION:An artificial disc and vertebra system could restore vertebral height and preserve the dynamic function of the surgical area and could theoretically reduce the risk of adjacent segment degeneration compared with the anterior fusion procedure. However, our results should be considered with caution because of the low power of the study. The use of a larger sample should be considered in future studies.

Atlanto-axial facet displacement during rotational high-velocity low-amplitude thrust: An in vitro 3D kinematic analysis

BackgroundVery little is known about the kinematics of the upper cervical spine in particular during Manual Therapy techniques. In fact no data about displacement of the atlanto-axial joint during High-Velocity Low-Amplitude (HVLA) thrust are available. Knowing the precise kinematics of these vertebrae might allow a better comprehension of such important technique and possible vital structures involvement. MethodsA Zebris CMS20 ultrasound-based motion tracking system was adopted. Twenty fresh human cervical specimens were used in this study. Facet joint displacements of C1 relative to C2 were analysed during three consecutive HVLA thrusts into rotation. Displacement during the thrust and the maximum displacement reached with the manoeuvre were analysed. ResultsDescriptive statistics showed a mean Norm displacement during the thrust of 0.5 mm (SD ± 0.5). The maximum displacement, representing the overall facet movement from neutral to end-range position, indicated a Norm value of 6.0 mm (SD ± 3.4). Heterogeneous displacement directions were found during the thrust. Intra and inter-rater reliability reached an insufficient reproducibility level. Considering the amount of displacement induced, no statistical significant differences between the registrations were shown. ConclusionDisplacement during the execution of HVLA thrust is unintentional, unpredictable and not reproducible. On the other hand and in accordance with other studies, the displacement induced with the present technique seems not to be able to endanger vital structure on the Spinal Cord and the Vertebral Artery. This study also adds to a better comprehension of the kinematic of the atlanto-axial segment during the performance of HVLA manipulation.

Reproducibility of the Kinematics in Rotational High-Velocity, Low-Amplitude Thrust of the Upper Cervical Spine: A Cadaveric Study

ObjectiveThis study aimed to investigate the reproducibility of the kinematics in rotational high-velocity, low-amplitude (HVLA) thrust of the upper cervical spine. MethodsTwenty fresh human cervical specimens were studied in a test-retest situation with 2 manual therapists. Kinematics of C1-C2 and C0-C1 were examined during segmental rotational HVLA manipulation through an ultrasound-based tracking system. The thrust moment was analyzed by 3-dimensional aspects: the range of motion of axial rotation, flexion-extension, lateral banding, and the cross-correlation between the axial rotation and the coupled lateral banding components. ResultsDuring rotational HVLA thrust on C1-C2, the main axial rotation demonstrates an intraexaminer relationship varying from almost perfect to fair (intraclass correlation coefficient =0.71; intraclass correlation coefficient = 0.35) and a substantial interexaminer correlation of 0.73. ConclusionsThis study showed substantial levels of reliability for the main axial rotation component of segmental manual rotational HVLA thrust on C1-C2. Intra- and interrater reliability for flexion-extension, lateral bending, and cross-correlation was low.

Improvement of DNA Extraction for Human Papillomavirus Genotyping from Formalin-Fixed Paraffin-Embedded Tissues

Mucosal human papillomaviruses (HPVs) play a crucial role in the development of cervical carcinoma, the third most common malignancy in women worldwide.1,2 These viruses are classified as high risk (HR) or low risk (LR), depending on their transforming ability.3,4 Formalin-fixed paraffin-embedded (FFPE) tissues represent the most frequent form of tissue storage in pathology departments. These archival tissues represent a potentially useful resource for retrospective epidemiological studies. Several HPV studies have used FFPE specimens to correlate HPV genotypes with histological classification,5–7 to establish the geographical distribution of HPV genotypes,8 or to search for these viruses in other primary cancers.9,10 In these tissues, the detection of viruses by molecular biological tools based on molecular hybridization between DNA or RNA targets and specific probes11 is problematic because fixation causes damage to nucleic acids. Formalin fixation induces protein–protein and protein–nucleic acid cross-linking.12 As a result of protein–nucleic acid cross-linkages, it is difficult to separate DNA from histones and to obtain pure nucleic acids at extraction.13,14 The fixation of tissues also leads to the fragmentation of nucleic acids, such that polymerase chain reaction (PCR) methods that amplify a smaller portion of the viral genome are most effective.15,16 The aim of this study was to test whether HPV genotyping techniques used routinely in our diagnostic laboratory could be applied to FFPE tissues. For recovery of HPV DNA from FFPE tissues, we had to adapt extraction protocols to obtain viral DNA useful for PCR amplification. We tested different extraction protocols for HPV DNA, mainly to simplify this step, and we tested two genotyping methods. The first genotyping method involved sequencing of the L1 open reading frame. This method links PCR amplification of a conserved HPV L1 segment using GP5+/GP6+ consensus primers with automated sequencing of amplified PCR products. The second method used the Greiner Bio-one (GBO) PapilloCheck® DNA microarray, which enables the detection and genotyping of 24 different HPV types (18 high risk and 6 low risk) from DNA preparations of human cervical cytology specimens.

Full-endoscopic cervical arcocristectomy for the treatment of spinal stenosis: results of a cadaver study.

Cervical spondylotic myelopathy is a multifactorial disease that is directly correlated by the degree of spinal stenosis. Surgery remains the best therapy. A posterior approach is often recommended in patients with multilevel dorsal cervical compression. Aim of the present experimental study was to evaluate the feasibility of a full-endoscopic arcocristectomy in a cadaver study. We performed full-endoscopic arcocristectomy on ten formalin-fixed human cervical specimens. Before and after decompression we obtained high-resolution computerized tomography (CT) data to evaluate the diameter of the cervical spinal canal. Overall, surgery was possible on 55 segments in ten cadaver specimens. A mean increase of 4.1 mm (±1.2 mm) in the sagittal diameter of the cervical spinal canal could be achieved (p < 0.05, t test). The full-endoscopic arcrocristectomy is feasible and achieves a sufficient decompression. This minimal invasive technique protects most of the dorsal structures and therefore probably preserves biomechanical functions, which has to be proven in future studies.

Biomechanical Cyclical Loading on Cadaveric Cervical Spines in a Corpectomy Model

Abstract Approved posterior cervical spinal fixation systems have been submitted to the U.S. Food and Drug Administration with results from standardized test protocols from the ASTM. The bench top mechanical studies are designed to minimize biologic and laboratory variability. However, for implant tests such as ASTM F1717 to be more clinically relevant, anatomical and physiologic considerations must be understood. The specific aim of this study was to determine if a human cadaveric cervical spine with a corpectomy and posterior fixation was effective in maintaining stability prior to and following cyclical loading. Six fresh frozen cadaveric human cervical specimens were harvested and prepared. A C5 corpectomy was performed. Posterior cervical instrumentation was implanted from C3 and C7 spanning across the C4–C6 defect. Each specimen followed an established pure moment test protocol to characterize the instrumented spine in flexion extension, lateral bending, and axial torsion at ±2.5 N m and axial compressive loading to 150 N. Subsequently, each specimen was subjected to 10 000 flexion extension cycles. Following the cyclical loading, each specimen was characterized a second time via the same test protocol. Statistical analyses were then performed on the third cycle data between the two pure moment tests. The mean FE bending range of motion (ROM) was 18.0° ± 10.7° prior to the 10 000 cyclical bending protocol. Following cyclical loading, the mean ROM measured 22.0° ± 19.9°. In axial compression, the mean ROM was 4.1 mm ± 1.9 mm prior to cycling and 4.2 mm ± 1.4 mm post-cycling. A statistically significant difference was detected only in the axial torsion mode of loading (p = 0.030). Although the ASTM standard provides consistent test methodologies, biomechanical cadaveric testing remains an important step in the validation of all spinal instrumentation. The pure moment biomechanical cadaveric test protocol for the same construct was capable of detecting significant changes pre- and post-flexion extension fatigue cycling only in the axial torsion mode of loading.

The Impact of Cervical Pedicle Screws for Primary Stability in Multilevel Posterior Cervical Stabilizations

A total of 12 human cervical spines were tested in vitro in a biomechanical nondestructive set-up to compare the primary stability of different posterior cervical instrumentations after a bilevel corpectomy. To evaluate the primary 3-dimensional stability with special focus on the impact of cervical pedicle screws. Cervical pedicle screw fixation gains popularity due to supposed higher stability. However, biomechanical studies are rare. Especially the impact of a combination of lateral mass and pedicle screws on stability in multilevel posterior stabilizations has not been evaluated until now. A total of 12 human cervical specimens were loaded with pure moments and unconstrained motion between C4 and C7 was measured. The specimen were tested in the intact state, all lateral mass screws (all LMS) from C4-C7, cervical pedicle screws (CPS) C4 and C7 left, LMS C4-C7 right, C5+C6 left, CPS C4+C7 bilateral, LMS C5+C6, and a anterior-posterior instrumentation (360°). All instrumentations showed a higher stability compared with the intact state. No difference was found for uni- or bilateral applied CPS. The all LMS showed comparable stability than the CPS instrumentations. From a biomechanical primary stability point it seems unnecessary to add CPS in a bilevel corpectomy model. If CPS are added, the unilateral application seems sufficient.

Reproducibility of global three-dimensional motion during manual atlanto-axial rotation mobilization: an in vitro study

The reproducibility of the three-dimensional (3D) kinematic aspects of motion coupling patterns during manual mobilizing techniques is still a debatable matter. The present in vitro study analysed segmental 3D motion of the atlanto-axial joint during manual axial rotation mobilization. Twenty fresh frozen human cervical specimens were studied in a test–retest situation with two examiners. The specimens were manually mobilized using three different techniques: (1) a regional mobilization technique of the cervical spine; (2) a segmental mobilization technique of the atlas with manual fixation of the axis; and (3) a segmental mobilization of the atlas on the axis applying a locking technique. Segmental atlanto-axial kinematics was registered with a Zebris CMS-20 ultrasound-based tracking system. The Euclidian norm was used as a representation of overall 3D motion. The results indicated good reproducibility (mean intraclass correlation coefficient, ICC: 0.87). Intraobserver reproducibility was slightly higher (mean ICC: 0.91; range: 0.76–0.99) than interobserver reproducibility (mean ICC: 0.85; range: 0.56–0.98) (P < 0.05). The total range of motion expressed as the Euclidean norm of 3D motion components was a parameter with good reproducibility in the study of segmental kinematics of manual atlanto-axial mobilization. Although previous studies have demonstrated poor inter-rater reliability of manual examination and mobilization of segmental motion components, the results of the present study shed a new and more positive light on the reproducibility of techniques for manual mobilization of the upper cervical spine.

Dramatic increase in signal by integration of polymerase chain reaction and hybridization on surface of DNA microarray

The cumbersome process required for diagnosis by DNA microarray can be simplified by simple extraction of nucleic acid from cells and by integration of liquid-phase polymerase chain reaction (PCR) and hybridization on the surface of a microarray slide. An unexpected benefit was the large (five- to sixfold) increase in detection signal that also is translated into an increase in sensitivity and the confidence level of diagnosis. The large increase in the detection signal appears to be due to participation of PCR primers as well as to extension of the immobilized capture probes during the hybridization process. The reason for the large increase in signal is not clear in view of only one round of DNA synthesis during the hybridization step. The integrated process correctly identified various genotypes of human papillomavirus (HPV) in the infected clinical human cervical specimens with specificity and efficiency. The process described in this article saves labor, time, and cost and should be applicable for automation of diagnosis by DNA microarray.

Reproducibility of kinematic motion coupling parameters during manual upper cervical axial rotation mobilization: A 3-dimensional in vitro study of the atlanto-axial joint

Introduction The reproducibility of the 3-dimensional (3D) kinematic aspects of motion coupling patterns of segmental manual mobilizing techniques is not yet known. This study analyzes the segmental 3D aspects of manual mobilization of the atlanto-axial joint in vitro. Methods and materials Twenty fresh human cervical specimens were studied in a test–retest situation with two examiners. The specimens were manually mobilized using three different techniques: a regional mobilization technique, a segmental mobilization technique on the atlas with manual fixation of the axis and a segmental mobilization applying a locking technique. Segmental kinematics were registered with a Zebris CMS20 ultrasound-based tracking system. The 3D aspects of motion coupling between main axial rotation and coupled lateral bending were analyzed by six parameters: the range of motion the three motion components, the cross-correlation, the ratio and the shift. Results The results indicate stronger intra- than inter-examiner reproducibility. The range of motion of the axial rotation component shows a substantial level of intra- and inter-examiner reproducibility (ICC’s 0.67–0.76). The parameters describing the coupling patterns show only moderate to substantial intra-examiner reproducibility for the more experienced of the two examiners (ICC’s 0.55–0.68). All other correlations were not significant and no differences could be observed between regional versus segmental techniques. Conclusion Reproducibility of segmental 3D-aspects of manual mobilization of the atlanto-axial joint in an in vitro situation can differ between examiners. The results of the present study may indicate a possible tendency to higher reproducibility if mobilizations are performed by an examiner with high expertise and experience in applying the specific techniques. Continued investigation including more examiners with different levels of experience and different techniques is necessary to confirm these observations.