Segmental Motion Research Articles

Understanding the Impact of Chain Mobility on Conformational Evolution and Kinetics of Mesophase Formation in Poly(ʟ-lactide) under Low-Pressure CO2.

Although the mesomorphic phase as an intermediate state has been introduced to understand polymer crystallization, the understanding of the mesomorphic phase is far from complete. Here, the effect of chain mobility on the mesophase structuring in melt-quenched poly(ʟ-lactide) (PLLA) treated in low-pressure CO2 at 1.6-2.0 MPa and 0 °C was investigated using infrared (IR) spectroscopy, differential scanning calorimetry (DSC), and atomic force microscopy (AFM). The IR and AFM results demonstrated that the final degree of order and the kinetics of structural evolution during the CO2-induced mesophase formation were critically dependent on the CO2 pressure. This was attributed to the distinct dynamics of conformational evolution (gg to gt conformer transition) due to the different CO2 pressures. The thermal behavior from the DSC results showed that CO2 pressure dominated both the scale and dynamics of the chain motion of PLLA. At a lower CO2 pressure of 1.6 MPa, smaller-scale segmental motion was not replaced by the larger-scale cooperative motion that occurred at a relatively higher CO2 pressure of 2 MPa, which was favorable for faster mesophase formation. Consequently, by inhibiting direct crystallization under limited mobility conditions, it was demonstrated that different chain mobility controlled by CO2 pressure and thus CO2 solubility impacted the dynamics of the mesophase formation of PLLA. The present results have implications for understanding the role of chain mobility in determining the intermediate structural phases in semicrystalline polymers.

High energy-dissipation PDMS polymer-fluid-gels over an ultra-wide temperature range

Viscoelastic polymers exhibit strong energy dissipation in the glass transition region due to the motion of chain segments. Yet, the damping temperature ranges are pretty narrow, and the damping effect is poor at low frequencies. Here, we report two PDMS polymer-fluid-gels prepared by traditional curing and solvothermal polymerization, both of which exhibit excellent energy-dissipation capacity with loss factor larger than 0.7 at 1 Hz both covering 255 K (−55 °C to 200 °C), and larger than 1.0 at 1 Hz covering 134.7 K and 146.7 K, respectively, exceeding all the literature reports. Furthermore, solvothermal polymerization realizes large cross-linking meshes in which polymer fluids can stretch with less restriction and have longer relaxation time, which is conducive to low-frequency damping. The lower the frequency, the more pronounced the relative increase in damping, with the ratio of the two being greater than 4 times in the measuring low-frequency range. Moreover, the gels can absorb impact in extreme environments and protect raw eggs from breaking at temperatures as low as −50 °C when dropped from a height of 2 m.

Versatile morphology transition of nano-assemblies via ultrasonics/microwave assisted aqueous polymerization-induced self-assembly based on host–guest interaction

Nano-assemblies have wide applications in biomedicine, functional coatings, Pickering emulsifiers, hydrogels, and so forth. The preparation of assemblies mainly utilizes the polymerization-induced self-assembly (PISA) method, which can produce high-concentration nanoscale assemblies in one step. However, the initiation processes of most reported PISA are limited to thermal initiation. Here, we reported two green and efficient methods for synthesizing nano-assemblies with various morphologies using ultrasound (20 kHz)/ microwave (500 W) assisted aqueous-phase RAFT-PISA in 3 h and 1 h. Cyclodextrin (CD) and styrene (St) nucleating monomer were complexed in a 1:1 ratio. Then, using Poly (ethylene glycol) methyl ether as the macromolecular reversible addition-fragmentation chain transfer (RAFT) agent (PEG-CTA) to control the CD/St complexes, the conversion rate of St monomer was respectively 27 %–60 %, 20 %–30 % within 3 h and 1 h under ultrasonics/microwave assisted PISA. Results showed that the morphologies of the assemblies are not only related to the length of PS block, but also to the assistance types and the remaining monomer concentration. The results showed that only PEG45-b-PS90 and PEG45-b-PS241 assemblies prepared by ultrasonics assisted PISA form evolved lamellaes and vesicles (100 nm), which break through the limitation of kinetic freezing. But the ultrasonic reaction on morphology of assemblies is not all favourable. For one thing, it can promote the movement of particles; for another, it makes reverse morphology transformation and sphere is preferred morphology. Therefore, the main reason of morphology evolution is the remaining monomer concentration of PEG45-b-PS90 and PEG45-b-PS241 assemblies reaches to 55 %–65 %, which promoting the segment movement. The results showed that the morphology of the assemblies prepared by microwave assisted PISA changed from spherical micelles to short rods, and finally to vesicles (120–140 nm) as the length of hydrophobic PS block increases. The kinetic freezing problem was solved in microwave-assisted PISA due to the action of microwaves and more remaining monomer concentration. Both them can boost particles movement.

Numerical investigation on the behaviour of Post-Tensioned Mechanically Stabilised Earth Walls (PT-MSEW)

This study reports on a numerical investigation on the behaviour of an innovative retaining wall system named Post Tensioned Mechanically Stabilised Earth Wall (PTMSEW). In the proposed system, Post-Tensioning (PT) technique was integrated into the common retaining wall and the Mechanically Stabilised Earth Wall (MSEW) construction method to improve the performance of MSEWs and limit their failure modes. The variables of this study were wall height, PT force, pre-cast segment size, surcharge load, foundation size, and soil reinforcement length. The study found that incorporating PT stress into the MSEW improved the performance of the retaining wall by decreasing horizontal displacement of the wall face, soil reinforcement tensile forces, and backfill settlements and significantly enhanced the passive resistance of the wall. The introduction of a small amount of PT force prevented local failures caused by the relative movement of face segments. It was observed that by applying only a small level of post-tensioning, the lateral load-carrying capacity and passive resistance of the proposed PT-MSEW system can be significantly improved over that of its conventional counterpart. This opens new possibilities for the use of MSEW in the construction of taller retaining walls.

Preoperative low Hounsfield units in the lumbar spine are associated with postoperative mechanical complications in adult spinal deformity.

To determine the most valid bone health parameter to predict mechanical complications (MCs) following surgery for adult spinal deformity (ASD). This multicenter study retrospectively examined the records of patients who had undergone fusion of three or more motion segments, including the pelvis, with a minimum two-year follow-up period. Patients with moderate and severe global alignment and proportion scores were included in the study and divided into two groups: those who developed MCs and those who did not. Bone mineral density (BMD) of the lumbar spine and femoral neck was measured using dual-energy X-ray absorptiometry, and Hounsfield units (HUs) were measured in the lumbar spine on computed tomography. Radiographic parameters were evaluated preoperatively, immediately after surgery, and at final follow-up. Of 108 patients, 30 (27.8%) developed MCs, including 26 cases of proximal junctional kyphosis/failure, 2 of distal junctional failure, 6 of rod fracture, and 11 reoperations. HUs were significantly lower in patients who experienced MCs (113.7 ± 41.1) than in those who did not (137.0 ± 46.8; P = 0.02). BMD did not differ significantly between the two groups. The preoperative and two-year postoperative global tilt, as well as the immediately postoperative sagittal vertical axis, were significantly greater in patients who developed MCs than in those who did not (P = 0.02, P < 0.01, and P = 0.01, respectively). Patients who experienced MCs following surgery for ASD had lower HUs than those who did not. HUs may therefore be more useful than BMD for predicting MCs following surgery for ASD.

Design Improvements and Validation of a Novel Fully 3D Printed Analogue Lumbar Spine Motion Segment

Design Improvements and Validation of a Novel Fully 3D Printed Analogue Lumbar Spine Motion Segment

The Relationship Between MRI Findings of Posterior Ligamentous Complex and Lumbar Instability in Degenerative Spondylolisthesis.

To determine the factors in posterior ligamentous complex indicating lumbar instability in patients diagnosed with degenerative spondylolisthesis on conventional magnetic resonance imaging (MRI). We retrospectively analyzed patients who underwent PLIF surgery for degenerative spondylolisthesis at our institution between 2018 and 2020 and who had complete eligible preoperative imaging data for review and study, including lumbar MRI and anteroposterior and flexion-extension radiographs. Fifty-three patients were confirmed to have lumbar instability (Unstable Group, 44%), while sixty-seven patients (Stable Group, 56%) did not have instability on radiographs. The patients in the stable group had more advanced status of the degeneration of intervertebral disc than in the unstable group (p<0.05). The degeneration of supraspinous ligament (SSL) was more severe in the unstable group (p<0.05). Compared with the patients with rotatory instability, advanced degeneration of interspinous ligament (ISL) and SSL was observed in patients with translatory instability (p<0.05). However, there was no significant difference with regard to the height of the spinous process and the interspinous distance in patients with or without instability. This MRI analysis showed that abnormal segmental motion is closely associated with the pathological characteristics of supraspinal ligament. Advanced degeneration of SSL in patients with degenerative spondylolisthesis should raise the suspicion for lumbar instability and additional evaluations. The status of ISL and ligamentum flavum (LF) may not be helpful for the diagnosis of lumbar instability. Functional radiographs combined with MRI may provide valuable information when diagnosing lumbar instability in patients with mechanical back pain.

Prevalence of Transitional Vertebra in Lumbar Disc Herniation in Bangabandhu Sheikh Mujib Medical University

Background: Lumbosacral transitional vertebrae (LSTV) occur as a congenital anomaly in the segmentation of lumbosacral spine that occur during intrauterine life. LSTV includes lumbarization and sacralization of the lumbosacral region. A transitional vertebra(TV) may have varying formations, the common feature being an atypical lumbosacral articulation between transverse process of the most inferior lumbar vertebra and the sacrum. There has been a lot of discussion regarding the prevalence of LSTV in lumbar disc herniation(LDH). Most of the studies showed increased prevalence while other studies showed TV is an incidental finding and there is no increased prevalence in LDH. LDH is a quiet common ailment encountered in neurosurgical practice. Numerous causes have been attributed to it. LSTV might have great importance in patients who clinically seem to have LDH where it’s presence in plain X-ray might provide a supportive evidence for diagnosis and it can help to counsel the patient. We will be able to recommend a plain x-ray of lumbosacral spine first, having history and clinical findings suggestive of LDH and can save the cost of MRI investigation until decision for operation. Beside this LSTV is an important entity for spinal surgeons , radiologists and also for those who do interventional procedures in the spine. For this reason the prevalence of TV in LDH should be known. This study was not carried out in our country yet. So this study will enrich our demographic information and will also help the spinal surgeons to counsel the patients about their congenital spinal morphological variation and different facts related with this. Objectives: General objective of this study is to observe the prevalence of LSTV in patients with LDH. Specific objective of this study was to identify the diathroidal joint or fusion between transverse process of last lumbar vertebra and ala of sacrum, to count the vertebral number from C2 to S1 in whole spine screening film, to identify the transitional vertebra as sacralization or lumbarization or absence of TV, to predict the future possibility of development of LDH from plain X-ray of lumbosacral spine. Methods: This study was a cross sectional type of observational study and was conducted in Department of Neurosurgery, Bangabandhu Sheikh Mujib Medical University (BSMMU). The patients (N=45) who fulfilled the selection criteria was enrolled in this study. Patient’s data were recorded in a predetermined data sheet. Patients were informed in details about the study, its merits and demerits in easy and understandable language and then informed consent was taken. Also assurance was given that all the information and records would be kept confidential and the study result would help the neurosurgeons to counsel the patients with LSTV about future possibility of development of LDH from plain X-ray of lumbosacral spine. This study was not responsible for any additional harm to the patient and study had no potential risk to the patient and no experimental drugs were used in this study. Results: A total of 45 patients of LDH were studied to see the prevalence of lumbosacral TV in LDH. Based on history and clinical findings, 100% of patients presented with low back pain, 100% of patients presented with sciatica, and 62.2% presented with gait difficulty and 02.2% of patients presented with cauda equina syndrome. Mean age of patients having LDH herniation was 38.08 ± 10.15 years. LSTV was found in 31.11% of patients with LDH. In this study, LSTV was diagnosed by plain X ray of Lumbosacral spine (A/P view) and supplemented with MRI of L/S spine with screening of whole spine (in most cases). Diagnosis of transitional vertebra was done by researcher and was further confirmed by guide and faculty members of BSMMU. In relation to gender, prevalence of LSTV in male was 25.9% and in female was 38.9% which indicated higher prevalence of TV in female but this is not statistically significant (p value 0.356).Incidence of disc herniation in patients with TV was at the space above the transition in 85.7% of cases. The most likely explanation for this is that the motion segment cephalad to the LSTV has to bear additional stresses by virtue of it being juxtaposed to a relatively non-mobile segment Conclusion: This study reveals that the prevalence of LSTV in LDH is 31.11% which is near the upper limit of its prevalence(according to literature). Association of TV with LDH can not be obtained as a control group of patient without LDH was not considered. So further study should be carried out incorporating large number of patients with control group with long study period to generalize the findings to target population. Bang. J Neurosurgery 2023; 12(2): 76-85

Effects of different step lengths at a preferred walking speed on forefoot, midfoot, and hindfoot motion in healthy young adults

Hindfoot, midfoot, and forefoot motion during the stance phase of walking provide insights into the forward progression of the body over the feet via the rocker mechanisms. These segmental motions are affected by walking speed. Increases in walking speed are accomplished by increasing step length and cadence. It is unknown if taking short, medium, and long steps at the same speed would increase hindfoot, midfoot, and forefoot motion similarly to walking speed. We examined effects of different step lengths at the same preferred walking speed on peak forefoot, midfoot, and hindfoot motions related to the foot rockers. Twelve young healthy adults completed five walking trials under three step length conditions in a random order as feet and lower extremity motion were measured via marker positions for the combined Oxford foot and conventional gait models. Peak hindfoot, midfoot, and forefoot joint angles indicating heel, ankle, and forefoot rockers were identified. When walking at the same preferred speed with increase in step length, there were increases in peak hindfoot-tibia plantarflexion angle (p < 0.001; ηp2 = 0.76) in early stance associated with the heel rocker and peak hindfoot-tibia dorsiflexion angle (p = 0.016; ηp2 = 0.39) in midstance associated with ankle rocker. In late stance, the peak hindfoot-tibia plantarflexion angle, forefoot-hindfoot angle, and forefoot-hallux dorsiflexion angle indicating forefoot rocker motion also increased with step length (p < 0.01). When foot kinematics are compared across different individuals or the same individual across different sessions, researchers and clinicians should consider the influence of step length as a contributor to differences in foot kinematics observed.

Microendoscopic Posterior Cervical Foraminotomy Using TELIGEN: 2-Dimensional Operative Video.

This operative video details the treatment of cervical radiculopathy caused by unilateral cervical foraminal stenosis through a microendoscopic posterior cervical foraminotomy in the sitting position using the TELIGEN system. A 67-year-old male patient presented with a unilateral C6-7 radiculopathy with imaging corroborating severe foraminal stenosis. Therefore, a microendoscopic posterior cervical foraminotomy was recommended rather than an anterior cervical diskectomy and fusion or arthroplasty to preserve segmental motion and minimize hardware-related complications. This video reviews the nuances of this approach and key surgical steps. Emphasis is given to the patient positioning and ergonomic favorability and enhanced visualization afforded by the TELIGEN endoscopic platform. The patient tolerated the procedure well and reported significant improvement of radiculopathy after surgery. At 2-week follow-up, the patient reported resolution of his preoperative symptoms and returned to normal activity without restrictions. The patient consented to the procedure, and the participants and any identifiable individuals consented to publication of his/her image.

The Injection of Gels Through an Intact Annulus Maintains Biomechanical Performance without Extrusion Risk.

For autologous-disc-derived chondrocyte transplantation (ADCT) a transglutaminase crosslinked gelatine gel and an albumin hyaluronic acid gel, crosslinked with bis-thio-polyethylene glycol, were injected through a syringe into a degenerated intervertebral disc, where they solidified in situ. This biomechanical in vitro study with lumbar bovine motion segments evaluated disc height changes, motion characteristics in a quasi-static spine loading simulators, and the potential extrusion risk of these biomaterials in a complex dynamic multi-axial loading set-up with 100,000 loading cycles. After the injection and formation of the gel in the center of the nucleus, the disc height increase was about 0.3 mm. During cyclic testing, a gradual decrease in height could be detected due to viscoelastic effects and fluid loss. No gel extrusion could be observed for all specimens during the entire test procedure. A macroscopic inspection after dissections showed an accumulation of the solidified gel in the center of the nucleus. The results demonstrate that the injection of in situ solidifying gels through the intact annulus allows for the stable maintenance of the injected gel at the target location, with high potential for use as a suitable scaffold to anchor therapeutically applied cells for disc regeneration within the treated nucleus pulposus.

Normal Functional Local Alignment and Segmental Motion at the Thoracolumbar Junction: A Cross-Sectional Study of Healthy Subjects

Several studies have investigated the mechanical behavior of the thoracolumbar spine. However, finding an accurate reference for the normal functional local alignment and segmental motion (SM) at the thoracolumbar junction (TLJ) is challenging. Therefore, this study aimed to assess age- and sex-related changes and differences in local alignment and SM at the TLJ. The study recruited healthy subjects aged 20 to 79 without complaints of back pain. Healthy subjects (60 males and 60 females) with appropriate imaging results were enrolled in the study. The subjects were divided into age groups (20-29, 30-39, 40-49, 50-59, 60-69, and 70-79years); each group included 10 subjects of each sex. The SM at the TLJ was small but noticeable, and the motion gradually increased toward the lower level of the TLJ, closer to the lumbar region. No significant differences were observed between male and female subjects in any SM measurements at the TLJ. The SM at the TLJ gradually decreased with age, while local kyphosis of TLJ progressed. The results also showed that the thoracolumbar slope value did not change with age and remained at a mean of-12.8±7.2° (P=0.893). This study's results provide valuable guidance for appropriate surgical planning and rehabilitation of patients with spinal diseases or trauma. Furthermore, the results can be the basis for categorizing accurate criteria to evaluate the degree of disability after treatment.

Relationship between cervical lordotic angle and cervical segmental motion during craniocervical flexion test: A cross-sectional study.

The craniocervical flexion test (CCFT) is commonly used for assessing the performance and function of the deep cervical flexor muscles; however, objective measurements of cervical segmental motion during craniocervical flexion (CCF) are lacking. Therefore, the purpose of this study aimed to investigate cervical segmental motions during CCFT and determine the relationship between changes of cervical segmental motions and the cervical lordotic angle. A cross-sectional study of prospectively collected data. Twenty healthy participants without neck pain underwent standing cervical radiography (lateral view) to measure the cervical lordotic angle, followed by radiography in supine position during the CCFT. The occipito-atlantal (OA) joint angle, atlantoaxial (AA) joint angle, and cervical spinous process posterior displacement (CSPPD) of the C1-C6 vertebrae were measured using lateral cervical radiographs taken during the initial (20 mm Hg) and low-stage (24 mm Hg) CCFT conditions. The CCF motion during the low-stage CCFT was characterized by a significantly increased OA joint angle, decreased AA joint angle, and increased C1-C6 CSPPD compared with the initial stage (P < .05). The change in the value of C1-C6 CSPPD at low-stage CCFT showed a significant positive correlation with the cervical lordotic angle. These results indicate that the cervical lordotic angle is important in minimizing CSPPD and performing appropriately-isolated CCF motion during CCFT.

Defining a systems framework for characterizing physical work demands with wearable sensors.

Measuring the physical demands of work is important in understanding the relationship between exposure to these job demands and their impact on the safety, health, and well-being of working people. However, work is changing and our knowledge of job demands should also evolve in anticipation of these changes. New opportunities exist for noninvasive long-term measures of physical demands through wearable motion sensors, including inertial measurement units, heart rate monitors, and muscle activity monitors. Inertial measurement units combine accelerometers, gyroscopes, and magnetometers to provide continuous measurement of a segment's motion and the ability to estimate orientation in 3-dimensional space. There is a need for a system-thinking perspective on how and when to apply these wearable sensors within the context of research and practice surrounding the measurement of physical job demands. In this paper, a framework is presented for measuring the physical work demands that can guide designers, researchers, and users to integrate and implement these advanced sensor technologies in a way that is relevant to the decision-making needs for physical demand assessment. We (i) present a literature review of the way physical demands are currently being measured, (ii) present a framework that extends the International Classification of Functioning to guide how technology can measure the facets of work, (iii) provide a background on wearable motion sensing, and (iv) define 3 categories of decision-making that influence the questions that we can ask and measures that are needed. By forming questions within these categories at each level of the framework, this approach encourages thinking about the systems-level problems inherent in the workplace and how they manifest at different scales. Applying this framework provides a systems approach to guide study designs and methodological approaches to study how work is changing and how it impacts worker safety, health, and well-being.

Tnfaip8 and Tipe2 Gene Deletion Ameliorates Immediate Proteoglycan Loss and Inflammatory Responses in the Injured Mouse Intervertebral Disc.

TNFAIP8 and TIPE2 belong to TNFa-induced protein 8 (TNFAIP8/TIPE) family. They control apoptosis and direct leukocyte migration. Nucleus pulposus cell loss is a hallmark of intervertebral disc degeneration in response to injury, and inflammation may cause pain. Here, we examined the effects of TNFAIP8/TIPE2 deficiency on the intervertebral discs in mice with these genes deleted. Tail intervertebral discs in Tnfaip8 or Tipe2 single and double knockout mice ( Tnfaip8 -/- , Tipe2 -/- , and Tnfaip8/Tipe2 dko) , and wild-type controls were injured. The spine motion segments were stained with safranin O to reveal proteoglycans. Macrophages were identified by immunostaining, and selected inflammatory marker and collagen gene expression was examined by Real Time PCR. The injured tail intervertebral discs of Tnfaip -/- , Tipe2 -/- , and Tnfaip8/Tipe2 dko mice all displayed higher levels of proteoglycans than wild-type controls. Fewer macrophages were found in the injured intervertebral discs of Tipe2 -/- and Tnfaip8/Tipe2 dko mice than wild type. Il6 , Adam8 , and Col1 gene expression was downregulated in the injured intervertebral discs of Tnfip8/Tipe2 dko mice. TNFAIP8 and TIPE2 loss of function ameliorated proteoglycan loss and inflammation in the injured intervertebral discs. They may serve as molecular targets to preserve disc structure and reduce inflammation.

Phosphine-Capped Effects Enable Full-Color Clusteroluminescence in Nonconjugated Polyesters.

Full-color luminophores have advanced applications in materials and engineering, but constructing color-tunable clusteroluminescence (CL) from nonconjugated polymers based on through-space interactions remains a huge challenge. Herein, we develop phosphine-capped nonconjugated polyesters exhibiting blue-to-red CL (400-700 nm) based on phosphine-initiated copolymerization of epoxides and cyclic anhydrides, especially P1-0.5TPP, which exhibits red CL (610 nm) with a high quantum yield of 32%. Experiments and theoretical calculations disclose that the phosphine-capped effect in polyesters brings about conformational changes and induces phosphine-ester clusters by through-space (n,π*) interactions. Moreover, CL colors and efficiencies can be easily tailored by types of phosphines, compositions and structures of polyesters, and concentration. Significantly, the role of polymer motions (group, segmental, and chain motions) on CL originating from microregions inside polyesters is revealed. Further, phosphine-capped nonconjugated polyesters are demonstrated to be nonconjugated dyes and fluorescent fibers and are also used for multicolor light-emitting diodes including white light. This work not only provides an engineering strategy based on the end-group effect to prepare full-color clusteroluminogens but also broadens the prospects for material applications.

Customizing superior surface insulation properties of polymeric dielectric via in-plane molecular chain orientation

Surface flashover is a common breakdown phenomenon on material surfaces for which surface charge migration property, determined by surface composition and molecular chain structure, is crucial. Precise modulation of charge migration property by simple and efficient methods to improve surface flashover voltage is the goal in industry. Here, in-plane molecular chain orientation (MCO) modulation by uniaxial stretching was proposed to achieve this goal and investigate the intrinsic mechanism of charge migration on flashover. Flashover voltage and accompanying leakage current, performed with electrodes oriented at varying angles to the MCO direction, show a consistent trend, which skillfully reveals that the facilitated charge migration is favorable for improving flashover voltage. When the stretching ratio is 3.5, the flashover voltage along the stretching direction (SD) increases by up to 48.7%, while the in-plane minimum flashover voltage remains essentially unchanged with the change in stretching ratio. Molecular chain segment motion properties along different directions further elucidate that the surprising improvement of flashover voltage along SD is primarily due to the MCO that promotes intra-chain charge migration. This work provides a new perspective on anti-flashover modification of polymeric dielectric and will promote the development of surface flashover mechanisms.

Spatiotemporal changes in imaging features associated with diffuse idiopathic skeletal hyperostosis (DISH)

ObjectivesThe purpose of our study was to characterise spatiotemporal features of disease progression in people with diffuse idiopathic skeletal hyperostosis (DISH), early-phase DISH, and those not meeting either criterion who...

Dynamics of structural transformations of intervertebral discs in humans in the fetal period

BACKGROUND:The process of formation of the intervertebral disc structure remains poorly understood. Therefore, evaluating the forecasts for the development of the disc’s fibrous component as the foundation of its strength and elastic properties in the postnatal period seems appropriate.&#x0D; AIM:To identify microstructural transformations of the annulus fibrosus and nucleus pulposus in the fetal period and compare them with the ontogenetic orientation of the spinal motion segment.&#x0D; MATERIAL AND METHODS:The study material included 150intervertebral discs obtained during autopsy of 50fetuses. The gestational age of 42fetuses was in the early fetal period, 8fetuses were in the late fetal period. Intervertebral discs СV–СVI, ThV–ThVI, LV–SIwere examined in each fetus. All histological preparations were stained with hematoxylin and eosin, silver impregnation method, PAS reaction, Alcian blue (pH=1.0), Van Gieson and Weigert stains. For intergroup comparisons, the Kruskal–Wallis, Mann–Whitney, and Newman–Keuls tests were used. Differences were considered statistically significant atp≤0.05.&#x0D; RESULTS:Elastic fibers in the late fetal period were found in the annulus fibrosus and the peripheral zone of the nucleus pulposus. The intensity of staining of collagen and elastic fibers was more pronounced in the outer layers of the annulus fibrosus. Analysis of the parameters of the vascular-connective tissue formations showed an increase in their number (p=0.0368) and an increase in the number of vessels in the vascular-connective tissue formations of the intervertebral disc (p=0.0449) in the direction of the lower levels of the spinal motion segments. Differences in these two indicators were obtained between the СV–СVIand LV–SIdiscs, as well as between the СV–СVIand ThV–ThVIdiscs. In relation to all the studied morphometric parameters of the vascular-connective tissue formations in the cervical and thoracic spine, no statistically significant differences were obtained between the early and late fetal periods.&#x0D; CONCLUSION:The development of the intervertebral disc occurs from the peripheral parts to the center; the source for its further development is the fibrous ring.

Poor postoperative pain control is associated with poor long-term patient-reported outcomes after elective spine surgery: an observational cohort study

BACKGROUND CONTEXTA significant proportion of patients experience poorly controlled surgical pain and fail to achieve satisfactory clinical improvement after spine surgery. However, a direct association between these variables has not been previously demonstrated. PURPOSETo investigate the association between poor postoperative pain control and patient-reported outcomes after spine surgery. STUDY DESIGNAmbispective cohort study. PATIENT SAMPLEConsecutive adult patients (≥18-years old) undergoing inpatient elective cervical or thoracolumbar spine surgery. OUTCOME MEASUREPoor surgical outcome was defined as failure to achieve a minimal clinically important difference (MCID) of 30% improvement on the Oswestry Disability Index or Neck Disability Index at follow-up (3-months, 1-year, and 2-years). METHODSPoor pain control was defined as a mean numeric rating scale score of >4 during the first 24-hours after surgery. Multivariable mixed-effects regression was used to investigate the relationship between poor pain control and changes in surgical outcomes while adjusting for known confounders. Secondarily, the Calgary Postoperative Pain After Spine Surgery (CAPPS) Score was investigated for its ability to predict poor surgical outcome. RESULTSOf 1294 patients, 47.8%, 37.3%, and 39.8% failed to achieve the MCID at 3-months, 1-year, and 2-years, respectively. The incidence of poor pain control was 56.9%. Multivariable analyses showed poor pain control after spine surgery was independently associated with failure to achieve the MCID (OR 2.35 [95% CI=1.59–3.46], p<.001) after adjusting for age (p=.18), female sex (p=.57), any nicotine products (p=.041), ASA physical status >2 (p<.001), ≥3 motion segment surgery (p=.008), revision surgery (p=.001), follow-up time (p<.001), and thoracolumbar surgery compared to cervical surgery (p=.004). The CAPPS score was also found to be independently predictive of poor surgical outcome. CONCLUSIONPoor pain control in the first 24-hours after elective spine surgery was an independent risk factor for poor surgical outcome. Perioperative treatment strategies to improve postoperative pain control may lead to improved patient-reported surgical outcomes.