Explore the vast range of titles available.

\"Violence strikes the heart of Duluth when a bomb goes off at a marathon, bringing the FBI to Detective Jonathan Stride's city. Was it terrorism, or something more personal?\"-- Provided by publisher.

While microstructural observations have improved our understanding of possible pathways of herniation progression, no studies have measured the mechanical failure properties of the inter-lamellar matrix (ILM), nor of the adjacent lamellae during progression to herniation. The aim of this study was to employ multiscale, biomechanical and microstructural techniques to evaluate the effects of progressive induced herniation on the ILM and lamellae in control, pre-herniated and herniated discs (N = 7), using 2 year-old ovine spines. Pre-herniated and herniated (experimental) groups were subjected to macroscopic compression while held in flexion (13°), before micro-mechanical testing. Micro-tensile testing of the ILM and the lamella from anterior and posterolateral regions was performed in radial and circumferential directions to measure failure stress, modulus, and toughness in all three groups. The failure stress of the ILM was significantly lower for both experimental groups compared to control in each of radial and circumferential loading directions in the posterolateral region (p < 0.032). Within each experimental group in both loading directions, the ILM failure stress was significantly lower by 36% (pre-herniation), and 59% (herniation), compared to the lamella (p < 0.029). In pre-herniated compared to control discs, microstructural imaging revealed significant tissue stretching and change in orientation (p < 0.003), resulting in a loss of distinction between respective lamellae and ILM boundaries.

Cauda Equina Syndrome (CES) is an emergency condition that requires acute intervention and can lead to permanent neurological deficit in working age adults. A Core Outcome Set (COS) is the minimum set of outcomes that should be reported by a research study within a specific disease area. There is significant heterogeneity in outcome reporting for CES, which does not allow data synthesis between studies. The hypothesis is that a COS for CES can be developed for future research studies using patients and healthcare professionals (HCPs) as key stakeholders. Qualitative semi-structured interviews with CES patients were audio-recorded, transcribed and analysed using NVivo to identify the outcomes of importance. These were combined with the outcomes obtained from a published systematic literature review of CES patients. The outcomes were grouped into a list of 37, for rating through two rounds of an international Delphi survey according to pre-set criteria. The Delphi survey had an overall response rate of 63% and included 172 participants (104 patients, 68 HCPs) from 14 countries who completed both rounds. Thirteen outcomes reached consensus at the end of the Delphi survey and there was no attrition bias detected. The results were discussed at an international consensus meeting attended by 34 key stakeholders (16 patients and 18 HCPs) from 8 countries. A further three outcomes were agreed to be included. There was no selection bias detected at the consensus meeting. There are 16 outcomes in total in the CESCOS. This is the first study in the literature that has determined the core outcomes in CES using a transparent international consensus process involving healthcare professionals and CES patients as key stakeholders. This COS is recommended as the most important outcomes to be reported in any research study investigating CES outcomes and will allow evidence synthesis in CES.

The plasticity and immunomodulatory capacity of mesenchymal stem cells (MSCs) have spurred clinical use in recent years. However, clinical outcomes vary and many ascribe inconsistency to the tissue source of MSCs. Yet unconsidered is the extent of heterogeneity of individual MSCs from a given tissue source with respect to differentiation potential and immune regulatory function. Here we use single-cell RNA-seq to assess the transcriptional diversity of murine mesenchymal stem cells derived from bone marrow. We found genes associated with MSC multipotency were expressed at a high level and with consistency between individual cells. However, genes associated with osteogenic, chondrogenic, adipogenic, neurogenic and vascular smooth muscle differentiation were expressed at widely varying levels between individual cells. Further, certain genes associated with immunomodulation were also inconsistent between individual cells. Differences could not be ascribed to cycles of proliferation, culture bias or other cellular process, which might alter transcript expression in a regular or cyclic pattern. These results support and extend the concept of lineage priming of MSCs and emphasize caution for in vivo or clinical use of MSCs, even when immunomodulation is the goal, since multiple mesodermal (and even perhaps ectodermal) outcomes are a possibility. Purification might enable shifting of the probability of a certain outcome, but is unlikely to remove multilineage potential altogether.

Traumatic cervical facet dislocation (CFD) is often associated with devastating spinal cord injury. Facet fractures commonly occur during CFD, yet quantitative measures of facet deflection, strain, stiffness and failure load have not been reported. The aim of this study was to determine the mechanical response of the subaxial cervical facets when loaded in directions thought to be associated with traumatic bilateral CFD – anterior shear and flexion. Thirty-one functional spinal units (6 × C2/3, C3/4, C4/5, and C6/7, 7 × C5/6) were dissected from fourteen human cadaver cervical spines (mean donor age 69 years, range 48–92; eight male). Loading was applied to the inferior facets of the inferior vertebra to simulate the in vivo inter-facet loading experienced during supraphysiologic anterior shear and flexion motion. Specimens were subjected to three cycles of sub-failure loading (10–100 N, 1 mm/s) in each direction, before being failed in a randomly assigned direction (10 mm/s). Facet deflection, surface strains, stiffness, and failure load were measured. Linear mixed-effects models (α = 0.05; random effect of cadaver) accounted for variations in specimen geometry and bone density. Specimen-specific parameters were significantly associated with most outcome measures. Facet stiffness and failure load were significantly greater in the simulated flexion loading direction, and deflection and surface strains were higher in anterior shear at the non-destructive analysis point (47 N applied load). The sub-failure strains and stiffness responses differed between the upper and lower subaxial cervical regions. Failure occurred through the facet tip during anterior shear loading, while failure through the pedicles was most common in flexion.

The subaxial cervical facets are important load-bearing structures, yet little is known about their mechanical response during physiological or traumatic intervertebral motion. Facet loading likely increases when intervertebral motions are superimposed with axial compression forces, increasing the risk of facet fracture. The aim of this study was to measure the mechanical response of the facets when intervertebral axial compression or distraction is superimposed on constrained, non-destructive shear, bending and rotation motions. Twelve C6/C7 motion segments (70 ± 13 yr, nine male) were subjected to constrained quasi-static anterior shear (1 mm), axial rotation (4°), flexion (10°), and lateral bending (5°) motions. Each motion was superimposed with three axial conditions: (1) 50 N compression; (2) 300 N compression (simulating neck muscle contraction); and, (3) 2.5 mm distraction. Angular deflections, and principal and shear surface strains, of the bilateral C6 inferior facets were calculated from motion-capture data and rosette strain gauges, respectively. Linear mixed-effects models (α = 0.05) assessed the effect of axial condition. Minimum principal and maximum shear strains were largest in the compressed condition for all motions except for maximum principal strains during axial rotation. For right axial rotation, maximum principal strains were larger for the contralateral facets, and minimum principal strains were larger for the left facets, regardless of axial condition. Sagittal deflections were largest in the compressed conditions during anterior shear and lateral bending motions, when adjusted for facet side.

Background The incidence of lumbar spinal stenosis (LSS) continues to rise, with both conservative and surgical management representing options for its treatment. The timing of surgery for LSS varies from shortly after the onset of symptoms to several months or years after conservative treatment. The aim of this study was to investigate the association between the duration of pre-operative conservative treatment and the ultimate outcome following surgical interventions for LSS. Methods The study was based on prospective multicentre registry data (Spine Tango). Cases of LSS with a documented duration of conservative treatment, undergoing spinal decompression with at least one post-operative patient assessment between 3 and 30 months, were included in the study. Cases of LSS with spondylolisthesis, additional spinal pathology or previous spinal surgery were excluded. Interrogation of the Spine Tango Registry listed 3478 patients meeting the prescribed inclusion criteria. This cohort was stratified into four groups: (1) no previous treatment ( n  = 497; 14.3%), (2) conservative treatment <6 months ( n  = 965; 27.8%), (3) conservative treatment between 6 and 12 months ( n  = 758; 21.8%), and (4) conservative treatment >12 months ( n  = 1258; 36.1%). Group 4 reference group in regression analysis. The inverse probability of treatment weighting (IPTW) was applied using the propensity score to balance the groups for their characteristics. Outcome measures included achievement of the minimum clinically important change (MCIC) score of 2 points for (a) back pain, (b) leg pain and (c) Core Outcome Measures Index (COMI), and (d) surgical complications, (e) general complications and (f) operation time >2 h. Results Patient group (“duration of conservative therapy”) was not associated with achievement of the MCIC for post-operative relief of leg pain ( p  = 0.22), achievement of MCIC for the COMI score ( p  = 0.054), surgical complications ( p  = 0.11) or general complications ( p  = 0.14). Only MCIC for post-operative relief of back pain ( p  = 0.021) and operation time were significantly associated with patient group ( p  = 0.038). However, compared with the reference group of >12 months of conservative treatment there was no significant difference in the likelihood of achieving the MCIC for those with none, <6 or 6–12 months of conservative treatment. Conclusions The duration of pre-operative conservative treatment was not associated with the ultimate outcome of decompression surgery. Further research is required to investigate optimal thresholds/indications for surgery and its appropriate timing in individual patients.

Despite the common use of one-handed lifting techniques for activities of daily living, these techniques have received little attention in the biomechanics literature. The braced arm-to-thigh technique (BATT) is a one-handed lifting method in which the dominant hand picks up objects, while the free hand braces the trunk on the ipsilateral thigh. The aim of this study was to compare the BATT to two-handed or unsupported one-handed lifting techniques with loads of 2 and 10 kg, by evaluating trunk motion and spine loading at L4/L5. Twenty healthy participants (30–70 years old) matched in age and sex to 18 participants with low back pain were recruited to the study. A three-axis load cell secured to the distal anterior thigh measured the bracing forces applied by the hand. The OpenSim Lifting Full-Body model was used to estimate trunk kinematics and spinal loading at L4/L5. Linear mixed-effects models were developed to compare trunk angles and L4/L5 moments and forces between lifting techniques. Trunk flexion angles were significantly reduced for the BATT lift compared to one-handed and two-handed stoop lifts (9–20%). However, the BATT also increased asymmetric trunk kinematics and moments at L4/L5. The BATT produced significantly lower moments (28–38%), and compressive (25–32%) and antero-posterior shear (25–45%) forces at L4/L5, compared to unsupported lifting techniques. Bracing the hand on the thigh to support the trunk can substantially reduce low back loading during lifting tasks of 2 to 10 kg.

PurposeTo evaluate the effect of the braced arm-to-thigh technique (BATT) (versus self-selected techniques) on three-dimensional trunk kinematics and spinal loads for three common activities of daily living (ADLs) simulated in the laboratory: weeding (gardening), reaching for an object in a low cupboard, and car egress using the two-legs out technique.MethodsTen young healthy males performed each task using a self-selected technique, and then using the BATT. The pulling action of weeding was simulated using a magnet placed on a steel plate. Cupboard and car egress tasks were simulated using custom apparatus representing the dimensions of a kitchen cabinet and a medium-sized Australian car, respectively. Three-dimensional trunk kinematics and L4/L5 spinal loads were estimated using the Lifting Full-Body OpenSim model and compared between techniques. Paired t-tests were used to compare peak values between methods (self-selected vs BATT).ResultsThe BATT significantly reduced peak extension moments (13–51%), and both compression (27–45%) and shear forces (31–62%) at L4/L5, compared to self-selected techniques for all three tasks (p < 0.05). Lateral bending angles increased with the BATT for weeding and cupboard tasks, but these changes were expected as the BATT inherently introduces asymmetric trunk motion.ConclusionThe BATT substantially reduced L4/L5 extension moments, and L4/L5 compression and shear forces, compared to self-selected methods, for three ADLs, in a small cohort of ten young healthy males without prior history of back pain. These study findings can be used to inform safe procedures for these three ADLs, as the results are considered representative of a mature population.