Spinal Unit Research Articles

Gynecologic and breast management in the perimenopause patients with motor disability: survey in dedicated service of the Careggi University Hospital

Background: The life expectancy of people with mobility impairment has substantially increased over the years, however, there is little data regarding how women with mobility impairment cope with life stage changes, such as the period from premenopause to postmenopause. The experience of the Pink Point outpatient clinic of the Careggi University Hospital in Florence, dedicated to women with motor disabilities through an observational study of a group of 35 women who came to the service for climacteric symptoms and/or peri- and/or postmenopausal gynecological and breast cancer screening is reported. Pink Point is a dedicated obstetric-gynecological care service designed in 2015 by Careggi University Hospital as part of the Maternal Department and Spinal Unit and is part of the Tuscany Region's PASS Program for equity of access to care for people with disability-related special needs. The service is adjacent to the Diagnostic and Breast Radiology Service with a dedicated chair for complex disabling conditions.

Outcome of Long Segment Posterior Spinal Stabilization Incorporating the Fractured Vertebra for Unstable Thoraco-Lumbar Junctional Brust Fracture

Objectives: To evaluate the outcome of long segment posterior spinal stabilization incorporating the fractured vertebra with posterolateral fusion for unstable thoraco-lumbar junctional brust fracture. Background: Thoracolumbar junction is the commonest site of traumatic spinal injury. Now a days, it is managed surgically most of the time because it is often associated with the spinal cord injury. Its mode of surgical management is a field of controversy. Huge debate is still going on between the superiority of long & short segment stabilization. In this study, we evaluated the outcome of long segment posterior spinal stabilization incorporating the fractured vertebra Materials & Method: This prospective interventonal study included 30 case of thoraco-lumbar junctional unstable brust fractures was carried out in the Spine unit of Orthopaedic surgery department of Bangabandhu Sheikh Mujib Medical University, Dhaka and other private hospital in Dhaka City, Bangladesh, from January 2016 to July 2022. All the patients with positive clinical findings, X-ray, MRI & CT scan findings and underwent long segment posterior spinal stabilization incorporating the fractured vertevra with posterolateral fusion. Average follow-up period was 12 months. Pre & Post-operatively, neurological assessment was done by the ASIA Impairment Score, improvement of pain control by VAS score, fusion rate by Bridwell’s criteria, Kyphotic angle was measured by Cobb’s angle measurement method & Overall functional assessment by modified Odom’s score. Results: Total number of patients was 30. Average age was 34 years (range 21- 47). ASIA score improved from B to C in 5 patients, B to D in 5 patients, C to D in 8 patients , C to E in 3 patients, patients, D to E in 7 patients. 2 patient did not improved following surgery. Fusion was achieved in 29 patients & 1 patient developed pseudoarthrosis. Pre & Post- operative VAS score was 7.30±1.9 & 3.3±1.8 respectively. The average kyphotic correction was 15 ∞. In our series, we have no bedridden patients after surgery. There was no radiographic progression after surgery. Conclusion: Early treatment within 21 days of injury with long segment posterior spinal stabilization incorporating the fractured vertevra with posterolateral fusion is a very effective surgical procedure with preservation of the motion segment to treat unstable thoracolumbar junctional brust fracture.

Novel 3D printed lattice structure titanium cages evaluated in an ovine model of interbody fusion.

The use of intervertebral cages within the interbody fusion setting is ubiquitous. Synthetic cages are predominantly manufactured using materials such as Ti and PEEK. With the advent of additive manufacturing techniques, it is now possible to spatially vary complex 3D geometric features within interbody devices, enabling the devices to match the stiffness of native tissue and better promote bony integration. To date, the impact of surface porosity of additively manufactured Ti interbody cages on fusion outcomes has not been investigated. Thus, the objective of this work was to determine the effect of implant endplate surface and implant body architecture of additive manufactured lattice structure titanium interbody cages on bony fusion. Biomechanical, microcomputed tomography, static and dynamic histomorphometry, and histopathology analyses were performed on twelve functional spine units obtained from six sheep randomly allocated to body lattice or surface lattice groups. Nondestructive kinematic testing, microcomputed tomography analysis, and histomorphometry analyses of the functional spine units revealed positive fusion outcomes in both groups. These data revealed similar results in both groups, with the exception of bone-in-contact analysis, which revealed significantly improved bone-in-contact values in the body lattice group compared to the surface lattice group. Both additively manufactured porous titanium cage designs resulted in increased fusion outcomes as compared to PEEK interbody cage designs as illustrated by the nondestructive kinematic motion testing, static and dynamic histomorphometry, microcomputed tomography, and histopathology analyses. While both cages provided for similar functional outcomes, these data suggest boney contact with an interbody cage may be impacted by the nature of implant porosity adjacent to the vertebral endplates.

Mechanical Response of Trapezoidal Cage on Cervical 6–Cervical 7 Level

Abstract The human cervical spine is the most essential support system of the whole body. It consists of vertebras, tissues, facet joints, intervertebral disks and ligaments. The problems in the cervical spine is more frequent, it can be due to accident or increase with the age. The objective of this study is to develop the interbody fusion cage with different porosity size and study the behavior of the cage for the compression loads. The bone graft introduced in the cage will provide osteointegration with the adjacent vertebra. For the biomechanical analysis we created the cervical level C6–C7 and inserted the cage in the functional spine unit and analyzed using finite element analysis for compression loadings. In this study, by introducing the semispherical shape porosity in the inferior and superior surface of the cage will reduce the cage stress and in the same porosity we introduced the bone graft for the better osteointegration. So, the reduced stress in the cage structure will reduce the occurrence of the subsidence and migration of the cage.

Finite element analysis of an intact lumbar spine model: Effects of loading under different coordinate systems.

Finite element (FE) analysis has been used in studying the biomechanics of the lumbar spine. While some FE studies used a follower load technique that intended to replace the compressing effect of local muscle force, other studies considered satisfying the relationship between the human body's posture and the centre of gravity (CG) for investigating spine biomechanics. However, the above studies did not reveal the importance of a coordinate system that gratifies the posture-CG relation and follower load techniques. The present FE study compares the variation in ranges of motion (ROM) and stress-strain distributions due to the application of loading via different coordinate systems, follower (FCS) and global (GCS). A subject-specific computed tomography scan-based intact spine (L1-L5) FE model was developed and simulated for physiological movements. The FE results indicated a minimum deviation in ROM of 2.7° for the L1-L5 full model at all physiological activities between the defined coordinate systems. The observed variation for the L3-L4 functional spinal unit was between 4.7° and 19°. The von Mises strain in the vertebrae was between 0.0007 and 0.003 for the FCS case. In contrast, the peak von Mises strain for the GCS case was above the compressive yield strain limit of cancellous bone by 38.5%. The GCS model transferred the load unsymmetrically, whereas the distribution was symmetrical for the FCS case, without any potential risk of bone failure. These observations clearly indicate that the selection of the appropriate loading coordinate system is as crucial as the magnitude of loading.

Multidrug-resistant Acinetobacter outbreak in spinal cord unit identified and stemmed through infection prevention epidemiologic efforts

Background: Drug-resistant pathogens are a significant source of increased cost and patient complications in long-term and/or congregate care settings. Once introduced, depending on the environmental niche in which they establish and the mechanisms they employ for survival, they can be difficult to eradicate. We report the details of an epidemiologic investigation of a multidrug-resistant Acinetobacter baumannii (MDR-A) outbreak in a spinal cord intervention (SCI) unit within a Veterans Affairs facility in San Antonio, Texas, that was identified after back tracing a positive wound culture from a long-term resident. Methods: All MDR-A isolates were matched to the patients harboring them. Their clinical, epidemiologic, and geographic histories within our facility were traced. All potentially shared characteristics between cases were evaluated closely. Results: In total, 5 cases were determined to be likely connected over a period of ~18 months starting December 2020. The extant isolates underwent molecular evaluation and were genetically related. Patient activity was traced by the infection prevention team to identify potential sources of transmission. Environmental sampling after standard cleaning found a common strain on a shower trolley shared by these patients. Following focused cleaning of this and other shared locations, no new related isolates have been identified from patient or environmental samples. Conclusions: In this case, investigation by the infection prevention team of a single multidrug-resistant organism led to identification and eradication of a potential pathogen. Despite standard cleaning processes, a likely shared fomite was identified and decontaminated, thereby preventing future infections. This case exemplifies the value of thorough epidemiologic study paired with modern molecular methods of identification.Disclosures: None

Effect of neglecting passive spinal structures: a quantitative investigation using the forward-dynamics and inverse-dynamics musculoskeletal approach.

Purpose: Inverse-dynamics (ID) analysis is an approach widely used for studying spine biomechanics and the estimation of muscle forces. Despite the increasing structural complexity of spine models, ID analysis results substantially rely on accurate kinematic data that most of the current technologies are not capable to provide. For this reason, the model complexity is drastically reduced by assuming three degrees of freedom spherical joints and generic kinematic coupling constraints. Moreover, the majority of current ID spine models neglect the contribution of passive structures. The aim of this ID analysis study was to determine the impact of modelled passive structures (i.e., ligaments and intervertebral discs) on remaining joint forces and torques that muscles must balance in the functional spinal unit. Methods: For this purpose, an existing generic spine model developed for the use in the demoa software environment was transferred into the musculoskeletal modelling platform OpenSim. The thoracolumbar spine model previously used in forward-dynamics (FD) simulations provided a full kinematic description of a flexion-extension movement. By using the obtained in silico kinematics, ID analysis was performed. The individual contribution of passive elements to the generalised net joint forces and torques was evaluated in a step-wise approach increasing the model complexity by adding individual biological structures of the spine. Results: The implementation of intervertebral discs and ligaments has significantly reduced compressive loading and anterior torque that is attributed to the acting net muscle forces by -200% and -75%, respectively. The ID model kinematics and kinetics were cross-validated against the FD simulation results. Conclusion: This study clearly shows the importance of incorporating passive spinal structures on the accurate computation of remaining joint loads. Furthermore, for the first time, a generic spine model was used and cross-validated in two different musculoskeletal modelling platforms, i.e., demoa and OpenSim, respectively. In future, a comparison of neuromuscular control strategies for spinal movement can be investigated using both approaches.

Minor microbial alterations after faecal diversion do not affect the healing process of anus-near pressure injuries in patients with spinal cord injury-results of a matched case-control study.

Retrospective matched case-control study including patients with spinal cord injury who presented with an anus-near pressure injury. Two groups were formed based on the presence of a diverting stoma. To evaluate the primary microbial colonisation and secondary infection of anus-near pressure injuries depending on the presence of a pre-existing diverting stoma and to investigate the effect on the wound healing. University hospital with a spinal cord injury unit. A total of 120 patients who had undergone surgery of an anus-near decubitus stage 3 or 4 were included in a matched-pair cohort study. Matching was realised according to age, gender, body mass index and general condition. The most common species in both groups was Staphylococcus spp.(45.0%). The only significantly different primary colonisation affected Escherichia coli, that was found in the stoma patients less often (18.3 and 43.3%, p < 0.01). A secondary microbial colonisation occurred in 15.8% and was equally distributed, except for Enterococcus spp. that was present in the stoma group only (6.7%, p < 0.05). The time to complete cure took longer in the stoma group (78.5 versus 57.0 days, p < 0.05) and was associated with a larger ulcer size (25 versus 16 cm2, p < 0.01). After correction for the ulcers' size, there was no association to outcome parameters such as overall success, healing time or adverse events. The presence of a diverting stoma alters the microbial flora of an anus-near decubitus slightly without impact on the healing process.

Long-term Outcomes Following Periprocedural and Spontaneous Spinal Cord Infarctions: A Population-Based Cohort Study.

Spinal cord infarction (SCInf) is a rare condition where consensus regarding diagnostic criteria is lacking and mis- or delayed diagnosis can be detrimental. The aim of this study was to describe baseline findings and predictors of long-term functional outcome in a population-based cohort of patients with SCInf. All adult patients (≥18 years) treated at the Spinal Cord Injury Unit of the study center, between 2006-2019, and discharged with a G95 diagnosis ("other and unspecified disease of the spinal cord") were screened for inclusion. The diagnostic criteria proposed by Zalewski et al. were retrospectively applied to evaluate the certainty of the SCInf diagnosis. 270 patients were screened and 57 were included in the study, of whom 30 had a spontaneous and 27 had a periprocedural SCInf. The median American Spinal Cord Injury Association Impairment Scale (AIS) on admission was C, which at median follow-up of 2.1 years had improved to D (p=0.002). Compared to periprocedural cases, spontaneous SCInf showed significantly better admission-AIS (median AIS D vs. B, p<0.001), fewer multilevel SCInf (27% vs. 59%, p=0.029), shorter hospital stay (median 22 vs. 44 days, p<0.001), as well as better AIS (median AIS D vs. C, p<0.001) and ambulatory status on long-term follow-up (66% vs. 1%, p<0.001). Regression analyses revealed that spontaneous SCInfs (OR=5.91 [1.92-18.1], p=0.002) and more favorable admission-AIS (OR=33.6 [7.72-146], p<0.001) were significant predictors of more favorable AIS at follow-up, with admission-AIS demonstrating independent predictive ability (OR=35.9 [8.05-160], p<0.001). SCInf is a rare neurological emergency lacking specific management guidelines. While the presumptive diagnosis is based on the typical presentation and clinical findings, T2-weighted and diffusion-weighted MRI were the most useful diagnostic tools in establishing a definitive diagnosis. Our data shows that spontaneous SCInf mostly affected a single spinal cord segment while periprocedural cases were more extensive, had poorer AIS on admission, poorer ambulatory function, and longer hospital stays. Regardless of the etiology, significant neurological improvements were seen at long-term follow-up, highlighting the importance of active rehabilitation.

Stigma following acquired brain injury and spinal cord injury: relationship to psychological distress and community integration in the first-year post-discharge

Purpose This study aimed to compare stigma levels after acquired brain injury (ABI) and spinal cord injury (SCI) during the first 12-months post-discharge and investigate relationships between stigma, psychological distress and community integration. Methods 110 adults with ABI (55%) or SCI (45%) were recruited from brain and spinal cord injury inpatient rehabilitation units of a tertiary healthcare facility. They were administered Neuro-QOL Stigma subscale and Depression Anxiety and Stress Scales (DASS-21) at discharge, 3-months and 12-months post-discharge, and Community Integration Measure at 12-months post-discharge. Results Stigma levels did not significantly differ between individuals with ABI and SCI. However, stigma significantly decreased between discharge and 12-months post-discharge for the total sample. Stigma was positively associated with psychological distress at discharge and 3-months post-discharge, but not at 12-months post-discharge. Lower functional status and power wheelchair use were associated with higher stigma at 12-months post-discharge. Stigma at 3-months post-discharge predicted community integration at 12-months post-discharge, controlling for psychological distress and functional status. Conclusion Experience of stigma in the first few months post-discharge may negatively impact individuals’ community reintegration. The early post-discharge period may be a pivotal time for supporting individuals to explore disability and injury-related appraisals and enhance connection to their community.

Cervical Spinal Cord Gray Matter Area is Associated with Motor Unit Number Index in Spinal Muscular Atrophy (S33.008)

<h3>Objective:</h3> To evaluate the association between spinal cord (SC) gray matter (GM) atrophy and Motor Unit Number Index (MUNIX) in patients with 5q-Spinal Muscular Atrophy (SMA). <h3>Background:</h3> There is an unmet need for valid imaging markers to monitor the disease course and therapeutic outcome in SMA. The novel rAMIRA (radially sampled Averaged Magnetization Inversion Recovery Acquisitions) method enables high in-plane resolution MR-imaging with improved contrast of SC GM in clinically feasible acquisition times. MUNIX is an established quantitative neurophysiological measure that provides an index of the number of functioning lower motor neurons that supply a muscle. The association between SC GM area and MUNIX has not been investigated in SMA yet. <h3>Design/Methods:</h3> Using axial 2D rAMIRA imaging, we prospectively investigated 21 patients with 5q-SMA, types 2 and 3 (mean age/SD 41.3/11.6y, 9 women) and 21 age- and sex-matched healthy controls (HC) (mean age/SD 41.7/11.4y, 9 women) at the intervertebral disc level C5/C6 perpendicular to the spinal cord. SC GM areas were determined using a semi-automated approach. MUNIX of the biceps brachii (BB) was measured following the ENCALS protocol. The association between SC GM area and MUNIX was assessed using multivariable regression analysis covarying for age and sex. <h3>Results:</h3> SC GM area at C5/6 was significantly reduced in patients compared to HC (mean GM area in mm² (SD): SMA 17.5 (2.2); HC 21.1 (2.3); relative reduction: 17.1% (p&lt;0.0001)). In multivariable regression analysis SC GM area at C5/6 explained 53% of MUNIX variance of the BB in SMA patients. <h3>Conclusions:</h3> In patients with SMA, SC GM area is strongly associated with motor neuron function quantitated by MUNIX in the corresponding myotome, indicating the functional relevance of this structural marker. Further longitudinal studies are necessary to evaluate the potential of this novel imaging marker for monitoring the disease course and therapeutic outcome. <b>Disclosure:</b> Dr. Wendebourg has nothing to disclose. Dr. Kesenheimer has nothing to disclose. An immediate family member of Dr. Weidensteiner has received personal compensation for serving as an employee of Siemens Healthineers. Dr. Sander has nothing to disclose. The institution of Matthias Weigel, PhD has received research support from Biogen. Matthias Weigel, PhD has received intellectual property interests from a discovery or technology relating to health care. Tanja Haas has nothing to disclose. The institution of Dirk Fischer has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Hoffmann La Roche AG. The institution of Dirk Fischer has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Hoffmann La Roche AG. Christoph Neuwirth has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Biogen USA. Christoph Neuwirth has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Biogen Switzerland. Nathalie Braun has nothing to disclose. Dr. Weber has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Biogen Idec. Dr. Weber has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Mitsubishi Tanabe. Dr. Granziera has nothing to disclose. Prof. Sinnreich has nothing to disclose. The institution of Oliver Bieri has received research support from Swiss National Science Foundation. The institution of Oliver Bieri has received research support from MIAC Foundation. The institution of Oliver Bieri has received research support from Biogen. Oliver Bieri has received intellectual property interests from a discovery or technology relating to health care. Regina Schlaeger has nothing to disclose.

Upregulation of β-catenin signaling represents a single common pathway leading to the various phenotypes of spinal degeneration and pain

Spine degeneration is an aging-related disease, but its molecular mechanisms remain unknown, although elevated β-catenin signaling has been reported to be involved in intervertebral disc degeneration. Here, we determined the role of β-catenin signaling in spinal degeneration and in the homeostasis of the functional spinal unit (FSU), which includes the intervertebral disc, vertebra and facet joint and is the smallest physiological motion unit of the spine. We showed that pain sensitivity in patients with spinal degeneration is highly correlated with β-catenin protein levels. We then generated a mouse model of spinal degeneration by transgenic expression of constitutively active β-catenin in Col2+ cells. We found that β-catenin-TCF7 activated the transcription of CCL2, a known critical factor in osteoarthritic pain. Using a lumbar spine instability model, we showed that a β-catenin inhibitor relieved low back pain. Our study indicates that β-catenin plays a critical role in maintaining spine tissue homeostasis, its abnormal upregulation leads to severe spinal degeneration, and its targeting could be an avenue to treat this condition.

The anatomic study and surgical technique for canal decompression with “pedicle-plasty” strategy in lumbar burst fractures with pedicle rupture

ABSTRACT In the treatment of lumbar burst fractures with nerve injury, fusion is often required to rebuild spinal stability, but it can lead to the loss of motor units and increase the occurrence of adjacent segment diseases. Thus, a novel approach of lumbar canal decompression with “pedicle-plasty” strategy (DDP) was needed in clincal treatment. Firstly, image measurement analysis, the images of 60 patients with lumbar spine CT examinations were selected to measure osteotomy angle (OA), distance from the intersection of osteotomy plane and skin to the posterior midline (DM),transverse length of the osteotomy plane (TLOP), and sagittal diameter of the outer edge of superior articular process (SD). Secondary, cadaver study, distance between the intermuscular space and midline (DMSM), anterior and posterior diameters of the decompression (APDD), and lateral traction distance of the lumbosacral plexus (TDLP) were measured on 10 cadaveric specimens. Finally, procedure of DDP was demonstrated on cadaver specimens. OA ranged from 27.68°+4.59° to 38.34°+5.97°, DM ranged from 43.44+6.29 to 68.33+12.06 mm, TLOP ranged from 16.84+2.19 to 19.64+2.36 mm, and SD ranged from 22.49+1.74 to 25.53+2.21 mm. DMSM ranged from 45.53+5.73 to 65.46+6.43 mm. APDD were between 10.51+3.59 and 12.12+4.54 mm, and TDLP were between 3.28+0.81 and 6.27+0.62 mm.DDP was successfully performed on cadaveric specimens. DDP, as a novel approach of decompression of burst fractures with pedicle rupture, can fully relieve the occupation and at the same time preserve the spinal motor unit because of no resection of intervertebral discs and no destruction of facet joints,and has certain developmental significance.

Predictive factors of destination at discharge after spinal cord injury

IntroductionOne of the main goals of the rehabilitation of patients with spinal cord injury (SCI) is the reintegration of the individual to their family, social, and work setting. The objective of this study was to identify the factors that determine the discharge destination after a traumatic spinal cord injury. Material and methodsWe conducted a retrospective descriptive study of 305 patients with SCI who completed the rehabilitation treatment at the spinal injury unit of Hospital Insular de Gran Canaria between 2001 and 2018. ResultsDuring the study period, we observed an increase in the number of patients referred to long-term care centres, from 9.14% between 2001 and 2010 to 18.4% between 2011 and 2018 (P < .01). Of 20 variables that presented a significant association with destination at discharge in the univariate study, 7 presented a significant association in the multivariate study: age (OR: 1.05; 95% CI, 1.02–1.08), living with a partner (OR: 0.26; 95% CI, 0.09−0.76), residing on another island (OR: 3.57; 95% CI, 1.32–9.63), smoking (OR: 3.44; 95% CI, 1.26–9.44), diabetes (OR: 6.51; 95% CI, 1.46–29.02), history of psychiatric disorders (OR: 3.79; 95% CI, 1.31–10.93), and scores on the Spinal Cord Independence Measure-III (SCIM-III) (OR: 0.48; 95% CI, 0.33−0.69). ConclusionsOur findings identified advanced age, living on the island of Tenerife, not being married, smoking, type 2 diabetes mellitus, history of psychiatric disorders, and low SCIM-III scores as predictive factors of referral to a long-term care centre in patients with traumatic SCI in the Canary Islands.

192 Effect of Helmet on Cervical Spine Biomechanics in Rear Impact Scenario (Whiplash)

INTRODUCTION: Rear impact (whiplash) is a common scenario has been studied previously by subjecting the head-neck complex under postero-anterior acceleration. There is a lack of studies investigating the effect of helmet on cervical spine biomechanics despite its common use in military and competitive automotive environments. METHODS: We developed a finite element model of the head-neck complex simulating the three spinal columns with layered intervetebral discs and ligaments. This was then validated against a cadaver (head to T1) model which was fixated to a sled on linear rails with a rear pendulum that simulated rear impact scenario. Standard-issue US Military Combat helmets in small, medium, large sizes were modeled and mounted on the finite element model. 1.8 m/s and 2.6 m/s velocity profiles were simulated and the range of motion at each functional spinal unit from C2-3 to C7-T1 was measured. RESULTS: Segmental motions were measured over 120 ms for all scenarios. 2.6 m/s vector resulted in peak acceleration of 3.5 g, and 1.8 m/s resulted in 2.5 g. Helmet use increased the range of motion at all segments from C2-3 to C7-T1. The greatest range of motion occurred at C5-6, followed by C6-7 and C7-T1. Greatest percentage increase in motion occurred at C2-3 followed by C5-6. Increasing helmet size resulted in increasing motion at all spinal segments. CONCLUSIONS: Helmet use, although protective for the cranium, significantly increases the motion at all spinal segments, especially C2-3 and C5-7, in a rear impact scenario (whiplash). Increasing helmet size results in greater motion change at all cervical spine segments. This is important to consider when designing the helmet and determining the need for additional head-mounted gear in both military and competitive automotive environments.

Improvement and validation of a female finite element model of the cervical spine

Although the cervical spine supports and controls the kinematics of the head, it is vulnerable to injuries during mechanical loading. Severe injuries often result in damage to the spinal cord, leading to significant ramifications. The role of gender in determining the outcome of such injuries has been established as significant. In order to better understand the essential mechanics and develop treatments or preventative measures, various forms of research have been conducted. Computational modelling is one of the most useful and extensively utilised methods, as it provides information that would otherwise be difficult to obtain. As such, the primary goal of this research is to create a new finite element of the female cervical spine that will more accurately represent the group most affected by such injuries. This work is a continuation of a previous study where a model was created from the computer tomography scans of a 46-year-old female. A functioning spinal unit consisting of the C6–C7 segment was simulated as a validation procedure. The experimental data obtained from cadaveric specimens, that assessed the range of motion of different cervical segments in flexion-extension, axial rotation, and lateral bending, was used to validate the reduced model.

Experimentally dissociating the overuse mechanisms of endplate fracture lesions and Schmorl's node injuries using the porcine cervical spine model

BackgroundCompared to the documented overuse mechanisms of endplate fracture lesions, the cause of Schmorl's node injuries remains unknown, despite existing hypotheses. Therefore, this study aimed to examine and dissociate the overuse injury mechanisms of these spinal pathologies. MethodsForty-eight porcine cervical spinal units were included. Spinal units were randomly assigned to groups that differed by initial condition (control, sham, chemical fragility, structural void) and loading posture (flexed, neutral). Chemical fragility and structural void groups involved a verified 49% reduction in localized infra-endplate trabecular bone strength and removal of central trabecular bone, respectively. All experimental groups were exposed to cyclic compression loading that was normalized to 30% of the predicted tolerance until failure occurred. The cycles to failure were examined using a general linear model and the distribution of injury types were examined using chi-squared statistics. FindingsThe incidence of fracture lesions and Schmorl's nodes was 31(65%) and 17(35%), respectively. Schmorl's nodes were exclusive to chemical fragility and structural void groups and 88% occurred in the caudal joint endplate (p = 0.004). In contrast, 100% of control and sham spinal units sustained fracture lesions, with 100% occurring in the cranial joint endplate (p < 0.001). Spinal units tolerated 665 fewer cycles when cyclically loaded in flexed postures compared to neutral (p = 0.015). Furthermore, the chemical fragility and structural void groups tolerated 5318 fewer cycles compared to the control and sham groups (p < 0.001). InterpretationThese findings demonstrate that Schmorl's node and fracture lesion injuries can result from pre-existing differences in the structural integrity of trabecular bone supporting the central endplate.

A Comparison of Magnetic Resonance Imaging and SPECT-CT Imaging in Complex Spine Pathology: Does SPECT-CT Provide Additional Diagnostic Information Over Magnetic Resonance Imaging?

Retrospective cohort study. Magnetic Resonance Imaging (MRI) is often regarded as the gold standard for spinal pathology, as it provides good structural visualisation. SPECT-CT, however, provides combined structural and functional information. There is a paucity of literature comparing SPECT-CT with MRI in the spine. Our aim was to determine whether SPECT-CT provides additional information to MRI in individuals with complex spinal pathology, including deformity, which altered management. We conducted a retrospective review of all individuals seen at our tertiary spinal unit that were investigated with both MRI and SPECT-CT of the spine between 2007-2020. We reviewed imaging reports, and collated diagnoses, surgical treatment and the relative contributions of MRI and SPECT-CT to management decisions. 104 individuals identified, with a mean age of 30 years (89 females and 15 males). Diagnostic categories were adolescent, adult, and congenital deformity, degenerative pathology, and miscellaneous pathology. MRI returned positive findings in 58 (55.8%), and SPECT-CT in 41 (39.4%) cases. SPECT-CT identified 10 cases of facet joint degeneration, 5 of increased uptake around metalwork suggestive of loosening, 1 pseudoarthrosis, 1 partial failure of fusion and 1 osteoid osteoma which were not reported on MRI, all in individuals who had previously undergone spinal instrumentation. Despite this, SPECT-CT only altered management for 6 individuals (5.8%). MRI is less useful in the setting of previous instrumentation due to metal artefact. Where MRI is inconclusive, particularly in individuals with previous spinal instrumentation, SPECT-CT may provide a diagnosis, but is not recommended as primary imaging.

Facial nerve vulnerability in spinal muscular atrophy and motor unit number index of the orbicularis oculi muscle.

Measures for assessing cranial nerve vulnerability in spinal muscular atrophy (SMA) have not yet been determined. Motor unit number index (MUNIX) studies have shown correlations with disease severity but have been used only in limb muscles. In the present study, we explore facial nerve response, MUNIX, and motor unit size index (MUSIX) of the orbicularis oculi muscle in a cohort of patients with SMA. Facial nerve response (measured as compound muscle action potential, CMAP), MUNIX, and MUSIX of the orbicularis oculi muscle were cross-sectionally recorded in patients with SMA and compared to healthy control subjects (HCs). Active maximum mouth opening (aMMO) was also measured at baseline in our SMA cohort. Thirty-seven patients with SMA (21 SMA II; 16 SMA III) and 27 HCs were recruited. CMAP of the facial nerve and MUNIX of orbicularis oculi proved to be feasible and well tolerated techniques. CMAP amplitude and MUNIX scores were significantly lower in patients with SMA compared to HCs (p < .0001). Both MUNIX and CMAP amplitude were significantly higher in patients with SMA III compared to SMA II. No significant difference emerged comparing CMAP amplitude, MUNIX and MUSIX scores between those with different functional status or nusinersen treatment. Our results provide neurophysiological evidence of facial nerve and muscle involvement in patients with SMA. CMAP of the facial nerve and MUNIX of orbicularis oculi showed high accuracy in discriminating between the various subtypes of SMA and in quantifying the motor unit loss of the facial nerve.

Quantitatively biomechanical response analysis of posterior musculature reconstruction in cervical single-door laminoplasty

Background and objectiveThe current trend of laminoplasty is developing toward the goal of muscle preservation and minimum tissue damage. Given this, muscle-preserving techniques in cervical single-door laminoplasty have been modified with protecting the spinous processes at the sites of C2 and/or C7 muscle attachment and reconstruct the posterior musculature in recent years. To date, no study has reported the effect of preserving the posterior musculature during the reconstruction. The purpose of this study is to quantitatively evaluate the biomechanical effect of multiple modified single-door laminoplasty procedures for restoring stability and reducing response level on the cervical spine. MethodsDifferent cervical laminoplasty models were established for evaluating kinematics and response simulations based on a detailed finite element (FE) head-neck active model (HNAM), including ① C3 – C7 laminoplasty (LP_C37), ② C3 – C6 laminoplasty with C7 spinous process preservation (LP_C36), ③ C3 laminectomy hybrid decompression with C4 – C6 laminoplasty (LT_C3 + LP_C46) and ④ C3 – C7 laminoplasty with unilateral musculature preservation (LP_C37 + UMP). The laminoplasty model was validated by the global range of motion (ROM) and percentage changes relative to the intact state. The C2 – T1 ROM, axial muscle tensile force, and stress/strain levels of functional spinal units were compared among the different laminoplasty groups. The obtained effects were further analysed by comparison with a review of clinical data on cervical laminoplasty scenarios. ResultsAnalysis of the locations of concentration of muscle load showed that the C2 muscle attachment sustained more tensile loading than the C7 muscle attachment, primarily in flexion-extension (FE) and in lateral bending (LB) and axial rotation (AR), respectively. Simulated results further quantified that LP_C36 primarily produced 10% decreases in LB and AR modes relative to LP_C37. Compared with LP_C36, LT_C3 + LP_C46 resulted in approximately 30% decreases in FE motion; LP C37 + UMP also showed a similar trend. Additionally, when compared to LP_C37, LT_C3 + LP_C46 and LP C37 + UMP reduced the peak stress level at the intervertebral disc by at most 2-fold as well as the peak strain level of the facet joint capsule by 2–3-fold. All these findings were well correlated with the result of clinical studies comparing modified laminoplasty and classic laminoplasty. ConclusionsModified muscle-preserving laminoplasty is superior to classic laminoplasty due to the biomechanical effect of the posterior musculature reconstruction, with a retained postoperative ROM and loading response levels of the functional spinal units. More motion-sparing is beneficial for increasing cervical stability, which probably accelerates the recovery of postoperative neck movement and reduces the risk of the complication for eventual kyphosis and axial pain. Surgeons are encouraged to make every effort to preserve the attachment of the C2 whenever feasible in laminoplasty.