Spinal Motion Research Articles

Comparative Biomechanical Analysis of Anterior Lumbar Interbody Fusion and Bilateral Expandable Transforaminal Lumbar Interbody Fusion Cages: A Finite Element Analysis Study.

Expandable transforaminal lumbar interbody fusion (TLIF) cages could offer an alternative to anterior lumbar interbody fusion (ALIF). Bilateral cage insertion enhances endplate coverage, potentially improving stability and fusion rates and maximizing segmental lordosis. This study aims to compare the biomechanical properties of bilateral expandable TLIF cages to ALIF cages using finite element modeling. We used a validated 3-dimensional finite element model of the lumbar spine. ALIF and TLIF cages were created based on available product data. Our focus was on analyzing spinal motion in the sagittal plane, evaluating forces transmitted through the vertebrae, and comparing an ALIF model with various TLIF cage models. The largest TLIF cage model exhibited a 407.9% increase in flexion motion and a 42.1% decrease in extension motion compared with the ALIF cage. The second largest TLIF cages resulted in more flexion motion and less extension motion compared with ALIF, while smaller cages were inferior to ALIF. ALIF cages were associated with increased adjacent segment motion compared with TLIF cages, primarily in extension. Endplate stress analysis revealed higher stress in the ALIF cage model with a more uniform stress distribution. ALIF cages excel in stabilizing L5 to S1 during flexion, while largest TLIF cages offer superior stability in extension. Large bilateral TLIF cages may provide biomechanical stability comparable to ALIF, especially in extension and could potentially reduce the risk of adjacent segment disease with lower adjacent segment motion.

Comparative effectiveness of two methods of applying essential oils in complex rehabilitation of patients with lumbosacral dorsopathies

Objective. To compare the effectiveness of two methods of local application of essential oils in complex rehabilitation programs for patients with lumbosacral dorsopathies. Materials and methods. The study involved 90 patients with lumbosacral dorsopathies who were divided into 3 groups: Group 1 (n=30; comparison group) – patients were given segmental massage with a 1% blend of oils (rosemary, cajaput and pearlberry diluted in 100 ml of base oil) recommended for dorsopathies; Group 2 (n=30; main) – patients were given biopuncture with this blend of oils; Group 3 (n=30; control) – patients were given biopuncture with sesame oil as a placebo. All patients also received standard therapy. Results. Local application of essential oils to reflexogenic points in the main group was shown to reduce pain syndrome, improve the amplitude of movement in the lumbar spine, reduce anxiety, and increase tolerance to psychological stress in comparison with the segmental massage group (comparison group) and the control group.

Use of Long Spinal Board Post-Application of Protocol for Spinal Motion Restriction for Spinal Cord Injury.

Historically, prehospital care of trauma patients has included nearly universal use of a cervical collar (C-collar) and long spine board (LSB). Due to recent evidence demonstrating harm in using LSBs, implementation of new spinal motion restriction (SMR) protocols in the prehospital setting should reduce LSB use, even among patients with spinal cord injury. Our goal in this study was to evaluate the rates of and reasons for LSB use in high-risk patients-those with hospital-diagnosed spinal cord injury (SCI)-after statewide implementation of SMR protocols. Applying data from a state emergency medical services (EMS) registry to a state hospital discharge database, we identified cases in which a participating EMS agency provided care for a patient later diagnosed in the hospital with a SCI. Cases were then retrospectively reviewed to determine the prevalence of both LSB and C-collar use before and after agency adoption of a SMR protocol. We reviewed cases with LSB use after SMR protocol implementation to determine the motivations driving continued LSB use. We used simple descriptive statistics, odds ratios (OR) with 95% confidence intervals (CI) to describe the results. We identified 52 EMS agencies in the state of Arizona with 417,979 encounters. There were 225 patients with SCI, of whom 74 were excluded. The LSBs were used in 52 pre-SMR (81%) and 49 post-SMR (56%) cases. The odds of LSB use after SMR protocol implementation was 70% lower than it had been before implementation (OR 0.297, 95% CI 0.139-0.643; P = 0.002). Use of a C-collar after SMR implementation was not significantly changed (OR 0.51, 95% CI 0.23-1.143; P = 0.10). In the 49 cases of LSB use after agency SMR implementation, the most common reasons for LSB placement were ease of lifting (63%), placement by non-transporting agency (18%), and extrication (16.3%). High suspicion of SCI was determined as the primary or secondary reason for not removing LSB after assessment in 63% of those with LSB placement, followed by multiple transfers required (20%), and critical illness (10%). Implementation of selective spinal motion restriction protocols was associated with a statistically significant decrease in the utilization of long spine boards among prehospital patients with acute traumatic spinal cord injury.

Role of intra-lamellar collagen and hyaluronan nanostructures in annulus fibrosus on lumbar spine biomechanics: insights from molecular mechanics-finite element-based multiscale analyses.

Annulus fibrosus' (AF) ability to transmit multi-directional spinal motion is contributed by a combination of chemical interactions among biomolecular constituents-collagen type I (COL-I), collagen type II (COL-II), and proteoglycans (aggrecan and hyaluronan)-and mechanical interactions at multiple length scales. However, the mechanistic role of such interactions on spinal motion is unclear. The present work employs a molecular mechanics-finite element (FE) multiscale approach to investigate the mechanistic role of molecular-scale collagen and hyaluronan nanostructures in AF, on spinal motion. For this, an FE model of the lumbar segment is developed wherein a multiscale model of AF collagen fiber, developed from COL-I, COL-II, and hyaluronan using the molecular dynamics-cohesive finite element multiscale method, is incorporated. Analyses show AF collagen fibers primarily contribute to axial rotation (AR) motion, owing to angle-ply orientation. Maximum fiber strain values of 2.45% in AR, observed at the outer annulus, are 25% lower than the reported values. This indicates native collagen fibers are softer, attributed to the softer non-fibrillar matrix and higher interfibrillar sliding. Additionally, elastic zone stiffness of 8.61 Nm/° is observed to be 20% higher than the reported range, suggesting native AF lamellae exhibit lower stiffness, resulting from inter-collagen fiber bundle sliding. The presented study has further implications towards the hierarchy-driven designing of AF-substitute materials.

Crossing the Cervicothoracic Junction: A Biomechanical Investigation of C7 vs T1 Caudal Selection's Effect on Adjacent Segment Motion in Posterior Cervical Fusion.

Biomechanical Study. This study aims to evaluate the biomechanical adjacent segment effects of multi-level posterior cervical fusion constructs that terminate at C7 compared to those that terminate at T1 in cadaveric specimens. The cervicothoracic junction poses unique challenges for spine surgeons. Deciding to terminate multi-level posterior cervical fusion constructs at C7 or extend them across the cervicothoracic junction remains a controversial issue. Six cadaveric specimens underwent biomechanical testing in the intact state and after instrumentation with constructs from C3 and terminating at either C7 or T1. Range of motion (ROM) was assessed in flexion-extension, lateral bending, and axial rotation globally and at cranial and caudal adjacent segments. There was a significant decrease in overall flexion/extension by both C7 (-35.5°, P=0.002) and T1 (-39.8°, P=0.002) instrumentation compared to the intact spine. T1 instrumentation had significantly lower (-4.3°, P=0.008) flexion/extension ROM compared to C7 instrumentation. There were significant decreases in axial rotation by both C7 (-31.4°, P=0.009) and T1 (-36.8°, P=0.009) instrumentation compared to the intact spine, but no significant differences were observed between the two. There were also significant decreases in lateral bending by both C7 (-27.9°, P=0.022) and T1 (-33.7°, P=0.022) instrumentation compared to the intact spine, but no significant differences were observed between the two. No significant differences were observed in ROM at cranial or caudal adjacent segments between constructs terminating at C7 and those extending to T1. This biomechanical investigation demonstrates that constructs that cross the cervicothoracic junction experience less overall spinal motion in flexion-extension compared to those that terminate at C7. However, contrary to prior studies there is no difference in cranial and caudal adjacent segment motion. Surgeons should make clinical decisions regarding the caudal extent of fusion in multi-level posterior cervical fusions without major concerns about adjacent segment motion.

Meridian massage in the treatment of cervical spondylotic radiculopathy

To observe the clinical efficacy of meridian massage in the treatment of cervical spondylotic radiculopathy. Sixty-four patients with cervical radiculopathy treated from March 2020 to June 2023 were divided into the observation group and the treatment group, with 32 cases in each group. The observation group received conventional treatment, including 14 males and 18 females with an average age of (41.34±7.23) years old ranging from 32 to 55 years old;the disease duration ranged from 9 to 17 months with an average of (14.23±3.56) months;C5 and C6 nerve root compression occurred in 12 cases, C7 nerve root compression occurred in 17 cases, C8 nerve root compression occurred in 3 cases. The treatment group received massage therapy on the basis of conventional treatment, including 17 males and 15 females with an average age of (40.86±6.97) years old ranging from 30 to 54 years old;the disease duration ranged from 8 to 18 months with an average of (15.43±3.48) months;C5 and C6 nerve root compression occurred in 14 cases, C7 nerve root compression occurred in 16 cases, C8 nerve root compression occurred in 2 cases. The clinical efficacy was evaluated by visual analogue scale(VAS), neck disability index(NDI) and clinical assessment scale for cervical spondylosis(CASCS) before and after 2-week treatment, and the range of motion of cervical spine was compared before and after treatment. After 2-week treatment, the VAS and NDI scores of the treatment group and the observation group decreased, while the CASCS scores increased(P<0.001). After 2-week treatment, the VAS and NDI scores were lower and the CASCS scores were higher in the treatment group than those of the observation group(P<0.001). Comparing with those before treatment, the range of motion of flexion, extension, left flexion, right flexion, left rotation and right rotation after 2-week treatment increased in two groups(P<0.05). Comparing with the observation group, the range of motion of flexion, extension, left flexion, right flexion, left rotation and right rotation increased more significantly in the treatment group(P<0.05). Meridian massage is effective in the treatment of cervical Spondylotic radiculopathy, which can effectively relieve neck pain, improve clinical symptoms and improve patient satisfaction.

Prehospital guidelines on in-water traumatic spinal injuries for lifeguards and prehospital emergency medical services: an international Delphi consensus study

BackgroundTrauma guidelines on spinal motion restriction (SMR) have changed drastically in recent years. An international group of experts explored whether consensus could be reached and if guidelines on SMR performed by trained lifeguards and prehospital EMS following in-water traumatic spinal cord injury (TSCI) should also be changed.MethodsAn international three-round Delphi process was conducted from October 2022 to November 2023. In Delphi round one, brainstorming resulted in an exhaustive list of recommendations for handling patients with suspected in-water TSCI. The list was also used to construct a preliminary flowchart for in-water SMR. In Delphi round two, three levels of agreement for each recommendation and the flowchart were established. Recommendations with strong consensus (≥ 85% agreement) underwent minor revisions and entered round three; recommendations with moderate consensus (75–85% agreement) underwent major revisions in two consecutive phases; and recommendations with weak consensus (< 75% agreement) were excluded. In Delphi round 3, the level of consensus for each of the final recommendations and each of the routes in the flowchart was tested using the same procedure as in Delphi round 2.ResultsTwenty-four experts participated in Delphi round one. The response rates for Delphi rounds two and three were 92% and 88%, respectively. The study resulted in 25 recommendations and one flowchart with four flowchart paths; 24 recommendations received strong consensus (≥ 85%), and one recommendation received moderate consensus (81%). Each of the four paths in the flowchart received strong consensus (90–95%). The integral flowchart received strong consensus (93%).ConclusionsThis study produced expert consensus on 25 recommendations and a flowchart on handling patients with suspected in-water TSCI by trained lifeguards and prehospital EMS. These results provide clear and simple guidelines on SMR, which can standardise training and guidelines on SMR performed by trained lifeguards or prehospital EMS.

Residual Strain and Joint Pressurization Maintain Collagen Tension for On-Joint Lumbar Facet Capsular Ligaments.

Modeling the lumbar facet capsular ligament's (FCL) mechanical behavior under various physiological motions has often been a challenge due to limited knowledge about the on-joint in situ ligament state arising from attachment to the bone or other internal loads. Building on prior work, this study presents an enhanced computational model of the lumbar facet capsular ligament by incorporating residual strain and joint pressurization strain, factors neglected in prior models. Further, the model can predict strain and stress distribution across the ligament under various spinal motions, highlighting the influence of the ligament's attachment to the bone, internal synovial fluid pressurization, and distribution of collagen fiber alignment on the overall mechanical response of the ligament. Joint space inflation was found to influence the total observed stress and strain fields, both at rest and during motion. A significant portion of the ligament was found to be in tension, even in the absence of external load. Additionally, the model's ability to account for residual strain offers a more realistic portrayal of the collagen fibers and elastin matrix's role in ligament mechanics. We conclude that (1) computational models of the lumbar facet capsular ligament should not assume that the ligament is unloaded when the joint is in its neutral position, and (2) the ligament is nearly always in tension, which may be important in terms of its long-term growth and remodeling.

Biomechanical Study of Symmetric Bending and Lifting Behavior in Weightlifter with Lumbar L4-L5 Disc Herniation and Physiological Straightening Using Finite Element Simulation.

Physiological curvature changes of the lumbar spine and disc herniation can cause abnormal biomechanical responses of the lumbar spine. Finite element (FE) studies on special weightlifter models are limited, yet understanding stress in damaged lumbar spines is crucial for preventing and rehabilitating lumbar diseases. This study analyzes the biomechanical responses of a weightlifter with lumbar straightening and L4-L5 disc herniation during symmetric bending and lifting to optimize training and rehabilitation. Based on the weightlifter's computed tomography (CT) data, an FE lumbar spine model (L1-L5) was established. The model included normal intervertebral discs (IVDs), vertebral endplates, ligaments, and a degenerated L4-L5 disc. The bending angle was set to 45°, and weights of 15 kg, 20 kg, and 25 kg were used. The flexion moment for lifting these weights was theoretically calculated. The model was tilted at 45° in Abaqus 2021 (Dassault Systèmes Simulia Corp., Johnston, RI, USA), with L5 constrained in all six degrees of freedom. A vertical load equivalent to the weightlifter's body mass and the calculated flexion moments were applied to L1 to simulate the weightlifter's bending and lifting behavior. Biomechanical responses within the lumbar spine were then analyzed. The displacement and range of motion (ROM) of the lumbar spine were similar under all three loading conditions. The flexion degree increased with the load, while extension remained unchanged. Right-side movement and bending showed minimal change, with slightly more right rotation. Stress distribution trends were similar across loads, primarily concentrated in the vertebral body, increasing with load. Maximum stress occurred at the anterior inferior margin of L5, with significant stress at the posterior joints, ligaments, and spinous processes. The posterior L5 and margins of L1 and L5 experienced high stress. The degenerated L4-L5 IVD showed stress concentration on its edges, with significant stress also on L3-L4 IVD. Stress distribution in the lumbar spine was uneven. Our findings highlight the impact on spinal biomechanics and suggest reducing anisotropic loading and being cautious of loaded flexion positions affecting posterior joints, IVDs, and vertebrae. This study offers valuable insights for the rehabilitation and treatment of similar patients.

Preliminary Studies on Changes in Static Plantar Pressure and Stabilometry in Patients with Ankylosing Spondylitis Undergoing an Exercise Program.

Background/Objectives: Studies have reported that patients suffering from ankylosing spondylitis (AS) have decreased postural stability in comparison to healthy subjects. Our study aims to compare static plantar pressure and stabilometry parameters in AS patients who performed an 8-week exercise program (spine motion and flexibility exercises; stretching of hamstring, erector spine, and shoulder muscles; control abdominal and diaphragm breathing exercises and chest expansion exercises), in three different testing conditions (eyes open, eyes closed, and head retroflexed). Methods: Plantar pressure (the loading of the first and fifth metatarsal heads (MT1, MT5) and calcaneus) and stabilometry (CoP path length, 90% confidence ellipse area, and maximum CoP speed) were recorded in 28 AS patients (age 56.64 ± 10.3 years; body mass index 29.4 ± 4.9 kg/m2) at the beginning of rehabilitation and after 8 weeks. At first evaluation, there were significant differences (p < 0.05) for the foot loading sites (MT1, MT5, and calcaneus), both for the right and left feet, when comparing eyes open with the other two testing situations. Results: After rehabilitation, significant differences were recorded between eyes-open and head-retroflexed conditions for MT1 (p = 0.03 for right; p = 0.004 for left) and calcaneus (p = 0.014 for right; p = 0.011 for left). A significantly higher CoP path length was registered in both initial and final assessments when tested with eyes closed. The maximum CoP speed had increased values at both evaluations when tested with head retroflexed. Conclusions: The CoP path length decreased after the physical exercise program, with a better postural stability after rehabilitation.

The effect of ATLS/PHTLS spinal motion restriction protocol on the incidence of spinal cord injury, a nationwide database study

PurposeTo study trends in incidence and outcome of patients with traumatic spinal cord injury (TSCI) in the Netherlands before, during and after implementation of the Advanced Trauma Life Support (ATLS®) and Pre-Hospital Trauma Life Support (PHTLS®)- Spinal Motion Restriction(SMR) protocol.MethodsIn an observational database we studied national hospital admission and emergency department databases to analyse incidence rates and outcome of traumatic spinal cord injury and spinal fractures in the emergency department and in admittances in The Netherlands between 1986 and 2021.ResultsA significant increase of 39% in TSCI in admitted patients with spinal fractures over the past 35 years (p < 0.001). This increase was especially prevalent in cervical spinal fractures (132%), while thoracic and lumbosacral spinal fractures showed a decrease in accompanied TSCI (64% and 88% respectively). The overall increase in spinal fractures was not significant. The duration of hospital admission decreased for spinal fractures without TSCI and with TSCI (66% and 56% respectively).ConclusionSince implementation of the SMR-protocol was aiming to limit TSCI in patients who suffered a spinal fracture, the increase in TSCI is an unexpected finding. Exact explanation for this increase is unclear and the contribution of the SMR-protocol is not fully understood due to confounders in the used datasets. Either way, the scientific evidence supporting this costly time- and labor-intensive SMR-protocol remains debated, along with evidence contradicting it. Therefore it stresses the need for clear, evidencebased reasoning for spinal immobilization according to ATLS, as this is currently lacking.

Analysis of spine motion during prehospital extrication procedures in motorsport.

The appropriate extrication techniques for trauma patients after car accidents remain a topic of controversy. Various techniques for immobilizing the cervical spine during prehospital extrication have been investigated. This explorative study compared the amount of spinal motion during five different extrication procedures from a racecar and a rallycar performed by two teams: a professional motorsport extrication team and a team of professional emergency medical technicians (EMTs). Two different microelectromechanical systems were used to measure spinal motion, and a motionscore was calculated to compare the amount of remaining spinal motion. A high motionscore indicates high remaining motion and a low motionscore indicates low remaining motion. The use of an extricable seat results in a mean overall motion score of 1617 [95% CI 308-2926]. Emergency extrication without equipment resulted in the lowest overall motionscore 1448 [95% CI 1070-1826]. In case of urgent extrication the Extrication team attained a motionscore of 2118 [95% CI 517-3718] and the EMT team a motionscore of 2932 [95% CI 1427-4435]. When performing the procedure with the aid of a rescue boa, the EMT team achieved an overall mean motionscore in the same range 2725 [95% CI 568-4881] with boa vs. 2932 [95% CI 1427-4435] without boa. When mean scores of individual spinal segments were analyzed, we found that the EMT team did especially worse in immobilizing the cervical spine 198 vs. 758. Regular training of extrication procedures has paid off considerably in reducing spinal movement during extrication from a racecar. If an extricable seat is available, extrication should be performed using it. However, if emergency extrication is necessary, an additional manual cervical spine immobilization should be conducted using the Rautek maneuver to sufficiently reduce cervical spine movement.

Biomechanical Effects on the Prostheses and Vertebrae of Three-Level Hybrid Surgery: A Finite Element Study.

Three-level hybrid surgery (HS) consisting of cervical disc arthroplasty (CDA) and anterior cervical discectomy and fusion (ACDF) has been partly used for the treatment of multi-level cervical degenerative disc disease (CDDD). The complications related to the implants and the collapse of the surgical vertebral bodies had been reported in multi-level anterior cervical spine surgery. Thus, this study aimed to explore the biomechanical effects on the prostheses and vertebrae in three-level HS. A FE model of cervical spine (C0-T1) was constructed. Five surgical models were developed. They were FAF model (ACDF-CDA-ACDF), AFA model (CDA-ACDF-CDA), FFF model (three-level ACDF), SF model (single-level ACDF), and SA model (single-level CDA). A 75-N follower load and 1.0-N·m moment was applied to produce flexion, extension, lateral bending, and axial rotation. Compared with the intact model, the range of motion (ROM) of total cervical spine in FAF model decreased by 34.54%, 54.48%, 31.76%, and 27.14%, respectively, in flexion, extension, lateral bending, and axial rotation, which were lower than those in FFF model and higher than those in AFA model. The ROMs of CDA segments in FAF and AFA models were similar to the intact model and SA model. Compared with the intact model, the ROMs at C3/4 segment in FFF model increased from 5.71% to 7.85%, and increased from 5.31% to 6.81% at C7/T1 segment, following by FAF model, then the FAF model. The maximum interface pressures of the Prestige-LP in FAF model were similar to SA model, however the corresponding values were increased in AFA model. The maximum interface pressures of the Zero-P were increased in FAF and AFA model compared with those in SF and FFF models. The stress was mainly distributed on the screws. In AFA model, the maximum pressures of the ball and trough articulation in superior and inferior Prestige-LP were all increased compared with those in SA and FAF model. In FFF model, the maximum pressures of the vertebrae were higher than those in other models. The stress was mainly distributed on the anterior area of the vertebral bodies. HS seemed to be more suitable than ACDF for the surgical treatment of three-level CDDD in consideration of the biomechanical effects, especially for the two-level CDA and one-level ACDF construct. But a more appropriate CDA prosthesis should be explored in the future.

Comparing contribution of bony and cartilaginous endplate changes to intervertebral disc degeneration.

To compare the degenerative features of cartilaginous endplate with bony endplate in association with intervertebral degeneration in local population at radiographic, macroscopic and microscopic level in human motion segments. This cross-sectional descriptive study examined 59 lumbar spine motion segments from adult male cadavers at the Department of Anatomy, University of Health Sciences, Lahore, between May and September, 2022. Radiographic assessment observed bony endplate (BEP) for the presence of sclerosis & osteophytes and degeneration scores from 1-8 were assigned. Macroscopic assessment was done to evaluate BEP, cartilaginous endplate (CEP) and IVD, and scores ranged from 1to 28 for BEP, 1-4 for CEP and 1-64 for IVD were assigned. Microscopic assessment revealed degeneration scores of CEP ranged from 1-42 and 1-30 for IVD. Segments with BEP defects were also identified on radiographs & macroscopy. Significant correlations were observed between the total degeneration scores of BEP with IVD and CEP scores (r=0.88 and r=0.909, respectively, p<0.001). Similarly, the total degeneration scores of the CEP is also significantly correlated with total IVD (r=0.86, p<0.001). Additionally, the samples with BEP defects were having higher IVD degeneration scores (p<0.001). This study, for the first time identifies that there exists a critical association of bony and cartilaginous endplate with intervertebral disc degeneration individually in the same tissue sections using multi-dimension assessment methods. Degeneration in any of the components of VEP is consonantly associated with IVD degeneration. The BEP & CEP, though, they are unique structures but are interlinked with each other structurally and functionally.

AIRWAY CHALLENGES IN A ANKYLOSING SPONDYLITIC PATIENT WITHTRAUMATIC CERVICAL SPINE FRACTURE - A CASE REPORT

Background:Ankylosing Spondylitis (AS) is a chronic inflammatory condition that results in the fusion of the spine and decreased flexibility, commonly known as bamboo spine. This condition presents significant challenges to anesthesiologists due to potential difficulties in managing the airway, cardiovascular issues, and compromised respiration. AS patients face an increased risk of fractures and spinal cord injury, especially in the cervical spine, which is prone to instability and higher morbidity and mortality rates. Maneuvers to manage the airway and intubation techniques may exacerbate movement in the cervical spine, potentially leading to further injury. Case Report: A 42-year-old man with a history of AS presented with a cervical spine injury after a road traffic accident. MRI showed fractures at the posterior arch of C1 and C4-C5 levels with nerve root compression. The patient, who was not regularly followed up, was taking medication. Preoperative assessment revealed a potentially difficult airway, and the patient had quadriparesis and reduced sensation. Due to the risk of spinal cord injury, an awake fiberoptic intubation (AFOI) was planned. The AFOI was successfully performed through the nasal route, and the patient underwent a C4-C5 discectomy and stabilization. The postoperative recovery was uneventful, with no new neurological deficits. Discussion: The case emphasizes the need to minimize movement of the cervical spine when managing the airway in AS patients with cervical spine fractures. Using AFOI is more effective than other techniques in this scenario, as it minimizes cervical movement and allows for post-intubation neurologic assessments. Although the glidescope video laryngoscope and intubating laryngeal mask airway are considered as alternatives to direct laryngoscopy, anesthesiologists still prefer AFOI as the primary option. Conclusion: This case report demonstrates the best airway management for an AS patient with a cervical spine fracture, with a focus on the role of the anesthesiologist in preventing further injury and neurologic deterioration. Awake fiberoptic intubation is the safest alternative for AS patients with cervical spine fractures, as long as the anesthesiologist has the requisite skills and knowledge.

A 32-year old lady who developed a complex generalized movement disorder in all four limbs after plasma exchange for myelitis

A 32-year old lady with AQP4-Antibody positive neuromyelitis optica developed a new-onset complex movement disorder after therapeutic plasma exchange, which was initially suspected to be hypocalcemic carpo-pedal spasm. However, when her bilateral, distal predominant, paroxysmal, stereotypic, wrist and finger flexor tonic contractions did not respond to serum calcium correction, other diagnoses were considered. The patient had a dramatic response to oral carbamazepine suggesting that the tonic spasms were likely a spinal movement disorder due to the primary demyelinating pathology.

Coordinating limbs and spine: (Pareto-)optimal locomotion in theory, in vivo, and in robots

Among vertebrates, patterns of movement vary considerably, from the lateral spine-based movements of fish and salamanders to the predominantly limb-based movements of mammals. Yet, we know little about why these changes may have occurred in the course of evolution. Lizards form an interesting intermediate group where locomotion appears to be driven by both motion of their limbs and lateral spinal undulation. To understand the evolution and relative advantages of limb versus spine locomotion, we developed an empirically informed mathematical model as well as a robotic model and compared in silico predictions to in-vivo data from running and climbing lizards. Our mathematical model showed that, if limbs were allowed to grow to long lengths, movements of the spine did not enable longer strides, since spinal movements reduced the achievable range of motion of the limbs before collision. Yet, in-vivo data show lateral spine movement is widespread among a diverse group of lizards moving on level ground or climbing up and down surfaces. Our climbing robotic model was able to explain this disparity, showing that increased movement of the spine was energetically favourable, being associated with a reduced cost of transport. Our robot model also revealed that stability, as another performance criterion, decreased with increased spine and limb range of motion—detailing the trade-off between speed and stability. Overall, our robotic model found a Pareto-optimal set of strides—when considering speed, efficiency, and stability—requiring both spine and limb movement, which closely agreed with movement patterns among lizards. Thus we demonstrate how robotic models, in combination with theoretical considerations, can reveal fundamental insights into the evolution of movement strategies among a broad range of taxa.

Validity of the estimated angular information obtained using an inertial motion capture system during standing trunk forward and backward bending

BackgroundBending the trunk forward and backward while standing are common daily activities and can have various patterns. However, any dysfunction in these movements can considerably affect daily living activities. Consequently, a comprehensive evaluation of spinal motion during these activities and precise identification of any movement abnormalities are important to facilitate an effective rehabilitation. In recent years, with the development of measurement technology, the evaluation of movement patterns using an inertial motion capture system (motion sensor) has become easy. However, the accuracy of estimated angular information obtained via motion sensor measurements can be affected by angular velocity. This study aimed to compare the validity of estimated angular information obtained by assessing standing trunk forward and backward bending at different movement speeds using a motion sensor with a three-dimensional motion analysis system.MethodsThe current study included 12 healthy older men. A three-dimensional motion analysis system and a motion sensor were used for measurement. The participants performed standing trunk forward and backward bending at comfortable and maximum speeds, and five sensors were attached to their spine. Statistical analysis was performed using the paired t-test, intraclass correlation coefficient, mean absolute error, and multiple correlation coefficient.ResultsResults showed that the estimated angular information obtained using each motion sensor was not affected by angular velocity and had a high validity.ConclusionsTherefore, the angular velocity in this study can be applied clinically for an objective evaluation in rehabilitation.

Biomechanical Comparison of Corticopedicular Spine Fixation versus Pedicle Screw Fixation in a Lumbar Degenerative Spondylolisthesis Finite Element Analysis Model

To compare the stability of a corticopedicular posterior fixation (CPPF) device with traditional pedicle screws for decompression and fusion in adult degenerative lumbar spondylolisthesis. Finite element analysis (FEA) was used in a validated model of grade 1 L4-L5 spondylolisthesis to compare segmental stability after laminectomy alone, laminectomy with pedicle screw fixation, or laminectomy with CPPF device fixation. A 500-N follower load was applied to the model and different functional movements were simulated by applying a 7.5-Nm force in different directions. Outcomes included degrees of motion, tensile forces experienced in the CPPF device, and stresses in surrounding cortical bone. At maximum loading, laminectomy alone demonstrated a 1° increase in flexion range of motion, from 6.35° to 7.39°. Laminectomy with pedicle screw fixation and CPPF device fixation both reduced spinal segmental motion to ≤1° at maximum loading in all ranges of motion, including flexion (0.94° and 1.09°), extension (-0.85° and -1.08°), lateral bending (-0.56° and -0.96°), and torsion (0.63° and 0.91°), respectively. There was no significant difference in segmental stability between pedicle screw fixation and CPPF device fixation during maximum loading, with a difference of ≤0.4° in any range of motion. Tensile forces in the CPPF device remained ≤51% the ultimate load to failure (487 N) and stress in surrounding cortical bone remained ≤84% the ultimate stress of cortical bone (125.4 MPa) during maximum loading. CPFF fixation demonstrated similar segmental stability to traditional pedicle screw fixation whereas tensile forces and stress in surrounding cortical bone remained below the load to failure.

Two-Stage Lumbar Dynamic Stabilization Surgery: A Comprehensive Analysis of Screw Loosening Rates and Functional Outcomes Compared to Single-Stage Approach in Osteopenic and Osteoporotic Patients.

Dynamic lumbar stabilization aims to preserve spinal movement, offering stability and controlled motion. However, screw loosening, especially in patients with osteopenia and osteoporosis, remains challenging. Between 2018 and 2022, a retrospective analysis was conducted on a total of 119 patients diagnosed with osteopenia and osteoporosis who underwent spinal dynamic instrumentation surgery. These patients were categorized into two groups: single-stage surgery (n = 67) and two-stage surgery (n = 52). Over the 48-month follow-up period, the occurrence and percentage of screw loosening were examined at each surgical level per patient, as well as by screw location (pedicular, corpus, tip). Clinical outcomes were evaluated using Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) scores. Total screw loosening rates were significantly lower in the two-stage group (2.83%) compared to the single-stage group (14.63%, p < 0.001). Patient-based loosening occurred in 5 patients (9.6%) in the two-stage group and 16 patients (23.9%) in the single-stage group. Loosening rates were lower in the two-stage group at L2 (7.78%, p = 0.040), L3 (5.56%, p < 0.001), L4 (8.89%, p = 0.002), and L5 (10.00%, p = 0.006), but higher at S1 (21.11%, p = 0.964), T12 (15.56%, p = 0.031), and iliac levels (15.56%, p = 0.001). Pedicular section exhibited the highest loosening (37 cases). VAS and ODI scores improved significantly in both groups, with better outcomes in the two-stage group at the 48. months (p < 0.001). The two-stage surgical approach significantly reduces screw loosening in patients with osteopenia and osteoporosis undergoing dynamic stabilization surgery, offering enhanced stability and better clinical outcomes.