Lumbar Spinal Segments Research Articles

Spondylophyte classification based on biomechanical effects on segmental stiffness

BACKGROUND CONTEXTThe biomechanical impact of spondylophytes on segmental stiffness is largely unknown, despite their high incidence. PURPOSEThe aim of this study was to quantify the biomechanical contribution according to location and cranio-caudal extent of spondylophytes and to create a clinically applicable radiological classification system. STUDY DESIGNBiomechanical cadaveric study. METHODSTwenty-six cadaveric human lumbar spinal segments with spondylophytes were tested with a displacement-controlled stepwise reduction method. The reduction in load required for the same motion after spondylophyte dissection was used to calculate the biomechanical contribution in flexion, extension, axial rotation, lateral bending, anterior, posterior and lateral shear. The spondylophytes were categorized by assessment of their anatomical position and cranio-caudal extent in computed tomography images (grade 1: spondylophytes spanning less than 50% of the disc-height, grade 2:>50%, grade 3:>90%, grade 4: bony bridging between the vertebrae) by two experienced radiologists. Cohen's kappa (κ) was used to report interreader reliability. RESULTSThe largest biomechanical effect of non-bridging spondylophytes (grade 1–3) was recorded during contralateral bending with a grade-dependent contribution of up to 35%. Other loading directions including ipsilateral bending and translational loading were affected with values below 13%. Spondylophytes with osseous bridging (grade 4) show large contribution to the segmental stiffness in most loading conditions with values reaching over 80%. Interreader agreement for the spondylophyte grading was “substantial” (κ=0.73, p<.001). CONCLUSIONSThe location and cranio-caudal extent of spondylophytes are essential parameters for their biomechanical effect. A reproducible classification has been validated biomechanically and helps evaluate the effect of specific spondylophyte configurations on segmental stiffness. CLINICAL SIGNIFICANCENon-bridging spondylophytes primarily act as tensile structures and do not provide relevant propping. A classification system is presented to support understanding of the biomechanical consequences of different spondylophyte configuration for clinical decision making in surgical planning.

Nuclear countdown

Case: A 50-year-old woman presented with a 10-year history of progressive symptoms, beginning with right facial numbness. She developed dysgeusia, and dysphagia before the onset of dysarthria. She had progressive gait instability with frequent backwards falls. A gastrostomy was inserted for persistent weight loss. She required hospital admission for aspiration pneumonia and type 2 respiratory failure. On examina- tion she had a head drop and staring expression with reduced blink frequency and hypophonia. There was bilateral facial weakness with temporalis and tongue wasting. She had a supranuclear gaze palsy and her saccadic eye movements were almost absent in all directions. Limbs were hypotonic with distal weakness and reduced reflexes.InvestigationsNCS/EMG showed chronic widespread partial denervation in the facial, trigeminal (motor) and hypoglossal-innervated muscles. Blink reflexes were absent bilaterally. There were chronic denerva- tion changes in the cervical and lumbar spinal segments. MRI brain showed global atrophy particularly implicating the temporal lobes and brainstem.DiagnosisA diagnosis of Facial-Onset Sensory and Motor Neuronopathy (FOSMN) was made. Given the additional clinical features of supranuclear gaze palsy we believe this is the first case of FOSMN-PSP overlap syndrome.ConclusionWe report a unique FOSMN case with some overlap features of PSP, not previously described. daniel.rice-wilson@nhs.net23

Caudal-Rostral Progression of Alpha Motoneuron Degeneration in the SOD1G93A Mouse Model of Amyotrophic Lateral Sclerosis.

Mice with transgenic expression of human SOD1G93A are a widely used model of ALS, with a caudal–rostral progression of motor impairment. Previous studies have quantified the progression of motoneuron (MN) degeneration based on size, even though alpha (α-) and gamma (γ-) MNs overlap in size. Therefore, using molecular markers and synaptic inputs, we quantified the survival of α-MNs and γ-MNs at the lumbar and cervical spinal segments of 3- and 4-month SOD1G93A mice, to investigate whether there is a caudal–rostral progression of MN death. By 3 months, in the cervical and lumbar spinal cord, there was α-MN degeneration with complete γ-MN sparing. At 3 months, the cervical spinal cord had more α-MNs per ventral horn than the lumbar spinal cord in SOD1G93A mice. A similar spatial trend of degeneration was observed in the corticospinal tract, which remained intact in the cervical spinal cord at 3- and 4- months of age. These findings agree with the corticofugal synaptopathy model that α-MNs and CST of the lumbar spinal cord are more susceptible to degeneration in SOD1G93A mice. Hence, there is a spatial and temporal caudal–rostral progression of α-MN and CST degeneration in SOD1G93A mice.

Circumferential Fusion Employing Transforaminal vs. Direct Lateral Lumbar Interbody Fusion-A Potential Impact on Implants Stability.

BackgroundDifferent fusion techniques were introduced in clinical practice in patients with lumbar degenerative disc disease, however, no evidence has been provided on the advantages of one technique over another.The Objective of This StudyIs to assess the potential impact of circumferential fusion employing transforaminal lumbar interbody fusion (TLIF) vs. direct lateral interbody fusion (DLIF) on pedicle screw stability.Materials and MethodsThis is a single-center prospective evaluation of consecutive 138 patients with degenerative instability of lumbar spinal segments. Either conventional transforaminal lumbar interbody fusion (TLIF) with posterior fusion or direct lateral interbody fusion (DLIF) using cages of standard dimensions, were applied. The conventional open technique was used to supplement TLIF with pedicle screws while percutaneous screw placement was used in patients treated with DLIF. The duration of the follow-up accounted for 24 months. Signs of pedicle screws loosening (PSL) and bone union after fusion were assessed by the results of CT imaging. Fisher‘s exact test was used to assess the differences in the rate of CT loosening and revision surgery because of implant instability. Logistic regression was used to assess the association between potential factors and complication rate.ResultsThe rate of PSL detected by CT and relevant revision surgery in groups treated with TLIF and DLIF accounted for 25 (32.9%) vs. 2 (3.2%), respectively, for the former and 9 (12.0%) vs. 0 (0%) for the latter (p < 0.0001 and p = 0.0043) respectively. According to the results of logistic regression, a decrease in radiodensity values and a greater number of levels fused were associated with a rise in PSL rate. DLIF application in patients with radiodensity below 140 HU was associated with a considerable decrease in complication rate. Unipolar or bipolar pseudoarthrosis in patients operated on with TLIF was associated with a rise in PSL rate while patients treated with DLIF tolerate delayed interbody fusion formation. In patients treated with TLIF supplementary total or partial posterior fusion resulted in a decline in PSL rate.ConclusionEven though the supplementary posterior fusion may considerably reduce the rate of PSL in patients treated with TLIF, the application of DLIF provide greater stability resulting in a substantial decline in PSL rate and relevant revision surgery.

The effects of pre-stressed rods contoured by different bending techniques on posterior instrumentation of L4-L5 lumbar spine segment: A finite element study.

Posterior pedicle screw instrumentation (PPSI) is a well-known method in lumbar spine surgery. Understanding how PPSI affects the biomechanics of the lumbar spine is an important issue. In particular, during PPSI operations, surgeons bend rods according to the patients' spinal curvatures based on their own experiences. As a result, residual stresses develop on the rods due to this bending. Although many finite element-based biomechanical studies have been performed for PPSI, studies comparing the effects of residual stresses arising from rod contouring on the construct stresses are lacking. Thus, this study aimed to investigate the effects of residual stress in PPSI using rods contoured with a French bender and an in-situ bender, as well as comparing the differences in stress increment with straight and contoured rods for different physiological motions. Accordingly, a finite element (FE) model of the L4-L5 lumbar spine segment was developed for PPSI and the effects of residual stresses on rods were investigated by using different bending methods. In the simulations, it was found that rods contoured with a French bender with residual stress resulted in significantly more increased stress in PPSI compared to those contoured with an in-situ bender. The results of this study emphasize that increased stress in PPSI due to the residual stresses for different physiological motions may increase the risk of PPSI failures. Additionally, the finite element modeling approach employed here could be used as a fundamental tool for further investigations of topics such as PPSI fatigue life and failure studies.

Development and Validation of a Whole Human Body Finite Element Model with Detailed Lumbar Spine

Investigations showed that low back pain of occupational drivers might be closely related to the whole-body vibration. Restricted by ethical concerns, the finite element method had become a viable alternative to invasive human experiments. Many mechanical behaviors of the human spine inside of the human body were unclear; therefore, a human whole-body finite element model might be required to better understand the lumbar behavior under whole-body vibration. In this study, a human whole-body finite element model with a detailed lumbar spine segment was developed. Several validations were performed to ensure the correctness of this model. The results of anthropometry and geometry validation, static validation, and dynamic validation were presented in this study. The validation results showed that the whole human body model was reasonable and valid by comparing with published data. The model developed in this study could reflect the biomechanical response of the human lumbar spine under vibration and could be used in further vibration analysis and offer proposals for protecting human body under whole-body vibration environment.

Magnetic Resonance Imaging Documentation of Approach Trauma With Lumbar Endoscopic Interlaminar, Translaminar, Compared to Open Microsurgical Discectomy.

Endoscopic spine surgery is associated with less approach trauma than conventional open translaminar surgery. However, objective evidence to corroborate this empiric observation is scarce. Preservation of the anatomic attachment and sensory function of multifidus muscles have been stipulated to be critical to maintaining the normal function of the lumbar spinal motion segment. The authors were interested in comparing the postoperative approach trauma between traditional open translaminar microsurgical and interlaminar endoscopic discectomy. The approach trauma to the paraspinal muscles due to interlaminar or open microsurgical discectomy was evaluated on T2-weighted axial magnetic resonance imaging (MRI) images of 39 consecutive patients who underwent lumbar disc surgery. Postoperative MRI images taken at 4 days and within 1 year after surgery were analyzed. Eleven patients underwent conventional open translaminar microdiscectomy surgery. Endoscopic discectomy was performed on 17 patients via the interlaminar and on another 11 patients via the transforaminal approach. The immediate surgical approach trauma was estimated as the defect zone by measuring the normalized relative cross-sectional area (rCSA) of muscle disruption in the surgical corridor 4 days postoperatively. The long-term effect of surgical approach trauma was assessed by measuring the area of the paraspinal muscles that had been replaced by fatty tissue 1 year postoperatively. The rCSA data showed diminished approach trauma with a smaller surgical defect zone in the interlaminar endoscopy group (17.6%) was smaller than in the microsurgical group 4 days postoperatively (41.2%). At 1 year postoperatively, the mean fatty replacement of the paraspinal muscles was 23.6% after microsurgery and 2.1% after the interlaminar endoscopy. Muscle recovery was substantially reduced in the interlaminar endoscopic group, with the muscle zone reducing from 20.3% to 2.1% when analyzed 1 year postoperatively. In the microsurgery group, the muscle damage by atrophy increased from 41.2% to 62.9% at 1 year postoperatively (P < 0.001). Fatty replacement of the multifidus muscle was seen on the ipsilateral and contralateral approach side. There was a negligible change in the muscle zone with the transforaminal approach. Tissue trauma was significantly reduced with endoscopic surgery techniques compared with the traditional translaminar microdiscectomy approach. There was a minor postoperative tissue trauma and hardly any long-term replacement of the multifidus and paraspinal muscles by fatty tissue 1 year postoperatively with the endoscopic technique. The transforaminal approach has the least effect on the paraspinal muscles of the surgical motion segment. Further study is needed to investigate whether these findings translate into decreased postoperative instability or low back pain following endoscopic discectomy surgery. MRI analysis of multifidus atrophy following various lumbar translaminar and transforaminal decompression techniques.

Correlation between bone mineral density of different sites and lumbar disc degeneration in postmenopausal women.

Osteoporosis and lumbar disc degeneration (LDD) have been common causes that make increasing patients suffer from different degrees of low back pain. At present, whether osteoporosis degenerates or protects disc is still controversial, and the correlation between hip bone mineral density (BMD) and LDD still remains unclear. Our study aims to analyze the correlation between BMD of different sites and LDD in postmenopausal women, and explore the potential pathophysiological mechanism of them.One hundred ninety-five postmenopausal female patients were enrolled and divided into osteoporosis, osteopenia, and normal bone mass groups. Their BMD and lumbar spine magnetic resonance imaging were retrospectively analyzed. Two spine surgeons were selected to assess LDD according to Pfirrmann grading system.Based on lumbar BMD, LDD of normal bone mass group was more severe than the other 2 groups in L1/2 and L2/3 segments (P < .05). Based on hip BMD, LDD of each disc from L1/2 to L5/S1 had no significant difference among the 3 groups (P > .05). Lumbar BMD (L1-L4) was positively correlated with corresponding degree of LDD (L1/2-L4/5) (P < .05), whereas there was no correlation between hip BMD and degree of LDD (P = .328).There is a positive correlation between lumbar BMD and LDD in postmenopausal women, which is more obvious in the upper lumbar spinal segments (L1, L2). However, there is no correlation between hip BMD and LDD, suggesting that in postmenopausal women with lumbar degenerative disease, hip BMD is more suitable for the diagnosis of osteoporosis.

Biomechanical Investigation of the Posterior Pedicle Screw Fixation System at Level L4-L5 Lumbar Segment with Traditional and Cortical Trajectories: A Finite Element Study.

There is no detailed biomechanical research about the hybrid CBT-TT (CBT screws at cranial level and TT screws at caudal level) and TT-CBT (TT screws at cranial level and CBT screws at caudal level) techniques with finite element (FE) method. Therefore, the purpose of this study was to evaluate and provide specific biomechanical data of the hybrid lumbar posterior fixation system and compare with traditional pedicle screw and cortical screw trajectories without fusion, in FE method. Specimens were from the anatomy laboratory of Xinjiang Medical University. Four FE models of the L4-L5 lumbar spine segment were generated. For each of these, four implanted models with the following instruments were created: bilateral traditional trajectory screw fixation (TT-TT), bilateral cortical bone trajectory screw fixation (CBT-CBT), hybrid CBT-TT fixation, and hybrid TT-CBT fixation. A 400 N compressive load with 7.5 Nm moments was applied so as to simulate flexion, extension, left lateral bending, right lateral bending, left rotation, and right rotation, respectively. The range of motion (ROM) of the L4-L5 segment and the posterior fixation, the von Mises stress of the intervertebral disc, and the posterior fixation in four implanted models were compared. CBT-TT displayed a lower ROM of the fixation segment (3.82 ± 0.633°) compared to TT-TT (4.78 ± 0.306°) and CBT-CBT (4.23 ± 0.396°). In addition, CBT-TT showed a lower ROM of the posterior fixation (0.595 ± 0.108°) compared to TT-TT (0.795 ± 0.103°) and CBT-CBT (0.758 ± 0.052°). The intervertebral disc stress of CBT-TT (4.435 ± 0.604 MPa) was lower than TT-TT (7.592 ± 0.387 MPa) and CBT-CBT (6.605 ± 0.600 MPa). CBT-TT (20.228 ± 3.044 MPa) and TT-CBT (12.548 ± 2.914 MPa) displayed a lower peak von Mises stress of the posterior fixation compared to TT-TT (25.480 ± 3.737 MPa). The hybrid CBT-TT and TT-CBT techniques offered superior fixation strength compared to the CBT-CBT and TT-TT techniques.

The use of electromyography and kinematic measurements of the lumbar spine during ergonomic intervention among workers of the production line of a foundry.

PurposeWorkers who perform repetitive movements are exposed to many risk factors leading to the occurrence of lumbar back pain. The aim of the research was to answer the question whether the ergonomic instruction conducted by a physiotherapist would change the tested range of motion of the segments of lumbar spine and the symmetry of the work of the torso and upper limbs muscles during work performed by foundry employees.MethodsThe study included 12 foundry production line workers with musculoskeletal pain. The workstation was built in the laboratory that perfectly simulates work on the production line. The workers performed two activities from their daily work, i.e. transferring and moving a casting. They were then given ergonomic instruction by a physiotherapist and performed the assigned tasks again. During the activities, the electromyographic signal from five muscles was recorded in terms of symmetry of their work. The maximum angular ranges of the motor segments of the lumbar spine were measured using gyroscopes.ResultsAfter the ergonomic instruction, the contralateral imbalance of muscle activity decreased statistically significantly during the first phase (p = 0.0004), second phase (p = 0.0002) and the third phase (p = 0.0069) of transferring the casting. While moving the casting , only erector spinae showed statistically significantly (p = 0.0131) more symmetrical work after the ergonomic instruction. During the transfer of the casting, statistically significantly lower values of the ranges of motion between the segments were obtained after carrying out the ergonomic instruction for the left (p = 0.0231) and right (p = 0.0032) lateral flexion. The ranges of movement between the segments differed statistically significantly for the flexion (p = 0.0117), extension (p = 0.0469) and left (p = 0.0031) and right lateral flexion movements (p = 0.0012).ConclusionConducting ergonomic instruction consisting in teaching the correct performance of a movement task reduced the contralateral imbalance of muscle activity and changes the ranges of movement of L1-S1 segments. The task of optimizing the load on the musculoskeletal system, including the lumbar spine, should be carried out by means of appropriate ergonomic instruction and multi-pronged measures, including analysis of the health of employees, their working environment and physical activity outside the workplace. Electromyography and measurements of the range of movement of the lumbar spine appear to be good tools for the evaluation of workplace ergonomics.

Failure tolerance of the human lumbar spine in dynamic combined compression and flexion loading

Vehicle safety systems have substantially decreased motor vehicle crash-related injuries and fatalities, but injuries to the lumbar spine still have been reported. Experimental and computational analyses of upright and, particularly, reclined occupants in frontal crashes have shown that the lumbar spine can be subjected to simultaneous and out-of-phase combined axial compression and flexion loading. Lumbar spine failure tolerance in combined compression-flexion has not been widely explored in the literature. Therefore, the goal of this study was to measure the failure tolerance of the lumbar spine in combined compression and flexion. Forty lumbar spine segments with three vertebrae (one unconstrained) and two intervertebral discs (both unconstrained) were pre-loaded with axial compression (2200N, 3300N, or 4500N) and then subjected to rotation-controlled dynamic flexion bending until failure. Clinically relevant middle vertebra fractures were observed in twenty-one of the specimens, including compression and burst fractures. The remaining nineteen specimens experienced failure at the potting-grip interface. Failure tolerance varied within the sample and were categorized by the appropriate data censoring, with clinically relevant middle vertebrae fractures characterized as uncensored or left-censored and potting-grip fractures characterized as right-censored. Average failure force and moment were 3290N (range: 1580N to 5042N) and 51Nm (range: 0Nm to 156 Nm) for uncensored data, 3686N (range: 3145N to 4112N) and 0Nm for left-censored data, and 3470N (range: 2138N to 5062N) and 101Nm (range: 27Nm to 182Nm) for right-censored data. These data can be used to develop and improve injury prediction tools for lumbar spine fractures and further research in future safety systems.

How annulus defects can act as initiation sites for herniation

PurposeBoth posture and loading rate are key factors in the herniation process and can determine the mechanism of disc failure. The aim of this study was to test the hypothesis that disruption visible with HR-MRI post-testing corresponds with microstructural features and further elucidate the mechanism by which this disruption weakens the disc. This will enable us to gain new insights into the herniation process.MethodsThirty ovine lumbar spinal segments were subjected to combinations of four loading conditions (0–12° flexion, 0–9° lateral bending, 0–4° axial rotation, 0–1500 N axial compression) for 1000 loading cycles at 2 Hz in a dynamic disc loading simulator. The discs were scanned in an ultra-high field MRI (11.7 T) then examined using brightfield microscopy to examine their microstructure.ResultsFour discs herniated and seven discs suffered nucleus displacement. These discs contained pre-existing defects in the central posterior annulus. Generally, following testing discs contained more posterior annulus disruption, Microstructural investigation revealed there was clear correspondence between HR-MRI and microstructural observations, and that the mid-outer annular-endplate junction had failed in all discs examined in this study.ConclusionsWhile all discs suffered outer annulus damage, only the discs containing pre-existing defects herniated. These pre-existing defects weakened the inner and mid annulus, allowing herniation to occur once the mid and outer annular wall was compromised. We propose this can occur during the degenerative cascade.

Patient-Specific Variations in Local Strain Patterns on the Surface of a Trussed Titanium Interbody Cage.

Introduction: 3D printed trussed titanium interbody cages may deliver bone stimulating mechanobiological strains to cells attached at their surface. The exact size and distribution of these strains may depend on patient-specific factors, but the influence of these factors remains unknown. Therefore, this study aimed to determine patient-specific variations in local strain patterns on the surface of a trussed titanium interbody fusion cage. Materials and Methods: Four patients eligible for spinal fusion surgery with the same cage size were selected from a larger database. For these cases, patient-specific finite element models of the lumbar spine including the same trussed titanium cage were made. Functional dynamics of the non-operated lumbar spinal segments, as well as local cage strains and caudal endplate stresses at the operated segment, were evaluated under physiological extension/flexion movement of the lumbar spine. Results: All patient-specific models revealed physiologically realistic functional dynamics of the operated spine. In all patients, approximately 30% of the total cage surface experienced strain values relevant for preserving bone homeostasis and stimulating bone formation. Mean caudal endplate contact pressures varied up to 10 MPa. Both surface strains and endplate contact pressures varied more between loading conditions than between patients. Conclusions: This study demonstrates the applicability of patient-specific finite element models to quantify the impact of patient-specific factors such as bone density, degenerative state of the spine, and spinal curvature on interbody cage loading. In the future, the same framework might be further developed in order to establish a pipeline for interbody cage design optimizations.

Different degeneration patterns of paraspinal muscles in degenerative lumbar diseases: a MRI analysis of 154 patients

Study designA retrospective study.ObjectiveTo evaluate the different degeneration patterns of paraspinal muscles in degenerative lumbar diseases and their correlation with lumbar spine degeneration severity.Summary of background dataThe degeneration characteristics of different paraspinal muscles in degenerative lumbar diseases remain unclear.Methods78 patients diagnosed with single-level degenerative lumbar spondylolisthesis (DLS) and 76 patients with degenerative lumbar kyphosis (DLK) were included as DLS and DLK groups. Paraspinal muscle parameters of psoas major (PS), erector spinae (ES) and multifidus muscle (MF) were measured, including fatty infiltration (FI) and relative cross-sectional area (rCSA), namely the ratio of the paraspinal muscle CSA to the CSA of the vertebrae of the same segment. Sagittal parameters including lumbar lordosis (LL) and sagittal vertical axis (SVA) were measured. The paraspinal muscle parameters and ES/MF rCSA ratio were compared between the two groups. Paraspinal muscles parameters including rCSA and FI were also compared between each segments from L1 to L5 in both DLS and DLK groups. In order to determine the influence of sagittal spinal alignment on paraspinal muscle parameters, correlation analysis was conducted between the MF, ES, PS rCSA and FI and the LL in DLS and DLK group.ResultMF atrophy is more significant in DLS patients compared with DLK. Also, MF fatty infiltration in the lower lumbar spine of DLS patients was greater compared to DLK patients. DLK patients showed more significant atrophy of ES and heavier ES fatty infiltration. MF FI was significantly different between all adjacent segments in both DLS and DLK groups. In DLS group, ES FI was significantly different between L2/L3 to L3/L4 and L4/L5 to L5/S1, while in DLK group, the difference of ES FI between all adjacent segments was not significant, and ES FI was found negatively correlated with LL.ConclusionsParaspinal muscles show different degeneration patterns in degenerative lumbar diseases. MF degeneration is segmental in both DLS and DLK patients, while ES degenerated diffusely in DLK patients and correlated with the severity of kyphosis. MF degeneration is more significant in the DLS group, while ES degeneration is more significant in DLK patients. MF is the stabilizer of the lumbar spine segments, while the ES tends to maintain the spinal sagittal balance.

A biomechanical analysis of prosthesis disc in lumbar spinal segment using three-dimensional finite element modelling

A biomechanical analysis of prosthesis disc in lumbar spinal segment using three-dimensional finite element modelling

A biomechanical analysis of prosthesis disc in lumbar spinal segment using three-dimensional finite element modelling

Lumbar total disc replacement (LTDR) could be an operation for handling of chronic disc illness and spinal mutilation to safeguard a range of motion (ROM). The SB Charité™ is the principal gadget for LTDR however it creates a lot of confusion and long-run problems that lead to a lack of SB Charité™ disc. The advancement of lumbar disc arthroplasty supports the calculations of the biomechanical model through three-dimensional (3D) finite element method (FEM). Accordingly, this paper exhibits a 3D biomechanical FEM model of L1 to L3 human lumbar spine by various kinds of materials and discs. There are some criteria like compressive force, Tresca stress, von Mises stress and strain that are used to estimate the proposed model. This lumbar model instructs spinal surgeons to the predication vision for disc implementation which can consequently turn out recovery from disc degeneration and bolster the surgical outcomes. The COMSOL Multiphysics® software is applied on the intact segment and four implanted models that are Charité™, Activ-L, ProDisc-L and M6-L to determine the endurance and stiffness rate of vertebral endplate at each intervertebral disc.

A ARTRODESE CURTA É TÃO EFICAZ QUANTO A ARTRODESE LONGA PARA O TRATAMENTO DE FRATURAS DA COLUNA TORACOLOMBAR DO TIPO B

ABSTRACT Objective: Thoracolumbar spine trauma is a world wide health concern that especially affects males of working age, being associated with an elevated morbidity. AO SPINE Type B fractures are unstable and require surgical stabilization. However, the decision between short or long fixation remains controversial. The objective of this study is to analyze the neurological, orthopedic and functional outcomes in patients with Type B spine fractures who have undergone short and long segment posterior arthrodesis. Methods: A prospective cohort study was performed at the Neurosurgery Department of Hospital Cristo Redentor from January 1, 2013 to December 31, 2018. Patients with spine fractures classified as AO SPINE Type B in the thoracic or thoracolumbar segments were eligible for the study. The variables analyzed included demographic data, information about the trauma, neurological status, the treatment performed, and the outcome. Results: A total of 31 patients were included in the study. The majority were Caucasian males with a mean age of 42.6(±15.6), and the main cause of the spine trauma was falling from height (N=18; 56.2%). Fifteen patients (48.3%) had subtype B1 fractures and 16 (51.6%) had subtype B2 fractures. Eleven (35.4%) patients were submitted to short arthrodesis and 20 (64.5%) were submitted to long arthrodesis. There was no statistical difference between groups in terms of neurological, orthopedic and functional outcomes. Conclusions: There is no difference in outcomes between short or long constructs for patients with type B single fracture in the thoracic, thoracolumbar and lumbar spine segments. Level of evidence III; Therapeutic Studies – Investigation of treatment results.

Reliability of ultrasound to measure the distance between lumbar interspinous processes

ObjectivesThis study aimed to determine the reliability of ultrasound to measure the distance between interspinous processes of the lumbar spine at the segmental level (i.e., L1–L2, L2–L3, L3–L4, and L4–L5). MethodsTen men with no history of orthopedic diseases or dysfunctions were included in this study. In total, 720 images of the lumbar spines of participants were analyzed (10 participants, 4 segments, 3 trials, 3 positions, 2 examiners). With participants in three different positions, images of each segment specifically focused on the distance between lumbar interspinous processes. Bland–Altman analysis (BAA) was used to determine intra- and inter-rater reliability. ResultsIntra-rater intraclass correlation coefficient (ICC) values (1, 1) were found to range from 0.840 to 0.988, whereas inter-rater ICC values (2, 1) ranged from 0.605 to 0.876. BAA results confirmed a fixed bias regarding the L4–L5 of the lumbar spine segment in the flexion position. ConclusionsInter-rater reliability decreased throughout this study; however, results showed that using ultrasound to measure the distance between lumbar segmental interspinous processes could be applied in clinical settings to evaluate lumbar segmental mobility.

Phosphoinositide-3-kinase regulatory subunit 4 participates in the occurrence and development of amyotrophic lateral sclerosis by regulating autophagy.

The development of amyotrophic lateral sclerosis (ALS) may be related to the abnormal alterations of multiple proteins. Our previous study revealed that the expression of phosphoinositide-3-kinase regulatory subunit 4 (PIK3R4) was decreased in ALS. However, the role of PIK3R4 in ALS pathogenesis remains unknown. This study was the first to find that transfection of PC12 cells with small interfering RNA against the PIK3R4 gene significantly decreased the expression levels of PIK3R4 and the autophagy-related proteins p62 and LC3. Additionally, in vivo experiments revealed that the PIK3R4 protein was extensively expressed in the anterior horn, posterior horn, central canal, and areas surrounding the central canal in cervical, thoracic, and lumbar segments of the spinal cord in adult mice. PIK3R4 protein was mainly expressed in the neurons within the spinal lumbar segments. PIK3R4 and p62 expression levels were significantly decreased at both the pre-onset and onset stages of ALS disease in Tg(SOD1*G93A)1Gur mice compared with control mice, but these proteins were markedly increased at the progression stage. LC3 protein expression did not change during progression of ALS. These findings suggest that PIK3R4 likely participates in the prevention of ALS progression. This study was approved by the Ethics Committee for Animal Care and Use of Jiangxi Provincial People's Hospital, Affiliated People's Hospital of Nanchang University (approval No. 2020025) on March 26, 2020.

Математичне і комп’ютерне моделювання поведінки сегментів поперекового відділу хребта після ендопротезування

Актуальність. Елементи біомеханічної системи, утвореної із сегмента поперекового відділу хребта й ендопротеза, піддаються в післяопераційний період комплексу силових впливів від розташованих вище мас. Мета — визначення компонент напружено-деформованого стану елементів біомеханічної системи, яка описує поперековий хребетно-руховий сегмент людини після проведення установки різних міжтілових ендопротезів. Матеріали та методи. Для проведення досліджень поперекового відділу хребта були створені тривимірні скінченно-елементні моделі, які описують поперековий сегмент L3–L5 і внутрішній ендопротез (виконаний із титану). Модель, яка описує поперековий відділ хребта, включала хребці сегмента L3–L5 (при цьому хребці мали поділ на складові кортикальну і губчасту кістки), а також були промодельовані міжхребцеві диски і хрящі. У модель були додані два додаткові елементи зверху і знизу таким чином, щоб максимально зменшити вплив закріплення моделі і для коректної передачі на неї навантаження. Результати. За результатами отриманих численних значень і полів розподілу компонент напружено-деформованого стану в елементах біологічних і біомеханічних систем поперекового сегмента L3–L5 можна стверджувати про ефективність використання запропонованого підходу проведення ендопротезування, оскільки поведінка біомеханічної моделі близька до вихідної біологічної системи; ця поведінка супроводжується деяким перерозподілом напружень всередині біомеханічної системи, за виключенням суміжних хребців, які контактують з ендопротезом, проте отримані значення напружень не перевищують граничних меж міцності, відповідних для кортикальної кістки — 160 МПа, для губчастої — 18–22 МПа і для титану — 1000 МПа. Висновки. Найкращою конструкцією для проведення оперативного лікування з розглянутих є схема, що відповідає 4-й розрахунковій моделі (ендопротез із додатковими торцевими елементами). Таким чином, проведені дослідження, в основу яких був покладений запропонований підхід, дали можливість отримати рішення, яке задовольняє всім вимогам за чинними критеріями й обмеженнями.