Lumbar Motion Segments Research Articles

To validate and correlate radiologic grading of central and foraminal stenosis post-surgical decompression on degenerative lumbar canal stenosis

Background: Lumbar canal stenosis (LCS) is characterized as a narrowing of the canal diameter with age, which can lead to degenerative bone and soft-tissue changes. Aims and Objectives: The aim of the study is to validate the radiologic grading of central and foraminal through correlation with outcome after surgical decompression in degenerative LCS. Materials and Methods: A total of 23 patients with degenerative LCS who satisfied inclusion criteria and consented to participate in the study were selected and their Oswestry Disability Index (ODI) and Visual Analog Scale (VAS) for back and leg pain were recorded and their magnetic resonance imaging (MRI) was graded. Results: LCS is the reduction in the dimension of the central or lateral lumbar canal that occurs most frequently as a result of chronic degenerative changes at the lumbar motion segments. In our study, ODI has comparable improvement in all groups and it does not correlate with the severity of stenosis. However, VAS for leg pain has a greater prevalence in the shorter durations group (<60 months) which had an average of 8.0. If VAS for leg pain was more preoperatively, a better outcome was seen postoperatively. Conclusion: Decompression surgery for degenerative LCS shows significant improvement in ODI and VAS for back pain and leg pain irrespective of the severity of the stenosis by MRI grading or the severity of symptoms as assessed by VAS or ODI.

Failure mechanical properties of lumbar intervertebral disc under high loading rate

BackgroundLumbar disc herniation (LDH) is the main clinical cause of low back pain. The pathogenesis of lumbar disc herniation is still uncertain, while it is often accompanied by disc rupture. In order to explore relationship between loading rate and failure mechanics that may lead to lumbar disc herniation, the failure mechanical properties of the intervertebral disc under high rates of loading were analyzed.MethodBend the lumbar motion segment of a healthy sheep by 5° and compress it to the ultimate strength point at a strain rate of 0.008/s, making a damaged sample. Within the normal strain range, the sample is subjected to quasi-static loading and high loading rate at different strain rates.ResultsFor healthy samples, the stress–strain curve appears collapsed only at high rates of compression; for damaged samples, the stress–strain curves collapse both at quasi-static and high-rate compression. For damaged samples, the strengthening stage becomes significantly shorter as the strain rate increases, indicating that its ability to prevent the destruction is significantly reduced. For damaged intervertebral disc, when subjected to quasi-static or high rates loading until failure, the phenomenon of nucleus pulposus (NP) prolapse occurs, indicating the occurrence of herniation. When subjected to quasi-static loading, the AF moves away from the NP, and inner AF has the greatest displacement; when subjected to high rates loading, the AF moves closer to the NP, and outer AF has the greatest displacement. The Zhu–Wang–Tang (ZWT) nonlinear viscoelastic constitutive model was used to describe the mechanical behavior of the intervertebral disc, and the fitting results were in good agreement with the experimental curve.ConclusionExperimental results show that, both damage and strain rate have a significant effect on the mechanical behavior of the disc fracture. The research work in this article has important theoretical guiding significance for preventing LDH in daily life.

The influence of geometry on intervertebral disc stiffness

Geometry plays an important role in intervertebral disc (IVD) mechanics. Previous computational studies have found a link between IVD geometry and stiffness. However, few experimental studies have investigated this link, possibly due to difficulties in non-destructively quantifying internal geometric features. Recent advances in ultra-high resolution MRI provides the opportunity to visualise IVD features in unprecedented detail. This study aimed to quantify 3D human IVD geometries using 9.4 T MRIs and to investigate correlations between geometric variations and IVD stiffness. Thirty human lumbar motion segments (fourteen non-degenerate and sixteen degenerate) were scanned using a 9.4 T MRI and geometric parameters were measured. A 1kN compressive load was applied to each motion segment and stiffness was calculated. Degeneration caused a reduction (p < 0.05) in IVD height, a decreased nucleus-annulus area ratio, and a 1.6 ± 3.0 mm inward collapse of the inner annulus. The IVD height, anteroposterior (AP) width, lateral width, cross-sectional area, nucleus-annulus boundary curvature, and nucleus-annulus area ratio had a significant (p < 0.05) influence on IVD stiffness. Linear relationships (p < 0.05, r > 0.47) were observed between these geometric features and IVD compressive stiffness and a multivariate regression model was generated to enable stiffness to be predicted from features observable on clinical imaging (stiffness, N/mm = 6062 – (61.2 × AP width, mm) – (169.2 × IVD height, mm)). This study advances our understanding of disc structure–function relationships and how these change with degeneration, which can be used to both generate and validate more realistic computational models.

Breaking the Rules in Three Dimensions: What to Expect After a Thoracic-only Fusion With Structural Thoracic and Thoracolumbar Curves.

Despite guidelines to fuse both thoracic and thoracolumbar/lumbar (TH/L) curves in patients with structural curves in both regions, a thoracic-only fusion allows preservation of lumbar motion segments. The purpose of this study was to assess the 2-year postoperative three-dimensional (3D) radiographic and clinical outcomes of patients with double or triple major (thoracic curves >TH/L curves) structural curves who underwent a thoracic-only fusion. A prospective adolescent idiopathic scoliosis registry was queried for double or triple major curves undergoing thoracic-only posterior fusion and a minimum 2-year follow-up. 3D reconstructions were generated from bi-planar radiographs. Paired sample t tests were used to assess differences in the coronal, sagittal, and axial planes pre and postoperatively, as well as Scoliosis Research Society Questionnaire-22 scores. Pearson correlations were utilized to identify variables related to spontaneous lumbar derotation. Twenty-two patients met the inclusion criteria. Both thoracic [61 ± 10 degrees to 20 ± 9 degrees ( P < 0.001)] and lumbar curves [41 ± 7 degrees to 22±7 degrees ( P < 0.001)] had significant coronal improvement and T5 to T12 kyphosis improved from 7 ± 14 degrees to 23 ± 8 degrees ( P < 0.001). The thoracic apical translation was significantly improved postoperatively (4.7 ± 1.5 to 0.5 ± 1cm, P < 0.001), but the lumbar apical translation was unchanged (-1.7 ± 0.6 to -1.7±0.8cm, P = 0.94). Scoliosis Research Society Questionnaire-22 scores significantly improved by 2 years postoperative. Unlike the 3D correction observed in nonstructural TH/L curves after thoracic-only fusion, patients with double or triple major curves demonstrated only spontaneous coronal correction of the lumbar curve, whereas the sagittal and axial planes were not significantly improved. These radiographic parameters did not negatively affect subjective or clinical outcomes at minimum 2-year follow-up. Level IV-therapeutic.

Biomechanical evaluation of graded ventralfacetectomy simulating foraminoplasty of percutaneous endoscopic lumbar discectomy.

To explore the lumbar spine biomechanics of graded ventral facetectomy and determine the appropriate extent of resection for foraminoplasty. We retrospectively measured several radiological parameters of superior articular process (SAP) and bony intervertebral foramen in computed tomography scans of 170 lumbar vertebral discs. The intact finite element (FE) spine of L2-sacrum was modified to simulate foraminoplasty with two typical graded ventral facetectomy methods (Method Ⅰ: basal part resection of SAP; Method Ⅱ: apical part resection of SAP) to explore the biomechanical effects under different physiological motions. Examination of the radiological parameters of the bony intervertebral foramen indicated that they were generally narrower than the diameters of commercially available working cannulas. Some of these parameters showed gender differences. The biomechanical evaluation indicated that the range of motion increased gradually with the expansion of the resection extent, and the differences compared to the intact spine at the same level were greater in Method I than in Method Ⅱ. The appropriate ventral resection extent of the basal part of the SAP (Method I) was 4 mm, 3 mm, and 3 mm on the lateral view at L3-L4, L4-L5, and L5-S1, respectively. The appropriate ventral resection extent of the apical part of the SAP (Method II) were 10 mm, 6 mm and 6 mm on the lateral view at L3-L4, L4-L5, and L5-S1, respectively. Extensive resection of foraminoplasty may destabilize lumbar motion segments.

Prediction of nature of hysteresis and hysteresis based extraction of viscoelastic material model parameters

As almost all materials exhibit viscoelastic behaviour, it is important to understand the material behaviour which would help in its application in different fields. The current research work firstly focuses on understanding the dissipating behaviour of any viscoelastic material through operator-based multi-element model from the experimental hysteresis subject to cyclic or periodic displacement loading. Genetic algorithm-based constrained optimization technique is used as an extraction technique by curve fitting. Further, the technique is used to predict the model parameters of a pig’s lumbar spinal motion segment subjected to periodic displacement loading. Following the derived model parameters, the effect of varying periodic loading on the calculated hysteresis is also compared.

Does Vitamin K2 Influence the Interplay between Diabetes Mellitus and Intervertebral Disc Degeneration in a Rat Model?

Intervertebral disc (IVD) degeneration is a common cause of low back pain in diabetes mellitus type 2 (T2DM) patients. Its pathogenesis and the vitamin (vit.) K2 influence on this disease remain unclear. Lumbar motion segments of male Zucker Diabetes Fatty (ZDF) rats (non-diabetic [control] and diabetic; fed without or with vit. K2) were used. Femur lengths and vertebral epiphyseal cross-section areas were measured. IVDs were histopathologically examined. Protein synthesis and gene expression of isolated IVD fibrochondrocytes were analyzed. T2DM rats showed histopathological IVD degeneration. Femur lengths and epiphyseal areas were smaller in T2DM rats regardless of vit. K2 feeding. Fibrochondrocytes synthesized interleukin (IL)-24 and IL-10 with no major differences between groups. Alpha smooth muscle actin (αSMA) was strongly expressed, especially in cells of vit. K2-treated animals. Gene expression of aggrecan was low, and that of collagen type 2 was high in IVD cells of diabetic animals, whether treated with vit. K2 or not. Suppressor of cytokine signaling (Socs)3 and heme oxygenase (Hmox)1 gene expression was highest in the cells of diabetic animals treated with vit. K2. Vit. K2 influenced the expression of some stress-associated markers in IVD cells of diabetic rats, but not that of IL-10 and IL-24.

Interspinous and spinolaminar synthetic vertebropexy of the lumbar spine

PurposeTo develop and test synthetic vertebral stabilization techniques (“vertebropexy”) that can be used after decompression surgery and furthermore to compare them with a standard dorsal fusion procedure.MethodsTwelve spinal segments (Th12/L1: 4, L2/3: 4, L4/5: 4) were tested in a stepwise surgical decompression and stabilization study. Stabilization was achieved with a FiberTape cerclage, which was pulled through the spinous process (interspinous technique) or through one spinous process and around both laminae (spinolaminar technique). The specimens were tested (1) in the native state, after (2) unilateral laminotomy, (3) interspinous vertebropexy and (4) spinolaminar vertebropexy. The segments were loaded in flexion–extension (FE), lateral shear (LS), lateral bending (LB), anterior shear (AS) and axial rotation (AR).ResultsInterspinous fixation significantly reduced ROM in FE by 66% (p = 0.003), in LB by 7% (p = 0.006) and in AR by 9% (p = 0.02). Shear movements (LS and AS) were also reduced, although not significantly: in LS reduction by 24% (p = 0.07), in AS reduction by 3% (p = 0.21). Spinolaminar fixation significantly reduced ROM in FE by 68% (p = 0.003), in LS by 28% (p = 0.01), in LB by 10% (p = 0.003) and AR by 8% (p = 0.003). AS was also reduced, although not significantly: reduction by 18% (p = 0.06). Overall, the techniques were largely comparable. The spinolaminar technique differed from interspinous fixation only in that it had a greater effect on shear motion.ConclusionSynthetic vertebropexy is able to reduce lumbar segmental motion, especially in flexion–extension. The spinolaminar technique affects shear forces to a greater extent than the interspinous technique.

Intradiscal treatment of the cartilage endplate for improving solute transport and disc nutrition.

Poor nutrient transport through the cartilage endplate (CEP) is a key factor in the etiology of intervertebral disc degeneration and may hinder the efficacy of biologic strategies for disc regeneration. Yet, there are currently no treatments for improving nutrient transport through the CEP. In this study we tested whether intradiscal delivery of a matrix-modifying enzyme to the CEP improves solute transport into whole human and bovine discs. Ten human lumbar motion segments harvested from five fresh cadaveric spines (38-66 years old) and nine bovine coccygeal motion segments harvested from three adult steers were treated intradiscally either with collagenase enzyme or control buffer that was loaded in alginate carrier. Motion segments were then incubated for 18h at 37 °C, the bony endplates removed, and the isolated discs were compressed under static (0.2MPa) and cyclic (0.4-0.8 MPa, 0.2Hz) loads while submerged in fluorescein tracer solution (376Da; 0.1mg/ml). Fluorescein concentrations from site-matched nucleus pulposus (NP) samples were compared between discs. CEP samples from each disc were digested and assayed for sulfated glycosaminoglycan (sGAG) and collagen contents. Results showed that enzymatic treatment of the CEP dramatically enhanced small solute transport into the disc. Discs with enzyme-treated CEPs had up to 10.8-fold (human) and 14.0-fold (bovine) higher fluorescein concentration in the NP compared to site-matched locations in discs with buffer-treated CEPs (p < 0.0001). Increases in solute transport were consistent with the effects of enzymatic treatment on CEP composition, which included reductions in sGAG content of 33.5% (human) and 40% (bovine). Whole disc biomechanical behavior-namely, creep strain and disc modulus-was similar between discs with enzyme- and buffer-treated CEPs. Taken together, these findings demonstrate the potential for matrix modification of the CEP to improve the transport of small solutes into whole intact discs.

Biomechanical responses of the human lumbar spine to vertical whole-body vibration in normal and osteoporotic conditions

BackgroundThe prevalence of osteoporosis is continuing to escalate with an aging population. However, it remains unclear how biomechanical behavior of the lumbar spine is affected by osteoporosis under whole-body vibration, which is considered a significant risk factor for degenerative spinal disease and is typically present when driving a car. Accordingly, the objective of this study was to compare the spine biomechanical responses to vertical whole-body vibration between normal and osteoporotic conditions. MethodsA three-dimensional finite-element model of the normal human lumbar spine-pelvis segment was developed using computed tomographic scans and was validated against experimental data. Osteoporotic condition was simulated by modifying material properties of bone tissues in the normal model. Transient dynamic analyses were conducted on the normal and osteoporotic models to compute deformation and stress in all lumbar motion segments. FindingsWhen osteoporosis occurred, vibration amplitudes of the vertebral axial displacement, disc bulge, and disc stress were increased by 32.1–45.4%, 25.7–47.1% and 23.0–42.7%, respectively. In addition, it was found that for both the normal and osteoporotic models, the response values (disc bugle and disc stress) were higher in L4–L5 and L5–S1 intervertebral discs than in other discs. InterpretationOsteoporosis deteriorates the effect of whole-body vibration on lumbar spine, and the lower lumbar segments might have a higher likelihood of disc degeneration under whole-body vibration.

The Root Causes of Lumbar Canal Stenosis: An Insight with a Narrative Review

In the older population, lumbar spinal stenosis is a frequent degenerative condition that can cause clinical symptoms such as neurogenic claudication or sciatica, either with or without low back pain. Anatomically, there are three different forms of lumbar spinal stenosis: central, foraminal, and lateral recess. The relationship between Ligamentum Flavum (LF) hypertrophy and mechanical stress, as seen in segmental instability or disc space expansion, and their correlation with lumbar facet joint arthropathy is still not clear. This review places particular emphasis on the causes like LF hypertrophy, lumbar segmental instability, lumbar segmental motion, disc degeneration, lumbar spine facet joint orientation, facet joint tropism and facet joint Osteoarthritis (OA) in Lumbar Canal Stenosis (LCS) studied in various different studies discovered in various other search databases. The present research will also help surgeons and radiologists to interpret neuroradiological data appropriately for surgery as well as non surgical treatment and get a better knowledge of the architecture of these structures and how they appear on neuroimaging investigations for further proper and apt management of LCS. Additionally, it would assist in creating a diagnostic algorithm for better functional results.

Schober Test and Its Modifications Revisited—What Are We Actually Measuring? Computerized Tomography-Based Analysis

Examine Schober test's (ST), Modified ST (MST), and Modified-Modified ST (MMST) surface markers' accuracy in spanning lumbar L1-S1 motion segments and repeatability related to actual patient anatomy as measured on sagittal CT scans. The study included 25 patients of varying heights, weights, and gender without prior spinal surgery or deformity. Researchers assessed patients' CT scans for ST, MST, and MMST skin levels of the measured cephalic and caudal endpoints. The original ST failed to include at least one lumbar motion segment in all patients, omitting the L1-L2 motion segment in 17 patients and the L2-L3 in another eight. The additional cephalic length of the MST did not improve the inclusion of the actual L1-S1 components. The MMST measured 19 'patients' entire L1-S1 motion segments, reaching a 76% accuracy rate. WMST, measuring 16 cm (instead of MMST's 15 cm), improved the measurement significantly, measuring the L1-S1 motion segments in all cases (with 100% accuracy). ST and its modifications fail to span the L1-S1 motion segments and are thus prone to underestimating lumbar spine motion. This study shows that the WMST is much more accurate than previous modifications and is a better tool for evaluating lumbar spine motion.

Retrospective analysis of restoration of the anatomy of the damaged thoracic and lumbar spinal motion segment using transpedicular repositioning device

Objective. To carry out a retrospective analysis of the restoration of the anterior and posterior vertebral body heights and the elimination of deformation of the anterior spinal canal wall caused by thoracic and lumbar spine injury, based on the data of spiral computed tomography (SCT).Material and Methods. The study analyzed SCT data and case histories of 50 patients with thoracolumbar spinal cord injury operated on at different times after injury: up to 10 days – Group 1 and 11–30 days – Group 2. All patients underwent spinal reposition using a transpedicular device. The preoperative and postoperative SCT parameters were compared with the initial ones, which were calculated. The restoration of vertebral body heights and the elimination of deformation of the anterior spinal canal wall were compared in two groups depending on the distraction of interbody spaces and changes in the angle of segmental deformity.Results. In Group 1, the anterior and posterior dimensions of the vertebral body were restored, on average, by 95.3 ± 1.9 and 96.9 ± 1.4 % of the initial height; in Group 2 – by 87.4 ± 4.2 and 96.6 ± 1.8 %, respectively. The maximum restoration of the anterior dimensions of the vertebral bodies was achieved with distraction of the anterior interbody spaces closer to 100 % of the original size in the first and second groups. The maximum recovery of the posterior dimensions of the vertebral bodies was obtained by distraction of the posterior interbody spaces by 97 % or more of the original dimensions. The maximum elimination of the displacement of bone fragments from the spinal canal was obtained by distraction of the interbody spaces to a distance close to 100 % of the initial one, and when the obtained angle of segmental deformity coincided with the initial one.Conclusion. In the first 10 days after the injury, a greater percentage of the restoration of the anterior and posterior vertebral body heights and a decrease in the deformation of the anterior wall of the spinal canal were obtained. It was possible to maximally eliminate the deformation of the anterior wall of the spinal canal and restore the height of the anterior and posterior walls of the damaged vertebra by approaching the obtained dimensions of interbody spaces and the angle of segmental deformity to the initial ones.

Assessment of the Asymmetry of the Intervertebral Foramina within the Lower Motion Segments of the Lumbar Spine on the Computer Tomography Sections

Asymmetry in the degenerative lumbar spine may eventually evolve to debilitating scoliosis. The point where it starts to accelerate in some individuals is obscure. Discreet preclinical asymmetry may be a prognostic feature of the condition. The aim of this study was to assess the asymmetry of the intervertebral foramina of lower lumbar motion segments of the spine based on morphometric measurements using novel techniques of three-dimensional imaging. Computed tomography scans of 19 subjects with axial low back pain aged 50 to 78 of both sexes were digitally processed, and 3D reconstruction of L4/L5 and L5/S1 motion segments were obtained. The planes of intervertebral foramina were defined in reference to the axis of the pedicles bordering the intervertebral canal and the measurements were performed yielding absolute values in millimeters. The circumference ranged from 33.4 mm to 63.86 mm on the left side and from 33.01 mm to 73.54 mm on the right side. The horizontal dimension ranged from 6.86 mm to 17.84 mm on the left side and from 5.41 mm to 17.63 mm on the right side. The vertical dimension ranged from 10.17 mm to 23.65 mm on the left side and from 9.04 mm to 29.69 mm on the right side. All the measurements were combined to assess the asymmetry. Only in three cases (15%), symmetry in both segments was confirmed. No defined lateralization of asymmetry was found, as well as no significant link between the sex and age could be confirmed. This is the first study confirming the asymmetry among the intervertebral foramina. It seems that it is the dominant phenotype for intervertebral foramina. As the observed asymmetry lacks the dominant lateralization, it may be linked with the same trait of degenerative scoliosis. Though no direct link between the age and sex was confirmed in this study, it suggests other factors should be considered in prediction of the progress and magnitude of the deformity.

37. Anatomic contributions to the stability of the L5-S1 segment under combined shear and compression: implications to isthmic/lytic spondylolisthesis

37. Anatomic contributions to the stability of the L5-S1 segment under combined shear and compression: implications to isthmic/lytic spondylolisthesis

The relationship between traction spurs, Modic change, vacuum phenomenon, and segmental instability of the lumbar spine

A thorough understanding of lumbar segmental motion is valuable to treat patients with degenerative lumbar disease, but kinematics associated with indicators of lumbar intervertebral instability [traction spur, Modic changes (MCs) and vacuum phenomenon (VP)] in the lumbar spine have not been well understood. The purpose of this study is to evaluate the relationships between traction spur, MCs and VP to radiographic measurements in the lumbar spine. A total of 525 lumbar discs from L1-2 to L5-S1 of 105 patients were evaluated. The sagittal translation (ST) and sagittal angulation were measured from the radiographs taken flexion–extension. The anterior disc height (ADH) was measured from the lateral radiographs, and ΔADH was measured as the difference from supine to sitting position. Logistic regression analyses were used to detect the association between the existence of traction spur, MCs and VP and related factors. Multivariate analysis showed that the traction spur was significantly related to translational motion (ST > 2 mm, OR 4.74) and the VP was significantly related to vertical motion (ΔADH > 3 mm, OR 1.94). These results suggest that the segments with traction spur and VP should be evaluated carefully because these may be a sign of lumbar intervertebral instability.

Ex vivo biomechanical evaluation of Acute lumbar endplate injury and comparison to annulus fibrosus injury in a rat model

Back pain is often associated with intervertebral disc (IVD) degeneration, and IVD degeneration phenotypes are commonly characterized by annulus fibrosus (AF)-driven and endplate (EP)-driven phenotypes. Few studies of EP injury exist in animal models, even though clinical studies show EP lesions are strongly associated with IVD pathology and pain. This project established an ex-vivo rat lumbar EP injury model and characterized effects of EP injury on motion segment biomechanical properties, as compared to AF injury, a common way of inducing IVD degeneration. Lumbar motion segments (39 total vertebra-IVD-vertebra sections) assigned to Intact (L1/L2), AF injury and EP injury (L3/L4 and L5/L6 randomly selected), and biomechanically tested in axial tension-compression, stress-relaxation and torsional testing in pre-injury and post-injury conditions using a repeated-measures design. EP injury involved superior vertebra endplate puncture transcorporeally and obliquely. AF injury involved mid-line punctures anterior and bilaterally. Axial ROM, tensile stiffness, hysteresis, and neutral zone stiffness were significantly affected by EP injury but not AF injury. Torque range, torsional stiffness and torsional neutral zone stiffness were significantly affected by AF injury but not EP injury. Stress-relaxation fast time constant was decreased for EP injury. EP and AF injuries induced distinct biomechanical changes in lumbar motion segments with EP injury having the largest impact on axial biomechanical properties and AF injury most prominently affecting torsional properties. This study deepens the understanding of biomechanical mechanism of EP-driven low back pain and provides methods and biomechanical characterization for future in vivo studies.

Does the neutral zone quantification method matter? Efficacy of evaluating neutral zone during destabilization and restabilization in human spine implant testing

Neutral zone (NZ) is an important biomechanical parameter when evaluating spinal instability following destabilizing and restabilizing events, with particular relevance for implant efficacy testing. It remains unclear what NZ calculation methods are most sensitive at capturing NZ changes across treatment conditions and a direct comparison is needed. The purpose of this study was to determine the most sensitive method at quantifying instability in human spines. Six cadaveric lumbar motion segments were subjected to a repeated measures implant testing schema of four sequential conditions: (1) Intact, (2) injury by herniation, (3) device implantation, (4) long-term cyclic fatigue loading. NZ was expected to increase after destabilization (steps 2 & 4) and decrease after restabilization (step 3). NZ methods compared in this study were: trilinear (TL), double sigmoid (DS), zero load (ZL), stiffness threshold (ST), and extrapolated elastic zone (EEZ). TL, ZL, and EEZ identified statistically significant NZ differences after each condition in flexion/extension and lateral bending. The ZL method also captured differences in axial rotation. All methods identified expected NZ changes after destabilization and restabilization, except DS in axial rotation. The TL, ZL, and EEZ methods were the most sensitive methods with this human cadaveric dataset. Future investigations comparing methods with additional datasets will clarify outcome generalizability and determine what curve profiles are most suitable for DS and ST methods. Understanding the applicability of NZ methods can enhance rigor and reliability of spinal instability measurements when quantifying the efficacy of novel implants and permits insight into clinically relevant biomechanical changes.

The Effects of Core Stabilization Exercise with the Abdominal Drawing-in Maneuver Technique versus General Strengthening Exercise on Lumbar Segmental Motion in Patients with Clinical Lumbar Instability: A Randomized Controlled Trial with 12-Month Follow-Up.

Trunk stability exercises that focus on either deep or superficial muscles might produce different effects on lumbar segmental motion. This study compared outcomes in 34 lumbar instability patients in two exercises at 10 weeks and 12 months follow up. Participants were divided into either Core stabilization (deep) exercise, incorporating abdominal drawing-in maneuver technique (CSE with ADIM), or General strengthening (superficial) exercise (STE). Outcome measures were pain, muscle activation, and lumbar segmental motion. Participants in CSE with ADIM had significantly less pain than those in STE at 10 weeks. They showed significantly more improvement of abdominal muscle activity ratio than participants in STE at 10 weeks and 12 months follow-up. Participants in CSE with ADIM had significantly reduced sagittal translation at L4-L5 and L5-S1 compared with STE at 10 weeks. Participants in CSE with ADIM had significantly reduced sagittal translations at L4-L5 and L5-S1 compared with participants in STE at 10 weeks, whereas STE demonstrated significantly increased sagittal rotation at L4-L5. However, at 12 months follow-up, levels of lumbar sagittal translation were increased in both groups. CSE with ADIM which focuses on increasing deep trunk muscle activity can reduce lumbar segmental translation and should be recommended for lumbar instability.

Development of a finite element lumbar spine model to predict intervertebral disc herniation risk factors

The objective of the current study was to develop a lumbar motion segment FE model that predicts disc herniation risk. The posterolateral nucleus extrusion force and disc pressure increased as the amount of flexion and magnitude of compression was increased in all loading scenarios. The nucleus extrusion force and posterior stress in the annulus both increased when exposed to a combination of compression and flexion. Results of the current study confirmed the authors hypothesis that the model would accurately predict herniation risk when exposed to a biomechanical environment known to cause herniations.