Comparative finite element analysis of the first thoracic vertebra in artiodactyls.

Artiodactyls exhibit a striking diversity of the cervical vertebral column in terms of length and overall mobility. Using finite element analysis, this study explores the morphology at the cervico-thoracic boundary and its performance under loads in artiodactyls with different habitual neck postures and body sizes. The first thoracic vertebra of 36 species was loaded with (i) a compressive load on the vertebral body to model the weight of the head and neck exerted onto the trunk; and (ii) a tensile load at the spinous process to model the pull via the nuchal ligament. Additional focus was laid on the peculiar shape of the first thoracic vertebra in giraffes. We hypothesized that a habitually upright neck posture should be reflected in the greater ability to withstand compressive loads compared to tensile loads, whereas for species with a habitually suspended posture it should be the opposite. In comparison to species with a suspended posture, species with an upright posture exhibited lower stress (except Giraffidae). For compressive loads in larger species, stress surprisingly increased. Tensile loads in larger species resulted in decreased stress only in species with an intermediate or suspensory neck posture. High stress under tensile loads was mainly reflecting the relative length of the spinous process, while high stress under compressive loads was common in more "bell"-shaped vertebral bodies. The data supports a stability-mobility trade-off at the cervico-thoracic transition in giraffes. Performance under load at the cervico-thoracic boundary is indicative of habitual neck posture and is influenced by body size.

Wearable Motion Analysis System for Thoracic Spine Mobility With Inertial Sensors.

This study presents a wireless wearable portable system designed for the automatic quantitative spatio-temporal analysis of continuous thoracic spine motion across various planes and degrees of freedom (DOF). This includes automatic motion segmentation, computation of the range of motion (ROM) for six distinct thoracic spine movements across three planes, tracking of motion completion cycles, and visualization of both primary and coupled thoracic spine motions. To validate the system, this study employed an Inter-days experimental setting to conduct experiments involving a total of 957 thoracic spine movements, with participation from two representatives of varying age and gender. The reliability of the proposed system was assessed using the Intraclass Correlation Coefficient (ICC) and Standard Error of Measurement (SEM). The experimental results demonstrated strong ICC values for various thoracic spine movements across different planes, ranging from 0.774 to 0.918, with an average of 0.85. The SEM values ranged from 0.64° to 4.03°, with an average of 1.93°. Additionally, we successfully conducted an assessment of thoracic spine mobility in a stroke rehabilitation patient using the system. This illustrates the feasibility of the system for actively analyzing thoracic spine mobility, offering an effective technological means for non-invasive research on thoracic spine activity during continuous movement states.

Numerical investigation of intra-abdominal pressure and spinal load-sharing upon the application of an abdominal belt.

Chronic low back pain patients may experience spinal instability. Abdominal belts (ABs) have been shown to improve spine stability, trunk stiffness, and resiliency to spinal perturbations. However, research on the contributing mechanisms is inconclusive. ABs may increase intra-abdominal pressure (IAP) and reduce paraspinal soft tissue contribution to spine stability without increasing spinal compressive loads. A finite element model (FEM) of the spine inclusive of the T1-S1 vertebrae, intervertebral discs (IVDs), ribcage, pelvis, soft tissues, and abdominal cavity, without active muscle forces was developed. An identical FEM with an AB was developed. Both FEMs underwent trunk flexion. Following validation, the models' intervertebral rotation (IVR), IAP, IVD pressure, and tensile stress in the multifidus (MF), erector spinae (ES), and thoracolumbar fascia (TLF) were compared. The inclusion of an AB resulted in a 3.8 kPa IAP increase, but a decreased average soft tissue tensile stress of 0.28 kPa. The TLF withstood the majority of tension being transferred across the paraspinal soft tissues (>70 %). The average IVR in the AB model decreased by 10 %, with the lumbar spine experiencing the largest reduction. The lumbar IVDs of the AB model likewise showed a 31 % reduction in average IVD pressure. Using an AB improved trunk bending stiffness, primarily in the lumbar spine. Wearing an AB had minimal effect on reducing tensile stress in theES. The skewed stress distribution towards the TLF suggests its large contribution to spine stability and the potential advantage in unloading the structure when wearing an AB, measured herein at8 %.

The biomechanical consequence of posterior interventions at the thoracolumbar spine on the passively stabilized flexed posture.

In the flexed end-of-range position (e.g., during slumped sitting), the trunk is passively stabilized. Little is known about the biomechanical consequence of posterior approaches on passive stabilization. The aim of this study is to investigate the effect of posterior surgical interventions on local and distant spinal regions. While being fixed at the pelvis, five human torsos were passively flexed. The change in spinal angulation at Th4, Th12, L4 and S1 was measured after level-wise longitudinal incisions of the thoracolumbar fascia, the paraspinal muscles, horizontal incisions of the inter- & supraspinous ligaments (ISL/SSL) and horizontal incision of the thoracolumbar fascia and the paraspinal muscles. Lumbar angulation (Th12-S1) was increased by 0.3° for fascia, 0.5° for muscle and 0.8° for ISL/SSL-incisions per lumbar level. The effect of level-wise incisions at the lumbar spine was 1.4, 3.5 and 2.6 times greater compared to thoracic interventions for fascia, muscle and ISL/SSL respectively. The combined midline interventions at the lumbar spine were associated with 2.2° extension of the thoracic spine. Horizontal incision of the fascia increased spinal angulation by 0.3°, while horizontal muscle incision resulted in a collapse of 4/5 specimens. The thoracolumbar fascia, the paraspinal muscle and the ISL/SSL are important passive stabilizers for the trunk in the flexed end-of-range position. Lumbar interventions needed for approaches to the spine have a larger effect on spinal posture than thoracic interventions and the increase of spinal angulation at the level of the intervention is partially compensated at the neighboring spinal regions.

Review of morphology, development, and evolution of the notarium in birds.

The notarium is a rigid bony structure, which resulted from the fusion of thoracic vertebrae of some pterosaurs and birds. It is high variable, ranging from two to six fused thoracic vertebrae. In this study, we reviewed and analyzed approximately 270 specimens of neornithine birds (representing 80% of the living orders) and some fossils in order to identify the number of fused vertebrae, degree and sites of vertebral fusion, occurrence of sutures, and other structures of potential phylogenetic and functional significance. These data were analyzed using a recent time-calibrated molecular phylogenetic tree and principal component analyses analysis evaluating the relationship with long bones in order to reconstruct macroevolutionary trends related to the evolution of the notarium. The occurrence of this structure shows a mosaic distribution over neornithine phylogeny, originating several times independently, especially during the Paleogene, in predominantly ground-dwelling forms. The notarium of these groups is characterized by: neural spines fused into single structure, intervertebral openings small to absent, large ventral keels forming ventral plates, and fused transverse processes. Derived neornithines, such as aquatic forms and long-legged birds, have a tendency to display a decreased degree of fusion between the vertebrae, which may indicate a reduction or disappearance of the notarium.

Measurable Thoracic Motion Remains at 1 Year Following Anterior Vertebral Body Tethering, with Sagittal Motion Greater Than Coronal Motion.

BACKGROUND: Anterior vertebral body tethering is an alternative to fusion surgery for the treatment of adolescent idiopathic scoliosis (AIS) that is purported to preserve spinal motion. There is limited information regarding the measurable motion that is maintained over the instrumented levels following thoracic anterior vertebral body tethering surgery in humans. The purpose of the present study was to assess radiographic spinal motion 1 year after anterior vertebral body tethering. METHODS: As part of a prospective U.S. Food and Drug Administration investigational device exemption study, 32 patients were treated with thoracic anterior vertebral body tethering. At 1 year postoperatively, patients were evaluated with standing flexion-extension and side-bending radiographs in a microdose biplanar slot scanning imaging system. The angle subtended by the screws at the upper instrumented vertebra (UIV) and lower instrumented vertebra (LIV) was measured on left and right-bending radiographs to evaluate the coronal arc of motion and was compared with preoperative values over the same levels. At 1 year postoperatively, the sagittal Cobb angle was measured over the instrumented levels on flexion and extension radiographs. RESULTS: Side-bending radiographs revealed that the mean angle subtended by the screws changed from 15° ± 8° on left-bending radiographs to 8° ± 6° on right-bending radiographs. The mean coronal arc of motion on bending was 7° ± 6°, with 20 (62.5%) of 32 patients having a coronal arc of motion of >5°. The mean preoperative coronal arc of motion over the instrumented segments was 30° ± 9°. On flexion-extension lateral radiographs made at 1 year postoperatively, the mean kyphotic angle over the instrumented segments was 33° ± 13° in flexion and 11° ± 14° in extension, for a mean postoperative arc of motion of 21° ± 12° between flexion and extension radiographs. CONCLUSIONS: At 1 year following thoracic anterior vertebral body tethering for the treatment of AIS, the thoracic spine showed a measurable range of coronal and sagittal plane motion over the instrumented levels without evidence of complete autofusion. Motion in the coronal plane decreased by 77% following anterior vertebral body tethering. These findings provide proof of concept that sagittal spinal motion is preserved after thoracic anterior vertebral body tethering, although the functional importance remains to be determined. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

3D kinematic of the thoracolumbar spine in Mangalarga Marchador horses performing the marcha batida gait and being led by hand-A preliminary report.

This study aimed to provide a preliminary description of the sagittal and transverse plane kinematics of the thoracolumbar spine of Mangalarga Marchador (MM) horses performing the marcha batida gait, led in-hand. We evaluated the pattern of angular movement and the mean amplitude of six specific angles. An optoelectronic system was used for 3D kinematic analysis (19 cameras, 250 Hz). They were positioned around the horses and an acquisition volume of 16 × 4.8 × 3 meters was used. Eight retroreflective markers were fixed on the spine of the animals over thoracic vertebrae 8 (T8), 12 (T12), 15 (T15) and 18 (T18); over the lumbar vertebrae 3 (L3) and 5 (L5); over the 1st sacral vertebra (S1); and over the 1st coccygeal vertebra (CD1). Five trials, led from a halter, with three complete gait cycles were evaluated for each marcha batida horse. The 3D coordinates of the markers were filtered with a second-order, low-pass, Butterworth filter (10 Hz). Six angles: T8-T12-T15, T12-T15-T18, T12-T18-L5, T15-T18-L3, T18-L3-L5, and L3-S1-CD1 were obtained and projected in the sagittal (Flexion and Extension) and transverse (Lateral bending) planes. We calculated, for each angle to represent the spine movements, the mean and standard deviation of the range of motion (ROM, difference between the maximum and minimum values in a stride cycle). In order to describe the movement over an average stride cycle we calculated the mean curve of angle variation. The T8-T12-T15 angle presented the largest ROM in the transverse plane, while in the sagittal plane the T8-T12-T15, T12-T15-T18 and T12-T18-L5 angles presented the largest ROMs. The L3-S1-CD1 angle (lumbosacral region) presented the lowest ROM in both planes. A reduced flexion close to a neutral spine was found, predominantly during the diagonal support and in the cranial thoracic region. At the same time, the thoracolumbar region remains in an extension which is highlighted in the lumbosacral region. During the change of the support phase, the cranial thoracic region moved from a flexion to a slight extent, and the thoracolumbar region was flexed which is emphasized in the lumbosacral region. The lateral bending of the spine followed the direction of the diagonal supports. The small amplitude in the latero-lateral and dorsoventral movements of the thoracolumbar spine of MM horses during the marcha batida gait could contribute to the smooth and natural sensations experienced when riding in this gait. The lower mobility of these angles should be considered during the clinical examination of marcha batida-gaited horses.

Can Exercise Targeting Mid-Thoracic Spine Segmental Movement Reduce Back Pain and Improve Sensory Perception in Cross-Country Skiers?

OBJECTIVE: To assess the role of exercise targeting proper trunk stabilization and segmental spinal movement in back pain and sensory perception among cross-country skiers. DESIGN: Randomized, controlled trial with blinded outcome assessors. SETTING: University Hospital, Department of Rehabilitation and Sports Medicine. PARTICIPANTS: Twenty elite cross-country skiers aged 17 to 27 years. INTERVENTIONS: Ten cross-country skiers integrated 3 types of exercise targeting segmental motion in mid-thoracic spine into their routine training practice for 2 months. The 10 controls performed routine athletic training. MAIN OUTCOME MEASURES: The Young Spine Questionnaire to measure intensity and frequency of back pain was completed at the start and end of study. Tactile sensory perception using 10-g Semmes-Weinstein monofilament, thermic perception using TIP THERM device, graphesthesia assessed by a touch monitor pencil, 2-point discrimination assessed by a digital caliper, and vibration perception assessed by a 128-Hz tuning fork measured in mid-thoracic spine 5 times. RESULTS: No significant group differences in pain and sensory perception were identified at baseline. Over the 2-month study interval, repeated-measures analysis of variance revealed that the experimental group improved significantly relative to the control group on pain intensity (P = 0.005 for cervical, P = 0.004 for thoracic, and P = 0.014 for lumbar) and frequency of pain in the thoracic area only (P = 0.011). Improvements were also observed in the experimental relative to control group on graphesthesia (P < 0.001), vibration perception (P = 0.002), and 2-point discrimination (P < 0.001). CONCLUSIONS: Exercise targeting the mid-thoracic spine may decrease back pain and improve sensory perception in cross-country skiers. LEVEL OF EVIDENCE: Original research, level I.

Dorsal muscle fatigue increases thoracic spine curvature in all-out recreational ergometer rowing.

The purpose of this study was to investigate fatigue-related changes in spinal kinematics, kinetics, and muscle activity of back muscles during a 2000 m all-out ergometer rowing performance. We analyzed ten male subjects with experience in both rowing and CrossFit exercises. We applied a novel kinematic method to describe spine curvature, determined bending moments at the spine using inverse dynamics and collected EMG data. We identified significant increases in spine curvature of the thoracic spine (i.e. vertebrae Th6 to Th11). Significant increases in peak moments were found only at the upper spine (i.e. Th2). We found no significant changes in EMG amplitudes, while the frequency analysis showed significant decreases in the mean frequencies (MNF) for the M. latissimus dorsi, the M. trapezius descendens and the M. deltoideus posterior. No significant changes on MNF were found for the Mm. erector spinae. We hypothesize that the significant increase in curvature for the thoracic spine is connected to the fatigued back muscles, especially the Mm. trapezius descendens, and might lead to an unbalanced loading of intervertebral discs and other structures. These findings are particularly important for athletes and coaches in CrossFit as strenuous rowing intervals are combined with technical exercises with high loads on the back and spine (e.g. power and Olympic lifting) leading to impaired muscular stabilization and potentially to an increased injury risk.

Thoracolumbar Burst Fracture: McCormack Load-sharing Classification: Systematic Review and Single-arm Meta-analysis.

STUDY DESIGN: A systematic review and single-arm meta-analysis of randomized clinical trials. OBJECTIVE: The aim of this study was to evaluate whether the load-sharing classification (LSC) is reliable to predict the best surgical approach for thoracolumbar burst fracture (TBF). SUMMARY OF BACKGROUND DATA: There is no previous review evaluating the efficacy of the use of LSC as a guide in the surgical treatment of burst fractures. METHODS: On April 19th, 2019, a broad search was performed in the following databases: EMBASE, PubMed, Cochrane, SCOPUS, Web of Science, LILACS, and gray literature. This study was registered on the International Prospective Register of Systematic Reviews. We included clinical trials involving patients with TBF undergoing posterior surgical treatment, classified by load-sharing score, and that enabled the analysis of the outcomes loss of segmental kyphosis and implant failure (IF). We performed random- or fixed-effects models meta-analyses depending on the data homogeneity. Heterogeneity between studies was estimated by I2 and τ2 statistics. RESULTS: The search identified 189 references, out of which nine studies were eligible for this review. All articles presenting LSC up to 6 proved to be reliable in indicating that only posterior instrumentation is necessary, without screw failures or loss of kyphosis correction. For cases where the LSC was >6, only 2.5% of the individuals presented IF upon posterior approach alone. For loss of kyphosis correction, only 5% of patients had this outcome where LSC >6. For both outcomes together, we had 6% of postoperative problems (I2 = 77%, τ2 < 0.0015, P < 0.01). CONCLUSION: Load-sharing scores up to 6 are 100% reliable, only requiring posterior instrumentation for stabilization. For scores >6, the risk of implant breakage and loss of kyphosis correction in posterior fixation alone is low. Thus, other factors should be considered to define the best surgical approach to be adopted.Level of Evidence: 1.

Age-related Changes in T1 and C7 Slope and the Correlation Between Them in More Than 300 Asymptomatic Subjects.

STUDY DESIGN: A cross-sectional analysis using T1 slope (T1S) and C7 slope (C7S) in asymptomatic individuals. OBJECTIVE: The aim of this study was to identify normative values, ranges of motion (ROMs), age-related changes in T1S and C7S, and correlation between the two slopes. SUMMARY OF BACKGROUND DATA: Few studies have reported age-related changes in the T1S and C7S angles. Additionally, studies investigating the effects of cervical position on these slopes are limited. METHODS: A total of 388 asymptomatic subjects (162 males and 226 females) for whom T1S measurement was performed on radiographs were enrolled in the study. The T1S and C7S angles were measured using neutral radiography of the cervical spine. ROMs were assessed by measuring the difference in alignment in the neutral position, flexion, and extension. RESULTS: The mean C7S and T1S angles were 19.6° (22.2° in males, 17.9° in females) and 24.0° (26.7° in men and 22.1° in women), respectively. The T1S angle was significantly greater than the C7S angle. Both the C7S and T1S angles significantly increased with age. The flexion ROM of C7S was higher than that of T1S, whereas no significant difference was detected between the extension ROMs of the two slopes. The flexion ROMs of the two slopes did not change, whereas the extension ROMs significantly increased with age. A significant positive correlation was observed between the C7S and T1S angles (r2 = 0.75). CONCLUSION: The normative values and age-related changes in C7S and T1S were analyzed. Both the C7S and T1S angles increased with age. The C7S angle was strongly correlated with the T1S angle, suggesting that C7S can substitute T1S on radiographic images.Level of Evidence: 3.

Reliability of shear-wave elastography in assessing thoracolumbar fascia elasticity in healthy male.

The objectives of this study were to examine the intra and inter-operator reliability of shear wave elastography (SWE) device in quantifying the shear modulus of thoracolumbar fascia (TLF) and the device's abilities to examine the shear modulus of the TLF during upper body forward. Twenty healthy male subjects participated in this study (mean age: 18.4 ± 0.7 years). Two independent operators performed the shear modulus of TLF during upper body forward using SWE, and interclass correlation coefficient (ICC) and minimum detectable change (MDC) were calculated. The shear modulus of the TLF was quantified by operator A using SWE at upper body forward 60°. The intra-operator (ICC = 0.860-0.938) and inter-operator (ICC = 0.904-0.944) reliabilities for measuring the shear modulus of the TLF with the upper body forward 0° were rated as both excellent, and the MDC was 4.71 kPa. The TLF shear modulus of upper body forward 60°was increased 45.5% (L3) and 55.0% (L4) than that of upper body forward 0°. The results indicate that the SWE is a dependable tool to quantify the shear modulus of TLF and monitor its dynamic changes. Therefore, this device can be used for biomechanical study and intervention experiments of TLF.

Assessing forces during spinal manipulation and mobilization: factors influencing the difference between forces at the patient-table and clinician-patient interfaces.

BACKGROUND: Spinal manipulative therapy (SMT) and mobilization (MOB) effects are believed to be related to their force characteristics. Most previous studies have either measured the force at the patient-table interface or at the clinician-patient interface. The objectives of this study were to determine 1) the difference between the force measured at the patient-table interface and the force applied at the clinician-patient interface during thoracic SMT and MOB, and 2) the influence of the SMT/MOB characteristics, participants' anthropometry and muscle activity (sEMG) on this difference. METHODS: An apparatus using a servo-linear motor executed 8 SMT/MOB at the T7 vertebrae in 34 healthy adults between May and June 2019. SMT and MOB were characterized by a 20 N preload, total peak forces of 100 N or 200 N, and thrust durations of 100 ms, 250 ms, 1 s or 2 s. During each trial, thoracic sEMG, apparatus displacement as well as forces at the patient-table interface and the clinician-patient interface were recorded. The difference between the force at both interfaces was calculated. The effect of SMT/MOB characteristics on the difference between forces at both interfaces and correlations between this difference and potential influencing factors were evaluated. RESULTS: Force magnitudes at the patient-table interface were, in most trials, greater than the force at the clinician-patient interface (up to 135 N). SMT/MOB characteristics (total peak force, thrust duration and rate of force application) affected the difference between forces at both interfaces (all p-values< 0.05). No factor showed significant correlations with the difference between forces at both interfaces for the 8 SMT/MOB. CONCLUSIONS: The results revealed that the force measured at the patient-table interface is greater than the applied force at the clinician-patient interface during thoracic SMT and MOB. By which mechanism the force is amplified is not yet fully understood.

The influence of the rib cage on the static and dynamic stability responses of the scoliotic spine.

The thoracic cage plays an important role in maintaining the stability of the thoracolumbar spine. In this study, the influence of a rib cage on static and dynamic responses in normal and scoliotic spines was investigated. Four spinal finite element (FE) models (T1-S), representing a normal spine with rib cage (N1), normal spine without rib cage (N2), a scoliotic spine with rib cage (S1) and a scoliotic spine without rib cage (S2), were established based on computed tomography (CT) images, and static, modal, and steady-state analyses were conducted. In S2, the Von Mises stress (VMS) was clearly decreased compared to S1 for four bending loadings. N2 and N1 showed a similar VMS to each other, and there was a significant increase in axial compression in N2 and S2 compared to N1 and S1, respectively. The U magnitude values of N2 and S2 were higher than in N1 and S1 for five loadings, respectively. The resonant frequencies of N2 and S2 were lower than those in N1 and S1, respectively. In steady-state analysis, maximum amplitudes of vibration for N2 and S2 were significantly larger than N1 and S1, respectively. This study has revealed that the rib cage improves spinal stability in vibrating environments and contributes to stability in scoliotic spines under static and dynamic loadings.

Dynamic changes in longitudinal stretching of the spinal cord in thoracic spine: Focus on the spinal cord occupation rate of dural sac.

OBJECTIVES: This study aimed to evaluate the anteroposterior diameters and cross-sectional areas of the dural sac and spinal cord in the thoracic spine, to elucidate the spinal cord occupation rate of the dural sac in these dynamic changes for each level using multidetector-row computed tomography (MDCT). PATIENTS AND METHODS: Fifty patients with cervical or lumbar spinal disease were prospectively enrolled. After preoperative myelography, MDCT was performed at maximum passive flexion and extension. The anteroposterior diameter and cross-sectional area of the dural sac and spinal cord in the axial plane and the thoracic spinal cord length in the sagittal plane were measured. The spinal cord occupation rate in the dural sac was calculated. RESULTS: The spinal cord occupation rate of the dural sac in anteroposterior diameter was lower on flexion than on extension, with significant differences from the T1/T2 to T11/T12 levels (p < 0.0001). The spinal cord occupation rate of the dural sac in cross-sectional area was lower on flexion than on extension, with significant differences except from T3/T4 to T6/T7 levels (p < 0.01). There was a bimodal increase in the occupation rate with elevations at the cervicothoracic junction and thoracolumbar junction. The thoracic spinal cord length on flexion was significantly longer than that on extension (p < 0.0001). CONCLUSIONS: The spinal cord occupation rate of the dural sac was lower on flexion than on extension, despite thoracic spine being considered a rigid region. The dynamic changes in longitudinal stretching and shrinkage of the spinal cord affected the occupation rate.

Comparison of cervical muscle activity and spinal curvatures in the sitting position with 3 different sloping seats.

Lumbar and pelvic alignment may have a huge impact on the posture of the spine and other parts. The aim of this study were to compare the spinal curvature of the cervical, thoracic, and lumbar spine and the muscle activity of the cervical erector spinae muscle, upper trapezius muscle, and thoracic erector spinae muscle when sitting at 3 different sloped, seating surfaces. A 10° wedge was used as the seating surface and we compared a forward sloping seat surface, a flat seating surface, and a rear sloping seat surface, in that order. Twenty healthy officers were recruited for this study. The subjects sat on the seat of 3 different slopes and watched a total of 3 videos, 10 minutes each. The rest time was 10 minutes. Subjects were photographed while viewing videos and muscle activity was measured. There were significant differences in cervical, thoracic, lumbar curvatures, and muscle activity in the 3 different sitting positions according to seat tilt (P < .05). Among the 3 slopes, the forward slope decreased forward head posture and cervical erector spinae muscle activity (P < .05). The activity of the cervical erector spinae muscle was 2.67% with a forward sloping seat, 5.45% with a flat sloping seat, and 6.77% with a rear sloping seat, revealing a significant difference (P < .05). This suggests that a forward sloping seat surface was effective in maintaining a neutral alignment of the spine, and this decreased the cervical spine erector muscle activity. Based on this result, equipment and chair development to incline seats forward may improve posture and health, and prevent chronic pain.

A field study on spinal postures and postural variations during smartphone use among university students.

This field study compared the real-time spinal movements and postural variations during smartphone-use versus non-use in university students. Ten males and eight females (mean age of 21.5 ± 2.6 years) participated, with similar daily phone use time between the two sexes. Five inertial motion sensors were attached to the cervical, thoracic and lumbar spinal regions, and kinematics was recorded for 3 h while participants went about their usual academic activities within the university campus. Significantly greater degrees of cervical and upper thoracic flexion were adopted during phone use versus non-use time (p < 0.01). There were also significantly greater frequency of postural variations (zero crossing per min) in all spinal regions in the sagittal plane (all p < 0.05), and in some of the movements in transverse and frontal planes comparing phone use vs non-use. The postural variables also showed some significant correlations with self-reported pre-existing neck and upper back pain scores.

The effect of age, prolonged seated work and sex on posture and perceived effort during a lifting task.

The purpose of this investigation was to determine the effect of prolonged seated work, lift task, age and sex on normalized lumbar angles, thoracic angles, perceived effort and duration of lifts. A total of 17 young and 17 mature participants were recruited with an average (standard deviation) age of 23.8 (5.0) years and 63.7 (3.9) years, respectively. Participants completed 3 different floor to knuckle lifts before and following 90 min of seated work. The lifts included; (i) 7 kg symmetrical, (ii) 4.5 kg symmetrical and (iii) 4.5 kg asymmetrical. Prolonged seated work and age interacted to affect normalized peak lumbar angles (p = 0.0469) where older adults adopted 56(15)% flexion after seated work compared to 67(16)% among younger adults. Older adults took significantly longer to complete the lifting tasks compared to younger adults while age did not affect perceived effort across lifting tasks. Older workers may require age specific interventions given age specific responses.

A biomechanical comparison of conventional classifications of bowling action-types in junior fast bowlers.

Fast bowling is categorised into four action types: side-on, front-on, semi-open and mixed; however, little biomechanical comparison exists between action types in junior fast bowlers. This study investigated whether there are significant differences between action-type mechanics in junior fast bowlers. Three-dimensional kinematic and kinetic analyses were completed on 60 junior male fast bowlers bowling a five-over spell. Mixed-design factorial analyses of variance were used to test for differences between action-type groups across the phases of the bowling action. One kinetic difference was observed between groups, with a higher vertical ground reaction force loading rate during the front-foot contact phase in mixed and front-on compared to semi-open bowlers; no other significant group differences in joint loading occurred. Significant kinematic differences were observed between the front-on, semi-open and mixed action types during the front-foot contact phase for the elbow and trunk. Significant kinematic differences were also present for the ankle, T12-L1, elbow, trunk and pelvis during the back-foot phase. Overall, most differences in action types for junior fast bowlers occurred during the back-foot contact phase, particularly trunk rotation and T12-L1 joint angles/ranges of motion, where after similar movement patterns were utilized across groups during the front-foot contact phase.

A finite element analysis of the intra-abdominal pressure and paraspinal muscle compartment pressure interaction through the thoracolumbar fascia.

Thoracolumbar fascia involvement is often neglected when studying the biomechanics of the spine. The purpose of this study was to develop, validate, and explore the use of a novel finite element model of the spine, inclusive of the Thoracolumbar Fascia, Paraspinal Muscular Compartment (PMC) and the Intra-Abdominal Pressure (IAP) based on published clinical studies. Reaction forces were acquired at five critical anatomical locations. Results showed that elevated IAP decreased the posterior force and balanced the anterior forces when PMC pressure was asymmetric. This novel finite element study demonstrated a link between the TLF compartments supporting its involvement in spinal stability.