Lumbopelvic rhythm during forward and backward sagittal trunk rotations: combined in vivo measurement with inertial tracking device and biomechanical modeling

Effect of asymptomatic intervertebral flexion patterns on lumbar disc pressure: A finite element analysis study

Movement patterns may be a factor for manipulating the lumbar load, although little information is yet available in the literature about the relationship between this variable and intervertebral disc pressure (IDP). A finite element model of the lumbar spine (49-year-old asymptomatic female) was used to simulate intervertebral movements (L2-L5) of 127 asymptomatic participants. The data from participants that at least completed a simulation of lumbar vertebral movement during the first 53% of a movement cycle (flexion phase) were used for further analyses. Then, for each vertebral angular motion curve with constant spatial peaks, different temporal patterns were simulated in two stages: (1) in lumbar pattern exchange (LPE), each vertebral angle was simulated by the corresponding vertebrae of other participants data; (2) in vertebral pattern exchange (VPE), vertebral angles were simulated by each other. The k-mean algorithm was used to cluster two groups of variables; peak and cumulative IDP, in both stages of simulations (i.e., LPE and VPE). In the second stage of the simulation (VPE), Kendall's tau was utilized to consider the relationship between different temporal patterns and IDPs for each individual lumbar level. Cluster analyses showed that the temporal movement pattern did not exhibit any effect on the peak IDP while the cumulative IDP changed significantly for some patterns. Earlier involvement in lumbar motion at any level led to higher IDP in the majority of simulations. There is therefore a possibility of manipulating lumbar IDP by changing the temporal pattern with the same ROM, in which optimal distribution of the loads among lumbar levels may be applied as preventive or treatment interventions. Evaluating load benefits, such as load, on biomechanically relevant lumbar levels, dynamically measured by quantitative fluoroscopy, may help inform interventional exercises.

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

BACKGROUND

Bending the trunk forward and backward while standing are common daily activities and can have various patterns. However, any dysfunction in these movements can considerably affect daily living activities. Consequently, a comprehensive evaluation of spinal motion during these activities and precise identification of any movement abnormalities are important to facilitate an effective rehabilitation. In recent years, with the development of measurement technology, the evaluation of movement patterns using an inertial motion capture system (motion sensor) has become easy. However, the accuracy of estimated angular information obtained via motion sensor measurements can be affected by angular velocity. This study aimed to compare the validity of estimated angular information obtained by assessing standing trunk forward and backward bending at different movement speeds using a motion sensor with a three-dimensional motion analysis system.

METHODS

The current study included 12 healthy older men. A three-dimensional motion analysis system and a motion sensor were used for measurement. The participants performed standing trunk forward and backward bending at comfortable and maximum speeds, and five sensors were attached to their spine. Statistical analysis was performed using the paired t-test, intraclass correlation coefficient, mean absolute error, and multiple correlation coefficient.

RESULTS

Results showed that the estimated angular information obtained using each motion sensor was not affected by angular velocity and had a high validity.

CONCLUSIONS

Therefore, the angular velocity in this study can be applied clinically for an objective evaluation in rehabilitation.

Spinal loads during dynamic full flexion and return to standing posture in different age and sex groups: A musculoskeletal model study

During forward flexion, spine motion varies due to age and sex differences. Previous studies showed that lumbar/pelvis range of flexion (RoF) and lumbo-pelvic ratio (L/P) are age/sex dependent. How variation of these parameters affects lumbar loading in a normal population requires further assessment. We aimed to estimate lumbar loads during dynamic flexion-return cycle and the differences in peak loads (compression) and corresponding trunk inclinations due to variation in lumbar/pelvis RoF and L/P. Based on in vivo L/P (0.11-3.44), temporal phases of flexion (early, middle, and later), the lumbar (45-55°) and hip (60-79°) RoF; full flexion-return cycles of six seconds were reconstructed for three age groups (20-35, 36-50 and 50+ yrs.) in both sexes. Six inverse dynamic analyses were performed with a 50th percentile model, and differences in peak loads and corresponding trunk inclinations were calculated. Peak loads at L4-L5 were 179 N higher in younger males versus females, but 228 N and 210 N lower in middle-aged and older males, respectively, compared to females. Females exhibited higher trunk inclinations (6°-20°) than males across all age groups. Age related differences in L4-L5 peak loads and corresponding trunk inclinations were found up to 415 N and 19° in males and 152 N and 13° in females. With aging, peak loads were reduced in males but were found non-monotonic in females, whereas trunk inclinations at peak loads were reduced in both sexes from young to middle/old age groups. In conclusion, lumbar loading and corresponding trunk inclinations varied notably due to age/sex differences. Such data may help distinguishing normal or pathological condition of the lumbar spine.

Lumbo-Pelvic Rhythm Monitoring Using Wearable Technology with Sensory Biofeedback: A Systematic Review

As an essential lower-back movement pattern, lumbo-pelvic rhythm (LPR) during forward trunk flexion and backward return has been investigated on a large scale. It has been suggested that abnormalities in lumbo-pelvic coordination are related to the risk of developing low back disorders. However, considerable differences in the approaches used to monitor LPR make it challenging to integrate findings from those investigations for future research. Therefore, the aim of this systematic review was to summarize the use of wearable technology for kinematic measurement with sensory biofeedback for LPR monitoring by assessing these technologies' specific capabilities and biofeedback capacities and exploring their practical viability based on sensor outcomes. The review was developed following the PRISMA guidelines, and the risk of bias was analyzed using the PREDro and STROBE scales. PubMed, Web of Science, Scopus, and IEEEXPLORE databases were searched for relevant studies, initially returning a total of 528 articles. Finally, we included eight articles featuring wearable devices with audio or vibration biofeedback. Differences in protocols and limitations were also observed. This novel study presents a review of wearable tracking devices for LPR motion-mediated biofeedback for the purpose of correcting lower back posture. More research is needed to determine the long-term effectiveness of these devices, as well as their most appropriate corresponding methodologies.

In vivo load on knee, hip and spine during manual materials handling with two lifting techniques

It is generally accepted that the lifting technique strongly influences physical loads within the human body and, thus, the risk of musculoskeletal disorders. However, there is a lack of knowledge regarding whether particular lifting techniques are effective in reducing loads. Hence, this retrospective study quantified (partly published) in vivo loads at joints within the human body during two typical lifting techniques, stoop lifting and squat lifting. Patients who had received instrumented implants underwent in vivo load measurements at either the knee (two patients), the hip (eight patients), or the upper lumbar spine (four patients) while lifting a 10 kg weight frontally with either straight (stoop) or bent (squat) knees. Contact forces and moments and the orientation of the contact force vector were determined and examined using the paired t test of Statistical Parametric Mapping. The two lifting techniques did not differ in terms of load magnitudes but did differ in terms of directions: (i) at the hip joint, the load vector varied significantly (p < 0.05) in the frontal and sagittal planes, (ii) at the knee joint, the load vector differed significantly (p < 0.05) in the sagittal plane (iii) while the load vector and magnitude did not differ at the upper lumbar spine (p > 0.05). Our findings indicate that the lifting technique causes changes in the orientation rather than the magnitude of lower extremity joint contact loads. Even though this quantification could only be performed in a small group of patients, the quantification of the relevance of such lifting technique recommendations will hopefully guide future recommendations towards a more scientific interpretation.

Effect of spinal fusion on joint space narrowing of the hip: comparison among non-fusion, short fusion, and middle or long fusion

BACKGROUND

Lumbar fusion corrects spinal deformities and improves spinal complications. Hip osteoarthritis (OA) is strongly correlated with spinal mobility, and joint space narrowing of the hip after spinal fusion has gained attention. This study aimed to elucidate the effect of spinal fusion on hip joint space narrowing.

MATERIALS AND METHODS

We retrospectively examined 530 hips of 270 patients who underwent spinal surgery. All the patients underwent whole-spine radiography before and at the final follow-up. Patients were divided into three groups (N group: non-spinal fusion, S group: up to three interbody fusions, and L group: more than four interbody fusions). The rates of joint space narrowing, spinal parameters (sagittal vertical axis, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence), and limb length discrepancy at the final follow-up were compared. A multilinear regression analysis was performed to identify the risk factors for the rate of joint space narrowing.

RESULTS

The rate of joint space narrowing was significantly higher in the L group than in the N and S groups (P < 0.001). No significant difference in the rate of joint space narrowing was observed between the N and S groups. Multiple linear regression analysis revealed that the number of fusion levels (p < 0.05) and follow-up period (p < 0.001) were independent risk factors for joint space narrowing. Spinal parameters at the final follow-up were not independent risk factors.

CONCLUSIONS

Long spinal fusion (more than four levels) led to significantly greater joint space narrowing of the hip than short (up to three levels) or no fusion. Spinal alignment did not affect joint space narrowing of the hip. Surgeons should be aware that more than four interbody fusions may result in worse joint space narrowing of the hip.

LEVEL OF EVIDENCE

IV, retrospective study.

Dynamic segmental kinematics of the lumbar spine during diagnostic movements

Background: In vivo measurements of segmental-level kinematics are a promising avenue for better understanding the relationship between pain and its underlying, multi-factorial basis. To date, the bulk of the reported segmental-level motion has been restricted to single plane motions. Methods: The present work implemented a novel marker set used with an optical motion capture system to non-invasively measure dynamic, 3D in vivo segmental kinematics of the lower spine in a laboratory setting. Lumbar spinal kinematics were measured for 28 subjects during 17 diagnostic movements. Results: Overall regional range of motion data and lumbar angular velocity measurement were consistent with previously published studies. Key findings from the work included measurement of differences in ascending versus descending segmental velocities during functional movements and observations of motion coupling paradigms in the lumbar spinal segments. Conclusion: The work contributes to the task of establishing a baseline of segmental lumbar movement patterns in an asymptomatic cohort, which serves as a necessary pre-requisite for identifying pathological and symptomatic deviations from the baseline.

Muscle-driven forward dynamic active hybrid model of the lumbosacral spine: combined FEM and multibody simulation

Most spine models belong to either the musculoskeletal multibody (MB) or finite element (FE) method. Recently, coupling of MB and FE models has increasingly been used to combine advantages of both methods. Active hybrid FE-MB models, still rarely used in spine research, avoid the interface and convergence problems associated with model coupling. They provide the inherent ability to account for the full interplay of passive and active mechanisms for spinal stability. In this paper, we developed and validated a novel muscle-driven forward dynamic active hybrid FE-MB model of the lumbosacral spine (LSS) in ArtiSynth to simultaneously calculate muscle activation patterns, vertebral movements, and internal mechanical loads. The model consisted of the rigid vertebrae L1-S1 interconnected with hyperelastic fiber-reinforced FE intervertebral discs, ligaments, facet joints, and force actuators representing the muscles. Morphological muscle data were implemented via a semi-automated registration procedure. Four auxiliary bodies were utilized to describe non-linear muscle paths by wrapping and attaching the anterior abdominal muscles. This included an abdominal plate whose kinematics was optimized using motion capture data from upper body movements. Intra-abdominal pressure was calculated from the forces of the abdominal muscles compressing the abdominal cavity. For the muscle-driven approach, forward dynamics assisted data tracking was used to predict muscle activation patterns that generate spinal postures and balance the spine without prescribing accurate spinal kinematics. During calibration, the maximum specific muscle tension and spinal rhythms resulting from the model dynamics were evaluated. To validate the model, load cases were simulated from -10° extension to +30° flexion with weights up to 20 kg in both hands. The biomechanical model responses were compared with in vivo literature data of intradiscal pressures, intra-abdominal pressures, and muscle activities. The results demonstrated high agreement with this data and highlight the advantages of active hybrid modeling for the LSS. Overall, this new self-contained tool provides a robust and efficient estimation of LSS biomechanical responses under in vivo similar loads, for example, to improve pain treatment by spinal stabilization therapies.

Spatio-temporal clustering of lumbar intervertebral flexion interactions in 127 asymptomatic individuals

The purpose of this study was to categorize asymptomatic participants based on the clustering of spatial and temporal intervertebral kinematic variables during lumbar flexion. Lumbar segmental interactions (L2-S1) were evaluated in 127 asymptomatic participants during flexion using fluoroscopy. First, four variables were identified consisting of: 1. Range of motion (ROMC), 2. Peaking time of the first derivative for separate segmentation (PTFDs), 3. Peaking magnitude of the first derivative (PMFD), and 4. Peaking time of the first derivative for stepwise (grouped) segmentation (PTFDss). These variables were used to cluster and order the lumbar levels. The number of participants required to constitute a cluster was chosen as 7. Participants formed eight (ROMC), four (PTFDs), eight (PMFD), and four (PTFDss) clusters, which included 85%, 80%, 77%, and 60% of them, respectively, according to the above features. For all clustering variables, angle time series of some lumbar levels showed significant differences between clusters. However, in general, all clusters could be categorized based on the segmental mobility contexts into three main groups as incidental macro clusters: the upper (L2-L4 > L4-S1), middle (L2-L3 < L3-L5 > L5-S1) and lower (L2-L4 < L4-S1) domains. There are spatial and temporal segmental interactions and between-subject variability in asymptomatic participants. In addition, the differences in angle time series among the clusters have provided evidence of feedback control strategies, while the stepwise segmentation facilitates consideration of the lumbar spine as a system and provides supplementary information about segmental interactions. Clinically, these facts could be taken into account when considering any intervention, but especially fusion surgery.

Finger-Floor Distance Is Not a Valid Parameter for the Assessment of Lumbar Mobility

Low back pain (LBP) could be associated with a reduced lumbar mobility. For the evaluation of lumbar flexibility, parameters such as finger-floor distance (FFD) are historically established. However, the extent of the correlation of FFD to lumbar flexibility or other involved joint kinematics such as pelvic motion, as well as the influence of LBP, is not yet known. We conducted a prospective cross-sectional observation study with 523 participants included (167 with LBP > 12 weeks, 356 asymptomatic). LBP-participants were matched for sex, age, height, and body-mass-index with an asymptomatic control cohort, resulting in two cohorts with 120 participants each. The FFD in maximal trunk flexion was measured. The Epionics-SPINE measurement-system was used to evaluate the pelvic and lumbar Range-of-Flexion (RoF), and the correlation of FFD to pelvic- and lumbar-RoF was evaluated. In an asymptomatic sub-cohort of 12 participants, we examined the individual correlation of FFD to pelvic- and lumbar-RoF under gradual trunk flexion. Participants with LBP showed a significantly reduced pelvic-RoF (p < 0.001) and lumbar-RoF (p < 0.001) as well as an increased FFD (p < 0.001) compared to the asymptomatic control cohort. Asymptomatic participants exhibited a weak correlation of FFD to pelvic-RoF and lumbar-RoF (r < 0.500). LBP patients revealed a moderate correlation of FFD to pelvic-RoF (male: p < 0.001, r = -0.653, female: p < 0.001, r = -0.649) and sex-dependent to lumbar-RoF (male: p < 0.001, r = -0.604, female: p = 0.012, r = -0.256). In the sub-cohort of 12 participants, gradual trunk flexion showed a strong correlation of FFD to pelvic-RoF (p < 0.001, r = -0.895) but a moderate correlation to lumbar-RoF (p < 0.001, r = -0.602). The differences in FFD in an individual patient, assuming consistent hip function, may be attributed partially to the differences in lumbar flexibility. However, the absolute values of FFD do not qualify as a measure for lumbar mobility. Rather, using validated non-invasive measurement devices should be considered.

Lumbar spinal loads and lumbar muscle forces evaluation with various lumbar supports and backrest inclination angles in driving posture

PURPOSE

The low back pain of professional drivers could be linked to excessive lumbar load. This study aims at developing a musculoskeletal model to study the lumbar spinal loads and lumbar muscle forces of the human body in driving posture, so as to contribute to a better understanding of low back pain and to improve the design of vehicle seats.

METHODS

A standing musculoskeletal model, including limbs, head and neck, that can reflect several activities of daily living was established based on the Christophy spine model. The model was then validated by comparing the calculated lumbar loads and muscle forces to the experimental data in the previous studies. Referring to radiology studies, the musculoskeletal model was adjusted into different driving postures with several different lumbar supports (0, 2 and 4 cm) and inclinations of the backrest (from 23° to 33°, by 2° intervals). The lumbar biomechanical load with various lumbar supports and backrest inclination angles was calculated.

RESULTS

The results showed that the overall lumbar spinal load and lumbar muscle force with 4 cm lumbar support were reduced by 11.30 and 26.24%. The lumbar spinal loads and lumbar muscle forces increased first and then decreased with the increase in backrest inclination angles from 23° to 33°. The lumbar biomechanical load varied slightly with the backrest inclination angles from 29° to 33°.

CONCLUSIONS

There are two findings: (i) the lumbar spinal loads at the L3-L4, L4-L5 and L5-S1, and lumbar muscle forces decreased obviously with the 4 cm lumbar support, while the seat cushion inclination angle was set to 10°. (ii) The recommended backrest inclination angles are 29° to 33° with a 10° seat cushion to the horizontal, which can keep a low level of the lumbar spinal loads and lumbar muscle forces. This study could be used to explain the association between drivers' sitting posture and the lumbar load change, and provide a reference for the prevention of low back pain.

Evaluation of spinal force normalization techniques

Division normalization is commonly used in biomechanics studies to remove the effect of anthropometric differences (e.g., body weight) on kinetic variables, facilitating comparison across a population. In spine biomechanics, spinal forces are commonly divided by the body weight or the intervertebral load during a standing posture. However, it has been suggested that offset and power curve normalization are more appropriate than division normalization for normalizing kinetic variables such as ground reaction forces during walking and running. The present study investigated, for the first time, the effectiveness of four techniques for normalizing spinal forces to remove the effect of body weight. Spinal forces at all lumbar levels were estimated using a detailed OpenSim musculoskeletal model of the spine for 11 scaled models (50-100 kg) and during 13 trunk flexion tasks. Pearson correlations of raw and normalized forces against body weight were used to assess the effectiveness of each normalization technique. Body weight and standing division normalization could only successfully normalize L₄L₅ spinal forces in three tasks, and L₅S₁ loads in five and three tasks, respectively; however, offset and power curve normalization techniques were successful across all lumbar spine levels and all tasks. Offset normalization successfully removed the effect of body weight and maintained the influence of flexion angle on spinal forces. Thus, we recommend offset normalization to account for anthropometric differences in studies of spinal forces.

Extraction of Lumbar Spine Motion Using a 3-IMU Wearable Cluster

Spine movement is a daily activity that can indicate health status changes, including low back pain (LBP) problems. Repetitious and continuous movement on the spine and incorrect postures during daily functional activities may lead to the potential development and persistence of LBP problems. Therefore, monitoring of posture and movement is essential when designing LBP interventions. Typically, LBP diagnosis is facilitated by monitoring upper body posture and movement impairments, particularly during functional activities using body motion sensors. This study presents a fully wireless multi-sensor cluster system to monitor spine movements. The study suggests an attempt to develop a new method to monitor the lumbopelvic movements of interest selectively. In addition, the research employs a custom-designed robotic lumbar spine simulator to generate the ideal lumbopelvic posture and movements for reference sensor data. The mechanical motion templates provide an automated sensor pattern recognition mechanism for diagnosing the LBP.

Facilitation of dependent transfers with functional neuromuscular stimulation: a computer simulation study

A two-part simulation process was developed to investigate the facilitation of vertical patient lifts with functional neuromuscular stimulation (FNS) in individuals with spinal cord injury (SCI). First, external lifting forces representing caregiver assistance were applied to a 3D musculoskeletal model representing the patient and optimized to enforce a specific lifting trajectory during a forward dynamic simulation. The process was repeated with and without the activation of the knee, hip, and trunk extensor muscles of the patient model to represent contractions of the paralyzed muscles generated via FNS. Secondly, the spinal compression experienced by a caregiver at the L5/S1 joint while generating these external lifting forces was estimated using a second musculoskeletal model representing the caregiver. Simulation without muscle activation predicted spinal compression in the caregiver model approximately 1.3 × the National Institute for Occupational Safety and Health (NIOSH) recommended "Action Limit." Comparatively, simulations with two unique patterns of muscle activation both predicted caregiver spinal compressions below NIOSH recommendations. These simulation results support the hypothesis that FNS activation of a patient's otherwise paralyzed muscles would lower the force output required of a caregiver during a dependent transfer, thus lowering the spinal compression and risk of injury experienced by a caregiver.

Validation of a Patient-Specific Musculoskeletal Model for Lumbar Load Estimation Generated by an Automated Pipeline From Whole Body CT

Background: Chronic back pain is a major health problem worldwide. Although its causes can be diverse, biomechanical factors leading to spinal degeneration are considered a central issue. Numerical biomechanical models can identify critical factors and, thus, help predict impending spinal degeneration. However, spinal biomechanics are subject to significant interindividual variations. Therefore, in order to achieve meaningful findings on potential pathologies, predictive models have to take into account individual characteristics. To make these highly individualized models suitable for systematic studies on spinal biomechanics and clinical practice, the automation of data processing and modeling itself is inevitable. The purpose of this study was to validate an automatically generated patient-specific musculoskeletal model of the spine simulating static loading tasks.

Methods: CT imaging data from two patients with non-degenerative spines were processed using an automated deep learning-based segmentation pipeline. In a semi-automated process with minimal user interaction, we generated patient-specific musculoskeletal models and simulated various static loading tasks. To validate the model, calculated vertebral loadings of the lumbar spine and muscle forces were compared with in vivo data from the literature. Finally, results from both models were compared to assess the potential of our process for interindividual analysis.

Results: Calculated vertebral loads and muscle activation overall stood in close correlation with data from the literature. Compression forces normalized to upright standing deviated by a maximum of 16% for flexion and 33% for lifting tasks. Interindividual comparison of compression, as well as lateral and anterior–posterior shear forces, could be linked plausibly to individual spinal alignment and bodyweight.

Conclusion: We developed a method to generate patient-specific musculoskeletal models of the lumbar spine. The models were able to calculate loads of the lumbar spine for static activities with respect to individual biomechanical properties, such as spinal alignment, bodyweight distribution, and ligament and muscle insertion points. The process is automated to a large extent, which makes it suitable for systematic investigation of spinal biomechanics in large datasets.

Adjacent segments biomechanics following lumbar fusion surgery: a musculoskeletal finite element model study

PURPOSE

This study exploits a novel musculoskeletal finite element (MS-FE) spine model to evaluate the post-fusion (L4-L5) alterations in adjacent segment kinetics.

METHODS

Unlike the existing MS models with idealized representation of spinal joints, this model predicts stress/strain distributions in all passive tissues while organically coupled to a MS model. This generic (in terms of musculature and material properties) model uses population-based in vivo vertebral sagittal rotations, gravity loads, and an optimization algorithm to calculate muscle forces. Simulations represent individuals with an intact L4-L5, a preoperative severely degenerated L4-L5 (by reducing the disc height by ~ 60% and removing the nucleus incompressibility), and a postoperative fused L4-L5 segment with either a fixed or an altered lumbopelvic rhythm with respect to the intact condition (based on clinical observations). Changes in spine kinematics and back muscle cross-sectional areas (due to intraoperative injuries) are considered based on in vivo data while simulating three activities in upright/flexed postures.

RESULTS

Postoperative changes in some adjacent segment kinetics were found considerable (i.e., larger than 25%) that depended on the postoperative lumbopelvic kinematics and preoperative L4-L5 disc condition. Postoperative alterations in adjacent disc shear, facet/ligament forces, and annulus stresses/strains were greater (> 25%) than those found in intradiscal pressure and compression (< 25%). Kinetics of the lower (L5-S1) and upper (L3-L4) adjacent segments were altered to different degrees.

CONCLUSION

Alterations in segmental rotations mainly affected adjacent disc shear forces, facet/ligament forces, and annulus/collagen fibers stresses/strains. An altered lumbopelvic rhythm (increased pelvis rotation) tends to mitigate some of these surgically induced changes.

Effect of Age on Thoracic, Lumbar, and Pelvis Coordination During Trunk Flexion and Extension

The purpose of this study was to investigate normative and age-related differences in trunk and pelvis kinematics and intersegmental coordination during sagittal plane flexion–extension. Trunk and pelvis kinematics were recorded while 76 participants performed a maximal range of motion task in the sagittal plane. Cross-correlation was calculated to determine the phase lag between adjacent segment motion, and coupling angles were calculated using vector coding and classified into one of 4 coordination patterns: in-phase, antiphase, superior, and inferior phase. A 2-way mixed-model multivariate analysis of variance was used to compare lumbar spine and pelvis angular kinematics, phase lags, and cross-correlation coefficients between groups. Young participants exhibited greater trunk range of motion compared with middle-aged participants. The lumbar spine and pelvis were predominantly rotating with minimum phase lag during flexion and extension movement for both age groups, and differences in coordination between the groups were seen during hyperextension and return to upright position. In conclusion, middle-aged adults displayed lower range of motion but maintained similar movement patterns to young adults, which could be attributed to protective mechanisms. Healthy lumbar and pelvis movement patterns are important to understand and need to be quantified as a baseline, which can be used to develop rehabilitation protocols for individuals with spinal ailments.

Relationships among lumbar hip motion angle, perceptual awareness, and low back pain in young adults

[Purpose] We aimed to examine the relationships among low back pain, lumbar-hip motion angle, and lumbar perceptual awareness in young adults to improve the treatment of low back pain. [Participants and Methods] Data were collected from 36 university students with low back pain. The items included for evaluation were the low back pain intensity (Numeric Rating Scale), disability due to low back pain (Oswestry Low Back Pain Disability Index), lumbar spine and hip motion angles in test movements, and perceptual awareness (Fremantle Back Awareness Questionnaire). The test movements employed included trunk forward bending, trunk back bending, and prone hip extension. The motion angles of the lumbar spine and hip joints were measured using a wearable sensor. [Results] The Numeric Rating Scale was not correlated with the lumbar hip motion angle and perceptual awareness. The Oswestry Low Back Pain Disability Index was correlated with lumbar hip motion angles, at the beginning of trunk forward bending and at maximum trunk backward bending, and with perceptual awareness. [Conclusion] There are relationships among disabilities due to low back pain, lumbar hip motion angles, and perceptual awareness in each test movement; however, they vary depending on the type and angle of the test movement conducted.

Spinal segment ranges of motion, movement coordination, and three-dimensional kinematics during occupational activities in normal-weight and obese individuals

Measurements of spinal segment ranges of motion (RoMs), movement coordination, and three-dimensional kinematics during occupational activities have implications in occupational/clinical biomechanics. Due to the large amount of adipose tissues, obese individuals may have different RoMs, lumbopelvic coordination, and kinematics than normal-weight ones. We aimed to measure/compare trunk, lumbar, and pelvis primary RoMs in all anatomical planes/directions, lumbopelvic ratios (lumbar to pelvis rotations at different trunk angles) in all anatomical planes/directions and three-dimensional spine kinematics during twelve symmetric/asymmetric statics load-handling activities in healthy normal-weight and obese individuals. Kinematics/motion data were collected from nine healthy young male normal-weight and nine age/height/sex matched obese individuals via a ten-camera Vicon motion capture system. Obese individuals had significantly smaller (p < 0.05) lumbar flexion (~9° in average) and larger pelvis right lateral bending (~5°) RoMs as well as smaller lumbopelvic ratios (~37%) in lateral bending and axial rotation movements as compared to normal-weight individuals. Moreover, the two groups had generally non-significant different segmental orientations (<20° and in most cases < 10°) in load-handling tasks that depended on the magnitude of load asymmetry angle (p < 0.05). Differences were larger for tasks performed near the floor, away from body, and at larger load asymmetry angles. Biomechanical models simulating pure lateral bending, axial rotation, or tasks involving large load asymmetry may therefore need subject-specific, rather than population-based, motion analysis due to the effects from body weight. In clinical applications, it should be noted that healthy obese individuals may have different RoMs and lumbopelvic rhythms than healthy normal-weight individuals in some anatomical planes/directions.

Characteristics of Lumbar Flexion Rhythm at Different Arm Positions

BACKGROUND

The lumbar spine displays its greatest mobility in ventral flexion, which is a potential risk factor for low back pain. The relative contribution of each segment to the complete flexion is denoted the spine rhythm, which is required to distinguish between normal and abnormal spinal profiles, and as well to calculate the spinal forces in musculoskeletal models. Nevertheless, different spine rhythms have been reported in literature and the effect of arm position has not been demonstrated. We therefore aimed to investigate the effects of different arm positions on spine rhythm during ventral flexion.

METHODS

A nonradiologic back measurement device was used to determine the real-time back lordosis during ventral flexion while participants (10 male and 10 female without low back pain) held their arms at 6 different positions.

RESULTS

During flexion with the arms naturally hanging down at both sides, the lumbar range of flexion was 52.6° ± 13.1°. Different arm positions displayed nonsignificant effect on lumbar range of flexion (P > 0.05). The middle and lower levels contributed more to the whole lumbar range of flexion than the upper level (P < 0.05), which is independent of arm position.

CONCLUSIONS

The lumbar spine displayed greater flexion in the middle and lower levels and its flexion rhythm remained unchanged at different arm positions. These results strike importance to explore for more reasons explaining the different lumbar flexion rhythms reported in literature.

Inter-joint coordination and the flexion-relaxation phenomenon among adults with low back pain during bending

BACKGROUND

Altered inter-joint coordination and reduced flexion-relaxation at end-range trunk flexion are common in people with low back pain. Inconsistencies in these behaviors, however, make assessment and treatment challenging for this population.

RESEARCH QUESTION

The study objective was to investigate patterns of regional lumbo-pelvic coordination and flexion-relaxation in adults with and without low back pain, during a bending task.

METHODS

Adults with low back pain (n = 16) and a healthy group (n = 21) performed three trials of a bending task. Motion capture and surface electromyography systems measured joint kinematics (hip, lower and upper lumbar spine) and muscle activity (erector spinae longissimus, iliocostalis, and multifidus). Continuous relative phase analysis determined inter-joint coordination of the hip/lower lumbar and lower lumbar/upper lumbar joint pairs, during flexion and extension periods. Flexion-relaxation ratios using normalized surface electromyography data determined the extent of flexion-relaxation for each muscle, during each period. For inter-joint coordination, two-way repeated measure mixed ANOVAs calculated the effects of group (healthy/low back pain), period, and their interactions. Separate hierarchical linear models were constructed and tested relationships between flexion-relaxation ratios and our independent variables, group and muscle, while controlling for patient characteristics.

RESULTS

The low back pain group had more out-of-phase coordination of the hip/lower lumbar joint pair compared to the healthy group (mean difference = 24.7°; 95 % confidence interval = 3.93-45.4), independent of movement period. No significant between group differences in lower lumbar/upper lumbar coordination were observed. The low back pain group demonstrated reduced flexion-relaxation of all muscles during full flexion (21.7 % reduction on average), with multifidus showing the least relaxation.

SIGNIFICANCE

Regional differences in the lumbar spine and the possibility of subgroups with distinct movement pattern should be considered when analyzing coordination in people with low back pain. Multifidus showed the largest changes in flexion-relaxation and should be included when measuring this construct.

An open-source musculoskeletal model of the lumbar spine and lower limbs: a validation for movements of the lumbar spine

Musculoskeletal models of the lumbar spine have been developed with varying levels of detail for a wide range of clinical applications. Providing consistency is ensured throughout the modelling approach, these models can be combined with other computational models and be used in predictive modelling studies to investigate bone health deterioration and the associated fracture risk. To provide precise physiological loading conditions for such predictive modelling studies, a new full-body musculoskeletal model including a detailed and consistent representation of the lower limbs and the lumbar spine was developed. The model was assessed against in vivo measurements from the literature for a range of spine movements representative of daily living activities. Comparison between model estimations and electromyography recordings was also made for a range of lifting tasks. This new musculoskeletal model will provide a comprehensive physiological mechanical environment for future predictive finite element modelling studies on bone structural adaptation. It is freely available on https://simtk.org/projects/llsm/.

Changes in Lumbo-Pelvic Coordination of Individuals With and Without Low Back Pain When Wearing a Hip Orthosis

Individuals with low back pain demonstrate an abnormal lumbo-pelvic coordination compared to back-healthy individuals. This abnormal coordination presents itself as a reduction in lumbar contributions and an increase in pelvic rotations during a trunk forward bending and backward return task. This study investigated the ability of a hip orthosis in correcting such an abnormal lumbo-pelvic coordination by restricting pelvic rotation and, hence increasing lumbar contributions. The effects of the hip orthosis on the lumbo-pelvic coordination were investigated in 20 low back pain patients and 20 asymptomatic controls. The orthosis reduced pelvic rotation by 12.7° and increased lumbar contributions by 11%. Contrary to our expectation, orthosis-induced changes in lumbo-pelvic coordination were smaller in patients; most likely because our relatively young patient group had smaller unrestricted pelvic rotations compared to asymptomatic individuals. Considering the observed capability of a hip orthosis in causing the expected changes in lumbo-pelvic coordination when there is a relatively large pelvic contribution to trunk motion, application of a hip orthosis may provide a promising method of correcting abnormal lumbo-pelvic coordination, particularly among patients who demonstrate larger pelvic rotation, that warrants further investigation.

In vivo hip and lumbar spine implant loads during activities in forward bent postures

Long-term measurements on the lumbar spinal alignment during daily life revealed that humans spent 90% of the day in a forward bent posture. Compared to standing, this posture leads to a substantial increase in spinal loading. The lumbar spine and pelvis, however, contribute differently to the total amount of flexion, which could possibly indicate a different timing of maximum loads in both structures during flexion. This study aimed to evaluate the in vivo implant forces in the hip and lumbar spine during activities in forward bent postures. This work utilized data collected in earlier in vivo measurements on patients either with telemeterized hip endoprostheses (HE) or vertebral body replacements (VBR). The following activities were investigated: standing, upper body flexion with and without weights in the hands using different lifting techniques (straight and bent knees). The maximum resultant forces in VBR were considerably lower than in HE. Increases in flexion inclinations caused direct increases of the resultant forces within VBR, followed by a plateau or even a decrease of the force until maximum inclination. The resultant force in HE displayed an almost continuous increase until the maximum inclination. This general curve behavior resulted in different HE-VBR load ratios, which were affected by lifting additional weights or different lifting techniques. The results emphasize that maximum loads in the spine, in contrast to the hip, do not necessarily occur at maximum upper body flexion as normally expected, rather already at intermediate flexion angles in VBR patients. The results form the basis for more detailed insilico analyzes.

Prediction of the Spinal Musculoskeletal Loadings during Level Walking and Stair Climbing after Two Types of Simulated Interventions in Patients with Lumbar Disc Herniation

Background

Low back pain (LBP) continues to be a severe global healthy problem, and a lot of patients would undergo conservative or surgical treatments. However, the improving capacity of spinal load sharing during activities of daily living (ADLs) after interventions is largely unknown. The objective of this study was to quantitatively predict the improvement of spinal musculoskeletal loadings during level walking and stair climbing after two simulated interventions.

Material and Methods

Twenty-six healthy adults and seven lumbar disc herniation patients performed level walking and stair climbing in sequence. The spinal movement was recorded using a motion capture system. The experimental data were applied to drive a musculoskeletal model to calculate all the lumbar joint resultant forces and muscle activities of seventeen main trunk muscle groups. Rehabilitation and reconstruction were selected as the representative of conservative and surgical treatment, respectively. The spinal load sharing after rehabilitation and reconstruction was predicted by replacing the patients' spine rhythm with healthy subjects' spine rhythm and altering the center of rotation at the L5S1 level, respectively.

Results

During both level walking and stair climbing, the joint resultant forces of the lower lumbar intervertebral discs were predicted to reduce after the two simulated inventions. In addition, the maximum muscle activities of the most trunk muscle groups decreased after simulated rehabilitation and conversely increased after simulated reconstruction.

Conclusion

The predictions revealed the different compensatory responses on the spinal load sharing after two simulated interventions, severing as guidance for making preoperative planning and rehabilitation planning.

Application-Based Production and Testing of a Core-Sheath Fiber Strain Sensor for Wearable Electronics: Feasibility Study of Using the Sensors in Measuring Tri-Axial Trunk Motion Angles

Wearable electronics are recognized as a vital tool for gathering in situ kinematic information of human body movements. In this paper, we describe the production of a core–sheath fiber strain sensor from readily available materials in a one-step dip-coating process, and demonstrate the development of a smart sleeveless shirt for measuring the kinematic angles of the trunk relative to the pelvis in complicated three-dimensional movements. The sensor’s piezoresistive properties and characteristics were studied with respect to the type of core material used. Sensor performance was optimized by straining above the intended working region to increase the consistency and accuracy of the piezoresistive sensor. The accuracy of the sensor when tracking random movements was tested using a rigorous 4-h random wave pattern to mimic what would be required for satisfactory use in prototype devices. By processing the raw signal with a machine learning algorithm, we were able to track a strain of random wave patterns to a normalized root mean square error of 1.6%, highlighting the consistency and reproducible behavior of the relatively simple sensor. Then, we evaluated the performance of these sensors in a prototype motion capture shirt, in a study with 12 participants performing a set of eight different types of uniaxial and multiaxial movements. A machine learning random forest regressor model estimated the trunk flexion, lateral bending, and rotation angles with errors of 4.26°, 3.53°, and 3.44° respectively. These results demonstrate the feasibility of using smart textiles for capturing complicated movements and a solution for the real-time monitoring of daily activities.

The effect of sagittal hip angle on lumbar and hip coordination and pelvic posterior shift during forward bending

PURPOSE

The purpose of this study was to investigate the effects of dynamic sagittal hip angle on lumbar and hip coordination and pelvic posterior shift during forward bending.

METHODS

A total of 44 asymptomatic younger female volunteers were recruited to this study. Following measurement of trunk forward bending, participants were divided into three groups based on hip flexion angle: group 1, < 30°; group 2, ≥ 30° and < 50°; and group 3, ≥ 50°. Lumbar spine and hip coordination and pelvic backward shift were recorded during trunk forward bending using a three-dimensional ultrasonic motion analysis system.

RESULTS

Pelvic and total angles increased with hip angle (group 3 > group 2 > group 1; p = 0.003 and p < 0.001, respectively), whereas lumbar/hip and pelvic/hip angle ratios decreased significantly (p < 0.001). The degree of pelvic posterior shift increased to a limited extent, whereas the pelvic posterior shift/hip angle ratio decreased significantly (p < 0.05).

CONCLUSIONS

Asymptomatic subjects with limited hip flexion showed reduced total pelvic anterior rotation and greater relative proportion of pelvic motion than insufficient hip motion. These subjects tended to increase the pelvic posterior shift/hip angle ratio during trunk forward bending, possibly increasing passive tension by elongating the hamstring muscles to increase hip motion. The results of this study provide information that will improve the assessment of lumbar spine and hip coordination patterns and facilitate movement strategies by determining the specific requirements of individuals. These slides can be retrieved under Electronic Supplementary Material.

Influence of passive elements on prediction of intradiscal pressure and muscle activation in lumbar musculoskeletal models

BACKGROUND AND OBJECTIVE

The objective of this study was to investigate the effect of incorporating various passive elements, which could represent combined or individual effects of intervertebral disc, facet articulation and ligaments, on the prediction of lumbar muscle activation and L4-L5 intradiscal pressure.

METHODS

The passive elements representing the intervertebral disc, facet articulations, and ligaments were added to the existed lumbar musculoskeletal model with nonlinear rotational stiffness or force-strain relationships. The model was fed with kinematics of trunk flexion, extension, axial rotation and lateral bending to calculate muscle activation and L4-L5 intradiscal pressure.

RESULTS

In the trunk axial rotation, the intradiscal pressure values predicted by the models with elements representing facet articulation were much higher than that predicated by models removing these elements. In the trunk flexion, the models with passive elements showed lower muscle activation of extensors than model with no passive elements. At the end of trunk flexion, extension, axial rotation and lateral bending, the intradiscal pressure values predicted by model with intact passive elements were 120.6%, 92.5%, 334.8% and 74.9% of the values predicted by model with no passive elements, respectively.

CONCLUSIONS

Caution must be taken while modeling facet articulation as elements with rotational stiffness, as they may lead to overestimation of intradiscal pressure in trunk axial rotation. The inclusion of ligaments as spring-like elements may improve the simulation of flexion-relaxation phenomenon in trunk flexion. Future models considering detailed properties of passive elements are needed to allow more access to understanding the mechanics of the lumbar spine.

Trunk muscle strength and lumbo-pelvic kinematics in adolescent athletes: Effects of age and sex

Considering their potential relevance for low-back pain, we investigated trunk muscle strength, sagittal lumbo-pelvic alignment while standing and lumbo-pelvic ratio during trunk flexion in adolescent athletes with regard to the effects of age and sex. Twenty-two early adolescent (EA: 13-15 years, 10 females) and 28 late adolescent (LA: 16-19 years, 14 females) high-level athletes (training duration more than 12 hours per week) participated in the study. We measured trunk extension and trunk flexion moments during maximum voluntary isometric contractions using a dynamometer. Further, we examined lumbo-pelvic kinematics in the upright standing position and during forward trunk bending using two 3-dimensional accelerometers. Using a lineal regression model in which the flexion moment from each participant was used as predictor for the corresponding extension moment, we found higher residuals (P < 0.001) in the EA compared to LA, indicating greater imbalances in the trunk muscle strength in EA. We found a higher lordosis in the upright position, greater pelvic rotation, and greater lordotic posture during the forward bending in females (P < 0.01). These age-related imbalances and sex-related characteristics in lumbo-pelvic kinematics might affect the neuromuscular control of trunk stability and the magnitude of spine loading. We recommend the implementation of specific coordination and stabilization programs for muscle groups that contribute to lumbo-pelvic kinematics and training routines that support a balanced strength development within the trunk muscles in adolescent athletes.

Twente Spine Model: A thorough investigation of the spinal loads in a complete and coherent musculoskeletal model of the human spine

Although in vivospinal loads have been previously measured, existing data are limited to certain lumbar and thoracic levels. A detailed investigation of spinal loads would assist with injury prevention and implant design but is unavailable. In this study, we developed a complete and coherent musculoskeletal model of the entire human spine and studied the intervertebral disc compression forces for physiological movements on three anatomical planes. This model incorporates the individual vertebrae at the cervical, thoracic, and lumbar regions, a flexible ribcage, and complete muscle anatomy. Intradiscal pressures were estimated from predicted compressive forces, and these were generally in close agreement with previously measured data. We found that compressive forces at the trunk discs increased during trunk lateral bending and axial rotation of the trunk. During flexion, compressive forces increased in the thoracolumbar and lumbar regions and slightly decreased at the middle thoracic discs. In extension, the forces generally decreased at the thoracolumbar and lumbar discs whereas they slightly increased at the upper and middle thoracic discs. Furthermore, similar to a previous biomechanical model of the cervical spine, our model predicted increased compression forces in neck flexion, lateral bending, and axial rotation, and decreased forces in neck extension.

Cross-correlation between spine and hip joint kinematics differs in healthy individuals and subgroups of ankylosing spondylitis patients during trunk lateral flexion

BACKGROUND

The effects of sacroiliitis and syndesmophyte formation on the cross-correlation between spine and hip joint kinematics in ankylosing spondylitis (AS) are poorly understood.

OBJECTIVE

To investigate the cross-correlation between spine and hip joint kinematics differs in healthy individuals and ankylosing spondylitis patients during trunk lateral flexion.

METHODS

Fifty AS patients and thirty-nine healthy adults (controls) were recruited from a medical center. The patients were divided into two subgroups, namely the sacroiliitis (n = 28) and syndesmophyte (n = 22) subgroups. An inertial motion system was used to record kinematic data of spine, pelvic and hip joints during lateral trunk flexion. The maximal cross-correlation coefficient (CCF) and time lag of motion between the spine and hip joint were analyzed.

RESULTS

The syndesmophyte group had the smallest range of motion in all recorded motion. The sacroiliitis group exhibited higher thoracic flexion, pelvic pitch, and pelvic rotation than the other two groups. In the syndesmophyte group, the CCF between lumbar lateral flexion (LLF) and hip abduction were weakly and LLF and hip rotation were strongly correlated. Considering in time sequence, LLF occurred earlier than hip abduction and hip rotation during trunk lateral flexion; however, both AS subgroups exhibited longer time lags than in the control group.

CONCLUSION

The cross-correlation between spine and hip joint kinematics differs in healthy individuals and AS patients during trunk lateral flexion. The motion pattern changes in patients with AS of differing severity may also alter the loads on the spine and hip joints.

Tracking Kinematic and Kinetic Measures of Sit to Stand using an Instrumented Spine Orthosis

Age related spinal deformity is becoming an increasingly prevalent problem, resulting in decreased quality of life. While spinal deformity can be corrected via surgical intervention, a large number of people with spinal fusions require follow-up surgery due to further degeneration. The identification of changes to a subjects kinematics and kinetics post-surgery are limited by a lack of methods to collect patient specific motion data over the course of surgical recovery. This paper introduces an Instrumented Spine Orthosis (ISO) that can capture the motions of the subjects torso without requiring the use of a control computer or other dedicated motion capture equipment. This system is used to collect the peak torso angles and velocities for a single subject performing sit-to-stand actions. The accuracy of the ISO is evaluated using motion capture, during different sit-to-stand protocols designed to highlight motion changes that have been seen in subjects with reduced mobility. This system was found to provide reliable measurements of these kinematic and kinetic torso measures across all tested motions, demonstrating the potential for the use of Instrumented Spine Orthotics to provide quantitative measures during the surgical recovery process.

Movement variability in adults with low back pain during sit-to-stand-to-sit

BACKGROUND

Differences in movement variability may be related to a guarded response to pain or a less robust movement pattern, indicating a potential dysfunction in motor control. The study objective was to compare patterns of lumbo-pelvic coordinative variability, during repeated sit-to-stand-to-sit, in individuals with low back pain and healthy adults.

METHODS

Participants were adults with low back pain (n = 16) and healthy controls (n = 21). Kinematics for the T12-L3, L3-S1, and hip segments were measured using electromagnetic motion capture during 10 sit-to-stand-to-sit trials. Continuous relative phase analysis using the Hilbert transform method determined coordination and variability of the Hip-L3S1, and L3S1-T12L3 segments, deconstructed into 4 periods (start/up/down/end). T-tests compared coordination and variability of the full task between groups, and a mixed ANOVA compared the effects of group and period for the two segments.

FINDINGS

Across the full task, the low back pain group demonstrated more variable (mean difference = -6.95, 95% CI = -12.3 to -1.59) and greater out-of-phase behavior (mean difference = -22.6, 95% CI = -39.1 to -6.03) in the LHip-L3S1 segment. Group-period interaction effects revealed greater variability in the start period (mean difference = -0.325, 95% CI = -0.493 to -0.156) and more out-of-phase behavior in the start (mean difference = -0.350, 95% CI = -0.549 to -0.150) and end (mean difference = -0.354, 95% CI = -0.602 to -0.105) periods for the LHip-L3S1 segment.

INTERPRETATION

Excessive variability may relate to reports of poor spinal proprioception in low back pain; however, based on our sample characteristics (low pain and disability) and lack of symptoms during the task, classifying our findings as dysfunctional may not be fully warranted.

The influence of spinal fusion length on proximal junction biomechanics: a parametric computational study

PURPOSE

Proximal junctional kyphosis and failure are frequent complications in adult spinal deformity surgery with long fusion constructs. The aim of this study was to assess the biomechanics of the proximal segment for fusions of various lengths.

METHODS

A previously established musculoskeletal model of thoracolumbar spine was used to simulate full-range flexion task for fusions (modeled by introduction of rigid constraints) with lower instrumented vertebrae at L5 or S1 and upper instrumented vertebrae (UIV) at any level above, up to T2. Inverse dynamics simulations with force-dependent kinematics were performed for gradually increasing spinal flexion in order to predict global and segmental range of flexion, maximum passive moment, segmental compression and shear forces, which were compared to the uninstrumented case.

RESULTS

For long fusions, with the UIV at T11 or higher, the model predicted an increase in segmental flexion (by 33-860%, or 1.6°-4.7°) and passive moment (by 39-1370%, or 13-31 Nm) at the proximal junction-generally increasing with fusion length. While the maximum shear force was 57-239% (135-283 N) higher for the proximal junction at the upper thorax (UIV at T6 or above), the compression forces were reduced by up to 44% (375 N).

CONCLUSIONS

The length of the instrumentation has an important effect on the proximal segment biomechanics. Despite the limitations of the current model, musculoskeletal modeling appears to be a promising and versatile method to support planning of spinal instrumentation surgeries in the future. These slides can be retrieved under Electronic Supplementary Material.

Continuous lumbar spine rhythms during level walking, stair climbing and trunk flexion in people with and without lumbar disc herniation

Low back pain(LBP) is one of the most prevalent diseases afflicting people today. Abnormal musculoskeletal loadings during activities of daily living (ADLs) have been deemed to be associated with spine rhythm. But no studies have reported abnormal continuous spine rhythms during ADLs in LBP patients. Therefore, the objective of this study was to investigate the continuous lumbar spine rhythms and their difference between people with and without lumbar disc herniation (LDH). Twenty-six healthy people and seven patients with LDH were recruited in this study. They performed level walking, stair climbing, and trunk flexion. Active optical markers placed on the landmark of the spinous process and pelvis were captured using motion analysis system to drive a musculoskeletal model to calculate the continuous lumbar spine rhythms. It was found that the lumbar spine rhythm was roughly constant throughout the analyzed cycle in both healthy people and LDH patients during trunk flexion. LDH patients displayed fluctuant lumbar spine rhythms during level walking and stair climbing and significantly higher segmental contributions of the lumbar segments in the lower lumbar region during stair climbing and trunk flexion. In conclusion, there were different compensatory responses to LDH in the continuous lumbar spine rhythms during different ADLs. This study provides a new insight into the abnormal spinal motion in LDH patients.

What does the shape of our back tell us? Correlation between sacrum orientation and lumbar lordosis

BACKGROUND CONTEXT

Sacral slope and lumbar lordosis (LL) have been studied extensively in recent years via X-ray examinations and strongly correlate with each other. This raises, first, the question of the reproducibility of this correlation in multiple standing phases and, second, if this correlation can be achieved using non-radiological measurement tools.

PURPOSE

This study aimed (1) to determine the extent to which the back-shape measurements correspond to the correlations between the sacral slope and LL found in previous radiological investigations, (2) to identify a possible effect of age and gender on this correlation, and (3) to evaluate the extent to which this correlation is affected by repeated standing phases.

STUDY DESIGN/SAMPLE

This is an observational cohort study.

PATIENT SAMPLE

A total of 410 asymptomatic subjects (non-athletes), 21 asymptomatic soccer players (athletes), and 176 patients with low back pain (LBP) were included.

OUTCOME MEASURES

The correlation between sacrum orientation (SO) and LL was determined in six repetitive upright standing postures.

MATERIALS AND METHODS

A non-invasive strain-gauge based measuring system was used.

RESULTS

Back-shape measurements yielded a similar correlation to that measured in previous X-ray examinations. The coefficient of determination (R²) between SO and LL ranged between 0.76 and 0.79 for the asymptomatic cohort. Athletes showed the strongest correlation (0.76≤R²≤0.84). For patients with LBP, the correlation substantially decreased (0.18≤R²≤0.39). R² was not strongly affected by repeated standing phases.

CONCLUSIONS

The correlation between SO and LL can be assessed by surface measurements of the back shape and is not influenced by natural variations in the standing posture.

Relationships Between Trunk Movement Patterns During Lifting Tasks Compared With Unloaded Extension From a Flexed Posture

OBJECTIVES

The purpose of this study was to investigate between movement patterns of trunk extension from full unloaded flexion and lifting techniques, which could provide valuable information to physical therapists, doctors of chiropractic, and other manual therapists.

METHODS

A within-participant study design was used. Whole-body kinematic and kinetic data during lifting and full trunk flexion were collected from 16 healthy male participants using a 3-dimensional motion analysis system (Vicon Motion Systems). To evaluate the relationships of joint movement between lifting and full trunk flexion, Pearson correlation coefficients were calculated.

RESULTS

There was no significant correlation between the amount of change in the lumbar extension angle during the first half of the lifting trials and lumbar movement during unloaded trunk flexion and extension. However, the amount of change in the lumbar extension angle during lifting was significantly negatively correlated with hip movement during unloaded trunk flexion and extension (P < .05).

CONCLUSIONS

The findings that the maximum hip flexion angle during full trunk flexion had a greater influence on kinematics of lumbar-hip complex during lifting provides new insight into human movement during lifting. All study participants were healthy men; thus, findings are limited to this group.

Sagittal alignment and mobility of the thoracolumbar spine are associated with radiographic progression of secondary hip osteoarthritis

OBJECTIVE

To identify predictors of radiographic progression of hip osteoarthritis (OA) over 12 months among functional hip impairments and spinal alignment and mobility.

DESIGN

Fifty female patients with secondary hip OA, excluding those with end-stage hip OA, participated in this prospective cohort study. Joint space width (JSW) of the hip was measured at baseline and 12 months later. With radiographic progression of hip OA over 12 months (>0.5 mm in JSW) as dependent variable, logistic regression analyses were performed to identify predictors for hip OA progression among functional impairments of the hip and spine with and without adjustment for age, body mass index (BMI), and minimum JSW at baseline. The independent variables were hip pain, Harris hip score (HHS), hip morphological parameters, hip passive range of motion (ROM) and muscle strength, and alignment and mobility of the thoracolumbar spine at baseline.

RESULTS

Twenty-one (42.0%) patients demonstrated radiographic progression of hip OA. Multivariable logistic regression analysis showed that larger anterior inclination of the spine in standing position (adjusted OR [95% CI], 1.37 [1.04-1.80]; P = 0.028) and less thoracolumbar spine mobility (adjusted OR [95% CI], 0.96 [0.92-0.99]; P = 0.037) at baseline were statistically significantly associated with radiographic progression of hip OA, even after adjustment for age, BMI, and minimum JSW.

CONCLUSIONS

The findings suggest that spinal alignment and mobility should be considered when assessing risk and designing preventive intervention for radiographic progression of secondary hip OA.

Thoracolumbar spine loading associated with kinematics of the young and the elderly during activities of daily living

Excessive mechanical loading of the spine is a critical factor in vertebral fracture initiation. Most vertebral fractures develop spontaneously or due to mild trauma, as physiological loads during activities of daily living might exceed the failure load of osteoporotic vertebra. Spinal loading patterns are affected by vertebral kinematics, which differ between elderly and young individuals. In this study, the effects of age-related changes in spine kinematics on thoracolumbar spinal segmental loading during dynamic activities of daily living were investigated using combined experimental and modeling approach. Forty-four healthy volunteers were recruited into two age groups: young (N = 23, age = 27.1 ± 3.8) and elderly (N = 21, age = 70.1 ± 3.9). The spinal curvature was assessed with a skin-surface device and the kinematics of the spine and lower extremities were recorded during daily living tasks (flexion-extension and stand-sit-stand) with a motion capture system. The obtained data were used as input for a musculoskeletal model with a detailed thoracolumbar spine representation. To isolate the effect of kinematics on predicted loads, other model properties were kept constant. Inverse dynamics simulations were performed in the AnyBody Modeling System to estimate corresponding spinal loads. The maximum compressive loads predicted for the elderly motion patterns were lower than those of the young for L2/L3 and L3/L4 lumbar levels during flexion and for upper thoracic levels during stand-to-sit (T1/T2-T8/T9) and sit-to-stand (T3/T4-T6/T7). However, the maximum loads predicted for the lower thoracic levels (T9/T10-L1/L2), a common site of vertebral fractures, were similar compared to the young. Nevertheless, these loads acting on the vertebrae of reduced bone quality might contribute to a higher fracture risk for the elderly.

Lumbar contribution to the trunk forward bending and backward return; age-related differences

Age-related differences in lumbar contribution to the trunk motion in the sagittal plane were investigated. Sixty individuals between 20-70 years old in five gender-balanced age groups performed forward bending and backward return with slow and fast paces. Individuals older than 50 years old, irrespective of the gender or pace, had smaller lumbar contribution than those younger than this age. The lumbar contribution to trunk motion was also smaller in female participants than male participants, and under fast pace than under the slow pace. Age-related differences in lumbar contributions suggest the synergy between the active and passive lower back tissues is different between those above and under 50 years old, differences that are likely to affect the lower back mechanics. Therefore, detailed modelling should be conducted in future to find the age-related differences in the lower back mechanics for tasks involving large trunk motion. Practitioner Summary: Lumbar contribution to the sagittal trunk motion was observed to be smaller in individuals above 50 years old than those below this age. This could be an indication of a likely change in the synergy between the active and passive lower back tissues, which may disturb the lower back mechanics.