Validity and reliability of the Spineangel lumbo-pelvic postural monitor

Concurrent validity of skin-based motion capture systems in measuring dynamic lumbar intervertebral angles

Spine kinematics are commonly measured by external sensors such as motion capture and accelerometers. However, these skin-based measures cannot directly capture intervertebral motion of the lumbar spine. To date, research in this area has focused on the estimation of intervertebral kinematics using static trials but no study has analyzed agreement throughout the dynamic range of motion. This study investigated the agreement between skin-based sensors (accelerometers and motion capture) and quantitative fluoroscopy (QF) in measuring lumbar spine kinematics for the duration of complete flexion and extension motion in a healthy female population. Twenty female participants (age 30-57, BMI < 30) were guided through a standing flexion and extension bending protocol while spine kinematics were concurrently measured by QF (L2, L3, L4, L5, and S1) and motion capture sensors and accelerometers positioned over the spinous processes of L2, L4, and S1. Intervertebral angles (L2-L4, L4-S1, L2-S1) and individual vertebrae levels were compared between measures. Non-parametric limits of agreement between QF and skin-based markers were greatest at the end-range of motion for both flexion and extension, but differences increased variably between participants, sometimes over-and sometimes underestimating angles, thus, disproving the common assumption that it increases linearly. The two skin-based marker systems showed good agreement with one another showing that they can be used interchangeably but they can only be used to estimate lumbar spine kinematics. Normalizing angles to a change in angle and considering the posture of instrumentation would be beneficial to reduce potential sources of errors.

Biofeedback Sensor vs. Physiotherapist Feedback During Core Stabilization Training in Patients with Chronic Nonspecific Low Back Pain

Core stabilization training utilizes principles of motor learning to retrain control of the trunk muscles and lead to improvements in chronic non-specific low back pain (CNLBP). To compare the effects of biofeedback sensor and conventional physiotherapist (PT) feedback during core stabilization and activity training in patients with CNLBP. Thirty-eight patients with CNLBP were randomly assigned to Biofeedback (n = 19) or PT feedback (n = 19) groups. Patients continued 12 sessions of combined core stabilization and activity training. An auditory and tactile biofeedback was given using a validated tilt sensor integrated with an application in the Biofeedback group. An experienced PT provided verbal and tactile feedback to maintain the neutral position in the PT Feedback group. The outcomes were; disability (Revised Oswestry Disability Index-RODI), muscle activity (m.transversus abdominis and m.multifidus), pain (Visual Analog Scale-VAS), proprioception error of the trunk, patient beliefs (Fear Avoidance Beliefs Questionnaire-FABQ) and presence of depressive symptoms (Beck Depression Index-BDI), and quality of life (Short Form (SF)-36). The main effect of time were statistically significant on VAS, RODI, m.transversus abdominis and m.multifidus muscle activities, flexion, and extension proprioception error of the trunk, FABQ, BDI, and SF-36 scores in Biofeedback and PT feedback groups (p < 0.05 for all). The time X group interaction was significant on flexion and extension proprioception error of the trunk PT feedback group (consecutively; p = 0.004, p = 0.022). Biofeedback sensor or PT feedback during core stabilization training equally improves pain, disability, muscle activity, depressive symptoms, patient beliefs, and quality of life in patients with CNLBP.

Variations in Concurrent Validity of Two Independent Inertial Measurement Units Compared to Gold Standard for Upper Body Posture during Computerised Device Use

Inertial measurement units (IMUs) may provide an objective method for measuring posture during computer use, but research is needed to validate IMUs' accuracy. We examine the concurrent validity of two different IMU systems in measuring three-dimensional (3D) upper body posture relative to a motion capture system (Mocap) as a potential device to assess postures outside a laboratory environment. We used 3D Mocap and two IMU systems (Wi-Fi and Bluetooth) to capture the upper body posture of twenty-six individuals during three physical computer working conditions (monitor correct, monitor raised, and laptop). Coefficient of determination (R2) and root-mean-square error (RMSE) compared IMUs to Mocap. Head/neck segment [HN], upper trunk segment [UTS], and joint angle [HN-UTS] were the primary variables. Wi-Fi IMUs demonstrated high validity for HN and UTS (sagittal plane) and HN-UTS (frontal plane) for all conditions, and for HN rotation movements (both for the monitor correct and monitor raised conditions), others moderate to poor. Bluetooth IMUs for HN, and UTS (sagittal plane) for the monitor correct, laptop, and monitor raised conditions were moderate. Frontal plane movements except UTS (monitor correct and laptop) and all rotation had poor validity. Both IMU systems were affected by gyroscopic drift with sporadic data loss in Bluetooth IMUs. Wi-Fi IMUs had more acceptable accuracy when measuring upper body posture during computer use compared to Mocap, except for trunk rotations. Variation in IMU systems' performance suggests validation in the task-specific movement(s) is essential.

Evidence for the Effectiveness of Feedback from Wearable Inertial Sensors during Work-Related Activities: A Scoping Review

Background: Wearable inertial sensor technology (WIST) systems provide feedback, aiming to modify aberrant postures and movements. The literature on the effects of feedback from WIST during work or work-related activities has not been previously summarised. This review examines the effectiveness of feedback on upper body kinematics during work or work-related activities, along with the wearability and a quantification of the kinematics of the related device. Methods: The Cinahl, Cochrane, Embase, Medline, Scopus, Sportdiscus and Google Scholar databases were searched, including reports from January 2005 to July 2021. The included studies were summarised descriptively and the evidence was assessed. Results: Fourteen included studies demonstrated a 'limited' level of evidence supporting posture and/or movement behaviour improvements using WIST feedback, with no improvements in pain. One study assessed wearability and another two investigated comfort. Studies used tri-axial accelerometers or IMU integration (n = 5 studies). Visual and/or vibrotactile feedback was mostly used. Most studies had a risk of bias, lacked detail for methodological reproducibility and displayed inconsistent reporting of sensor technology, with validation provided only in one study. Thus, we have proposed a minimum 'Technology and Design Checklist' for reporting. Conclusions: Our findings suggest that WIST may improve posture, though not pain; however, the quality of the studies limits the strength of this conclusion. Wearability evaluations are needed for the translation of WIST outcomes. Minimum reporting standards for WIST should be followed to ensure methodological reproducibility.

Effectiveness of a lumbopelvic monitor and feedback device to change postural behaviour: the ELF cluster randomised controlled trial

OBJECTIVES

The aim of this clustered, randomised controlled trial was to assess the effectiveness of a lumbopelvic postural feedback device for changing postural behaviour in a group of healthcare workers. We hypothesised that workers exposed to auditory postural feedback would reduce the number of times forward bending posture is adopted at work.

METHODS

This was a participant and assessor blinded, randomised, sham-controlled trial with blocked cluster random allocation. We recruited healthcare workers from aged care institutions. Healthcare sites were randomly allocated to the feedback or sham group (SG). A postural monitoring and feedback device was used to monitor and record lumbopelvic forward bending posture, and provided audio feedback whenever the user sustained lumbopelvic forward bending posture that exceeded predefined thresholds. The primary outcome measure was postural behaviour (exceeding thresholds). We used a robust variant of repeated measures mixed-effect model for assessing within-group and between-group differences in postural behaviour.

RESULTS

We recruited 19 sites, and 130 healthcare workers participated. There were no within-group changes on the number of times postural threshold was exceeded at 1-week follow-up (feedback group: -0.7, 95% CI -2.61 to 0.72; SG -0.3, -1.65 to 0.98), and no differences (0.05, 95% CI -1.83 to 1.94) between SG and feedback group.

CONCLUSIONS

Findings from this trial indicate that audio feedback provided by a postural monitor device did not reduce the number of times healthcare workers exceeded the postural threshold.

TRIAL REGISTRATION NUMBER

ACTRN12616000449437.

Electronic Skin Wearable Sensors for Detecting Lumbar-Pelvic Movements

Background: A nanomaterial-based electronic-skin (E-Skin) wearable sensor has been successfully used for detecting and measuring body movements such as finger movement and foot pressure. The ultrathin and highly sensitive characteristics of E-Skin sensor make it a suitable alternative for continuously out-of-hospital lumbar–pelvic movement (LPM) monitoring. Monitoring these movements can help medical experts better understand individuals’ low back pain experience. However, there is a lack of prior studies in this research area. Therefore, this paper explores the potential of E-Skin sensors to detect and measure the anatomical angles of lumbar–pelvic movements by building a linear relationship model to compare its performance to clinically validated inertial measurement unit (IMU)-based sensing system (ViMove). Methods: The paper first presents a review and classification of existing wireless sensing technologies for monitoring of body movements, and then it describes a series of experiments performed with E-Skin sensors for detecting five standard LPMs including flexion, extension, pelvic tilt, lateral flexion, and rotation, and measure their anatomical angles. The outputs of both E-Skin and ViMove sensors were recorded during each experiment and further analysed to build the comparative models to evaluate the performance of detecting and measuring LPMs. Results: E-Skin sensor outputs showed a persistently repeating pattern for each movement. Due to the ability to sense minor skin deformation by E-skin sensor, its reaction time in detecting lumbar–pelvic movement is quicker than ViMove by ~1 s. Conclusions: E-Skin sensors offer new capabilities for detecting and measuring lumbar–pelvic movements. They have lower cost compared to commercially available IMU-based systems and their non-invasive highly stretchable characteristic makes them more comfortable for long-term use. These features make them a suitable sensing technology for developing continuous, out-of-hospital real-time monitoring and management systems for individuals with low back pain.

Clinically acceptable agreement between the ViMove wireless motion sensor system and the Vicon motion capture system when measuring lumbar region inclination motion in the sagittal and coronal planes

Background

Wireless, wearable, inertial motion sensor technology introduces new possibilities for monitoring spinal motion and pain in people during their daily activities of work, rest and play. There are many types of these wireless devices currently available but the precision in measurement and the magnitude of measurement error from such devices is often unknown. This study investigated the concurrent validity of one inertial motion sensor system (ViMove) for its ability to measure lumbar inclination motion, compared with the Vicon motion capture system.

Methods

To mimic the variability of movement patterns in a clinical population, a sample of 34 people were included – 18 with low back pain and 16 without low back pain. ViMove sensors were attached to each participant’s skin at spinal levels T12 and S2, and Vicon surface markers were attached to the ViMove sensors. Three repetitions of end-range flexion inclination, extension inclination and lateral flexion inclination to both sides while standing were measured by both systems concurrently with short rest periods in between. Measurement agreement through the whole movement range was analysed using a multilevel mixed-effects regression model to calculate the root mean squared errors and the limits of agreement were calculated using the Bland Altman method.

Results

We calculated root mean squared errors (standard deviation) of 1.82° (±1.00°) in flexion inclination, 0.71° (±0.34°) in extension inclination, 0.77° (±0.24°) in right lateral flexion inclination and 0.98° (±0.69°) in left lateral flexion inclination. 95% limits of agreement ranged between -3.86° and 4.69° in flexion inclination, -2.15° and 1.91° in extension inclination, -2.37° and 2.05° in right lateral flexion inclination and -3.11° and 2.96° in left lateral flexion inclination.

Conclusions

We found a clinically acceptable level of agreement between these two methods for measuring standing lumbar inclination motion in these two cardinal movement planes. Further research should investigate the ViMove system’s ability to measure lumbar motion in more complex 3D functional movements and to measure changes of movement patterns related to treatment effects.

Effectiveness of a lumbopelvic monitor and feedback device to change postural behaviour: a protocol for the ELF cluster randomised controlled trial

INTRODUCTION

Low back pain (LBP) is the most common, costly and disabling musculoskeletal disorder worldwide, and is prevalent in healthcare workers. Posture is a modifiable risk factor for LBP shown to reduce the prevalence of LBP. Our feasibility research suggests that postural feedback might help healthcare workers avoid hazardous postures. The Effectiveness of Lumbopelvic Feedback (ELF) trial will investigate the extent to which postural monitor and feedback (PMF) can reduce exposure to hazardous posture associated with LBP.

METHODS

This is a participant-blinded, randomised controlled trial with blocked cluster random allocation. Participants will include volunteer healthcare workers recruited from aged care institutions and hospitals. A postural monitoring and feedback device will monitor and record lumbopelvic forward bending posture, and provide audio feedback whenever the user sustains a lumbopelvic forward bending posture that exceeds predefined thresholds. The primary outcome measure will be postural behaviour (exceeding thresholds). Secondary outcome measures will be incidence of LBP, participant-reported disability and adherence. Following baseline assessment, we will randomly assign participants to 1 of 2 intervention arms: a feedback group and a no-feedback control group. We will compare between-group differences of changes in postural behaviour by using a repeated measures mixed-effect model analysis of covariance (ANCOVA) at 6 weeks. Postural behaviour baseline scores, work-related psychosocial factors and disability scores will be input as covariates into the statistical models. We will use logistic mixed model analysis and Cox's proportional hazards for assessing the effect of a PMF on LBP incidence between groups.

DISCUSSION

Posture is a modifiable risk factor for low back disorders. Findings from the ELF trial will inform the design of future clinical trials assessing the effectiveness of wearable technology on minimising hazardous posture during daily living activities in patients with low back disorders.

TRIAL REGISTRATION NUMBER

ACTRN12616000449437.

The effectiveness of a lumbopelvic monitor and feedback device to change postural behavior: a feasibility randomized controlled trial

STUDY DESIGN

Feasibility randomized controlled trial.

OBJECTIVES

To assess the feasibility of a trial to investigate the effectiveness of a lumbopelvic monitor as a feedback device for modifying postural behavior during daily work-related activities.

BACKGROUND

Frequent or sustained flexed postures play a role in the development or maintenance of nonspecific low back pain. The provision of postural feedback could help individuals with or at risk of nonspecific low back pain improve their postural awareness and avoid hazardous or pain-provoking postures.

METHODS

Sixty-two participants employed in a health care organization were randomly allocated into 1 of 3 groups: a control group, an intermittent feedback group, and a constant feedback group. Adherence and follow-up rates were assessed. Differences in postural pattern between baseline and follow-up measurements were used to assess the effectiveness of the lumbopelvic monitor as a postural feedback device.

RESULTS

Adherence was approximately 75%. With the exception of 1 center, the follow-up overall rates exceeded the a priori desired threshold of 80%. Within-group comparisons revealed no significant differences in postural pattern for the control group and intermittent feedback group. The constant feedback group showed a significant reduction in flexed posture at the follow-up period compared with the baseline period. Differences between groups did not reach statistical significance; however, the constant feedback group, compared with the control group, demonstrated an effect size (d) of 0.60.

CONCLUSION

The provision of constant postural feedback seems promising for promoting changes in postural behavior. This feasibility trial identified adherence and follow-up rates and sample-size estimates important to the conduct of a fully powered efficacy trial. Level of Evidence Therapy, level 2b-.