A Lower-Back Exoskeleton with a Four-bar Linkage Structure for Providing Extensor Moment and Lumbar Traction Force

Effects of a lumbar exoskeleton that provides two traction forces on spinal loading and muscles

In workplaces with prolonged or repetitive stooping, disc herniation due to excessive pressure at the lumbar L5/S1 joints has been a difficult condition to prevent and treat in the field of lower back pain. Previous research on lumbar exoskeletons mainly focused on the impact of assistive torque on muscle activation, overlooking the fact that providing assistive torque is not the optimal approach when bending over with a low load. Instead, using traction force to reduce disc pressure is a more adaptable method to mitigate the risk of intervertebral disc herniation. In this paper, a novel lumbar exoskeleton mechanism is proposed. The exoskeleton principle is similar to a lever arranged on the torso, which provides two types of traction forces using a single compression spring with a lower support moment and higher traction performance. Subsequently, a kinetic simulation model covering passive physiologic tissues and spring stiffness was developed to determine the optimal range of traction forces for a given load, to predict the disc pressure and muscle activation at optimal traction forces. Eight subjects were invited to wear the exoskeleton for stooping and lifting tests under extreme loads, using myoelectric sensors to measure muscle activation. The results confirm that optimal traction force effectively reduces L5/S1 disc pressure without additionally increasing muscle activation. The exoskeleton in this study provides an alternative idea for the design of lumbar exoskeletons adapted to light load stooping.

Design and evaluation of powered lumbar exoskeleton based on human biomechanics

OBJECTIVES

In view of the gradual rejuvenation and acceleration of lumbar spondylosis, a wearable powered lumbar exoskeleton based on a 6-SPU/SP parallel mechanism is designed based on the rehabilitation treatment method of lumbar forward flexion/extension, left/right lateral flexion and rotation.

METHODS

First, the changes in human lumbar muscles are analyzed based on human biomechanics, and then the prototype design of the powered lumbar exoskeleton is implemented, including the mechanical mechanism design, and hardware module design. Finally, the simulation experiment of muscle force and output sensitivity test in the resistive mode are conducted.

RESULTS

The simulation results show that the external oblique muscle can be relieved about 20 % and the iliopsoas muscle can be decreased by 33 % when wearing the powered lumbar exoskeleton in the lateral flexion. The pressure sensors can measure the output force of each actuator in real-time when the resistance force reaches the set value of 15 N at the resistive model.

CONCLUSIONS

The results show that the powered lumbar exoskeleton can assist the human lumbar spine in rehabilitation training of traction, forward flexion and extension, left and right lateral flexion, and rotation. This research provides new ideas for future clinical research.

Evaluation of the efficacy of a novel lumbar exoskeleton with multiple interventions for patients with lumbar disc herniation: a multicenter randomized controlled trial of non-inferiority

Background

Lumbar disc herniation (LDH) occurs when the nucleus pulposus or annulus fibrosus protrudes into the intervertebral space, potentially compressing nerve roots and causing symptoms such as sciatica, restricted mobility, and lower extremity weakness. The development of portable lumbar exoskeleton devices offers a new approach, combining traction, range of motion (ROM) exercises, and resistance training in a single system, potentially reducing treatment complexity and enhancing LDH patient outcomes.

Objective

This study aims to evaluate the efficacy and safety of a novel lumbar exoskeleton device compared to traditional traction methods combined with rehabilitation therapy for patients with LDH.

Methods

A multicenter, non-inferiority randomized controlled trial was conducted with 118 participants diagnosed with LDH. Participants were randomly assigned to the Exoskeleton Group or the Traction Group. The Exoskeleton Group used the novel device for traction, ROM, and resistance training, while the Traction Group underwent traditional traction and rehabilitation therapy. Outcomes included efficacy rate after 10 treatments, Visual Analogue Scale (VAS), Oswestry Disability Index (ODI), and lumbar ROM-were assessed at 3, 6, and 10 treatments.

Results

A total of 118 eligible participants were recruited. After 10 treatments, both groups showed significant improvements in VAS scores, ODI, and lumbar ROM compared to baseline (P < 0.001). However, there was no significant difference in the overall efficacy rate between the two groups (P = 0.748).

Conclusion

The novel lumbar exoskeleton device demonstrates comparable efficacy and safety to traditional traction therapy combined with rehabilitation, offering a promising alternative for the conservative treatment of LDH.

Multidisciplinary collaboration on exoskeleton development adopting user-centered design: a systematic integrative review

Purpose: The world population is ageing, along with an increasing possibility of functional limitations that affect independent living. Assistive technologies such as exoskeletons for rehabilitative purposes and daily activities assistance maintaining the independence of people with disabilities, especially older adults who wish to ageing-in-place. The purpose of this systematic integrative review was threefold: to explore the development team compositions and involvement, to understand the recruitment and engagement of stakeholders, and to synthesise reported or anticipated consequences of multidisciplinary collaboration.Methods: Databases searched included PubMed, CINAHL Plus, PsycINFO, Web of Science, Scopus, and IEEE Xplore. A total of 34 studies that reported the development of exoskeleton adopting user-centered design (UCD) method in healthcare or community settings that were published in English from 2000 to July 2022 were included.Results: Three major trends emerged from the analysis of included studies. First, there is a need to redefine multidisciplinary collaboration, from within-discipline collaboration to cross-discipline collaboration. Second, the level of engagement of stakeholders during the exoskeleton development remained low. Third, there was no standardised measurement to quantify knowledge production currently.Conclusion: As suggested by the synthesised results in this review, exoskeleton development has been increasing to improve the functioning of people with disabilities. Exoskeleton development often required expertise from different disciplines and the involvement of stakeholders to increase acceptance, thus we propose the Multidisciplinary Collaboration Appraisal Tool to assess multidisciplinary collaboration using the UCD approach. Future research is required to understand the effectiveness of multidisciplinary collaboration on exoskeleton development using the UCD approach.IMPLICATIONS FOR REHABILITATIONGlobal trend of population ageing causes a higher risk of disability in older adults who require rehabilitation and assistance in daily living.Assistive technologies such as exoskeletons have the potential to contribute to rehabilitation training and daily activity assistance demand closer multidisciplinary collaboration.A Multidisciplinary Collaboration Appraisal Tool using user-centered design approach (MCAT) is proposed to understand the effectiveness as well as limitations and barriers associated with multidisciplinary collaboration in developing exoskeletons.

Assessment of Muscle Coordination Changes Caused by the Use of an Occupational Passive Lumbar Exoskeleton in Laboratory Conditions

The introduction of exoskeletons in industry has focused on improving worker safety. Exoskeletons have the objective of decreasing the risk of injury or fatigue when performing physically demanding tasks. Exoskeletons' effect on the muscles is one of the most common focuses of their assessment. The present study aimed to analyze the muscle interactions generated during load-handling tasks in laboratory conditions with and without a passive lumbar exoskeleton. The electromyographic data of the muscles involved in the task were recorded from twelve participants performing load-handling tasks. The correlation coefficient, coherence coefficient, mutual information, and multivariate sample entropy were calculated to determine if there were significant differences in muscle interactions between the two test conditions. The results showed that muscle coordination was affected by the use of the exoskeleton. In some cases, the exoskeleton prevented changes in muscle coordination throughout the execution of the task, suggesting a more stable strategy. Additionally, according to the directed Granger causality, a trend of increasing bottom-up activation was found throughout the task when the participant was not using the exoskeleton. Among the different variables analyzed for coordination, the most sensitive to changes was the multivariate sample entropy.

A Method of Predicting Posture-related Pain Using Biomechanical Parameters for Patients with Lumbar Spinal Disc Herniation

Lumbar spinal disc herniation is a disease in which the protruding nucleus pulposus presses on the nerve due to actions that place loads on the disc, causing pain in the lower back and lower limbs. About 80% of treatments of disc herniation are conservative treatments, and although it is necessary to live with pain for a long time, there have been no studies that clearly define the relationship between pain and biomechanical parameters. In this study, we proposed a method of identifying biomechanical parameters that predict posture-related pain in patients with lumbar spinal disc herniation. The pain values were quantitatively evaluated by the Numerical Rating Scale (NRS) and the biomechanical parameters were analyzed by OpenSim. Lasso regression was performed to narrow down the biomechanical parameters that were related to pain and derive the mathematical model of the relationship. Therefore, many of the parameters of the obtained mathematical model were related to the lumbar spine and were consistent with areas that be related to lumbar spinal disc herniation.