1
|
Ghaneh-Ezabadi S, Abdoli-Eramaki M, Arjmand N, Abouhossein A, Zakerian SA. The Validity and Inter-Rater Reliability of a Video-Based Posture-Matching Tool to Estimate Cumulative Loads on the Lower Back. J Biomed Phys Eng 2022; 12:417-430. [PMID: 36059286 PMCID: PMC9395627 DOI: 10.31661/jbpe.v0i0.2203-1474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 06/19/2022] [Indexed: 06/15/2023]
Abstract
Background Low back pain (LBP) is known as one of the most common work-related musculoskeletal disorders. Spinal cumulative loads (CLs) during manual material handling (MMH) tasks are the main risk factors for LBP. However, there is no valid and reliable quantitative lifting analysis tool available for quantifying CLs among Iranian workers performing MMH tasks. Objective This study aimed to investigate the validity and inter-rater reliability of a posture-matching load assessment tool (PLAT) for estimating the L5-S1 static cumulative compression (CC) and shear (CS) loads based on predictive regression equations. Material and Methods This experimental study was conducted among six participants performing four lifting tasks, each comprised of five trials during which their posture was recorded via a motion capture (Vicon) and simultaneously a three-camera system located at three different angles (0°, 45°, and 90°) to the sagittal plane. Results There were no significant differences between the two CLs estimated by PLAT from the three-camera system and the gold-standard Vicon. In addition, ten raters estimated CLs of the tasks using PLAT in three sessions. The calculated intra-class correlation coefficients for the estimated CLs within each task revealed excellent inter-rater reliability (> 0.75), except for CS in the first and third tasks, which were good (0.6 to 0.75). Conclusion The proposed posture-matching approach provides a valid and reliable ergonomic assessment tool suitable for assessing spinal CLs during various lifting activities.
Collapse
Affiliation(s)
- Saeed Ghaneh-Ezabadi
- PhD Candidate, Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Abdoli-Eramaki
- PhD, Professor, School of Occupational and Public Health, Ryerson University, Toronto, Canada
| | - Navid Arjmand
- PhD, Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - Alireza Abouhossein
- PhD, Department of Ergonomics, School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- PhD, Workplace Health Promotion Research Center (WHPRC), School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Seyed Abolfazl Zakerian
- PhD, Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| |
Collapse
|
2
|
Skals S, Bláfoss R, de Zee M, Andersen LL, Andersen MS. Effects of load mass and position on the dynamic loading of the knees, shoulders and lumbar spine during lifting: a musculoskeletal modelling approach. APPLIED ERGONOMICS 2021; 96:103491. [PMID: 34126573 DOI: 10.1016/j.apergo.2021.103491] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 05/27/2021] [Accepted: 06/02/2021] [Indexed: 06/12/2023]
Abstract
Musculoskeletal models may enhance our understanding of the dynamic loading of the joints during manual material handling. This study used state-of-the-art musculoskeletal models to determine the effects of load mass, asymmetry angle, horizontal location and deposit height on the dynamic loading of the knees, shoulders and lumbar spine during lifting. Recommended weight limits and lifting indices were also calculated using the NIOSH lifting equation. Based on 1832 lifts from 22 subjects, we found that load mass had the most substantial effect on L5-S1 compression. Increments in asymmetry led to large increases in mediolateral shear, while load mass and asymmetry had significant effects on anteroposterior shear. Increased deposit height led to higher shoulder forces, while the horizontal location mostly affected the forces in the knees and shoulders. These results generally support the findings of previous research, but notable differences in the trends and magnitudes of the estimated forces were observed.
Collapse
Affiliation(s)
- Sebastian Skals
- Musculoskeletal Disorders and Physical Workload, National Research Centre for the Working Environment, Lersø Parkallé 105, 2100 Copenhagen East, Denmark; Sport Sciences - Performance and Technology, Department of Health Science and Technology, Aalborg University, Niels Jernes Vej 12, 9220 Aalborg East, Denmark.
| | - Rúni Bláfoss
- Musculoskeletal Disorders and Physical Workload, National Research Centre for the Working Environment, Lersø Parkallé 105, 2100 Copenhagen East, Denmark; Research Unit for Muscle Physiology and Biomechanics, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
| | - Mark de Zee
- Sport Sciences - Performance and Technology, Department of Health Science and Technology, Aalborg University, Niels Jernes Vej 12, 9220 Aalborg East, Denmark.
| | - Lars Louis Andersen
- Musculoskeletal Disorders and Physical Workload, National Research Centre for the Working Environment, Lersø Parkallé 105, 2100 Copenhagen East, Denmark; Sport Sciences - Performance and Technology, Department of Health Science and Technology, Aalborg University, Niels Jernes Vej 12, 9220 Aalborg East, Denmark.
| | - Michael Skipper Andersen
- Department of Materials and Production, Aalborg University, Fibigerstræde 16, 9220 Aalborg, Denmark.
| |
Collapse
|
3
|
Trunk Posture during Manual Materials Handling of Beer Kegs. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18147380. [PMID: 34299831 PMCID: PMC8307858 DOI: 10.3390/ijerph18147380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/22/2021] [Accepted: 07/03/2021] [Indexed: 12/03/2022]
Abstract
Craft brewing is a rapidly growing industry in the U.S. Most craft breweries are small businesses with few resources for robotic or other mechanical-assisted equipment, requiring work to be performed manually by employees. Craft brewery workers frequently handle stainless steel half-barrel kegs, which weigh between 13.5 kg (29.7 lbs.) empty and 72.8 kg (161.5 lbs.) full. Moving kegs may be associated with low back pain and even injury. In the present study, researchers performed a quantitative assessment of trunk postures using an inertial measurement unit (IMU)-based kinematic measurement system while workers lifted kegs at a craft brewery. Results of this field-based study indicated that during keg handling, craft brewery workers exhibited awkward and non-neutral trunk postures. Based on the results of the posture data, design recommendations were identified to reduce the hazardous exposure for musculoskeletal disorders among craft brewery workers.
Collapse
|
4
|
Bouffard J, Martinez R, Plamondon A, Côté JN, Begon M. Sex differences in glenohumeral muscle activation and coactivation during a box lifting task. ERGONOMICS 2019; 62:1327-1338. [PMID: 31282824 DOI: 10.1080/00140139.2019.1640396] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 06/24/2019] [Indexed: 06/09/2023]
Abstract
Manual material handling is associated with shoulder musculoskeletal disorders, especially for women. Sex differences in glenohumeral muscle activity may contribute to women's higher injury risk by affecting shoulder load and stability. We assessed the effects of sex (25 women vs 26 men) and lifting load (6 kg vs 12 kg) on muscle activation during box lifting from hip to eye level. Surface and intramuscular electromyography were recorded from 10 glenohumeral muscles. Most muscles were more activated for the heavier box and for women. These effects were larger for 'prime movers' than for stabilisers and antagonists. Despite their apparently heterogeneous effects on muscle activity, sex and mass did not affect Muscle Focus, a metric of coactivation. This may be partly related to the limited sensitivity of the Muscle Focus. Nevertheless, sex differences in strength, more than in coactivation patterns, may contribute to the sex imbalance in the prevalence of musculoskeletal disorders. Practitioner summary: We studied sex differences in glenohumeral muscle activity in a lifting task to eye level. Women lifting a 6-kg box activated their muscles similarly to men lifting a 12-kg box, i.e. up to 48% of their maximum capacity. Interventions minimising shoulder load should be implemented, especially for women. Abbreviations: BB: biceps brachii; DeltA: anterior deltoid; DeltL: lateral deltoid; DeltP: posterior deltoid; DoF: degrees of freedom; ED: effect duration; EMG: electromyography; ES: effect size; Infra: infraspinatus; Lat: latissimus dorsi; MF: muscle focus; MMH: manual material handling; MVA: maximal voluntary activation; Pect: pectoralis major; Subscap: subscapularis; Supra: supraspinatus; TB: triceps brachii.
Collapse
Affiliation(s)
- Jason Bouffard
- Laboratoire de Simulation et Modélisation du Mouvement, Département de Kinésiologie, Université de Montréal , Laval , Canada
- Kinesiology and Physical Education, McGill University , Montréal , Canada
| | - Romain Martinez
- Laboratoire de Simulation et Modélisation du Mouvement, Département de Kinésiologie, Université de Montréal , Laval , Canada
| | - André Plamondon
- Institut de Recherche Robert Sauvé en Santé et Sécurité du Travail (IRSST) , Montréal , Canada
| | - Julie N Côté
- Kinesiology and Physical Education, McGill University , Montréal , Canada
| | - Mickaël Begon
- Laboratoire de Simulation et Modélisation du Mouvement, Département de Kinésiologie, Université de Montréal , Laval , Canada
| |
Collapse
|
5
|
Martinez R, Bouffard J, Michaud B, Plamondon A, Côté JN, Begon M. Sex differences in upper limb 3D joint contributions during a lifting task. ERGONOMICS 2019; 62:682-693. [PMID: 30696384 DOI: 10.1080/00140139.2019.1571245] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 09/27/2018] [Accepted: 10/02/2018] [Indexed: 06/09/2023]
Abstract
Sex-related differences in work technique may contribute to increasing the risk of musculoskeletal joint disorders among women. In lifting tasks, sex differences have been reported for the trunk and lower limb, although women present a higher prevalence of shoulder disorders. We investigated sex differences in the upper limb technique during a lifting task. Trunk and upper limb kinematics were recorded in 27 women and 27 men lifting a box (6 or 12 kg) from hip to eye level. Work technique was quantified through the three-dimensional contribution of each joint to overall box height. The glenohumeral joint showed a higher contribution in women with a 6 kg box and wrist and elbow joints did with a 12 kg box, compared to men at either 6 or 12 kg. Sex differences occurred systematically above shoulder level. Our results argue for careful consideration of sex during ergonomic intervention, particularly during the overhead task. Practitioner Summary: We investigated the sex-related differences in upper limb technique during lifting tasks. Results highlight a sex-specific kinematic strategy above the shoulder level on the glenohumeral joint and on the wrist and elbow joints. To help reduce women's shoulder disorders in overhead task, ergonomic interventions should account for those differences. Abbreviations: DoF: degree-of-freedom; WR/EL: wrist and elbow; GH: glenohumeral; SC/AC: sternoclavicular and acromioclavicular; TR/PE: pelvo-thoracic.
Collapse
Affiliation(s)
- Romain Martinez
- a Laboratoire de Simulation et Modélisation du Mouvement, Département de Kinésiologie , Université de Montréal , Laval , Canada
| | - Jason Bouffard
- a Laboratoire de Simulation et Modélisation du Mouvement, Département de Kinésiologie , Université de Montréal , Laval , Canada
| | - Benjamin Michaud
- a Laboratoire de Simulation et Modélisation du Mouvement, Département de Kinésiologie , Université de Montréal , Laval , Canada
| | - André Plamondon
- b Institut de Recherche Robert Sauvé en Santé et Sécurité du Travail (IRSST) , Montréal , Canada
| | - Julie N Côté
- c Department of Kinesiology and Physical Education , McGill University , Montréal , Canada
| | - Mickaël Begon
- a Laboratoire de Simulation et Modélisation du Mouvement, Département de Kinésiologie , Université de Montréal , Laval , Canada
| |
Collapse
|
6
|
Daniel M, Tomanová M, Hornová J, Novotná I, Lhotská L. Biomechanical analysis of INFINITY rehabilitation method for treatment of low back pain. J Phys Ther Sci 2017; 29:832-838. [PMID: 28603355 PMCID: PMC5462682 DOI: 10.1589/jpts.29.832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 02/07/2017] [Indexed: 11/24/2022] Open
Abstract
[Purpose] Low back pain is a pervasive problem in modern societies. Physical rehabilitation in treatment of low back pain should reduce pain, muscle tension and restore spine stability and balance. The INFINITY® rehabilitation method that is based on a figure of eight movement pattern was proved to be effective in low back pain treatment. The aim of the paper is to estimate the effect of a figure of eight motion on the L5/S1 load and lumbar spine muscle activation in comparison to other motion patterns. [Subjects and Methods] Three-dimensional model of lumbar spine musculoskeletal system is used to simulate effect of various load motion pattern induced by displacement of the center of gravity of the upper body. Four motion patterns were examined: lateral and oblique pendulum-like motion, elliptical motion and figure of eight motion. [Results] The simple pendulum-like and elliptical-like patterns induce harmonic muscle activation and harmonic spinal load. The figure of eight motion pattern creates high-frequency spinal loading that activates remodeling of bones and tendons. The figure of eight pattern also requires muscle activity that differs from harmonic frequency and is more demanding on muscle control and could also improve muscle coordination. [Conclusion] The results of the study indicate that complex motion pattern during INFINITY® rehabilitation might enhance the spine stability by influencing its passive, active and neural components.
Collapse
Affiliation(s)
- Matej Daniel
- Department of Mechanics, Biomechanics and Mechatronics, Faculty of Mechanical Engineering, Czech Technical University in Prague, Czech Republic
| | | | - Jana Hornová
- Department of Mechanics, Biomechanics and Mechatronics, Faculty of Mechanical Engineering, Czech Technical University in Prague, Czech Republic
| | - Iva Novotná
- Czech Institute of Informatics, Robotics and Cybernetics, Czech Technical University in Prague, Czech Republic
| | - Lenka Lhotská
- Czech Institute of Informatics, Robotics and Cybernetics, Czech Technical University in Prague, Czech Republic
| |
Collapse
|
7
|
Cardoso M, Girouard M, McKinnon C, Callaghan JP, Albert WJ. Quantifying the postural demands of patrol officers: a field study. INTERNATIONAL JOURNAL OF OCCUPATIONAL SAFETY AND ERGONOMICS 2016; 23:185-197. [PMID: 27753541 DOI: 10.1080/10803548.2016.1249729] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Police officers are at high risk for developing musculoskeletal injuries. This study aimed to determine differences in physical demands of patrol officers during day shifts and night shifts. Sixteen participants were recruited (10 males, 6 females) for in-vehicle observation over one full day shift and one full night shift. Dynamic pressure distribution when seated in the vehicle was assessed and compared between the first and last parts of each shift. Activity characterization and postural analyses were conducted from video that was recorded continuously for the duration of each shift to determine time spent in each task and corresponding postures. Postural analysis and cumulative joint loads were used to identify higher-risk tasks. Several activities caused the officers to adopt non-neutral postures of the neck, shoulders and back. Future work needs to focus on modifying the interior of the vehicle, as well as decreasing exposure time to activities resulting in non-neutral postures.
Collapse
Affiliation(s)
| | | | - Colin McKinnon
- b School of Kinesiology and Health Studies , University of Waterloo , Canada
| | - Jack P Callaghan
- b School of Kinesiology and Health Studies , University of Waterloo , Canada
| | - Wayne J Albert
- a Faculty of Kinesiology , University of New Brunswick , Canada
| |
Collapse
|
8
|
Image driven subject-specific finite element models of spinal biomechanics. J Biomech 2016; 49:919-925. [DOI: 10.1016/j.jbiomech.2016.02.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 02/04/2016] [Accepted: 02/05/2016] [Indexed: 11/20/2022]
|
9
|
Zwambag DP, Brown SHM. The effect of contralateral submaximal contraction on the development of biceps brachii muscle fatigue. HUMAN FACTORS 2015; 57:461-470. [PMID: 25875435 DOI: 10.1177/0018720814550034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 08/06/2014] [Indexed: 06/04/2023]
Abstract
OBJECTIVE The aim of this study was to determine if a submaximal contraction in the contralateral limb affected the fatigability of the dominant limb. BACKGROUND Muscle fatigue is a known risk factor for musculoskeletal injury; however, it is unknown whether a submaximal contraction in the nondominant limb, such as for stabilizing a tool or load, affects the rate of development of fatigue, potentially increasing risk of injury. Current ergonomic assessments of injury risk do not involve consideration of submaximal contralateral demands. It was hypothesized that increased neuromuscular drive and active muscle mass during bilateral contractions would increase fatigability. METHOD Twelve males isometrically maintained a 30% unilateral contraction and a 30% dominant + 15% nondominant bilateral contraction until failure on two different collection days, separated by 7 days. RESULTS No statistically significant differences were found for time to task failure (p = .6204), decrease in maximal force (p = .1698), or alterations in electromyography amplitude (p = .7223) or frequency (p = .3292) between unilateral and bilateral conditions. CONCLUSION The hypothesis that the addition of a lesser submaximal isometric contraction would increase fatigability was rejected. APPLICATION These findings indicate that in ergonomic settings, muscle fatigability can be estimated by the more demanding task and do not need to be complicated by lesser submaximal contractions in the opposing limb.
Collapse
|
10
|
Howarth SJ, Giangregorio LM, Callaghan JP. Development of an equation for calculating vertebral shear failure tolerance without destructive mechanical testing using iterative linear regression. Med Eng Phys 2013; 35:1212-20. [PMID: 23337706 DOI: 10.1016/j.medengphy.2012.12.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2011] [Revised: 11/30/2012] [Accepted: 12/26/2012] [Indexed: 10/27/2022]
Abstract
Equations used to determine vertebral failure tolerances without the need for destructive testing are useful for scaling applied sub-maximal forces during in vitro repetitive loading studies. However, existing equations that use vertebral bone density and morphology for calculating compressive failure tolerance are unsuitable for calculating vertebral shear failure tolerance since the primary site of failure is the pars interarticularis and not the vertebral body. Therefore, this investigation developed new equations for non-destructively determining vertebral shear failure tolerance from morphological and/or bone density measures. Shear failure was induced in 40 porcine cervical vertebral joints (20 C3-C4 and 20 C5-C6) by applying a constant posterior displacement to the caudal vertebra at 0.15 mm/s. Prior to destructive testing, morphology and bone density of the posterior elements were made with digital calipers, X-rays, and peripheral quantitative computed tomography. Iterative linear regression identified mathematical relationships between shear failure tolerance, and morphological and bone density measurements. Along with vertebral level, pars interarticularis length and lamina height from the cranial vertebra, and inferior facet height from the caudal vertebra collectively explained 61.8% of shear failure tolerance variance. Accuracy for this relationship, estimated using the same group of specimens, was 211.9 N or 9.8% of the measured shear failure tolerance.
Collapse
Affiliation(s)
- Samuel J Howarth
- Department of Graduate Education and Research Programs, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada
| | | | | |
Collapse
|
11
|
Howarth SJ, Callaghan JP. The impact of shear force magnitude on cumulative injury load tolerance: a force weighting approach for low-back shear loads. THEORETICAL ISSUES IN ERGONOMICS SCIENCE 2013. [DOI: 10.1080/1463922x.2011.637581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
|
12
|
Heydari H, Hoviattalab M, Azghani MR, Ramezanzadehkoldeh M, Parnianpour M. INVESTIGATION ON A DEVELOPED WEARABLE ASSISTIVE DEVICE (WAD) IN REDUCTION LUMBAR MUSCLES ACTIVITY. BIOMEDICAL ENGINEERING-APPLICATIONS BASIS COMMUNICATIONS 2013. [DOI: 10.4015/s101623721350035x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A new wearable assistive device (WAD) was developed to decrease required force on the lumbar spine in static holding tasks. In order to obtain moments on lumbar spine in two conditions, with and without WAD, a biomechanical static model was used for estimation of external moments on lumbar spine. The results of biomechanical models indicated that there was a reduction in the lumbar moment ranging from 20% to 43% using WAD depending on the load and flexion angle. A total of 15 male healthy subjects were tested to experimentally verify the predicted reduction of external moments on the spine by wearing WAD. Normalized electromyography (EMG) of the right and left lumbar and thoracic erector spinae (LES, TES), latissimus dorsi (LD), external oblique (EO), internal oblique (IO) and rectus abdominus (RA) muscles were monitored at three lumbar flexion positions (0°, 30° and 60°) in symmetric posture with three different loads (0, 5 and 15 kg) in two conditions of with and without WAD. The effects of WAD and load were significant for all muscles but the interaction effects were only significant for extensor muscles groups (p < 0.016). Results of statistical analysis (ANOVA) on the normalized EMG while wearing WAD indicated that the muscle activity of right and left LES, TES and LD muscles significantly decreased (p < 0.001). This reduction for right LES, TES, LD muscles at 15 kg load and 60° trunk flexion were 23.2%, 30% and 27.8%, respectively which were in good agreement with the biomechanical model results.
Collapse
Affiliation(s)
- Hadi Heydari
- Department of Mechanical Engineering, Sharif University of Technology, Azadi Avenue, Tehran, Iran
| | - Maryam Hoviattalab
- Department of Mechanical Engineering, Sharif University of Technology, Azadi Avenue, Tehran, Iran
| | - Mahmood Reza Azghani
- Department of Mechanical Engineering, Sahand University of Technology, Tabriz, Iran
| | - Masoud Ramezanzadehkoldeh
- Department of Structural Engineering, Norwegian University of Science and Technology, Trondheim, Norway
| | - Mohamad Parnianpour
- Department of Industrial and Management Engineering, Hanyang University Ansan, Republic of Korea
| |
Collapse
|
13
|
Howarth SJ, Callaghan JP. Towards establishing an occupational threshold for cumulative shear force in the vertebral joint - an in vitro evaluation of a risk factor for spondylolytic fractures using porcine specimens. Clin Biomech (Bristol, Avon) 2013; 28:246-54. [PMID: 23360894 DOI: 10.1016/j.clinbiomech.2013.01.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 12/11/2012] [Accepted: 01/02/2013] [Indexed: 02/07/2023]
Abstract
BACKGROUND Injury models for spondylolytic fracture of the pars interarticularis have long considered repetitive shear loading as a risk factor without quantifying the relationship between shear force magnitude and fatigue life. This investigation sought to quantify the relationship using a basic in vitro approach. METHODS Thirty-two (16 C3-C4, 16 C5-C6) porcine cervical specimens were exposed to repetitive shear loading to 20%, 40%, 60%, or 80% of their calculated ultimate anterior shear failure tolerance. Shear force was cyclically applied at 1Hz for 21,600cycles or until bone failure was detected. Cumulative shear force and the number of cycles sustained until failure were calculated. Failure patterns were also documented. FINDINGS Cumulative shear and the number of cycles sustained prior to failure demonstrated a strong non-linearly decreasing relationship with increased force magnitude. In particular, sustained cumulative shear by the 40% group was 2.52 and 2.63MN∗s higher than for the 60% and 80% groups (P<0.0001). Despite undergoing an average of 230 more loading cycles, cumulative shear force sustained by the 60% group was not statistically different from the 80% group. Bilateral fractures of the cranial vertebra's pars interarticularis were most common, but less consistent at higher force magnitudes. INTERPRETATION Our investigation suggested that pars interarticularis damage may begin non-linearly accumulating with shear forces between 20% and 40% of failure tolerance (approximately 430 to 860N). Models of pars interarticularis injury and estimates of cumulative shear exposure may be enhanced from a tissue-based weighting method for low-back shear.
Collapse
Affiliation(s)
- Samuel J Howarth
- Canadian Memorial Chiropractic College, Toronto, Ontario, Canada
| | | |
Collapse
|
14
|
Ferguson SA, Marras WS, Allread WG, Knapik GG, Splittstoesser RE. Musculoskeletal disorder risk during automotive assembly: current vs. seated. APPLIED ERGONOMICS 2012; 43:671-8. [PMID: 22036450 PMCID: PMC3796442 DOI: 10.1016/j.apergo.2011.10.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 10/05/2011] [Accepted: 10/05/2011] [Indexed: 05/09/2023]
Abstract
Musculoskeletal disorder risk was assessed during automotive assembly processes. The risk associated with current assembly processes was compared to using a cantilever chair intervention. Spine loads and normalized shoulder muscle activity were evaluated during assembly in eight regions of the vehicle. Eight interior cabin regions of the vehicle were classified by reach distance, height from vehicle floor and front to back. The cantilever chair intervention tool was most effective in the far reach regions regardless of the height. In the front far reach regions both spine loads and normalized shoulder muscle activity levels were reduced. In the middle and close reach regions spine loads were reduced, however, shoulder muscle activity was not, thus an additional intervention would be necessary to reduce shoulder risk. In the back far reach region, spine loads were not significantly different between the current and cantilever chair conditions. Thus, the effectiveness of the cantilever chair was dependent on the region of the vehicle.
Collapse
Affiliation(s)
- Sue A Ferguson
- The Ohio State University, Integrated Systems Engineering, Biodynamics Laboratory, Center for Occupational Health in Automotive Manufacturing, 210 Baker Systems, 1971 Neil Avenue, Columbus, OH 43210, USA.
| | | | | | | | | |
Collapse
|
15
|
Howarth SJ, Callaghan JP. Compressive force magnitude and intervertebral joint flexion/extension angle influence shear failure force magnitude in the porcine cervical spine. J Biomech 2012; 45:484-90. [DOI: 10.1016/j.jbiomech.2011.11.051] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 10/25/2011] [Accepted: 11/27/2011] [Indexed: 11/30/2022]
|
16
|
Graham RB, Sadler EM, Stevenson JM. Does the personal lift-assist device affect the local dynamic stability of the spine during lifting? J Biomech 2011; 44:461-6. [DOI: 10.1016/j.jbiomech.2010.09.034] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Revised: 09/20/2010] [Accepted: 09/27/2010] [Indexed: 11/24/2022]
|