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Radwin RG, Hu YH, Akkas O, Bao S, Harris-Adamson C, Lin JH, Meyers AR, Rempel D. Comparison of the observer, single-frame video and computer vision hand activity levels. Ergonomics 2023; 66:1132-1141. [PMID: 36227226 PMCID: PMC10130228 DOI: 10.1080/00140139.2022.2136407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 10/10/2022] [Indexed: 05/11/2023]
Abstract
Observer, manual single-frame video, and automated computer vision measures of the Hand Activity Level (HAL) were compared. HAL can be measured three ways: (1) observer rating (HALO), (2) calculated from single-frame multimedia video task analysis for measuring frequency (F) and duty cycle (D) (HALF), or (3) from automated computer vision (HALC). This study analysed videos collected from three prospective cohort studies to ascertain HALO, HALF, and HALC for 419 industrial videos. Although the differences for the three methods were relatively small on average (<1), they were statistically significant (p < .001). A difference between the HALC and HALF ratings within ±1 point on the HAL scale was the most consistent, where more than two thirds (68%) of all the cases were within that range and had a linear regression through the mean coefficient of 1.03 (R2 = 0.89). The results suggest that the computer vision methodology yields comparable results as single-frame video analysis.Practitioner summary: The ACGIH Hand Activity Level (HAL) was obtained for 419 industrial tasks using three methods: observation, calculated using single-frame video analysis and computer vision. The computer vision methodology produced results that were comparable to single-frame video analysis.
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Affiliation(s)
| | - Yu Hen Hu
- University of Wisconsin, Madison, WI, USA
| | - Oguz Akkas
- University of Wisconsin, Madison, WI, USA
| | - Stephen Bao
- SHARP Program, Washington State Department of Labor and Industries, Olympia, WA, USA
| | | | - Jia-Hua Lin
- SHARP Program, Washington State Department of Labor and Industries, Olympia, WA, USA
| | - Alysha R. Meyers
- Division of Field Studies and Engineering, National Institute for Occupational Safety and Health, Cincinnati, OH, USA
| | - David Rempel
- University of California-San Francisco, San Francisco, CA, USA
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Kim JH, Vaughan A, Kincl L. Characterization of Musculoskeletal Injury Risk in Dungeness Crab Fishing. J Agromedicine 2023; 28:309-320. [PMID: 35440281 PMCID: PMC9869738 DOI: 10.1080/1059924x.2022.2068715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVES Commercial Dungeness crab fishermen's manual crab pot handling activities can be done in harsh outdoor working environments at sea and can pose well-known physical risk factors associated with musculoskeletal injury including forceful exertion, repetition and awkward posture. The nonfatal injury rate in this fishing fleet is 3.4 per 1,000 full-time equivalent workers. Two-thirds of self-reported injuries in the fleet were musculoskeletal sprains and strains. To date, no objective biomechanical assessment of musculoskeletal disorder (MSD) risk has been conducted due to the challenging work environment. METHODS The aim of this study was to determine the feasibility of collecting objective biomechanical assessments (i.e., posture and repetition) using inertial measurement unit (IMU) sensors placed on the arms and torso of professional deckhands (n = 7) while at sea, harvesting Dungeness crab. Based on the IMU-measured posture data, fishermen's anthropometry, and crab pot weights, biomechanical loading of the low back and both shoulders was estimated. RESULTS The IMU sensor data showed that commercial Dungeness crab fishing is highly repetitive and poses awkward postures in the shoulders and back. The estimated static low back compression, shear force, and flexion moment about the shoulders and low back (L5/S1) indicate potential injury risk associated with harvesting crab. CONCLUSION The results indicate that objective biomechanical assessment using the IMU sensors is feasible in the commercial fishing environment.
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Affiliation(s)
- Jeong Ho Kim
- Environmental and Occupational Health Program, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Amelia Vaughan
- Environmental and Occupational Health Program, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Laurel Kincl
- Environmental and Occupational Health Program, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon, USA
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Ehmke S, Farias Zuniga A, Keir PJ. Effect of Force, Posture, and Repetitive Wrist Motion on Intraneural Blood Flow in the Median Nerve. J Ultrasound Med 2021; 40:939-950. [PMID: 32896908 DOI: 10.1002/jum.15467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 06/21/2020] [Accepted: 06/28/2020] [Indexed: 06/11/2023]
Abstract
OBJECTIVES Pinching, deviated wrist postures, and repetitive motion are risk factors for carpal tunnel syndrome. Hypervascularization of the median nerve and increased intraneural blood flow proximal to the carpal tunnel result in finger force and deviated wrist postures. The purpose of this study was to determine the effects of pinching with and without force, wrist posture, and repetitive wrist motion on intraneural blood flow in the median nerve. METHODS Eleven healthy and 11 carpal tunnel syndrome-symptomatic individuals completed 3 sections of this study: 15 pinch posture force trials, 3 repetitive wrist motion trials, and 3 static wrist posture trials. Intraneural blood flow (centimeters per second) was measured with pulsed wave Doppler ultrasound during each trial. Transverse B-mode images obtained from static trials were used to calculate the median nerve cross-sectional area and circumference. RESULTS An analysis of variance statistical analysis revealed significant main effects of pinch posture force (F4,80 = 21.397; P < .001) and wrist posture (F2,40 = 14.545; P < .001). Intraneural blood flow velocities were significantly greater when 6 N of force was applied by the thumb, finger, or pinch compared to no applied force in the same postures. Intraneural blood flow velocities were higher at 30° wrist flexion (mean ± SD, 2.24 ± 0.42 cm/s) than neutral (2.06 ± 0.45 cm/s) and 30° wrist extension (1.97 ± 0.46 cm/s). No changes were found in response to repetitive wrist motion. CONCLUSIONS Flexed wrists as well as applied finger and thumb forces increase median nerve blood flow at the entry to the carpal tunnel, which may negatively affect the median nerve.
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Affiliation(s)
- Samantha Ehmke
- Occupational Biomechanics Laboratory, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Amanda Farias Zuniga
- Occupational Biomechanics Laboratory, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Peter J Keir
- Occupational Biomechanics Laboratory, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
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Jaeger JW, Adkins SC, Perez-Tamayo SC, Werth KE, Hansen G, Nimunkar AJ, Radwin RG. Automated Device for Uncapping Multiple-Size Bioanalytical Sample Tubes Designed to Reduce Technician Strain and Increase Productivity. SLAS Technol 2020; 26:320-326. [PMID: 33089763 DOI: 10.1177/2472630320967622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Technicians in a commercial laboratory manually uncap up to 700 sample tubes daily in preparation for bioanalytical testing. Manually twisting off sample tube caps not only is a time-consuming task, but also poses increased risk for muscle fatigue and repetitive-motion injuries. An automated device capable of uncapping sample tubes at a rate faster than the current workflow would be valuable for minimizing strain on technicians' hands and saving time. Although several commercial sample tube-uncapping products exist, they are not always usable for a workload that uses a mix of tube sizes and specific workflow. A functioning uncapping device was developed that can semi-automatically uncap sample tubes with three different heights and diameters and was compatible with the workflow in a commercial laboratory setting. Under limited testing, the average success rate with uncapping each of the three sample tube sizes or a mix of them was 90% or more, more than three times faster than manual uncapping, and met standard acceptance criteria using mass spectrometry. Our device with its current performance is still a prototype, requiring further development. It showed promise for ergonomic benefit to the laboratory technicians, however, reducing the necessity to manually unscrew caps.
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Affiliation(s)
- Jacob W Jaeger
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Scottland C Adkins
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Samuel C Perez-Tamayo
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Katelyn E Werth
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | | | - Amit J Nimunkar
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Robert G Radwin
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA.,Department of Industrial and Systems Engineering, University of Wisconsin-Madison, Madison, WI, USA
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Xiao L, Zhang Y, Liao B, Zhang Z, Ding L, Jin L. A Velocity-Level Bi-Criteria Optimization Scheme for Coordinated Path Tracking of Dual Robot Manipulators Using Recurrent Neural Network. Front Neurorobot 2017; 11:47. [PMID: 28928651 PMCID: PMC5591439 DOI: 10.3389/fnbot.2017.00047] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 08/17/2017] [Indexed: 11/13/2022] Open
Abstract
A dual-robot system is a robotic device composed of two robot arms. To eliminate the joint-angle drift and prevent the occurrence of high joint velocity, a velocity-level bi-criteria optimization scheme, which includes two criteria (i.e., the minimum velocity norm and the repetitive motion), is proposed and investigated for coordinated path tracking of dual robot manipulators. Specifically, to realize the coordinated path tracking of dual robot manipulators, two subschemes are first presented for the left and right robot manipulators. After that, such two subschemes are reformulated as two general quadratic programs (QPs), which can be formulated as one unified QP. A recurrent neural network (RNN) is thus presented to solve effectively the unified QP problem. At last, computer simulation results based on a dual three-link planar manipulator further validate the feasibility and the efficacy of the velocity-level optimization scheme for coordinated path tracking using the recurrent neural network.
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Affiliation(s)
- Lin Xiao
- College of Information Science and Engineering, Jishou University, Jishou, China
| | - Yongsheng Zhang
- College of Information Science and Engineering, Jishou University, Jishou, China
| | - Bolin Liao
- College of Information Science and Engineering, Jishou University, Jishou, China
| | - Zhijun Zhang
- School of Automation Science and Engineering, South China University of Technology, Guangzhou, China
| | - Lei Ding
- College of Information Science and Engineering, Jishou University, Jishou, China
| | - Long Jin
- School of Information Science and Engineering, Lanzhou University, Lanzhou, China
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Park JK. Job Hazard Analyses for Musculoskeletal Disorder Risk Factors in Pressing Operations of Dry-cleaning Establishments. Saf Health Work 2016; 7:389-393. [PMID: 27924244 PMCID: PMC5127904 DOI: 10.1016/j.shaw.2016.05.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 04/24/2016] [Accepted: 05/08/2016] [Indexed: 11/30/2022] Open
Abstract
Job hazard analyses were conducted to assess exposure to musculoskeletal disorder (MSD) risk factors in seven workers of three dry-cleaning establishments. In accordance with the Washington State Ergonomics Rule, the analyses were performed in two separate steps: (1) observation and checklist approaches were made to identify a "caution zone job" in the seven workers' pressing operations across the three shops; and (2) detailed posture and motion analyses were undertaken to determine a "MSD hazard" in one worker's operation using a video technique. One "caution zone job" was identified and it was the pressing operation job in which five physical risk factors were found in the pressing operations. The detailed analyses confirmed that one "MSD hazard", i.e., awkward posture in shoulders, was prevalent in the pressing operations of the three dry-cleaning facilities. It would be desirable to reduce MSD risk factors including awkward shoulder posture in the dry-cleaning industry.
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Affiliation(s)
- Jung-Keun Park
- Occupational Safety and Health Research Institute, Korea Occupational Safety and Health Agency, Ulsan, Republic of Korea
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Kociolek AM, Keir PJ. Development of a kinematic model to predict finger flexor tendon and subsynovial connective tissue displacement in the carpal tunnel. Ergonomics 2015; 58:1398-1409. [PMID: 25679821 DOI: 10.1080/00140139.2015.1013575] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
UNLABELLED Finger flexor tendinopathies and carpal tunnel syndrome are histologically characterised by non-inflammatory fibrosis of the subsynovial connective tissue (SSCT) in the carpal tunnel, which is indicative of excessive and repetitive shear forces between the finger flexor tendons and SSCT. We assessed flexor digitorum superficialis (FDS) tendon and adjacent SSCT displacements with colour Doppler ultrasound as 16 healthy participants completed long finger flexion/extension movements captured by a motion capture system. FDS tendon displacements fit a second-order regression model based on metacarpophalangeal and proximal interphalangeal joint flexion angles (R(2) = 0.92 ± 0.01). SSCT displacements were 33.6 ± 1.7% smaller than FDS tendon displacements and also fit a second-order regression model (R(2) = 0.89 ± 0.01). FDS tendon and SSCT displacement both correlated with finger joint thickness, enabling participant-specific anthropometric scaling. We propose the current regression models as an ergonomic method to determine relative displacements between the finger flexor tendons and SSCT. PRACTITIONER SUMMARY Relative displacements between the finger flexor tendons and SSCT provide insight into gliding and friction in the carpal tunnel. Our regression models represent a move towards mechanistic-based ergonomic risk assessment of the wrist/hand. This is a natural evolution of ergonomic methods based on tendon-joint interaction.
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Affiliation(s)
- Aaron M Kociolek
- a Department of Kinesiology , McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4K1 , Canada
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Abstract
A new equation for predicting the hand activity level (HAL) used in the American Conference for Government Industrial Hygienists threshold limit value®(TLV®) was based on exertion frequency (F) and percentage duty cycle (D). The TLV® includes a table for estimating HAL from F and D originating from data in Latko et al. (Latko WA, Armstrong TJ, Foulke JA, Herrin GD, Rabourn RA, Ulin SS, Development and evaluation of an observational method for assessing repetition in hand tasks. American Industrial Hygiene Association Journal, 58(4):278-285, 1997) and post hoc adjustments that include extrapolations outside of the data range. Multimedia video task analysis determined D for two additional jobs from Latko's study not in the original data-set, and a new nonlinear regression equation was developed to better fit the data and create a more accurate table. The equation, HAL = 6:56 ln D[F(1:31) /1+3:18 F(1:31), generally matches the TLV® HAL lookup table, and is a substantial improvement over the linear model, particularly for F>1.25 Hz and D>60% jobs. The equation more closely fits the data and applies the TLV® using a continuous function.
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Affiliation(s)
- Robert G. Radwin
- Department of Industrial and Systems Engineering, University of Wisconsin-Madison
- Corresponding Author University of Wisconsin-Madison, 1550 Engineering Drive, Madison, WI 53706-1608,
| | - David P. Azari
- Department of Industrial and Systems Engineering, University of Wisconsin-Madison
| | - Mary J. Lindstrom
- Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison
| | - Sheryl S. Ulin
- Department of Industrial and Operations Engineering, University of Michigan
| | | | - David Rempel
- Department of Medicine, University of California, San Francisco
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Akkas O, Azari DP, Chen CHE, Hu YH, Ulin SS, Armstrong TJ, Rempel D, Radwin RG. A hand speed-duty cycle equation for estimating the ACGIH hand activity level rating. Ergonomics 2015; 58:184-94. [PMID: 25343278 PMCID: PMC4664886 DOI: 10.1080/00140139.2014.966155] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
An equation was developed for estimating hand activity level (HAL) directly from tracked root mean square (RMS) hand speed (S) and duty cycle (D). Table lookup, equation or marker-less video tracking can estimate HAL from motion/exertion frequency (F) and D. Since automatically estimating F is sometimes complex, HAL may be more readily assessed using S. Hands from 33 videos originally used for the HAL rating were tracked to estimate S, scaled relative to hand breadth (HB), and single-frame analysis was used to measure D. Since HBs were unknown, a Monte Carlo method was employed for iteratively estimating the regression coefficients from US Army anthropometry survey data. The equation: HAL = 10[e(-15:87+0:02D+2:25 ln S)/(1+e(-15:87+0:02D+2:25 ln S)], R(2) = 0.97, had a residual range ± 0.5 HAL. The S equation superiorly fits the Latko et al. ( 1997 ) data and predicted independently observed HAL values (Harris 2011) better (MSE = 0.16) than the F equation (MSE = 1.28).
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Affiliation(s)
- Oguz Akkas
- a Department of Industrial and Systems Engineering , University of Wisconsin-Madison , Madison , WI , USA
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Chen CH, Azari D, Hu YH, Lindstrom MJ, Thelen D, Yen TY, Radwin RG. The accuracy of conventional 2D video for quantifying upper limb kinematics in repetitive motion occupational tasks. Ergonomics 2015; 58:2057-66. [PMID: 25978764 PMCID: PMC4684497 DOI: 10.1080/00140139.2015.1051594] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Marker-less 2D video tracking was studied as a practical means to measure upper limb kinematics for ergonomics evaluations. Hand activity level (HAL) can be estimated from speed and duty cycle. Accuracy was measured using a cross-correlation template-matching algorithm for tracking a region of interest on the upper extremities. Ten participants performed a paced load transfer task while varying HAL (2, 4, and 5) and load (2.2 N, 8.9 N and 17.8 N). Speed and acceleration measured from 2D video were compared against ground truth measurements using 3D infrared motion capture. The median absolute difference between 2D video and 3D motion capture was 86.5 mm/s for speed, and 591 mm/s(2) for acceleration, and less than 93 mm/s for speed and 656 mm/s(2) for acceleration when camera pan and tilt were within ± 30 degrees. Single-camera 2D video had sufficient accuracy (< 100 mm/s) for evaluating HAL. Practitioner Summary: This study demonstrated that 2D video tracking had sufficient accuracy to measure HAL for ascertaining the American Conference of Government Industrial Hygienists Threshold Limit Value(®) for repetitive motion when the camera is located within ± 30 degrees off the plane of motion when compared against 3D motion capture for a simulated repetitive motion task.
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Affiliation(s)
- Chia-Hsiung Chen
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison
| | - David Azari
- Department of Industrial and Systems Engineering, University of Wisconsin-Madison
| | - Yu Hen Hu
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison
| | - Mary J. Lindstrom
- Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison
| | - Darryl Thelen
- Department of Mechanical Engineering, University of Wisconsin-Madison
| | - Thomas Y. Yen
- Department of Industrial and Systems Engineering, University of Wisconsin-Madison
| | - Robert G. Radwin
- Department of Industrial and Systems Engineering, University of Wisconsin-Madison
- Corresponding Author Robert G, Radwin, PhD, 1550 Engineering Drive, University of Wisconsin-Madison, Madison, WI 53706, 608-263-6596, 608-262-8454,
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Taş S, Balta S, Benlier E. Spontaneous Rupture of the Extensor Pollicis Longus Tendon due to Unusual Etiology. Balkan Med J 2014; 31:105-6. [PMID: 25207178 DOI: 10.5152/balkanmedj.2013.9027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 09/12/2013] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND The etiology of spontaneous rupture of the extensor pollicis longus tendon includes systemic or local steroid injections, wrist fracture, tenosynovitis, synovitis, rheumatoid arthritis, and repetitive wrist motions. CASE REPORT We encountered a case of extensor pollicis longus tendon rupture with an unusual etiology, cow milking. In this case, transfer of the extensor indicis proprius tendon was performed successfully. At 1 year after surgery, extension of the thumb was sufficient. CONCLUSION It appears that patients with occupations involving repetitive motions are at a high risk of closed tendon ruptures.
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Affiliation(s)
- Süleyman Taş
- Department of Plastic, Reconstructive and Aesthetic Surgery, Trakya University Faculty of Medicine, Edirne, Turkey
| | - Serkan Balta
- Department of Plastic, Reconstructive and Aesthetic Surgery, Trakya University Faculty of Medicine, Edirne, Turkey
| | - Erol Benlier
- Department of Plastic, Reconstructive and Aesthetic Surgery, Trakya University Faculty of Medicine, Edirne, Turkey
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Abstract
OBJECTIVE A new method is described for automatically quantifying repetitive hand activity with the use of digital video processing. BACKGROUND The hand activity level (HAL) is widely used for evaluating repetitive hand work. Conventional methods involving either a trained observer on- or off-site or manual off-site video analysis are often considered inaccurate, cumbersome, or impractical for routine work assessment METHOD A cross-correlation-based template-matching algorithm was programmed to track the motion trajectory of a selected region of interest across successive video frames for a single camera to measure repetition frequency, duty cycle, and HAL. A simple, paced, load transfer task was used to simulate a repetitive industrial activity. A total of 12 participants were videoed performing the task for varying HAL conditions. The automatically predicted HAL was compared with the manually measured HAL with the use of frame-by-frame video analysis. RESULTS Predicted frequency, duty cycle, and HAL were in concert with the manually measured HAL conditions. The linear regression slopes of the automatically predicted values with respect to the manually measured values were 0.98 (R2 = .79), 1.27 (R2 = .63), and 1.06 (R2 = .77) for frequency, duty cycle, and HAL, respectively. CONCLUSION A proof-of-concept for automatic video-based direct exposure assessment was demonstrated. APPLICATION The video assessment method for repetitive motion is promising for automatic, unobtrusive, and objective exposure assessment, which may offer broad availability with the use of a camera-enabled mobile device for helping evaluate, prevent, and control exposure to repetitive motions related to upper-extremity injuries in the workplace.
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Affiliation(s)
- Chia-Hsiung Chen
- University of Wisconsin-Madison, 1550 Engineering Dr., Madison, WI 53706-1608, USA
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Abstract
BACKGROUND Pneumatic nail guns used in wood framing are equipped with one of two triggering mechanisms. Sequential actuation triggers have been shown to be a safer alternative to contact actuation triggers because they reduce traumatic injury risk. However, the sequential actuation trigger must be depressed for each individual nail fired as opposed to the contact actuation trigger, which allows the trigger to be held depressed as nails are fired repeatedly by bumping the safety tip against the workpiece. As such, concerns have been raised about risks for cumulative trauma injury, and reduced productivity, due to repetitive finger motion with the sequential actuation trigger. PURPOSE This study developed a method to predict cumulative finger flexor tendon travel associated with the sequential actuation trigger nail gun from finger joint kinematics measured in the trigger actuation and productivity standards for wood-frame construction tasks. METHODS Finger motions were measured from six users wearing an instrumented electrogoniometer glove in a simulation of two common framing tasks-wall building and flat nailing of material. Flexor tendon travel was calculated from the ensemble average kinematics for an individual nail fired. RESULTS Finger flexor tendon travel was attributable mostly to proximal interphalangeal and distal interphalangeal joint motion. Tendon travel per nail fired appeared to be slightly greater for a wall-building task than a flat nailing task. The present study data, in combination with construction industry productivity standards, suggest that a high-production workday would be associated with less than 60 m/day cumulative tendon travel per worker (based on 1700 trigger presses/day). CONCLUSION AND APPLICATIONS These results suggest that exposure to finger tendon travel from sequential actuation trigger nail gun use may be below levels that have been previously associated with high musculoskeletal disorder risk.
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Affiliation(s)
- Brian Lowe
- National Institute for Occupational Safety and Health, Division of Applied Research and Technology, Robert A. Taft Laboratories, 4676 Columbia Parkway, Mail Stop C-24, Cincinnati, OH 45226, USA
| | - James Albers
- National Institute for Occupational Safety and Health, Division of Applied Research and Technology, Robert A. Taft Laboratories, 4676 Columbia Parkway, Mail Stop C-24, Cincinnati, OH 45226, USA
| | - Stephen Hudock
- National Institute for Occupational Safety and Health, Division of Applied Research and Technology, Robert A. Taft Laboratories, 4676 Columbia Parkway, Mail Stop C-24, Cincinnati, OH 45226, USA
| | - Edward Krieg
- National Institute for Occupational Safety and Health, Division of Applied Research and Technology, Robert A. Taft Laboratories, 4676 Columbia Parkway, Mail Stop C-24, Cincinnati, OH 45226, USA
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Abstract
Work-related musculoskeletal disorders (WMSDs) represent approximately one third of workers' compensation costs in US private industry, yet estimates of acceptable exposure levels for forceful and repetitive tasks are imprecise, in part, due to lack of measures of tissue injury in humans. In this review, the authors discuss the scope of upper-extremity WMSDs, the relationship between repetition rate and forcefulness of reaching tasks and WMSDs, cellular responses to injury in vivo and in vitro, and animal injury models of repetitive, forceful tasks. The authors describe a model using albino rats and present evidence related to tissue injury and inflammation due to a highly repetitive reaching task. A conceptual schematic for WMSD development and suggestions for further research are presented. Animal models can enhance our ability to predict risk and to manage WMSDs in humans because such models permit the direct observation of exposed tissues as well as motor behavior.
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Affiliation(s)
- Ann E Barr
- Physical Therapy Department, College of Allied Health Professions, Temple University, 3307 N Broad St (602-00), Philadelphia, PA 19140, USA.
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