Construction Safety Association of Ontario 21 Voyager Court South, Etobicoke, Ontario, Canada M9W 5M7

.

.

(416) 674-CSAO (2726) 1-800 781-CSAO(2726) Fax: (416) 674-8866 www.csao.org [email protected]

Final Report (WSIB Grant #01023)

Reducing Risk Of Musculoskeletal Disorders and Promoting Return-To-Work Through The Use Of Rebar Tying Machines

Tony Almeida

Peter Vi

International Association of Bridge Structural and Ornamental Iron Workers, Local 721 (416) 236-4026

Construction Safety Association of Ontario 416-679-4050 [email protected]

September, 2004

Table Of Contents 1.0 Plain Language Summary.................................................................................................... 1 2.0 Executive Summary .................................................................................................................. 2 2.1 Research Objectives.............................................................................................................. 2 2.2 Research Publications & Presentation at Research Conferences.......................................... 2 2.3 Presentations and reports to worksite partners and trade association ................................... 3 2.4 Reducing risk of musculoskeletal disorders through the use of rebar-tying machines......... 5 Methodology ........................................................................................................................... 5 Findings................................................................................................................................... 5 Implications and Recommendations ....................................................................................... 6 2.5 A Field Study of Rebar Tying Machine as a Tool to Reduce Risk of Musculoskeletal Disorders ..................................................................................................................................... 7 Methodology ........................................................................................................................... 7 Findings................................................................................................................................... 7 Implications and Recommendations ....................................................................................... 8 2.6 Promoting Early Return To Pre-injury Job Using A Rebar-Tying Machine ....................... 9 Methodology ........................................................................................................................... 9 Findings................................................................................................................................. 10 Implications and Recommendations ..................................................................................... 10 Appendix A:.................................................................................................................................. 12 Appendix B: .................................................................................................................................. 25 Appendix C: .................................................................................................................................. 60

Rodworkers Intervention Studies

WSIB Grant #01023

1.0 Plain Language Summary The purpose of this study was to determine the potential reduction in the risk of musculoskeletal injuries to rodworkers when using an automatic rebar tying machine, and to determine the efficacy of the rebar tying machine as a rehabilitation device for the purpose of assisting injured workers in an early return to work program. The research project was divided into three phases. The first phase of the study was conducted in a controlled laboratory setting to investigate the biomechanical differences between manual tying and using the rebar-tying machine. In the second phase of the study, a field experiment was conducted to investigate the long-term health benefits of using the rebar-tying machine. The last stage of the study was also conducted in the field setting to test the efficacy of the rebar-tying machine as a rehabilitation device to assist injured workers in an early return-to-work program.

The results from the first two studies consistently showed a reduction in awkward posture of the trunk, wrist, and arms when rodworkers worked with the rebar-tying machine. The reduction in awkward wrist/hand motion and static awkward trunk poster can lead to a reduction in the risk of musculoskeletal injuries. The first two phases also revealed the tying machine’s ability to tie rebar of various sizes and at the same time increase tying speed when comparing to traditional manual method in some applications. Subjective inputs from experienced rodworkers indicated that they prefer to work with the tying machine. The perception of “de-skilling” the rebar trade when using the tying machine was not found to be a factor in preventing the use of the mechanical tool. In the third phase of the study, the tying machine was evaluated for its potential promotion of early return to work. The results from the four injured rodworkers indicated the tying machine was able to accommodate their injuries, allowing the workers to return to their pre-injury job. 1 of 78

Rodworkers Intervention Studies

WSIB Grant #01023

2.0 Executive Summary

2.1 Research Objectives 1. To determine the potential reduction in the risk of musculoskeletal injuries to rodworkers when using an automatic rebar tying machine.

2. To determine the efficacy of the rebar tying machine as a rehabilitation device for the purpose of assisting injured workers in an early return to work program.

3. To share the results with rodworkers, and other construction trades and firms so that exposure to ergonomic hazards can be eliminated or reduced.

2.2 Research Publications & Presentation at Research Conferences Most findings have been written and submitted for publication in research journals and conferences. All of these papers can be found in the Appendix of this final report. The results of each paper will be reported below as an executive summary rather than repeating the contents of the papers. The research papers submitted to date are:

1. Vi, P., (2003). Reducing risk of musculoskeletal disorders through the use of rebar-tying machines. Applied Occupational and Environmental Hygiene, 18:1-6. (Appendix A)

2 of 78

Rodworkers Intervention Studies

WSIB Grant #01023

2. Vi, P, and Almeida P. Using rebar tying machine to reducing awkward trunk posture while performing reinforcing steel work. Submitted to the Human Factors and Ergonomics Society 49th Annual Meeting.

3. Vi, P, and Almeida P. A field study of rebar tying machine as a tool to reduce risk of musculoskeletal injuries. Submitting to International Journal of Industrial Ergonomics. (Appendix B)

4. Vi P. Promoting early return to pre-injury job using a rebar tying machine. Submitted to Applied Occupational and Environmental Hygiene. (Appendix C)

2.3 Presentations and reports to worksite partners and trade association Presentations and reports to worksite partners, CSAO’s Labour-Management Committees, and trade association magazine are listed below. Due to the volume and redundancy with the journal article submissions, these reports and presentation have not been included in the final report.

1. “Reducing Risk Of Musculoskeletal Disorders and Promoting Return-To-Work Through The Use Of Rebar Tying Machines – Executive Summary”. Presentation to Rodworkers’ Labour-Management Health & Safety Committee, Toronto, ON, August, 2004.

2. “Rebar-tying machines – Part 1: An effective way to reduce upper limbs MSIs”. Trade magazine article published in the Construction Safety Magazine, Volume 12 (number 4), 2003.

3 of 78

Rodworkers Intervention Studies

WSIB Grant #01023

3. “Rebar-tying machines – Part 2: An effective way to reduce low back MSIs”. Trade magazine article published in the Construction Safety Magazine, Volume 14 (number 1), 2004.

4. “More than rebar”. Trade magazine article published in the NetworkNews, September 2004.

5. Final report and presentation for CSAO Rodworkers Labour-Management Committee, October, 2004.

6. Final report and presentation for CSAO Electrician Labour-Management Committee, October, 2004.

7. “A field study of rebar tying machine”. Submitted to CSAO Construction Safety Magazine, November 2004.

8. “Promoting early return-to-work using a rebar tying machine”. Submitted to the CSAO Construction Safety Magazine, February 2005.

4 of 78

Rodworkers Intervention Studies

WSIB Grant #01023

2.4 Reducing risk of musculoskeletal disorders through the use of rebar-tying machines

Methodology To evaluate the potential risk of low-back and upper limb injury and the benefits of using the rebar-tying machine, a controlled experiment with nine apprentices was conducted. The experiment took place at the International Association of Bridge, Structural, Ornamental, and Reinforcing Ironworkers Local 721 Training Centre. Simulated rebar tying tasks were performed to evaluate the biomechanical/ergonomic stresses on rodworkers. Two rebar tying methods were evaluated in this experiment: (1) manual tying, and (2) using a MAX RB392 (MAX USA, New York) rebar-tying gun. For each tying method, participants were asked to perform 50 horizontal ties of 15 mm by 15 mm rebar combination located at floor level. To evaluate the biomechanical stresses on rodworkers, rebar-tying tasks were evaluated using electrogoniometers (to measure wrist and arm angles), and electromyography (to measure low-back muscle activities).

Findings 1. For all planes of motion (flexion/extension, radial/ulnar, and pronation/supination), significant (p110-120

>100-110

>90-100

>80-90

>70-80

>60-70

>50-60

>40-50

>30-40

>20-30

>10-20

>-10-10

0-1

10 >8-10

7-8 6-7

>6-8

5-6 4-5

>4-6 Time (sec)

3-4 >2-4

2-3 1-2

>1-2 0-1

>90

>80-90

>70-80

>60-70

>50-60

>40-50

>30-40

>20-30

>10-20

>-10-10