Workplace Ergonomics: Understanding and Preventing Musculoskeletal Disorders and Injuries

1. Workplace Ergonomics: Understanding and Preventing Musculoskeletal Disorders and Injuries Part II: Identifying the Risk Factors for Musculoskeletal Disorders Developers: Margaret Nuesca and Karen Traicoff (Occupational Therapy Students) Project Advisors: Tiffany Boggis, MBA, OTR/L and Zachery Collins, MOTR/L, CEAS Director, School of Occupational Therapy: John White, Ph. D, OTR/L Spring 2010

2. Ergonomic Risk Factor Interaction • Risk factors inherent in the Worker: • Physical • Psychological • Non-work related activities • Risk factors inherent in the Job: • Work procedures • Equipment • Workstation design • Risk factors inherent in the environment • Physical • Psychosocial “climate” Worker Task/Job Environment The goal of ergonomics is to design the job to fit the worker NOT make the worker fit the job

3. Risk Factors that lead to Musculoskeletal Disorders • Repetition • Force • Posture • Duration • Contact Stresses • Psychosocial factors

4. Repetition • Repetition is performing the same postures or motions again and again • Can be very frequent over short period of time • Can be less frequent but repeated over time • A job is considered repetitive if the basic cycle time is less than 30 seconds primarily for hand/wrist motions • Example: Typing on a keyboard • A job requiring back or shoulder movements is considered repetitive with a several minute interval • Example: Lifting boxes from the floor • Repetition combined with other risk factors such as awkward postures and force can increase the risk injury. • Examples: • Typing on a keyboard with wrist bent • Holding a phone with shoulder and cheek • Lifting heavy material without proper body mechanics

5. Force • Defined as a strenuous physical exertion usually with heavy loads, may be performed as a push, pull or lift. • Common activities contributing to excessive force: • Lifting and carrying • Pushing and pulling • Reaching to pick up loads • Prolonged holding • Pinching or squeezing • Force combined with other risk factors such as awkward postures and duration can increase the risk injury. • Maximum Force Guidelines to take into consideration by Wick & McKinnis (1998): • Pinch Grip max of 8 lbs (3.6 kg) • Power Grip max of 25 lbs (11.3 kg) • Push max of 24 lbs (11 kg) • Pull max of 18 lbs (8.2 kg) • Static Force Exertion max of 60 seconds

6. Posture • Proper Neutral Posture consist of: • Spine in 3 natural curves (back straight) • Arms & legs parallel to the torso (arms & shoulders down to the side, legs straight) • Elbows, hips, & knees may be at 90 degrees or more (elbows bent, body sitting) • Awkward Postures • Are often caused by misalignment between the user’s body/joints and the accessories and/or computer components • Occurs when the body moves out of a neutral sitting/standing position • Awkward postures that can lead to injury are: • Reaching to pick up loads • Twisting while lifting • More than 60 seconds in an awkward posture may become a risk factor, such as: • Working overhead • Bending over to floor/ground • Working with wrist bent or typing at the computer

7. Duration • Defined as maintaining a task or position for an extended time • There are various forms of duration • Short Duration: Occurring less than 1 hour a day • Moderate Duration: Occurring 1-2 hours a day • Long Duration: Occurring more than 2 hours a day • Examples of duration that produce higher risks: • Prolonged sitting and standing with no rest/stretch breaks increases the risk of low-back pain • Holding arms over head or arms/elbows extended in a fixed awkward position for a long duration becomes a risk factor • Sustaining a fixed task or position for long periods of time decreases blood circulation

8. Contact Stresses • Defined as pressure of the soft tissue and skin against any hard surface • Contact stress combined with force and repetition increases risk factor • Examples: • Resting wrist or forearm over the edge of the work tables • Legs lose circulation by contact with edge of a chair • Using one’s hand as a hammer, such as compacting items or pushing down on a stapler • Working on knees without cushions • Sustaining a fixed position for long periods of time decreases blood circulation and may damage tissue or a nerve • Examples: • damaged ligaments leading to tendonitis • damaged median nerve leading to carpal tunnel syndrome

9. Psychosocial factors • Work-related job stressors as seen in: • High mental demands • Workloads and deadlines • Low job control • Poor social support • Non work-related stressors may include: • Depression and anxiety • Symptoms of psychological distress • Home problems • There is increasing evidence that psychosocial factors related to job and work environment play a role in the development of work-related MSDs of the UE and back. • Studies have shown that psychosocial demands may produce increased muscle tension and exacerbated task-related biomechanical strain (National Institute for Occupational Safety and Health, 1997). • Psychosocial demands may affect awareness and reporting of MSD symptoms, and/or perceptions of their cause.

10. Part II Summary • Risk factors that contribute to MSD’s within the workplace are: • Repetition • Force • Posture • Duration • Contact Stresses • Psychosocial • A combination of these risk factors can increase the likelihood for injury

11. References Claiborne, D. K., Powell, N. J. & Reynolds-Lynch, K. (1999). Ergonomics and cumulative trauma disorders: A handbook for occupational therapists. San Diego: Singular Publishing Group, Inc. Konz, S. & Johnson, S.  (2004).  Work design:  Occupational ergonomics. Scottsdale, AZ:  Holcomb Hathaway.  National Institute for Occupational Safety and Health (1997). Musculoskeletal disorders and workplace factors: A critical review of epidemiologic evidence for work-related musculoskeletal disorders of the neck, back, upper extremity, and low back. Retrieved from http://www.cdc.gov/niosh/docs/97-141/ergotxt1.html Department of Business and Consumer Business Oregon OSHA (no date). Introduction to Ergonomics: How to indentify, control, and reduce musculoskeletal disorders in your workplace. Retrieved from http://www.cbs.state.or.us/external/osha/educate/training/pages/201outline.html University of Oregon, Labor Education and Research Center, & Oregon Occupational Safety and Health Administration(2008). Applied Ergonomics for Long Term Care [PowerPoint slides]. Retrieved from http://www.orosha.org/grants/resident_handling/docs/SRHAppliedErgonomicstraining2008.ppt. Wick, J. & McKinnis, M. (1998). A structured ergonomics design review process. In S. Kumar (Ed.), Advances in Occupational Ergonomics and Safety (pp. 143-146). Amsterdam: IOS Press.