Preventing Musculoskeletal Illnesses through Ergonomics Session Objectives ERGONOMICS

Preventing Musculoskeletal Illnesses through Ergonomics

Session Objectives ERGONOMICS l l l l Define ergonomics and provide brief history SMU Statistics Discuss purpose, scope and goal of ergonomics Design and Task Factors that effect ergonomics Physical effects of risk factors Present application strategies with emphasis on job design Examples

What Is Ergonomics? ERGONOMICS ¢Ergonomics focuses on fitting jobs and tasks to the worker that must perform them. ¢The basic definition is “the study of work in relation to the physiological and psychological capabilities and limitations of people. ” ¢Ergonomics utilizes the principles of many different disciplines, engineering, physics, psychology, human physiology, and business management. ¢Ergonomists are able to reach their goals through engineering and workplace designs. Ergonomics from the Greek words: ¢Ergo = work ¢Nomos = laws

Other Terms ERGONOMICS Engineering psychology l Human factors l Human engineering l Biomechanics l Work physiology l Engineering anthropometry l

History of Ergonomics Stover H. Snook Ph. D. , Harvard School of Public Health ERGONOMICS PHYSIOLOGICAL ROOT • Ramazzini (1633 -1714) • Alice Hamilton (1869 -1970) • Health of Munnition Workers Committee (1915)--UK • Industrial Fatigue Research Board (1918)--UK • Industrial Health Research Board (1928)--UK • Harvard Fatigue Laboratory (1927 -1946) ANTHROPOMETRIC ROOT • WWI--Army surveys for clothing size • U. S. . Depts. of Agriculture and Commerce (1939) Surveys of women and children, and standards in clothing sizes • WWII--Military surveys for clothing and equipment PSYCHOLOGICAL ROOT • Hawthorne Studies (1924 -1927 NRC) • WWII weapons systems • Army gunnery studies (Tufts University) • Navy systems Research Lab (Harvard, Johns Hopkins) • Air Corps flight program (Ohio State) ENGINEERING ROOT • Frederick W. Taylor (1856 -1915)--time study • Frank and Lillian Gilbreth--motion study • WWII radar, computers, nuclear devices, high performance aircraft • Biomechanics--medical applications

(4/1/00 to 3/31/03)

(4/1/00 to 3/31/03)

Ergonomics ERGONOMICS The overall goals of ergonomics are: ¢Provide a safe and healthful work environment engineered to the capabilities of the human body ¢Decrease worker fatigue and discomfort through the elimination or minimization of excess effort ¢Increase efficiency and productivity ¢Improve production by providing designs that reduce the potential for human error ¢Enhance customer service through improved worker morale ¢Elevate job satisfaction ¢Reduce injuries/illnesses ¢Reduce Costs Improved Work Methods Increased Efficiency Better Tools Less Fatigue Fewer Errors Less Rework Increased Productivity

Anthropometry ERGONOMICS The average person fallacy

Individual Differences: Most Important Are Age and Gender ERGONOMICS l l l l We get shorter as we age We get weaker as we age Women have less than 50% of the isometric strength as men Female heart rates are higher Females recover faster from exertions 8% of males are color deficient Response time, vision, and hearing deteriorate with age 10% of population is left handed

Material Characteristics Task/Workplace Characteristics Task Demands Organizational Characteristics Environmental Characteristics Personal Characteristics Physiological Capacity Primary factors influencing task demands to worker capacity (dempsey, 1998) Quality Performance Fatigue Discomfort Injury Worker Capacity Psychological Capacity Biomechanical Capacity P. G. Dempsey, A Critical review of biomechanical, epidemiological, physiological and psychophysical criteria for designing manual handling tasks, Ergonomics, 1998, Vol. 41. No 1

Ergonomics Process ERGONOMICS Pre - Injury Prevention Management Leadership Targeting Primary Cost Drivers Ergonomic Job Accommodations Job Hazard Analysis Transitional Duty Worker Health Care Liaison Plan Rehabilitation Services Disability Management Programs Hazard Reduction & Control Education and Training Employee Participation Job Placement Medical Evaluations Post - Injury Action and Return to Work

Shoulder/Neck/Back ERGONOMICS The shoulder joint is perhaps one of the most mobile and most complex of the joints in the human body. The importance of the shoulder joint becomes apparent when one considers the types of activities associated with the shoulder: • Pushing • Pulling • Lifting • Pressing • Holding The shoulder joint is involved either as a prime mover or as a support for almost every activity that involves the arms. This is accomplished by the inherent mobility of the shoulder. The shoulder is made up of complex bones and muscles that interact to form the “shoulder girdle. ”

Shoulder/Neck/Back ERGONOMICS There are several bones involved in the shoulder joint. These bones Include: ¢Scapula ¢Humerus ¢Clavicle ¢Acromion ¢Coracoid Process Several of these bones have laymen’s terms by which they are known, including “shoulder blade” for scapula, “upper arm” for the humerus, and “collar bone” for the clavicle.

Shoulder/Neck/Back ERGONOMICS The vertebrae are the bone components of the back, and collectively Form the spine. The vertebrae are classified based on their location In the spine, including: ¢Cervical ¢Thoracic ¢Lumbar ¢Sacrum ¢Coccygeal

Shoulder/Neck/Back ERGONOMICS Each vertebra of the spine is separated from its neighboring vertebrae by the intervertebral discs. The discs provide cushioning between the vertebrae and allow for some degree of mobility, which enables the vertebrae to twist and bend in relation to one another. The overall structure of the discs and vertebrae is held together by ligaments, and moved through the action of muscles. The muscles also provide stability to the torso and allow for posturing of the back. The vertebrae themselves offer protection to the spinal cord, which passes between vertebrae via the foramen. Foramen is the space between vertebrae.

CTDs ERGONOMICS Cumulative Trauma Disorders: l l l To start with, CTDs are disorders of the musculoskeletal system. That means that they are related to the muscles, nerves, tendons, ligaments, cartilage, and joints of the body. Typically, CTDs are not sudden injuries, but are rather illnesses that develop gradually over time. CTDs are commonly a resultant of repeated mechanical stresses on the body. CTDs can result in losses of mobility and strength of the body. CTDs are also commonly known as Work-Related Musculoskeletal Disorders, which means that the person’s occupation played a role in development of the condition, or made a preexisting condition worse.

Common CTD Symptoms ERGONOMICS l l Loss of feeling, sluggish or weak muscle or joint Numbness Tingling Soreness in evenings or after extended activity periods

Hand/Wrist/Arm ERGONOMICS l Common ergonomic risk factors to the hand/wrist/arm include: l Awkward Postures l Forceful Exertions l Repetitive Movements l Mechanical Stress l Vibration l Temperature Extremes Wrist Flexion Ulnar Deviation Wrist Extension Radial Deviation

Hand/Wrist/Arm ERGONOMICS The nerves that service the forearm and hand include the ulnar, radial, and musculocutaneous nerves. The nerves that connect and move the wrist and hand include the radial, ulnar, and median nerves. The ulnar nerve and arteries travel along the forearm and outside the carpal tunnel. The median nerve passes through the carpal tunnel.

Hand/Wrist/Arm ERGONOMICS The hand/arm/wrist are subjected to several different stresses. Therefore, there are quite a few CTDs associated with the hand/arm/wrist. These include: Tendonitis l Tenosynovitis l De Quervain’s Disease Trigger Finger Carpal Tunnel Syndrome (CTS) l Ganglion Cysts l Epicondylitis l

Hand/Wrist/Arm ERGONOMICS l Tendonitis Inflammation of tendons. Tendons are the connective tissue that links muscles to bones, and allows for translation of muscular contraction into skeletal movement. Undue physical force and repetitive motions can cause inflammation of the tendons, resulting in tendonitis.

Hand/Wrist/Arm ERGONOMICS l Tenosynovitis (De Quervain’s Disease, Trigger Finger) Inflammation of a tendon sheath. Tendon sheath provide lubricated pathways in the human body so tendons can move freely along their designed axis of movement. The sheath minimizes friction which helps to protect the tendon. Repetitive motion cause inflammation of these sheaths.

Hand/Wrist/Arm ERGONOMICS ¢Carpal Tunnel Syndrome - CTS Compression of the median nerve within the carpal tunnel. The carpal tunnel is a location where several tendons pass through the wrist, connecting to the fingers of the hand. The median nerve also passes through the carpal tunnel. When pressure in the carpal tunnel is increased (possibly due to ergonomic risk factors) that pressure is translated to the median nerve, causing inflammation to the nerve. This can result in symptoms of numbness, tingling or burning in the area of the hand connected by the median nerve (first 3 fingers)

Hand/Wrist/Arm ERGONOMICS ¢Ganglion Cysts A benign cystic tumor connected to a joint membrane or a tendon sheath. These cysts consist of a thin fibrous capsule enclosing a clear mucinous fluid. Most commonly seen on the backside of the wrist, ganglionic cysts may also form at the shoulder, elbow, or knees.

Hand/Wrist/Arm ERGONOMICS ¢Epicondylitis Inflammation of the tendons that anchor the muscles of the forearm to the elbow. These muscles and tendons also connect to both the fingers and the hand. Repetitive use of these muscles and tendons, in maneuvers such as grasping, twisting, and gripping, can cause inflammation, and thus epicondylitis. Other terms by which epicondylitis is also known are: ¢Lateral Epicondylitis – Tennis Elbow ¢Medial Epicondylitis – Golfer’s Elbow

Awkward Postures = Postures outside of neutral. Neutral is the optimal position of each joint that provides the most strength and control Awkward or unsupported postures that stretch physical limits, can compress nerves and irritate tendons Before: Technician tilts his neck forward to view the screen into a non-neutral posture. He also bends over resting on his forearms to write on the documents. Ergonomic Improvement: Technician easily views the screen from a neutral posture. The workstation adjusts to accommodate different working heights and users. When standing, work should be about elbow height.

Repetition = Performing the same motion or group of motions excessively. Examples of Repetition l l Repeating the same motion every few seconds or repeating a cycle of motions involving the same body parts more than twice per minute for more than 2 consecutive hours in a row Using a tool or an input device, such as a keyboard in a steady manner for more than 4 hours total in a work day Excessive repetition of movements can irritate tendons and increase pressure on nerves

Force = A strong physical exertion Exertion = the tension produced by muscles and transmitted through tendons Excessive muscle tension can contract muscles to their maximum capability which can lead to fatigue and possible damage to the muscles and other tissues. Before: Three employees climb on garbage bin to dump cart full of waste. They risk back strain and lacerations while tipping cart over to empty it. Ergonomic Improvement: One worker easily dumps waste in half the time.

Applications of Ergonomics ERGONOMICS Workplace design l Product design l System design l

Control Strategies ERGONOMICS Engineering l The design and layout of the workplace, systems to be assembled, and the selection of equipment/accessories. Work Methods l How the task is being completed. Administrative l Scheduling of work, work habits, case management, & training.

Administrative Controls ERGONOMICS Early Symptom Reporting l Gradual Break – In l Job Rotation l Breaks/Stretching l Training on Job Tasks l Case Management of Injuries l

Psychosocial Factors ERGONOMICS l l l l l Work Environment/Organization Performance/Time Pressures Role within Process – Clarity/Ambiguity Recent Changes in Process/Equipment Advancement Opportunities Perceived Workload Job Satisfaction Safety Culture Employee Relationship w/Management

Neutral Posture for Computer Use ERGONOMICS Position the monitor about an arm’s length away directly in front of you. The top of the screen no higher than eye level (Unless the user wears bi-focal glasses) Use a document holder close to the monitor rather than laying papers flat Mouse should be next to keyboard both at a height equivalent to the user’s seated elbow height Knees comfortably bent with feet resting on the floor. If the chair is raised so the keyboard height equals elbow height, use a footrest. Adjust the seat height so upper arms hang vertically, elbows bent about 90 degrees, shoulders relaxed and wrists fairly straight Adjust the back rest to provide firm support to the small of the back

Task Breaks and Stretches ERGONOMICS l l l Task breaks are VERY effective in reducing the risk of CTD Short recovery periods are beneficial every 30 minutes Use specific movements to optimize recovery Take a deep breath! Exhale!

ERGONOMICS Time Out for Busy Hands • Spread fingers wide and hold for 5 counts. • Grasp palm and fingers; gently bend back wrist. Hold 5 counts. • Rotate wrist in circular motion. • Curl fingers into a fist starting with the little finger. Hold for 5 counts. • Flex and extend wrist in waving motion.

ERGONOMICS Shoulder/Back Stretches • Lean back gently with hands supporting lower back. Hold for 5 counts. Don’t over arch. • Gently roll shoulders backwards 5 times and then forward 5 times. • Move arms overhead in a climbing motion 10 times.

ERGONOMICS Neck Stretches • Gently tilt your head back as if you are looking at the ceiling/sky. • Gently tilt your head forward bringing your chin towards your chest. • Gently tilt your head from side to side

FURNITURE AND WORKSTATION ERRORS ERGONOMICS l Ergonomic features that seem to add value but don’t l Keyboard height side surface is too shallow for a computer. l Overhead file cabinet blocks monitor – forcing an awkward setup.

FURNITURE AND WORKSTATION ERRORS ERGONOMICS l Armrests that get in the way. l l l Too large, too far forward Keep worker from sitting close to workstation. Forces long reach… OR Workers sit at edge of chair Here, this worker bought his own back pad to compensate for the problem.

Examples ERGONOMICS BEFORE AFTER

Examples ERGONOMICS

Examples