ISE 3600 Review Guide, Mid-term 2 (AU 2024) PDF

**ISE 3600 Review Guide, Mid-term 2** What are some general trends regarding the incidence of back injuries? Who is affected? How long do these injuries last? **Lower back is most common injury, back injuries are most common in ages 25-54, 25% of back injuries result in 31 days or more of days los...

**ISE 3600 Review Guide, Mid-term 2** What are some general trends regarding the incidence of back injuries? Who is affected? How long do these injuries last? **Lower back is most common injury, back injuries are most common in ages 25-54, 25% of back injuries result in 31 days or more of days lost.** Spine structure: What does the front part of the vertebra (the vertebral body) do? What do the components on the posterior portion (a.k.a. posterior elements or components) of the vertebra do? How can these be injured? **Vertebral Body (front part of vertebra) -- Load bearing structure, can be injured through crush fractures.** **Posterior Portion of Vertebra -- Where the muscles attach via tendons, can be injured through excessive anterior/posterior shear forces** What are factors that affect whether tendons and ligaments will be injured? **Rate of loading, amount of load, repetition and existing damage. Strain occurs when the joint is carried through a large range of motion. Ligaments have higher percentage of elastic fibers then tendons, connect bone to bone.** What does cartilage do? Where is cartilage found in the human body? How are nutrients delivered to these tissues? **Cartilage absorbs shock and distributes loads. Prevents direct wear on bones by allowing relative movement of opposing join surfaces with minimal friction and wear. Fibrocartilage in discs and hyaline in vertebral endplates. Cartilage is viscoelastic and has no blood vessels...nutrition is supplied through diffusion and spine motion.** What are the two main parts of bone? **Outer compact bone that provides strength and stiffness** **Inner trabecular inner network provides large capacity for energy storage** What is Wolf's Law? **Bone remodels in response to load.** What kind of occupational injury concerns exist with bone tissue? **Fatigue fractures, osteoporosis in older workers, susceptibility to crush.** What are the primary parts of the intervertebral disc? Describe them. **Nucleus pulposus gelatinous mass, 88% water when young and dries up as you get older, resists compressive spinal loads.** **Annulus fibrosis layers of crossed collagen fibers, contains elastic properties of disc and gets less elastic with age, resists shear loads on the spine.** What does the disc do? **Serves as a shock absorber, has a moveable joint where motion occurs in the spine, the spacer allows room for nerve roots.** What is the vertebral endplate and why is it important? **Serves as the connection between the disc and the vertebral body. It allows nutrient exchange with blood vessels in the vertebral body. Endplate fractures can occur due to excessive compressive loads while in a neutral position.** What happens when spinal discs degenerate, bulge, and herniate? **Endplate fractures compressive loading** **Herniation full end range of motion, with moderate compressive loading. Cell death within nucleus pulpous under excessive compressive loading** **Degeneration less water due to age or load exposure** What tissues can potentially be the source of back pain? **Disc, ligament, tendon, facet joint, muscle.** What is meant by "idiopathic" low back pain? **Pain that has no apparent underlying cause...85% of LBP is idiopathic.** Where are the Latissimus Dorsi and Erector Spinae muscles? Where do they connect? **Back, connect to the rib cage.** When do people use their Latissimus Dorsi muscles? When are the Erector Spinae muscles used? **Latissimus Dorsi Pulling tasks (extension, adduction, shoulder rotation), and support lifting tasks.** **Erector Spinae Extend the spine, keep posture erect and allow spinal extension and lateral flexion. Supports lifting and pulling tasks.** In addition to the back muscles, what other muscles support and help move the spine and torso? **Posterior trunk muscles, rectus abdominus, transverse abdominus, external/internal oblique.** What is the difference between an agonist and an antagonist muscle? When lifting a box in front of the body, which muscles that move the spine are agonist muscles and which are antagonistic muscles? **Agonist Erector Spinae** **Antagonist Rectus Abdominus** The amount of back muscle force needed in a particular lifting task depends on.... **How much weight you lift and how far you reach. Torque = Weight \* Reach** How much force must be generated by the back muscles when holding a given weight (i.e. 20 lbs) a distance X (i.e. 20 inches) in front of the spine? \^ What do the disc pressure studies show us? **Disc pressure increases when angle of flexion or load increases** What is the relationship between spine compression force and low pain incidence rates? **Lower back pain incident frequency increases with increased predicted compressive forces on a disc.** How does the tolerance to spine compression change as a function of age? **Younger ages need a higher compressive force to result in a disc-vertebrae failures (it takes a lower force to cause failure in older individuals).** Describe three loading scenarios by which tissues within and supporting the spine can become injured. 1. **Tissue tolerance is exceeded by a single high intensity excessive load** 2. **Tissue tolerance reduces in response to repeated low level loading** 3. **Over time under a constant low applied load tissue tolerance is reduced due to creep** What are generic physical risk factors for musculoskeletal discomfort? **Excessive spinal load can be due to awkward postures, excessive force, repetitive activity, lack of rest, environmental stressors.** Risk Factor Matrix \-- what are the rows, columns, and the questions in each cell? **Risk Factors** **Duration** **Frequency** **Intensity** ------------------ ------------------------------ ---------------------------------------------------- --------------------------------------------- **Force** How long is force applied? How many extensions per unit time? How much force? **Posture** How long is posture held? How many repetitions of the posture per unit time? What is the posture? **Motion** How long is work period? How many motions per unit time? How fast are the motions? **Vibration** How long is the work period? How often is someone exposed? What is the frequency and the acceleration? Why is posture a risk factor for low back injury? **Muscles are strongest with a little bit of forward bending. Muscle length changes with posture, and strength changes with length. Pressure on facet joints increases with twisting and reaching. Extreme forward bending puts stress on spinal ligaments (increase laxity).** Why are we concerned about spine twisting? **Twisting strains selected disc fibers and pressure on facet joints increases with twisting.** What is the "J" curve relationship between physical activity and low back pain? **Y axis has LBP risk and x axis has increasing physical demands. Curve is J shaped** What did the Lumbar Motion Monitor (LMM) study show us about low back injury risk? **LBD risk distribution of repetitive materials handling jobs have either high number of low back strains or zero low back strains and zero turnover.** Where are people exposed to whole body vibration? **When seated, vibration is linked to increased LBD risk.** What are psychosocial factors? How do they potentially increase musculoskeletal injury risk? **Job enjoyment, relationship with supervisor, social environment are some examples of psychosocial factors.** What can you say about the Boeing studies that initially defined these risk factors? **Both the initial and retrospective study and the second prospective study identified significant relationships between psychosocial variables and reported injury.** Why are psychosocial factors important when considering the lost time associated with injuries (disability)? **Psychosocial factors are widely recognized to affect LBP disability. Return to work programs need to address these factors. Early return to work, communicate with disabled employee to show they are missed and cared about.** Describe the links shown in the following model: **Workplace Parameters lifting, pulling, carrying, etc.** **Individual gender, age, strength, etc.** **Work organization how long workers must perform tasks** **Psychosocial supervisor relationships, job environment** What can we say about seating and the pressure on the spine? **Disc pressure is higher when seating in comparison to standing** What happens with increased lumbar support or increasing back rest inclination angles? What happens when you increase both of these seating parameters? **Increased lumbar support decreases disc pressures. Increasing backrest inclination decreases disc pressures. Increasing both is optimal for least amount of disc pressures.** What happens with arm rests? Why? **Adding an arm rest decreases disc pressure, because your disc is no longer supporting the weight of your arms.** What is the purpose of Balans chairs? **Meant to reduce lower back strain by dividing the burden of the weight between the knees and butt.** When you are providing seats to people who have historically stood, what are things you should consider? **Back support, leg room, leg length on chair, chair height, arm rests, lumbar support, casters, breathable fabric, reclinable** Where are incidents of neck and shoulder pain more common? **Health care and computer work.** What is the primary muscle and tendon often implicated in rotator cuff shoulder pain? **Supraspinatus tendon and muscle.** We sometimes talk about impingement of this shoulder muscle's tendon. What bony part of the skeleton is responsible for this? **Acromion when frequently raised inflames subdeltoid bursa** What is the relationship between shoulder abduction angle or shoulder flexion angle and shoulder fatigue? **The higher the abduction angle, the less time it takes for the shoulder to fatigue** What is the relationship between reach distance and shoulder fatigue? Why does this happen? **The larger the reach distance, the less time it takes the shoulder to fatigue due to the moment arm and muscle length.** What anatomical structures pass through the carpal tunnel in the wrist? **Flexor tendons on the forearm and the median nerve.** Which nerves are responsible for sensation in the hand? Which pass through the carpal tunnel? **Median, ulnar and radial nerves are responsible for sensation in the hand. The median nerve passes through the carpal tunnel.** Be able to describe wrist postures. How do deviated postures affect hand strength and symptom experienced at work? How does grip span affect strength? **Ulnar is pinky outwards, radial is thumb inwards, neutral. Strength lowers when the wrist moves from the neutral posture.** Define the following: Carpal Tunnel Syndrome - **Compression of median nerve** - **Inflammation of tendon** - **Inflammation of tendon sheath** DeQuervain's disease - **Tenosynovitis of the tumb** Lateral epicondylitis - **Tennis elbow, inflammation of lateral elbow tissue due to forceful forearm rotation** How common is carpal tunnel syndrome? How much time is lost, on average due to CTS? **Very common, average of 28 days lost per case** How is carpal tunnel syndrome assessed in an individual? **Numbness, tingling, pain in the wrists, slowing of nerve conduction** What did the monkey studies show us about carpal tunnel syndrome? **CTS develops as a direct result of exposure to voluntary, repetitive manual task that requires moderately forceful exertions applied with a pinch-grip.** What are the primary risk factors associated with upper-extremity cumulative trauma disorders? **High rates of manual repetition, high force exerted, postural stress, insufficient recovery time, sustained muscle use, vibration, cold temperatures, and pinching.** What is the relationship between neck posture and neck symptoms? **Larger degree of head tilt means shorter time for each muscle fatigue. Larger degree leads to greater neck pain and stiffness.** What are factors that often influence neck posture and use? **Distance from screen, screen height, screen adjustment, desk height, using a headset.** **Assessment Tools** Assessment Tool How does it work? Where would it work best? Example of a job where you would choose to use this method. --------------------------------------- ---------------------------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------------------- ------------------------------------------------------------- REBA Give posture scores, use left and right sides, use table for score When whole body is exerting force Lab worker RULA Give score based on pictures for various postures, use tables to get score. When upper limbs are exerting force Garbage man, lifting tasks Liftshitz and Armstrong checklist Yes/No questions (20) add up yes's higher score is better (\>17) When jobs focus on hand and wrist usage. Factory worker using operating tools PATH Categorize the various postures using images Jobs that are non-cyclical or have long/irregular cycle times. Construction worker/smoothing concrete HAL 0-10 rating from idle to rapid motion Jobs that solely use hand motions Desk job/typing on a computer Revised Strain Index Rate intensity of exertion and multiply by observation variable, duration, effort, posture, speed When analyzing jobs for risk of distal upper extremity disorders Reaching jobs 3D Static Strength Prediction Program Calculate spine compression force and compare predicted spine loads with criteria to determine if damage is likely. Back injuries to predict forces acting on the selected spinal motion segments Soda carrier/deliverer AIHA Lifting TLV Tables with workplace lifting conditions that people can be exposed to without lower back or shoulder disorders When lifting is done with 2 hands, involve 1 task, within 30 degrees of mid sagittal plane Furniture mover NIOSH Work Practices Guide When used to predict an acceptable load given a set of work conditions Lifting job in a factory setting Lumbar Motion Monitor Device strapped to patients to measure lumbar range of motion, velocity and acceleration In workplace where the risk is high for LBD Throwing bags, something with lots of twisting Psychophysical Data Accounts for 75% of females, back injury assessment tool. Tables to indicate what the population is willing to lift. When assessing lift, push, or pull Heavy lifting, pushing a hospital bed LiFFT What is the difference between REBA and RULA? **REBA has 2 levels of wrist posture, fewer neck categories, and more detail for legs. Load is 5 kg increments, coupling is included, and more action levels. RULA focuses on upper limb assessment.** What factors are included in the computation of the NIOSH lifting index? **Know how to do the calculations.** Example Problem:  Multiplier Origin Data Origin Multiplier Destination Data Destination Multiplier ------------ ------------- ------------------- -- ------------------ ------------------------ HM VM DM FM AM CM RWL LI When is the multi-task approach recommended by NIOSH useful? How does the ACGIH Lifting TLV work? Where could this be useful? How do the biomechanically based guidelines for pushing and pulling work? Where could these be useful? What is the advantage of using the Lumbar Motion Monitor as an assessment tool? What are the key variables in the LMM analysis? What does the probability value tell you? How well does the LMM predict risk relative to the NIOSH lifting equation? Why does this difference exist? Where would the Lifting Fatigue Failure Tool be the appropriate tool to use? Why? What data need to be collected when using the LiFFT tool?