Office Ergonomics
Definition Ergonomics is a science of fitting workplace conditions & job demands to the capabilities of the working population - OSHA
Why talk about Ergonomics?
Poor ergonomics invariably leads to health impacts
What is `Office Ergonomics about? Workstation setup & Postures Illumination Ambient Temperature Task related movements Repetitive actions Noise
Common health impacts of poor Ergonomics Spondylosis & Other Musculoskeletal Disorders (MSD) Visual strains Circulatory disturbances
Spondylosis
Load of Spondylosis & Muscular pain Affects 50% of those between 30 to 44 yrs. of age Affects 90% of those between 40 to 65 yrs. Of age One in every five persons suffers from backache in a month irrespective of changes of spondylosis.
Is it Spondylosis or Spondylitis? Any.itis indicates infective process e.g. Appendicitis, Pneumonitis Most degenerative processes are indicatd as.osis e.g. Arthrosis Atherosclerosis. Spondylosis is degenerative
Structure of Spinal Column 33 Vertebrae but only 23 intervertebral disks Intervertebral disk occupy 1/3 of length Divided into Cervical, Thoracic, Lumbar & Sacrococcygeal areas.
Intervertebral Disk Majority of symptoms are due to Disk related problems
Disk Structure Size 45 x 64 x 11mm Nucleus pulposus, Annulus Fibrosus hyaline cartilage.
The Intervertebral Disk No blood supply; 65% to 90% water Water content changes with load Nutrition depend on water content
Pressure in intervertebral disk prone 15 psi (Pascals per Square Inch) side-lying 21 psi, Sneezing 55 psi Lifting 129 psi
Disk Pressure Comparisons Car tires 30-35 psi heavy truck tires 120 psi Lifting 129 psi
The Intervertebral Disk Functioning depends on nutrition Nutrition depends on Percolation Water content Adjacent blood supply Movement
The Intervertebral Disk Disk transfer load; allow bending twisting Loading causes loss of disk height & water Deformation depends on rate & period of loading `Creep effect if load is maintained leading to 25% fluid loss in a day. Fluid loss causes loss of height & degeneration due to lack of nutrition & a brittle disk
Degenerated Disks
Prolapsed I.V.Disk
Types of Muscles Slow twitch or Postural Muscles Fast Twitch or Action Muscles Each category meant for specific activity Activities cannot be interchanged for too long
Postural Muscles Meant for holding body position aided by locking mechanism & gravity Not meant for quick movements
Fast Twitch Muscles Awkward position brings Fast Twitch into action for holding the position Fatigue sets in very fast in awkward positions Fatigue causes spasm & pain Commonest problems: Driving VDT usage
Spinal Risk Factors Lifting / Loading : Depends on Posture, Weight, Load positioning, Visual requirements Smoking : Reduces nutrients transportation within 20 min. Vibration 5-10 Hz reduces blood supply & nutrition Taller persons suffer more often(thicker disks with nutritional problem + ergonomic issues)
Other Compounding Factors Vitamin D deficiency Stress related muscle spasm Effervescent (sparkling) soft drinks
Symptoms Of Spondylosis Pain (Neck/ arm/ head/ Ears/ Chest) Tingling numbness Giddiness Motor disturbances at later stage Worsening towards evening
Symptoms of Musculoskeletal Disorders Decreased range of movement Deformities Decreased grip strength Loss of function Tingling numbness
Risk Factors for MSD Force Repetition Awkward Posture Static posture
Investigations & Diagnosis Diagnosis is mostly clinical based on age & symptoms. Radiology is helpful but not necessarily corroborative!! Nerve conduction studies can help
Prevention & Treatment Life style modification Vitamin D monitoring & supplementation Ergonomic improvements Regular neck exercises Cervical traction Short wave diathermy or ultrasound NSAIDs
Neck excercises
Cervical Traction
Workstation Posture Feet Resting Flat Position fully back Thighs resting on seat 90 degrees angle at knees, hips, elbows Upper arm in line with body Top of monitor in line of vision at 1.5 feet Wrists resting on soft surface & turned slightly inwards
Keyboard and mouse Angle Keyboard: Flat or negative sloped Keep wrists straight or slightly flexed Wrist pad (obstacles) can help (bio-feedback)
Movements to be avoided Twisting & Lifting Over-reaching Using hand as a hammer Leaning arm or elbow on table
Movement Guidelines Keep common object close within reach Plan before beginning to bring work near to you Common task near to body at waist level Store between shoulder & knee heights Always lift using thigh muscles strength
Illumination & Eyes Related Glare Background light Flicker Reflection Conjunctival drying Issues
Lighting Guidelines Balanced lighting Bright enough to see text but... Low enough to avoid glare and image wash out Positioned to avoid direct glare Task lamp provides source for reading documents VDT is a source of light Background lighting should equal or slightly lower
Circulatory Disturbances
Venous Circulation of Lower Limbs
Circulatory Disturbances Oedema feet Deep Vein Thrombosis
Beating VDT work stress Neck movements Visual focus changes Eye lid movements Calf movements
Other repetitive office work Stapling Stamping Sorting Counting Writing