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Posture and ergonomics as is relates to the dental hygiene profession. Overview of common injuries, pain syndromes and musclulskeletal disorders with ways to manage them.
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Ergonomics: Health Implications for Dental Hygienists
Overview: Ergonomics and Health Implications for Dental Hygienists
Increase awareness Increase awareness
Decrease work-related pain and injuriesDecrease work-related pain and injuries
Heighten productivityHeighten productivity
Improve musculoskeletal healthImprove musculoskeletal health
Increase comfortIncrease comfort
Improve quality of lifeImprove quality of life
Extend careersExtend careers
What is Ergonomics?
Ergonomics is the study of workers and their relationship with their occupational environment
How you position yourself, your patient, how equipment is utilized, how the workplace is designed and how it impacts your health
ERGONOMICS is a way to work smarter, more efficiently with less effort and discomfort to the human body
Ergonomics in the Dental Health Field
Studies show work-related Studies show work-related pain in the dental field is not pain in the dental field is not decreasingdecreasing
Over half of all dental Over half of all dental professionals continue to professionals continue to experience work-related experience work-related pain pain
Why?Why? The physically The physically challenging nature of the challenging nature of the work with numerous work with numerous risk factorsrisk factors
Risk Factors
Prolonged Static Postures
Repetitive Movements
Working in a confined space
Challenges with positioning yourself or the patient
Limitations with the tools and equipment used
©2008, Valachi from “Practice Dentistry Pain-Free”
Reasons for Early Retirement Among Dental Health Professionals
Musculoskeletal Disorders (29.5 %)
Cardiovascular Disease (21.2%)
Neurotic Symptoms (16.5%)
Tumors (7.6%)
Diseases of the Nervous System (6.1%)
©2008, Valachi from “Practice Dentistry Pain-Free”
Ergonomics: The Human Factor
People Are Different
We come in different shapes and sizes yet the workplace is often set up for “one size fits all”
People Have Limitations
We have physical and mental limits for working
- The wrist cannot tolerate excessive extension
- The back cannot tolerate excessive bending or twisting
- The neck was not meant to be in constant flexion
- Muscles will fatigue if under constant tension
©2008, Valachi from “Practice Dentistry Pain-Free”
Consequences of Poor Ergonomics
Fatigue
Pain/Discomfort
Illness/Injury
Missed days at work
Errors
Lower productivity
Patient dissatisfaction
Poor Ergonomics: Signs and Symptoms
Physical Signs
Decreased range of motion
Deformity
Decreased grip strength
Loss of muscle function
Symptoms
Pain
Numbness
Tingling
Burning
Cramping
Stiffness
©2008, Valachi from “Practice Dentistry Pain-Free”
Poor Ergonomics = Musculoskeletal Disorders
The World Health Organization definition: The World Health Organization definition:
Musculoskeletal Disorder is “a disorder of the muscles, tendons, peripheral nerves or vascular system not directly resulting from an acute trauma or instantaneous event”
Two Most Common Causes for Musculoskeletal
Disorders in the Dental Health Profession
Cumulative Traumas
Prolonged Static Postures
©2008, Valachi from “Practice Dentistry Pain-Free”
Cumulative Trauma
Repetitive Movements like Scaling and Polishing are Cumulative Traumas
Vibrations transmitted by dental handpieces or mechanical scalers are Cumulative Traumas
Cumulative Traumas add up
These microtraumas cause “wear and tear” on the muscles, tendons, and nerve tissue
Prolonged Static Postures
Human body was designed for movement
Dental hygiene procedures means practitioners must maintain static postures
Hygienists hold postures that require more than 50% of the body’s muscles to contract to resist gravity
Muscle overload leads to decreased blood flow and increased pressure on the muscles and joints
©2008, Valachi from “Practice Dentistry Pain-Free”
Flowchart: Static Overload
PROLONGED STATIC POSTURES
Muscle Fatigue and Muscle Imbalance
Muscle Ischemia, Trigger Points, Muscle Substitution
PAIN
Protective Muscle Contraction
Joint Hypomobility, Nerve Compression, Spinal Degeneration/Herniation
MUSCULSKELETAL DISORDERS
©2008, Valachi from “Practice Dentistry Pain-Free”
Static Postures leads to Muscular Imbalances
Muscles responsible for rotating the body to one side become tighter (shorter), while opposing muscles become weaker (longer)
Right handed hygienists repeatedly assume NECK ROTATION TO LEFT with SIDE-BENDING TO RIGHT to gain better visibility
Problems with NECK ROTATION TO RIGHT with SIDE-BENDING TO LEFT
©2008, Valachi from “Practice Dentistry Pain-Free”
Static Postures = Muscle Ischemia
As postures deviate from neutral, muscles contract harder to maintain working postures
During static muscle contraction, the vascular supply to muscle and surrounding tissues is restricted
Results in depleted nutrient and oxygen supply (ischemia)
Lactic acid and other metabolites accumulates causing pain and tissue damage
Cumulative Traumas and Prolonged Static Postures Lead to Musculoskeletal Disorders
Trigger Points and Myofascial Pain Disorders of Neck
Degenerative Joint Disease (Arthritis)
Thoracic Outlet Syndrome
Tendinitis
Carpal Tunnel
Syndrome
Trigger Finger
Nerve Entrapment Syndromes
Lower Back Pain
Sciatica
Myofascial Pain: Trigger Points
Trigger PointsTrigger Points: groups of : groups of muscle fibers that are in a muscle fibers that are in a constant state of contraction constant state of contraction inside a tight band of muscleinside a tight band of muscle
Feels like a knot or a small pea Feels like a knot or a small pea in muscles, and when pressed in muscles, and when pressed on can refer pain to distant on can refer pain to distant parts of the bodyparts of the body
Ischemic areas are susceptible Ischemic areas are susceptible to the development of trigger to the development of trigger pointspoints
Myofascial Pain: Trigger Points
Myofascial Pain: Trigger Points
Static Postures: Degenerative Joint Disease
Synovial fluid, which lubricates Synovial fluid, which lubricates the joints, is produced each the joints, is produced each time a joint movestime a joint moves
Lack of movement and Lack of movement and contracted muscles from static contracted muscles from static postures reduces the synovial postures reduces the synovial fluid production, resulting in fluid production, resulting in joint hypomobilityjoint hypomobility
This loss of mobility leads to This loss of mobility leads to degenerative changes and degenerative changes and more musculoskeletal more musculoskeletal disordersdisorders
Static Postures: Degenerative Joint Disease
SymptomsSymptoms
Intermittent/chronic pain Intermittent/chronic pain and stiffnessand stiffness
““Creaking” or “cracking” of Creaking” or “cracking” of jointsjoints
Swelling in the jointsSwelling in the joints
Loss of motion in the jointsLoss of motion in the joints
Increased pain with activity Increased pain with activity or useor use
Neck and Shoulder Disorders Thoracic Outlet Syndrome
Condition resulting from compression of the nerves, arteries, and veins as they pass through from the neck to the arm (thoracic outlet)
Possible causes: tight scalenes, cervical rib, tight pectoralis muscle, traumas
Often misdiagnosed
Neck and Shoulder Disorders Thoracic Outlet Syndrome
Symptoms
Pain in the neck, shoulder, arm or hand
Numbness and tingling of fingers
Muscle weakness/fatigue
Cold sensation in the arm, hand or fingers
Cumulative Trauma Injury: Tendinitis
When tendons slide back and forth through their sheaths friction is created
As with any other moving part, enough friction can cause wear and tear along with inflammation
When tendons or sheaths swell, and there is pain and tenderness
Wrist Tendinitis
Pain, swelling and inflammation on the thumb side of the wrist
Made worse with grasping and twisting activities (polishing and scaling)
Occasional “catching” or snapping when moving thumb
Shoulder Tendinitis
Elevated arm postures cause shoulder impingement
Leads to tendinitis in the rotator cuff
Pain is usually felt in the front or the side of the shoulder
Worse with activity
Carpal Tunnel Syndrome
Compression of the Median Compression of the Median Nerve as it passes through Nerve as it passes through the Carpal Tunnelthe Carpal Tunnel
Caused by pinching and Caused by pinching and gripping activities with the gripping activities with the wrist bentwrist bent
Made worse with repetitive Made worse with repetitive flexion and extension flexion and extension activities at the wristsactivities at the wrists
Carpal Tunnel Syndrome
Symptoms
“Pins and needles” in the hands and fingers
Pain in the thumb, index and middle finger
Limited range of motion at the wrist
Pain radiating up the arm
Decreased grip strength
More pain at night
Trigger Finger (Tenosynovitis)
Sustained forceful grips and repetitive motion irritates the tendon and tendon sheath (tenosynovium)
Nodules form in tendon causing warmth, swelling, tenderness of the tendon
Pain occurs during movement that place tendons in tension
Fingers lock in “Trigger Position”
Cubital Tunnel Syndrome
Prolonged use of the elbow while flexed or trauma from overuse can compress the Ulnar Nerve
Pain, numbness, tingling and impaired sensation in the little and ring fingers, side and back of hand
Loss of fine control
Reduced grip strength
Compression of ulnar nerve in Guyon’s canal at the base of the palm
Caused by repetitive wrist flexing or excessive pressure on palm/base of hand
Pain, weakness, numbness, tingling, burning in the little finger and part of the ring finger
Symptoms may worsen at night or early morning
Guyon’s Syndrome
Upper Crossed Syndrome
Tight Levator Scapulae Upper Trapezius
Scalenes Pectorals
Weak Middle/Lower Traps Rhomboids Serratus Anterior
Deep Neck Flexors
Elevated shoulders
Forward head postures
Jutting shoulder blades
Neck Pain and Upper Back Pain
Low Back Pain
Low Back Pain is the leading cause of occupational disability in the dental healthcare profession
Studies show that low back pain is clearly related to seated postures and sitting duration
Low Back Pain
We often think of a back injury as caused by a single event, like lifting a heavy load
The lower back is vulnerable to Cumulative Trauma
More lower back injuries result from the cumulative effects of bending, twisting, or excessive sitting
Working continuously in a seated position places tremendous static load on the back muscles, discs, and joints
Low Back Pain: The Problem with Sitting
With seated postures, pressure in the lumbar disks increases by 50% from standing
Unsupported sitting causes 2x more axial loading in the spine than standing
During forward flexion and rotation (a position often assumed by dental hygienists) the pressure increases by 200%
Low Back Pain: Disc Degeneration, Bulge and Herniation
Spinal discs provide for flexibility shock absorption
Discs are composed of tough outer layer (annulus fibrosis) and gel-like center (nucleus pulposis)
When weight is applied to the disc, the nucleus expands outward and puts pressure on the annulus fibrosis
Low Back Pain Disc Degeneration and Herniation
Sitting while flexing forward compresses the discs in the front
Uneven pressure on the disc leads to disc bulging and herniation
When the disc bulges or herniates backwards the nerves can become pinched
Low Back Pain: Sciatica
Pain from lower back or hip radiating to the buttocks and legs
Leg weakness, numbness, or tingling
Commonly caused by prolapsed intervertebral disc pressuring the sciatic nerve
Worsened with prolonged sitting or excessive bending and lifting
Low Back Pain: A Vicious Cycle
People with back problems seem to be faced with this vicious cycle
There is considerable evidence that bed rest and passive treatments have limited value
We now know that activity and the right kind of exercise are critical to treating back pain
Stop Moving
Back Pain Hurts to Move
Stiffness
Weakness
Lower Crossed Syndrome
Tight Hip Flexors Lower Back
Muscles
Weak Abdominal Muscles Gluteus Maximus
Swayback - excessive curve of the lower back
Anterior Pelvic Tilt - hips tilted forward
Lower Back Pain
What is the best position to sit in?Traditional 90º Sitting Is not It
Problems with Traditional 90° Sitting
Looks nice but it’s just not comfortable
Natural curve of the lower back collapses
Leads to muscle tension and misaligned vertebrae
Increases static load on the discs
Decreases circulation in lower extremities
What is the best position to sit in?Leg Balanced Sitting
Allows for forward and upward postures to transfer some of the body’s support to the feet
Hip angle of 100 ° to 120°°
Knee angle of 110° to 135°
Forward seat tilt of 45° to 55° from horizontal
Opposing muscle groups are balanced and curve in lower back is maintained
Chair Selection
Saddle Seat Design
True waterfall design is an essential feature
Hydraulic piston assembly for the widest range of motion
Seat should be adjustable so hips can be slightly elevated beyond parallel without restricting blood flow to the legs
Ergonomics for Dental HygienistsWorkstation Layout
Clutter threatens the safety and cleanliness of the dental operatory
Allows convenient positioning when required
Provide a clear line of sight to the oral cavity and all required equipment
Ergonomics for Dental HygienistsWorkstation Layout
Optimize space for work from 7 o’clock to 1 o’clock position for right handed Hygienists (11° to 5° if Left Handed)
Instruments should be accessible while seated (within 20 inches of the front of body)
Hoses should be positioned away from the body
Over-the-Patient or Over-the-Head equipment is most ergonomic
Use mobile carts for less commonly used Use mobile carts for less commonly used equipmentequipment
Ergonomics for Dental Hygienists Scheduling
Scheduling of procedures should be considered.
Difficult procedures scheduled back-to-back does not allow your body sufficient relaxation time
Potential strategies
– Increase treatment time for more difficult patients
– Alternate heavy and light calculus patients within a schedule
– Vary procedures within the same appointment
– Shorten patient’s recall interval
Ergonomics for Dental HygienistsReduce Physical Effort
Avoid bent or unnatural posturesAvoid bent or unnatural postures
Minimize sustained effort
Brief but frequent rest pauses can minimize fatigue and enhance productivity
Incorporate different activities to shift musculoskeletal demands from one part of the body to another
Ergonomics for Dental Hygienists Equipment Equipment
If your air/water syringe has a tightly coiled cord, consider replacing it with a lightweight hose
Swiveling devices can be placed on a handpiece to reduce torque
Newer handpieces are much lighter than the older models
Ergonomics for Dental HygienistsHand InstrumentsHand Instruments
Look for:
Hollow or resin handles
Round, textured grooves, and compressible handles
Carbon-steel construction
Color-coding may make instrument identification easier
Ergonomics for the Dental HygienistsMagnification Systems
Should improve neck postures and Provide clearer vision
Consider additional lighting
Weight should also be considered
Ergonomics for Dental HygienistsErgonomics for Dental HygienistsGlovesGloves
Gloves are one of the most Gloves are one of the most overlooked ergonomic itemsoverlooked ergonomic items
Hand-specific gloves allow the Hand-specific gloves allow the thumb to be in a more natural thumb to be in a more natural positionposition
Gloves should not be too tight Gloves should not be too tight across the palm or too across the palm or too constricting at the wristconstricting at the wrist
The finger length should be The finger length should be adequate to allow for adequate to allow for comfortable finger movementcomfortable finger movement
Preventing Ergonomic Injuries
MoveChange PositionThere is no one “correct” posture best for an entire working dayThe Human Body Needs Change and Mobility
Preventing Ergonomic Injuries
Taking frequent, shorter breaks is preferable to taking longer, fewer breaks
Change positions before painful symptoms arise
Remember to go back to neutral postures
Preventing Ergonomic InjuriesStretching Guidelines
Never stretch to the point of pain or discomfort
Do not bounce or use quick, jerky movements
Stretch should be performed every half hour
Suboccipital Muscles
Deep muscles at the base of the skull responsible for protraction, rotation, and tilting of the head
Suboccipitals become shortened with forward head postures
Common cause for headaches
Levator Scapulae
Primary function is to elevate the scapula
Also bends the neck to the side
Tightens up when carrying a bag with a strap or talking on the phone
Scalenes
Functions to stabilize the neck during lateral movements
Aids in inspiration
Becomes tight with awkward leaning positions while seated
Trapezius
Upper elevates the shoulders
Middle retracts the shoulder blades
Lower rotates the shoulder blade downwards
Becomes tight with elevated arm postures
Pectoralis Minor
Functions to draw the shoulder blade forward and downward
Tight in people with a rounded shoulder posture
Shortened pec minor is a possible cause for Thoracic Outlet Syndrome
Wrist Flexors/Extensors
Prime function is to flex and extend the wrist
“Tennis Elbow” is pain on the lateral side of elbow
“Golfer’s Elbow” is pain on the medial side of the elbow
Hamstrings
Main function is to bend the knee
Secondary role in extending the hip
Weak low back and glute muscles increases tightness in the hamstrings
Prolonged seated postures also causes tight hamstrings
Iliopsoas
Primary function is to flex the hip (bring thigh up towards the abdomen)
People with chronic lower back pain often have very tight hip flexors
Commonly shortened with prolonged seated postures
Piriformis
Main function is to externally rotate the hip/thigh
Shortened in people who sit for long periods of time
“Piriformis Syndrome” causes compression of the Sciatica nerve
Questions and Answers