MDA Chapter 25: Ergonomics

Carpal Tunnel Syndrome (CTS)

pain associated /continued flexion & extension of the wrist; caused by repetitive and forceful motion that make tendons swell & exert pressure on median nerve; also caused by knitting, gardening, using keyboard; 1st symptom is painful tingling in one/both hands @ night; next, decrease in ability & power to squeeze objects or make tight fist; in advance cases, the thenar muscle may weaken causing feeling of decreased strength in handgrip; pts who are pregnant, taking oral contraceptives, or have PMS or rheumatoid arthritis have higher risk; frequently resting than hands is one of most important factors in preventing

Carpal Tunnel

anatomic area of hand & risk; 8 carpal bones arranged as tunnel form area; 9 flexor tendons & median nerve inside tunnel

Cumulative Trauma Disorders

painful conditions that result from ongoing stresses to muscles, tendons, nerves, and joints

Ergonomics

adaptation of work environment and tasks to the human body; ergon = work, nomos = law; goal is to help ppl stay healthy while performing work more effectively; donee by changing workplace design, modifying instruments, strengthening muscles, taking breaks, using certain products, and providing proper training; work area is designed around human body, rather than having body adapt to environment

Maximum Horizontal Reach

reach created when the upper arm is fully extended

Maximum Vertical Reach

reach created by a vertical sweep of the forearm while the elbow is kept a midtorso level

Musculoskeletal Disorders

aka MSDs; painful conditions that affect both muscles & bones; ex. neck & back pain, carpal tunnel syndrome; symptoms include back & joint pain, neck & shoulder pain, wrist & hand pain, and headaches; early onset of paoin should alert worker that an imbalance exists and can cause serious damage over time if ignored; caused by dental team sitting while working & often using excessive motion and unbalance posture; many dental professionals have MSDs

Neutral Position

position when the body is properly aligned and the distrubution of weight throughout the spine is equal; ideal way to wkr; legs should be separated w/feet flat on floor (operator) or on foot rest of stool (DA); back should be pressed against back of chair for lumbar support; hips should lead forward to rotate pelvis backward; properly aligned spine resembles gentle “S”; when spine is properly aligned, ears, shoulders, and hips are in straight vertical alignment; provides balance, support, and equal distribution of weight throughout spine

Normal Horizontal Reach

reach created by a sweep of the forearm w/the upper arm held at the side

Sprains

injuries caused by sudden twisting/wrenching of a joint w/stretching or tearing of ligaments

Strains

injuries caused by extreme stretching of muscles/ligaments

Thenar Eminence

fleshy mound on the palm at the base of the thumb

Why are ergonomics important?

many DAs have had to give up career bc of acute pain; DAs frequently suffer from headaches, neck & shoulder pain, or numbness & tingling in hands & wrists; often when DA seeks help, pain is sever and structural damage may be irreversible

What should a worker do if they experience pain when working?

inform employer; take steps to reduce musculoskeletal inflammation & facilitate healing; if one ignores early symptoms of pain & stiffness, chronic disease may develop

What three categories of risk factors contribute to MSDs?

posture, repetition, and force

Posture

affects ability of DA to reach, hold, and use equipment; position influences how long DA can perform takes w/out adverse health effects; most DAs are seated while working on pts; sitting is less fatiguing than standing, any position will become fatiguing over time; may lead to lower back pain

Deviations & Problems

DA tends to deviate from neutral position while assisting dentist; includes leaving forward, twisting, overbending back, and reaching; can lead to aches, pains, numbnes, & tingling; DA should alternate sitting & standing when possible; frequent reaching, twisting, & working w/arms in awkward positions can cause strains & sprains; shoulder problems caused byen one repeatedly reached behind body for instruments/supplies

Reaching Movements

keep frequently used items (air-wtr syringe, handpiece, saliva ejector, high-volume oral evac) within comfy distance; not above shoulder lvl or below waist; adjust instrument tray & Equipment so items are within normal horizontal rach; keep operatory light within safe max vertical reach; other supplies less frequently used should be placed within max horizontal reach; reaches should be made ot front only; reaching behind back & lifting can cause shoulder rinjuringy; when turnign is necessary, rotate chair to avoid twisting body

Repetition & Force

repetitive motion, overflexion, and overextension of writst can significantly increase risk for cumulative Trauma disorders, especially when tasks require force; take breaks; when scheduling pts, alternate difficult procedures w/less stressful procedures; repetitive stress on bend in writs over long period can lead to carpal tendon injury; DA should periodically changes grasp on evactuator to straighten wrist

How can one improve ergonomics while working chairside?

use muscles to remain balanced for ease of movement; avoid prolonged, awkward positions; do no remain in one position for extended time; do not constantly lean forward or to the side; remain in good physical condition; take breaks to stretch neck, shoulders, & hands; avoid repetitive, forceful movements; rearrange items in operatory for easy use

How should the DA be positioned?

sit at pt’s shoulder; knees even w/edge of pt headrest; head in upright position; back straight & supported w/backrest; thighs parallel to floor; elbows kept close to body; avoid sitting on edge of chair; keep eye level about 6 in above dentist’s

How should the operator be positioned?

head in upright position; elbows kept close to body; thighs parallel to floor; work in neutral position; reposition pt as necessary; do not reach, lean, or bend for better access

How do gloves affect ergonomics?

use of ambidextrous gloves can place excessive tension on thenar eminence and hypothenar eminence by forcing hand to work against vertical alignment of glove form; right-left gloves that are properly sized support hands naturally & properly position thumb, index finger, & middle finger

How should gloves be fitted?

important to wear gloves that fit properly; gloves that are too tight can cause circulation problems to fingers & hands and place pressure on carpal tunnel across wrist; gloves that are too loose make it difficult ot grasp & transfer instruments; excess glove material @ fingertips hinders ability to roll instruments/oral evacuators while assisting

Why are muscle-strengthening exercises important?

stretching & strengthening muscles that support back & neck & those used in forearm, wrist, and hand help keep muscles strong & healthy; should do periodic stretching throughout workday; check w/physician before any exercise program, especially if you have pain with any movements

How can one strengthen their hand muscles?

slowly open & close hands; press palms together, then relax them; hold one arm out in front of body w/hand extended, then w/fingers of other hand gently pull back on extended fingers to increase stretch

How can one relieve eyestrain?

look up from task & focus eyes @ a distance for 20 sec; practice frequently throughout day to use full range of vision & reduce eyestrain

How can one relieve stresses placed on back, neck, and shoulders?

full back release (let head move down slowly, allowing arms & head to fall between knees); head rotations for next stiffness; tilt head forward, backward, left, and right; shoulder shrugging stretch shoulder muscles which may be stressed from holing instruments & oral evacuatorss; pull shoulders up toward ears, then roll them backward & forward in circular motion

Muscle Strengthening Exercises

pelvic tilt, hyperextension, knee-to-chest, sit-ups, suspend from a bar, doorways stretch, neck isometric, rubber ball squeeze, and rubber band stretch

Pelvic Stretch

muscle strengthening exercise; strengthens lumbar spine; (1) lie on back (ideally), or if at work, stand flat against wall; (2) keep knees slightly bent; (3) flatten & press back into floor or wall; (4) hold briefly, then repeat

Hyperextension

muscle strengthening exercise; safeguards lumbar curve; (1) lie on stomach; (2) arch body backward in upward motion; (3) hold briefly; (4) return to original position, avoiding straightening legs; (5) repeat

Knee-To-Chest

muscle strengthening exercise; stretches lumbar spine; (1) lie on back; (2) bring both knees to chest; (3) hold briefly; (4) return to original position; avoid straightening legs; (5) repeat

Sit-Ups

muscle strengthening exercise; strengthens abdominal muscles; (1) lie on back; (2) bend knees; (3) support neck; (4) gently raise shoulders toward knees; (5) hold briefly & return; (6) repeat

Suspend From A Bar

muscle strengthening exercise; relieves lower back pain; (1) firmly grasp bar; (2) suspend body from bar; lift feet slowly; (3) hold for a short time; (4) repeat

Doorway Stretch

muscle strengthening exercise; reverses poor posture; (1) stand in front of an open doorway; (2) place hand on either side of doorframe; (3) gently allow body to lean forward through doorway; (4) hold briefly and return; (5) repeat

Neck Isometric

muscle strengthening exercise; stretches cervical spine & relieves neck muscle strain; (1) grasp hands behind head; (2) gently press head back; (3) do not allow any backward movement; (4) hold briefly; (5) repeat

Rubber Ball Squeeze

muscle strengthening exercise; strengthens hand & finger muscles; (1) grasp a rubber ball firmly in your hand; (2) gently squeeze; (3) hold briefly; (4) repeat

Rubber Band Stretch

muscle strengthening exercise; strengthens hand & finger muscles; (1) extend rubber band between fingers of hand; (2) gently stretch rubber band until you feel resistance; (3) hold briefly; (4) release rubber band; (5) repeat