Ergonomics
Cumulative Trauma Injury -- Carpal Tunnel Syndrome
Randy Q. Ligh, DDS
Copyright 2002 Journal of the California Dental Association.
About the Author: Randy Q. Ligh practices pediatric dentistry in San Jose, Calif. He is also an ACE and ACSM certified physical trainer/health fitness instructor. Dr. Ligh was previously a clinical associate professor of pediatric dentistry at the University of the Pacific School of Dentistry and is presently a specialist consultant with the Veterans Administration Hospital General Practice Residency Program in Palo Alto, Calif.
To request a printed copy of this article, please contact: Randy Q. Ligh, DDS, 2211 Moorpark Ave, Suite 130, San Jose, CA 95128.
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In discussing cumulative trauma injuries all three contributing factors should be considered: the worksite environment, the job, and the worker. Research and the literature have an abundance of information discussing ergonomics and its relationship to the worksite environment. Preventive exercise information is limited. The author summarizes preventive measures using the acronym R.E.S.T. Exercise supporting this preventive philosophy are presented pictorially and descriptively.
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From their most recent year of statistical reporting (1999), the Bureau of Labor Statistics claims there were 582,300 musculoskeletal disorders that resulted in employees missing time from work.1 Most dentists are self-employed so the total number of disabling musculoskeletal injuries that actually occur in dentistry are not reported to the Bureau and may be more than what is documented.
One-third of all disability claims are hand, wrist or upper extremity cumulative trauma injuries according to Zenith, a workers’ compensation insurance provider. According to Dave Strong, MPH, CLII, of Zenith’s safety and health department, cumulative trauma in upper extremities accounts for half of workers’ compensation costs.2
If a dental employee is not allowed to perform his or her normal job because of a cumulative trauma injury, the insurer could disburse about $23,000 to a dentist, $14,000 to a hygienist, $11,000 to a bookkeeper, $7,000 to a receptionist and $6,000 to a dental assistant in guaranteed wages.3 Of course, there would be additional costs and downtime to interview, seek and train a new employee replacement.
A survey reported by the American Dental Association in 1997 reported that 9.2 percent of dentists had been diagnosed by a physician as having some type of repetitive motion injury.4,5 An affected dentist might incur the personal expense of medical diagnosis and treatment, physical and occupational therapies, rehabilitation, possible pharmacological or surgical intervention and a potential career ending disability.
In discussing cumulative trauma injuries all three contributing factors should be considered: the worksite environment, the job and the worker.2,6 Research and the literature have an abundance of information discussing ergonomics and its relationship to the worksite environment.7-11 Primary risk factors related to the job such as forceful exertions, repetitive motions and awkward or static postures have been discussed in the literature.7-9 Secondary risk factors related to the job such as contact stresses, vibration, cold temperature and personal factors have also been discussed in the literature.11-14
The literature also delves into a host of surgical and nonsurgical treatment options. Physical and neuromuscular therapy, acupuncture, reflexology, microcurrent electrical stimulation, spinal manipulation, and splint therapy are to name a few.12,15,16 Medication in the form of aspirin or other nonsteroidal antiinflammatory drugs17 or corticosteroids and cortisone-like medications are also considered.18
The dental literature has very little preventive information dealing with activities "outside" of the job analysis to benefit the worker.19 Why do we wait until symptomatolgy occurs before we address proactively the issue of cumulative trauma injury?
In a profession that bases its philosophy on prevention, it seems myopic to disregard or leave to serendipity the possibility of cumulative trauma injury and not institute personal measures of prevention.
Before embarking on this proposed preventive approach toward cumulative trauma injuries a thorough medical evaluation should be done with your physician. Any contraindications should be heeded and recommendations followed.
The medical conditions that might underlie cumulative trauma injuries include obesity,20 diabetes mellitus, hypothyroidism, the use of birth control pills, premenstrual syndrome and pregnancy.15,21 Cumulative trauma injuries might arise as a result of the potential for fluid retention and possible relative or absolute nutrient deficits related to these conditions.16 Vitamin B6 deficiency has been linked with carpal tunnel syndrome.15,16
Other medical conditions such as sarcoidosis, rheumatoid arthritis, osteoarthritis, gout, acromegaly, amyloidosis, tumors, Paget’s disease of bone, fractures and dislocations may also provide contributory influences for cumulative trauma injures.15,21 They are more likely to induce cumulative trauma injury by more direct mechanical factors with fluid retention and nutrient deficits playing a more minor role.16
Recurrent symptoms of tingling, itching, pain or burning sensations, stiffness, cramping, weakness, numbness or decreased sensation to touch should not be handled in a cavalier manner.18,22 Symptoms may begin suddenly or gradually. Don’t try to "work through" the suspicious symptoms. The basis behind a preventive approach is to avoid a condition and not to aggravate a predisposing situation24 or to even cause a condition by exceeding a "quantitative threshold"25 above which a cumulative trauma condition would be expected to occur.
The American Heart Association, the National Institute of Health, the United States Department of Health and Human Services, the President’s Council on Fitness and Sports, the Office of the Surgeon General and the American College of Sports Medicine all strongly support the role of physical activity for maintaining good health.26-28
Ideally supervision by a trained/certified professional (health fitness instructor/personal trainer) is prudent. As a practicing dentist and a certified health fitness instructor, I have coined an acronym, which summarizes the preventive measures to implement. The acronym is R.E.S.T. The components of R.E.S.T.will be described.
R -- Rest your muscles to allow them to recuperate from their daily repetitive stresses.
E -- Exercise your muscles to allow them to become stronger and better able to withstand future repetitive stresses.
S -- Stretch your muscles to maintain your flexibility and range of motion. Stretching also improves blood flow to the muscles.
T -- Train specifically those muscles you are targeting to prevent and to avoid those conditions which we are concerned about (cumulative trauma injuries involving the upper extremities).
If a cumulative trauma injury is suspected do not attempt the following exercises until specific advice or clearance is given by a physician.
Figures 1 and 2. Hold your arms straight out in front of you. Rotate your arms so the backs of your hands face each other.8,29,30 Hold for 5-10 seconds.
Figure 3. Hold your hands straight out in front of you. Rotate your arms so the palms of your hands face up.8Õ29Õ30
Hold for 5-10 seconds.
The radio-ulnar pronator and the radio-ulnar supinator muscles are alternately stretched and contracted. 31
FIGURE 4 - FIGURE 5
Clench your fist as tight as you can and then release and fan out your fingers as far as you can. Repeat 5-10 times.
The lumbricalis, flexor digitorum superficialis, flexor digitorum proflindus and interossei muscles are alternately stretched and contracted.35
FIGURE 6
With the fingers of one hand, grab each finger on the other hand and individually pull gently the fingers into an extension. Include the thumb in this exercise.23 Hold each stretch for 5-10 seconds for each finger in both hands.
There are no muscles within the hand that flex the interphalangeal joints of the fingers or thumb. Instead, muscular contraction within the forearm is transmitted to the fingers of the hand by way of the flexor 35,36 digitorum profundus, flexor digitorum superficialis and flexor pollicis longus tendon to produce flexion. The tendons of these flexor muscles attach to various places on the hands and fingers and all of them cross the wrist through a small space known as the carpal tunnel.37 If the tendons become swollen or inflamed they can compress the blood vessels and/or median nerve as they pass through the tunnel.38
In this exercise the flexor muscles of the forearm (mentioned above) and their tendons are stretched.
FIGURE 7-FIGURE 8
Stretch your thumb across the palm of your hand towards the base of your little finger as far as you can and hold for 5 seconds. Then extend your thumb outward and hold for 5 seconds. Repeat 5 times for each hand.
In this exercise the flexor pollicis longus of the forearm and the abductor pollicis brevis,abductor pollicis longus, flexor pollicis brevis, opponens pollicis and adductor pollicic muscles are alternately stretched and contracted.35
FIGURE 9-FIGURE 10
Place the palms of your hands together in front of your chest with your fingers extended upward (prayer position) and then raise your elbows so your wrists are being stretched and hold for 5 seconds.
Repeat 4 times.
In this exercise the muscles on the anterior forearms (flexor carpi radialis and flexor carpi ulnaris ) are stretched while the muscles on the posterior forearms (extensor carpi radialis brevis and longus and extensor carpi ulnaris) are contracted.
FIGURE 11 - FIGURE 12
Hold the exercising arm in front of you with your elbow straight. Position your hand with your palm face down and fingers extended. Bring your palm back toward your body. With the nonexercising hand, reach around the top of the fingers of the exercising hand and gently assist with a little pull back toward the body.30 Hold for 5 seconds and repeat 4 times for each hand.
In this exercise the muscles on the posterior forearms (extensor carpi radialis longus, extensor carpi radialis brevis and extensor carpi ulnaris) are stretched while the wrist flexor muscles (flexor carpi radialis and flexor carpi ulnaris) are contracted.
FIGURE 13
While standing or sitting, drop your arms to your sides. Gently shake out your anns and hands for a few seconds, relax and repeat. Breathe slowly and deeply.
This exercise allows for the muscles of the shoulder, back, and upper extremities to relax and relieve tension. Circulation is enhanced in the shoulder (gleno-humeral ) joints.
FIGURE 14-FIGURE 15
Stand upright. Shrug your shoulders and roll them forward and then roll them backward with your arms at your sides. Repeat 2 sets of 5 repetitions.
In this exercise the serratus anterior, pectoralis minor along with the trapezius, rhomboids and levator scapulae are contracted.
FIGURE 16
Stand with your feet separated and your arms by your sides. Lift one arm, with the elbow bent, and raise it across your chest over the opposite shoulder until your hand reaches down your back. Use the other hand
to give a gentle assist at the elbow at the end of the movement.22 Repeat 4 times for a count of 5 seconds on each side.
In this exercise the external shoulder rotators (teres minor and infraspinatus) along with the posterior deltoid are stretched. The pectoralis major, anterior deltoid, subscapularis and coracobrachialis muscles are contracted.
FIGURE 17
Utilizing a small ball made of foam, soft rubber, moldable putty or sponge-like material compress material for 3 seconds and then relax. Repeat 5 times for each hand.
This exercise alternately contracts and relaxes the muscles of the hand and forearm. Blood flow is also facilitated to these muscles by the alternate pumping action. Sponge balls are available in different sizes (o.7 kg to 3.6 kg) each necessitating a different compression force.42
None of the previously mentioned stretches or exercises should cause pain or discomfort. Overzealous efforts should be avoided. Moderation is the key.
Cumulative trauma injuries are usually an overuse injury as a result of activities both on and off the job.43 Practice prevention for your hand, wrist and upper extremities to reduce the risk of cumulative trauma at all times.The body does not differentiate cumulative trauma inflicted on itself as a result of work or playThere are factors to help prevent the occurrence of injuries. Prevention is following my previously stated acronym REST. both at home and at work.
R (Rest) Pay attention to signals the body may be sending. The first of which is often fatigue. Take a break from the routine you might be subjecting yourself to in order to improve circulation, change position or to restore range of motion (stretching).
E (Exercise) Overuse ~ is a relative term. If someone makes it a habit to exercise to keep your hands, wrist and upper extremities strong and flexible, they would ultimately be able to handle a greater workload. Their tolerance or "overuse" limit would be greater than a non-exercising individual.
S(Stretch) No matter how ergonomically designed and seemingly comfortable your work environment is, repetitive motion task will fatigue and tighten up specific muscles you are abusing. Use every excuse to stretch and maintain your range of motion. This also facilitates circulation.
T(Train) If we are aware that in our profession we are vulnerable to cumulative trauma injuries (carpal tunnel injuries), we should proactively train those muscles and areas that could be affected. The exercises I have described and demonstrated "train" those specific areas.
We do know that an increased frequency of strengthening exercises seems to be associated with a decreased risk of musculoskeletel syndromes among dentists." Some of the physiologic benefits of "preventive interventions" is discussed in Hansford’s article.45 Significant reductions in lost-time injuries ranging from 56%-9 1% have been demonstrated in companies utilizing "workplace preventive programs." 46 Successful strategies and outcomes have been documented and followed in workplace preventive approaches. A ten-year experience history at nearly 300 companies throughout the United States successfully supports prevention strategies.48
CONCLUSION
It seems prudent to acknowledge potential problems as a result of our lifestyles whether this is personal or professional. Acknowledgement alone without personal behavioral efforts to prevent or mitigate injury is potentially self-destructive and blindly irresponsible.
Using R.E.S.T. as a guideline and following the previously mentioned and described exercises will hopefully help the dental professional avoid functional impairment with all of its long-term and often permanent negative consequences.
BIBLIOGRAPHY
1) Belt, Debra "Proverbs Shine Light on Ergonomics" CALIFORNIA DENTAL ASSOCIATION JOURNAL Volume 29, Number 7 (July 2001), pp.478-480
2) Strong, David et al "Carpal Tunnel Syndrome" CALIFORNIA DENTAL ASSOCIATION JOURNAL Volume Number (April 1992), pp. 27-37
3) AMERICAN DENTAL ASSOCIATION NEWS Volume 31, Number 22 (Decemeberl 1,2000)
4) American Dental Association 1997 SURVEY OF CURRENT ISSUES IN DENTISTRY: REPETITIVE MOTION INJURIES (ADA. Chicago, 1998)
5) Hamann, Curt et al "Prevalence of Carpal Tunnel Syndrome and Median Mononeuropathy Among Dentists" JOURNAL OF THE AMERICAN DENTAL ASSOCIATION Volume 132, (February 2001) pp.163-170
6) Guay, Albert H. "Commentary: Ergonomically Related Disorders in Dental Practice" JOURNAL OF THE AMERICAN DENTAL ASSOCIATION Volume 129, (February 1998) pp. 184-186
7) ARRANGING YOUR WORKSTATION TO FIT YOU (The Stay Well Company, 1998)
8) PREVENTING REPETITIVE STRAIN (Krames Communications, California, 1989)
9) OFFICE ERGONOMICS (Comprehensive Loss Managemeent, Minnesota, 1993)
10) Liskiewiccz, Susanne Tishler "Cumulative Trauma Disorders: An Ergonomic Approach for Prevention" JOURNAL OF DENTAL HYGIENE Volume 71, Number 4 (Summer 1997) pp.1 62-167
II) Macleod, Dan et al THE ERGONOMIC MANUAL (Ergo Tech Inc., Minneapolis, 1990)
12) PREVENTING REPETITIVE MOTION INJURIES (Krames Communications, California, 1989)
13) Ellison,Deborah "Carpal Tunnel Syndrome" BODY MATTERS -AMERICAN COUNCIL ON EXERCISE (November/December 1996)
14) Murphy, Denise C. "Ergonomics and Dentistiy" NEW YORK STATE DENTAL JOURNAL (August/September 1997)
15) McCall, Timothy "Carpal Tunnel Syndrome: What Doctors Don’t Know" HEALTH Volume 15, Number 9, (September 2001) p. 8
16) Wunderlich, Ray C. THE NATURAL TREATMENT OF CARPAL TUNNEL SYNDROME (Keats Publishing Company, Los Angeles, 1993)
17) GETTING A HAND UP ON CARPAL TUNNEL SYNDROME (American Physical Therapy Association)
18) TAKING CARE OF YOUR HAND, WRIST AND ELBOW (American Physical Therapy Association, Virginia, 1995)
19) Lincoln, A. E. et al "Interventions for the primary prevention of work-related carpal tunnel syndrome" AMERICAN JOURNAL OF PREVENTIVE MEDICINE Volume 18 (May 2000) pp. 37-50
20) ERGONOMICS AND YOU (Krames Communications, California, 1995)
21) CARPAL TUNNEL SYNDROME (American Academy of Orthopaedic Surgeons, 1995)
22) CARPAL TUNNEL SYNDROME: A PHYSICAL THERAPIST’S PERSPECTIVE (American Physical Therapy Association, Virginia, 1996)
23) Oliphant, Jeff "Recognizing Carpal Tunnel Syndrome" PERSONAL FITNESS PROFESSIONAL (July 2000) pp. 36-40
24) Krivickas, L. S. "Anatomical factors associated with overuse sports injuries" SPORTS MEDICINE Volume 24, Number2 (August 1997) pp. 132-146
25) Kroemer, K. H. "Avoiding cumulative trauma disorders in shops and offices" AMERICAN INDUSTRIAL HYGIENE ASSOCIATION JOURNAL Volume 53, Number 9 (September 1992) pp. 596-604
26) American College of Sports Medicine ACSM’S GUIDELINES FOR EXERCISE TESTING AND PRESCRIPTION (Sixth Edition) (Lippincott, Williams. And Wilkins, Phiuladelphia, 2000)
27) Howley, Edward T. et al HEALTH FITNESS INSTRUCTOR’S HANDBOOK (Third Edition) (Human Kinetics, Champaign, Illinois, 1998)
28) American Council on Exercise PERSONAL TRAINER MANUAL (Reebok University Press, Boston, 1991)
29) EXERCISES AT YOUR WORKSTATION (The Stay Well Company, California, 1999)
30) Nova Care Inc. Outpatient Rehabilitation Cupertino, California "General Stretching Exercises for Repetitive Stress Injury" and "Wrist and Forearm Exercises~~
31) Wharton, Jim THE WHARTON’S STRETCH BOOK (Times Books, New York, 1996) pp. 76-90, 185-186, 225
32) "A Workout For Your Hands" CONSUMER REPOETS ON HEALTH Volume 13, Number 6 (June 2001) p. 10
33) ERGONOMICS IN THE DENTAL OFFICE (Zenith Insurance Company, California)
34) Hunter, James M. et al REHABILITATION OF THE HAND: SURGERY AND THERAPY (Fourth Edition) (Mosby, St. Louis, 1993)
35) Olson, Todd R. STUDENT ATLAS OF ANATOMY (Williams and Wilkens, Baltimore, 1996) pp. 284-291
36) Chin, Doug H. C. L. et al "Repetitive Motion Hand Disorders" JOURNAL OF THE CALIFORNIA DENTAL ASSOCIATION Volume 30, Number2 (Februarey 2002) pp. 149-160
37) Ellison, Deborah "Total-Body Benefits" BODY MATTERS - AMERICAN COUNCIL ON EXERCISE (November/December 1996)
38) Ellison, Deborah "Training the Body’s Small Giants" BODY MATThRS - AMERICAN COUNCIL ON EXERCISE (November/December 1996)
39) EXERCISES TO DO AT WORK TO PREVENT CARPAL TUNNEL SYNDROME (American Academy of Orthopaedic Surgeons, Rosemont, Illinois)
40) Westcott, Wayne STRENGTH, FITNESS, PHYSIOLOGICAL PRINCIPLES AND TRAINING TECI-INIQUES (Fourth Edition) (Brown and Benchmark, Madison, Wisconsin, 1995)
41) PREVENTING CARPAL TUNNEL SYNDROME (The Stay Well Company, California, 1998)
42) WORKPLACE ERGONOMICS CATALOGUE (North Coast Medical Ergonomic Products Division, Morgan Hill, Califomia)
43) Stockwell, John W. et al "Prevalence of Upper Extremity Neuropathy In A Clinical Dentist Population" JOURNAL OF THE AMERICAN DENTAL ASSOCIATION Volume 124 (August 1993) pp. 67-73
44) Rucker, Lance M. et al "Ergonomic Risk Factors Associated with Clinical Dentistry" JOURNAL OF THE CALIFORNIA DENTAL ASSOCIATION Volume 30, Number2 (February 2002) pp. 139-148
45) Hansford, P.; et al: "Blood Flow Changes at the Wrist in Manual Workers After Preventive Interventions": JOURNAL OF HAND SURGERY (1968) Number 1 IA, pp. 503-508
46) Allers, V.: "Workplace Preventive Programs Cut Costs of Illness and Injuries": JOURNAL OF OCCUPATIONAL HEALTH AND SAFETY (October 1989) pp. 26-29
47) Hebert, L. "Stretching Exercises in the Workplace".ORTHOP PT PRACTICE Volume 11, Number 4, 1999
48) Hebert, L. "Body At Work; Preventive Stretching on the Job". JOURNAL OF OCCUPATIONAL HEALTH AND SAFETY (October 1992) pp. 48-48
49) Hebert, L. "Preventive Stretching Exercises". IND SAFETY AND HYGIENE NEWS (April 1992)
50) Hebert, L. "A Cumulative Trauma School for Industry". INDUSTRIAL REHAB QUARTERLY (Fall 1992)
51) Lutz, G.;et al: "Cumulative Trauma Disorder Controls: The Ergonomics Program at Ethicon, Inc.".JOURNAL OF HAND SURGERY (1987) Number 12A (2,part 2) pp. 863-866
52) Sawyer, K.: "An On-Site Exercise Program to Prevent Carpal Tunnel Syndrome". PROFESSIONAL SAFETY (May 1987) pp. 17-20
53) Sheley, Elizabeth: "Preventing Repetitive Motion Injuries". HUMAN RESOURCE MANAGEMENT MAGAZINE (October 1995)
The author wishes to give thank and express appreciation to:
Hong Zhang, MS, MB
Associate Professor of Anatomy
Palmer College of Chiropractic West
San Jose, California
And
Denise G. Bradley, P.T.
Nova Care Rehabilitation
Cupertino, California for Iheir respective supportive inputs and advice.
