Repetitive Strain Injury (RSI)
Leo M. Rozmaryn, MD
Repetitive strain injury or cumulative trauma disorders is defined
as those conditions of muscle, tendon, bone or nervous system that
are caused, precipitated or aggravated by repeated exertions or
movements of the body. (This definition reflects the philosophy of
workers' compensation laws in most western countries.) These
represent a failure of any of these systems from overuse and
repeated stress for a specific part of the body causing a
disruption of connective tissue. (Microtear or fracture.)
RSI is not a specific diagnosis but a class of disorders with
similar characteristics. This will include all sudden injuries
Sub categories of RSI include:
Muscle -myalgia
-myofascial pain syndrome
Tendon -tendinitis
-tendinosis
-peri-tendinitis
-teno-synovitis
-trigger digits
-impingement syndrome
-tennis elbow
-golfers' elbow
Nerve -carpal tunnel syndrome
ulnar tunnel syndrome
-pronator syndrome
-cubital tunnel syndrome
-radial tunnel syndrome
-anterior and posterior interosseous syndrome
-thoracic outlet syndrome
-vibration hand syndrome
Bone -stress fractures
-periostitis.
Common traits -relate to the duration and intensity of work
-require weeks, months, or years to develop
-symptoms can be poorly localized, non-specific,
and episodic
-multi-factorial, under reported
-may require weeks, months, or years to
rehabilitate
Symptoms of RSI depend on the location of overuse and the specific
tissue injury. Commonly, patients experience pain, fatigue, a loss
of dexterity, a weakness, numbness, and tingling distally when the
upper extremities are involved. This eventually leads to
depression and loss of sleep.
The difference between simple fatigue and RSI is the duration and
intensity of symptoms. Fatigue is short-lived after work/shift and
will usually recover before the next shift as the body's
reparative processes take over. If these cannot keep up with the
level of occupational strain, patients may begin their day or week
with the pain. Thus the cycle begins. As a general rule, workers
should not be experiencing symptoms from the previous day's work.
Occupational risk factors
-repetitive/sustained static postures
-forceful exertions
-localized mechanical stress
-vibration
Course
Initially symptoms are ignored, and in many cases resolve on their
own with simple rest, ice, and over-the-counter NSAID. However,
some patients begin a typical course that in most cases have an
unhappy ending. Typically, it goes like this:
An employee first visits the company nurse, who refers the
patient to the company MD or HMO, who give the patient time
off. Upon the employee's return, the symptoms also return,
and he or she is referred to a specialist. More conservative
treatment follows. Then, a battery of diagnostic tests
followed by surgery ensues. Initially, there is relief of
symptoms, return to light duty at work, then regular duty.
The symptoms then return, and the patient is eventually hid
off. Workers' compensation claim is denied. An attorney is
now involved, with a court hearing. A rehab nurse for the
insurance carrier now steps in for a permanent disability
evaluation, and a second medical opinion is sought for a
permanent disability payoff This can take many years, and
patients' lives are literally consumed by this process. There
is a loss of self-esteem and income, causing home strife,
etc. People see themselves as unemployable, especially in a
bad economy, and end up as a tax payers' burden.
Treatment is multi-faceted. In order to succeed, it must be based
on prospective protocols and treatment algorithms based on
multi-center outcome studies, rather than simple reactive and
haphazard intuition. The surgeon that has until now had a central
role in treatment must assume a side role.
Incidence, prevalence, and cost
In 1984, the AAOS National Survey revealed the cost of all
muscular skeletal injuries was greater than $27.5 billion for
direct and indirect cost per year. In 1980, Kelsey showed the
frequency and cost of upper extremity disorders to reach a total
of 16 million injured per year, 90 million days of restricted
activity, 16 million workdays lost, and 500,000 hospitalizations.
There were 12 million physician visits. To date, there have been
no good figures for RSI, because the classification systems are
still evolving and coherent definitions need to be reached before
a tracking system is instituted.
In 1988, AAOS research revealed that carpal tunnel surgery was the
tenth most common performed surgery in the United States. For the
Medicare group alone, the cost was $15.5 minion. For example, in
Oregon in 1984 there were 607 claims, at a total cost of $5,000
per case, or a total of $3 minion in payments. Assuming no
additional expenses, this would equal $ 150 million nationwide for
carpal tunnel alone. Considering that the average settlement cost
of an occupational injury is $10,000, this figure is mind-boggling
Mallory in 1992 reported that 51% of all occupational injuries
reported were due to RSI at an estimated annual cost of $13
billion. According to Bureau of Labor Statistics: upper extremity
complaints now outnumber low back complaints. In 1989 they
numbered almost 150,000.
One may ask, "Why are we seeing more of this today than in
previous years?" In my opinion, workers are more legally and
medically astute and will seek help earlier. Furthermore, with the
growth of automation, larger segments of the population are now
involved with keyboarding. There is also a must greater awareness
of occupational safety nowadays than before. Previously, workers
suffered in silence.
Characteristics
Repetitiveness -assembly-line packers = 25,000 cycles per day
-ratchet screw drivers = 1,000 screws daily at 5
exertions per screw = 5,000 exertions per day
-tea packers = 7,500-12,000 exertions per shift
-work cycle ' 30 seconds performed > 50% of the
time
Vibration -ie. jack hammer--low frequency vibration
Poor intrinsic body mechanics-gender and occupation ally specific
Control on a mass scale needs to center around prevention. The
employee health unit in any company or plant can no longer be a
passive clinic, waiting for patients to come in, and addressing
problems as they occur. They need to be active participants in a
multi-disciplinary team. This team must include workers,
management, representatives, occupational physicians, ergonomic
engineers, industrial psychologists, plus a team coordinator.
Ergonomic teams -job site, workstation analysis
-machine, toot worker interface
-toxic chemical thermal vibration exposure
Surveillance -identify work sites at risk
-workers' screening for job suitability
-pre-employment and ongoing in-service
-clear, standardized records of employee complaints
-anonymous job satisfaction survey
-job rotation
-records of lost workdays
-restricted workdays
-periodic physical exams, medical and psycho-social
Intervention -employee education and retraining
-evaluation of national statistics to assess
relative risk
-job site analysis and redesign
-use of computer simulations
-real time video
-increase employee satisfaction
-process must be active, positive, and ongoing
Prospective mechanisms need to exist for retraining within the
company that are independent of job seniority, despite potential
friction with local labor unions. Employer priorities are commonly
manufacture of a product, generation of capital and
infrastructural stability. Employee drop-off will affect all
three. In patients with acute injuries, there is a known onset and
cause. Employers, however, have a problem with RSI for the
following reasons:
(1) onset is not precise
(2) symptoms are vague
(3) an appearance of depression with the perception of malingering
and secondary gain
(4) white-collar workers will bypass the workers' comp system and
proceed directly to private MDs, bypassing the screening and
recording mechanism
(5) many employees don't react until workers' compensation bills
are so high, and the policy is canceled
(6) unions get involved, OSHA investigates, and there is
protracted litigation, bringing the cost up to $20,000 in a
six-month period.
Employers commonly deny that a problem exists, rapidly replace an
injured worker, try to "increase motivation by incentive pay"
possibly aggravating RSI, tell their workers not to come back
until they are completely well While this may work for acute
injuries, in RSI, this is a recipe for disaster. There needs to be
an appreciation of the need to sacrifice short-term gains and
inconvenience for long-term growth. This has worked well at the
Volvo and Boeing plants, and in Japan. There must be on site rehab
and a work hardening program. In addition, with certain jobs,
employees and employers need to understand that the employees can
only perform until a certain age. A prospective mechanism for
change needs to be put into place based on personal ability, and
not seniority.
At this time, employees with RSI are frequently fired on a
pretext. The rapid turnover of the work force has a major
deleterious effect on the productivity of the American worker.
Unless business and industry can police itself in this fashion,
the federal government will have to step in. Unfortunately, the
federal bureaucracy in and of itself is a major offender in these
matters, i.e. The Department of Labor and The Post Office. Many
health care providers in trying to treat federal workers run into
an absolute morass of bureaucracy and paperwork causing serious
delays in evaluation and treatment. Currently trying to implement
workstation ergonomic modification in a federal workplace is
practically impossible. While trying to regulate private industry
there seems to be no ability to police itself.
Therapy Of The Occupationally Injured Hand And Upper Extremity
Modalities have an adjunctive role in the treatment of these
conditions. They assist in neuromuscular reeducation, exercise
performance, and activities of daily living. They may reduce
inflammation, edema, vasomotor instability (sympathetic), and
pain. Joint range of motion and soft tissue flexibility are
enhanced. Distal circulation and sensation improve.
There are many types of modalities. These include thermal,
electrical, ultrasound, iontophoresis, phonophoresis, whirlpool,
fluidotherapy, and paraffin. Thermal modalities may be hot or
cold. Heat modalities increase metabolic rate, cause arterial
dilatation ,with stretching will increase soft tissue flexibility,
and increase analgesia. These are best used 48 hours after injury.
Heat modalities come in two types: conduction and convection.
Simple conduction involves the transfer of heat from one surface
to another. The application of hot packs and paraffin baths fit
this description and are useful in a static mode. Transfer of heat
by convection ( from a moving or flowing surface to the extremity)
will allow exercise both active and passive to occur. Typically
whirlpool and fluidotherapy are used. It has been experimentally
determined that heat will penetrate to 1 cm. if administered in
this fashion. Deeper heat penetration, up to 5 cm. can be achieved
with the use of ultrasound. These high frequency sound waves can
be used to carry medications such as corticosteroids beneath the
skin without the use of a needle. This is known as phonophoresis.
Cooling treatments when used in conjunction with compression
reduces edema . It is also useful in slowing the inflammatory
response that accompanies an acute injury or progressive chronic
strain. Electrical stimulation (direct current) can slow muscle
atrophy by externally causing muscle tissue to contract. This will
augment tissue circulation and maintain flexibility of muscle-
tendon units Increasing the voltage can deepen the penetration of
this effect.
Alternating current increases sensory nerve stimulation,
peripheral vasodilation, and analgesia . Transcutaneous electrical
stimulation (TENS) is use in the treatment of autonomically
mediated pain. It is believed to effect the release of natural
opiates made in the brain called endorphins. In addition it may
"short circuit" neurological pain pathways by preferentially
stimulating ' tactile' beta fibers.
Splinting as a modality has been grossly misused. It is a leading
cause joint stiffness, muscle atrophy, chronic weakness,
osteopenia ( bone loss), and sympathetically mediated disuse
dystrophy. Muscle tendon units lose their flexibility rapidly as
well as their ability to contract efficiently. Thus this treatment
form must be used very judiciously with clear objectives and time
limits to achieve maximal therapeutic benefit. When used
correctly, and are fashioned properly, splints will: 1) protect
overstrained joints and muscles 2) allow safer posturing of a limb
and maintain that posture 3) Reduce forceful exertion 4) Reduce
edema and inflammation. In addition 'dynamic ' splints can reduce
joint stiffness and actually increase active joint range of
motion. Splints may also protect arthritic joints from excessive
movement. In patients with RSI it is helpful to fashion a soft
support made from neoprene (wet suit material) for use during the
day and save the more rigid splint for use at night. It is also
important that patients be monitored for compensatory movements
from adjacent joints that may stem from splint wear. These may or
may not create RSI in these new locations.
Exercise is the mainstay of therapy for RSI. These include the
various types of active, passive, and resistive types. Early on in
treatment, muscle stretching is paramount. Muscle groups are
brought out to their resting lengths, spasm is eased, blood
circulation is increased and muscle -tendon units are allowed to
contract more forcefully and efficiently. Tight muscle groups that
took part in compressive neuropathy are allowed to relax somewhat
thus relieving pressure on nerves .This is seen in Thoracic Outlet
Syndrome, myofascial pain syndrome, and cervical-brachial
syndrome.
Isometric muscle loading allows for the build-up of muscle tension
without movement This is useful in patients with intrinsically
limited range of motion such as in arthritics. Isotonic loading is
the more typical exercise modality . Concentric muscle loading
occurs i.e. tension is produced, movement occurs as muscle
shortens. This modality must be discontinued is symptoms
redevelop. Eccentric muscle loading is a very effective means of
muscle loading to achieve a training ' effect. As a muscle
contracts in one direction an overpowering force is placed in
opposition. However, this method can rapidly lead to muscle strain
and overuse.
Isokinetic exercise now popular, is safer and at least as
effective as the other types. The load matches the resistance
offered and the rate is kept constant. Tendon gliding exercises
will reduce adhesions increase muscle -tendon flexibility and
increase local blood circulation.
General Guidelines for Job Retraining
One needs to lower the maximal liking limit to 30% maximum in
those tasks that require constant repetition, and 50% to tasks
done occasionally. Minimize contact stresses by spreading the area
of force to a larger part of the hand or arm. Automate repetitive
tasks. Mechanically stabilizing large objects, providing pneumatic
assistance whenever possible and sharpening tools to increase
their efficiency will go a long way in preserving employee
longevity.
Hand tools should be modified so that 1) tools heavier than 25
lbs. are suspended and counterbalanced. 2) finger pinch is kept to
less than 7 Lbs. 3) power grip is less than 35 lbs 4) allowing
full hand grip whenever possible. Care must be taken so that the
work station is at the correct height i.e. 2-4 inches above the
elbow for fine object manipulation, 2-4 inches below the elbow for
general hand use, manual work will require 6-15 inches of leeway.
The wrist should be kept in neutral for most tasks. Any deviation
will lower muscle efficiency and increase the likelihood of
fatigue. Vibration must be avoided if possible . Prolonged
exposure to vibration will result in permanent changes in the fine
blood vessels in the hand causing a condition known as vibration
white finger. Tools must be padded and the exposure time should be
circumscribed. There is no valid treatment for this problem
surgical or non.
Repetitive Strain injury at the Computer Workstation
Over the past fifteen years we have witnessed a revolution in the
way information is stored and processed. The typewriter, file
cabinet, desk top, mailbox, adding machine, and even the pen,
writing pad, and the telephone have all been replaced by the
desktop computer. Many of us are only beginning to come to terms
with this marvel. The productive workstation has indeed been
transformed in many unforeseen ways. Whether one is a research
geologist, musical composer, graphic artist, or a real estate
agent, the traditional tools of the trade has given way to the
electronic medium. While this has increased productivity
enormously, it has brought with it a whole new set of problems. A
whole new disease complex now called: electronic workstation
repetitive strain injury. The pathogenesis of this illness is
multifactorial. The two main components include 1) maladaptive
posturing with the maintenance of poor body posturing over
extended periods of time, frequently under high physical and
emotional stress situations. 2) chronic repetitive overuse at the
key board or mouse.
Examples of maladaptive posturing include:
1) sitting hunched over in a chair with poor lumbar support
2) Chair is too high or too low so that either the feet are
insufficiently supported at the floor or the hips are flexed too
much throwing the lumbar spine forward.
3) round shouldered position caused by chronically looking down at
the desktop, keyboard etc.
4) neck strain caused by chronic bending or twisting, this is
caused by a poorly positioned monitor, either too high, too low,
angled improperly, either up or down, too far away, too close, or
a monitor that is too far off to the side and not collinear with
the keyboard. The use of a traditional telephone receiver cradled
between neck and shoulder while using the keyboard will in short
order cause nerve compression in the neck or arm
5) arm and wrist strain caused by insufficient support and
malpositioning Keyboards maybe too high, too low, too close to the
edge of the working surface, or the simple fact that the keyboard
is straight.
These are only a few examples of the myriad of possibilities that
can occur. Curiously, most workstation modifications are easy to
execute and are inexpensive. The following are a short list of
tips that may go a long way in alleviating the problems. Firstly,
if telephone use exceeds forty five minutes a day, a telephone
headset should be purchased . Newer models are extremely
lightweight. The monitor should be straight ahead of the keyboard,
placed between 20-30 inches from the head and placed in such a
position so that the neck is tilted approximately 20-25 degrees
down from the horizontal. The table bearing the key board should
be placed at umbilicus level with the key board squarely placed on
it. The key board should be offset from the edge of the table by
approximately 4-5 inches and depending on the height of the
keyboard a wrist rest made of soft foam rubber can be used. If
ones occupation involves large amounts of data entry with document
copying, a vertical document holder attached to the monitor should
be used. Also helpful is a strong chair with good lumbar support
preferably with padded armrests. The elbows should be flexed to
near 90 degrees the wrists in neutral and the finger held as flat
as possible. In addition keeping the wrists and forearms in full
probation for long periods (palm down) is also detrimental. Taking
short breaks allowing the wrists to move into supination (palm up)
for periods during then day may be quite helpful. If the RSI is
well established the use of a split keyboard may be the only
solution. There are many new models on the market and it is not
yet clear which ones are more effective. What is clear is that
keyboarding with the wrists in less probation is much more
comfortable. It has become apparent that those involved in the
operation of electronic workstations must several times be allowed
to take a micro exercise break. These short programs allow the
squaring off of the shoulder girdles stretching the muscles m the
front of the shoulder opening the thoracic outlet. Gentle neck
mobilization with stretching of sore muscles and tendons around
the neck, Shoulders and arms will not only give sense of well-
being but will make the worker more productive and may actually
prevent RSI from ever occurring.
In summary, RSI is treatable but one needs to concentrate on
prevention and only with prospective handling will we be able to
stem its relentless rise.
Future Directions in the Management of Repetitive Motion
Nerve Injury
Leo M. Rozmaryn M.D.
1. Ergonomics: Further studies are indicated to delineate basic
guidelines for correct ergonomics at a given workstation, whether
it be white or blue collar. This could be done either through
laboratory analysis of human kinetics using work simulation.
Studying energy cons Option and the biomechanics of fatigue in an
attempt to find the most energy efficient method to perform a Even
task. As a first stage this would be done in a laboratory setting
. Then this model would be made portage and taken into the work
station for field studies. Using coherent models of what
constitutes an ergonomically correct activity with classification
systems specific recommendations can be made.
2. Treatment Sequence: Models using various forms of treatments in
prospective outcome studies comparing currently used treatment
modalities to assess the long term efficacy of treatment are
needed. For example, is nerve mobilization or immobilization the
key to nonoperative treatment of compressive neuropathy. If both
are to be used, how are they to be employed to mammal advantage.
How far is one to go with non operative management before
resorting to surgery, especially in workers compensation cases.
What is the role of non steroidal anti inflammatories in the
management of repetitive strain nerve iffy. Further evaluation of
other modalities of nerve testing must be done to increase the
sensitivity and specificity of nerve tests especially with regard
to unmyelinated nerve fibers which may be responsible for the
early symptoms. In addition more sensitive methods of testing
those populations at risk must be employed.
