CUMULATIVE TRAUMA DISORDERS

     HISTORY, PATHOGENESIS AND TREATMENT

          Mark A. Mandel, M.D., F.A.C.S.

   Los Angeles, California

Click here to go to
The California Injured Worker Advisor's
Home Page

Cumulative trauma disorders have been exceedingly common in the 1990's.  They go by many names including repetitive strain disorder, cervical brachial syndrome, occupational overuse syndrome, work-related disorders, and repetitive motion disorders.  This is a concern to large and small manufacturers, insurance carriers, health care providers, and government agencies.

Epidemiology:            The usual cause of these conditions is repetitiveness and forcefulness of work, which causes localized stress in the tissues.  This leads to altering of their homeostatic state which in early stages is reversible, but in later stages usually is not reversible.  There is no simple solution to the problem.  There is no algorithm that will guide management in all cases.  Cumulative trauma disorders develop over a period of time ranging from weeks to years.  It is noted that intensive repetitive activity or forceful use done on a daily basis does not allow the tissues a chance to recover.  The daily repetitiveness of the tasks is usually additive.  The symptoms usually do not subside at the end of the working day.  Variables include the type of the task, frequency, forcefulness, length of time on the job, and age of the patient.  Also to be considered are, of course, non occupational activities including sports, hobbies and other recreational pursuits.

Historical Perspective: Long before the industrial revolution swept the civilized world, work-related injuries were described by Ramazzini in 1713.  It was noted even earlier by Ellenbog with goldsmiths in 1473, and Paracelsus with miners in 1567, that a variety of work-related conditions were found.  It was not, however, until the early 1700's that Ramazzini published a complete treatise about the subject.

Ramazzini stated some 300 years ago that, "Various and manifold is the harvest of diseases reaped by certain workers from the crafts and trades that they pursue.  All the profit that they get is fatal injury to their health, mostly from two causes.  The first and most potent is the harmful character of the materials they handle.  The second I ascribe to certain violent and irregular motions and unnatural positions of the body, by reason of which the natural structure of the vital machine is impaired so serious disease gradually develops therefrom." Thus, the words of Ramazzini some 300 years ago still ring true today.  Ramazzini was law came to light and it replaced the law where the worker had to prove that the employer was at fault.  In 1906, the Workers' Compensation Act was passed in Great Britain.

As with any new system, abuses arose and new terminology developed when workers starting applying for benefits for the most "trivial problems." Sir John Collie in London and Archibald McKendrick in Edinborough wrote books on "Malingering and Feigned Sickness." Malingerers were classified as real, partial or subconscious.  This was brought about by the telegrapher's cramp epidemic of 1912.  Telegraphy and communications were just commencing.  People repetitively used their hands and some 60% of the work force came down with symptoms including fatigue and a variety of nervous conditions.

It became apparent in the late 1920's, even to such non believers as Sir John Collie, that certain conditions required coverage under a workers' compensation system.  Conditions at that time included the following: anthrax from herding and sheep exposure; heavy metal poisoning; a variety of conditions from mining including beat knee, beat elbow and beat hand; inflammation of a variety of joints from mining; and hand difficulties called telegraphist's, writer's and twister's cramp.

Tenosynovitis of the hand was first recognized as a clinical entity formally by the State of Ohio in 1929.  They recognized that frequent repetitive motion and vibration caused swelling, and this was an early recognition of one of the causative factors in cumulative trauma problems.  It was not until 1934 that Hammer noted that swelling was accompanied by burning and numbness, and this was really the first report of carpal tunnel syndrome.  It was not until some 13 years later, however, that Brain and his co-workers actually described carpal tunnel syndrome as an entity.

The proverbial question is: which came first, the chicken or the egg?  Issues that are critical are: Can the activity cause the disease?  And, to what extent do emotional and psychological factors amplify and prolong physical symptoms? 

This became apparent in the repetitive strain injury (RSI) epidemic that occurred in Australia a decade ago.  Some 30% of all workers in the telecommunication fields developed a variety of problems.  The difficulty was the findings were migratory, all the studies were normal, and that people who were operated upon did worse after surgery than they did if nothing was done.  Rather remarkable was the fact that those keyboard operators that had the lowest salary and the lowest stroke rate had the highest incidence of difficulties, whereas the skilled typists had the lower rate of difficulties.  This inconsistency indicated that psychosocial factors were playing a major role and what happened was the epidemic disappeared when compensation was denied and the problem simply went away.  The repetitive stress problem is one in which symptoms were noted without findings.  What we are dealing with today is a totally different story, namely cumulative trauma disorders, and these are cases in which there are not only symptoms, but there are findings and abnormal tests that indicate a true pathophysiologic process is ongoing.

Cumulative trauma disorders are not new.  It is simply that we are recognizing them.  The names are for tissues affected or activities associated with their development.  Thus, in the upper limb there are a variety of disorders.

Disorders of the Upper Limb

Tendonitis

Epicondylitis

Carpal tunnel syndrome

Cubital tunnel syndrome

Myalgia

De Quervain's tenosynovitis

Traumatic arthritis

People recognized that these conditions existed and in centuries past a variety of conditions were present that were classified based upon the activities done at those times.  These include washer woman's sprain, gamekeeper's thumb, drummer's palsy, pipetter's thumb, reedmaker's elbow, pizza cutter's palsy, and flute player's hand.

Few of the activities listed above are still in vogue, however, we now know that many occupations are currently involved in cumulative trauma disorders of the upper extremity and prevalent among them are the following.

Occupations Currently Involved

Data entry workers

Automobile workers

Poultry workers

Meat packers

Rock drillers

Dentists and hygienists

 Pathophysiology:            Cumulative trauma disorders develop because the human body simply was not constructed to perform certain tasks.  Ramazzini noted 300 years ago that unusual motions and unnatural postures caused difficulty.  This is, of course, a multifactorial problem since not everybody in the same industry develops difficulties.  Thus, there is an individual patient response, but critical is the work situation and also playing a role are nonindustrial factors such as recreational activities, prior injuries and other situations.  One of the problems is many of the jobs today are repetitive.  The patients do not approach work enthusiastically.  In looking at the job site, it is often not pleasant, it is quite often boring, there are organizational conflicts, people are fearful of layoffs, and they feel they are trapped in a job with no way out.  There are also some intrinsic problems that play a role.  People come to work out of condition.  One-third of the population of the United States is overweight, we have an older work force, some patients are guilty of symptom magnification, and there are communication problems not only with the employee and employer, but also problems at home.  Furthermore, the production process has been dehumanized.  People are being asked to do more repetitions, line speeds are higher and in general there appears to be a lack of management concern in many industries.

The Bureau of Labor Statistics in 1992 noted that cumulative trauma disorders have tripled since 1984.  The nature of our industry has changed and some 20% of the work force is at risk for hand problems alone.  One of the key factors is ergonomic stressors, and these result in problems such as carpal tunnel syndrome, a variety of tendon and muscle irritation, as well as upper and lower back difficulties.

Scientific verification exists that the incidence of the disorder is far higher than that in the normal population.  Silverstein, reporting in the Journal of Hand Surgery in 1987, noted that the combination of high force and high repetition has caused an incidence of carpal tunnel syndrome and tendonitis 30 times greater than the normal population.  Stock, reporting in the American Journal of Industrial Medicine in 1991, noted that again a strong relationship between repetitive force and upper extremity disorders exists.  Some 30 times the incidence of tendonitis and 15 times the incidence of carpal tunnel syndrome is present in certain workers than in the normal population.  Susan Mackinnon, reporting in the Journal of Hand Surgery in 1994, noted in a prospective randomized control series that there is a definite relationship between abnormal postures, positions and movements with a variety of cumulative trauma problems.

Naysayors always exist.  N.M. Hadler and some others feel that the cumulative trauma disorders do not exist at all and are really a sociopolitical phenomenon, that the system is abusive, and he does feel that NIOSH is the problem and not the solution.

Pathogenesis:            In looking at why these disorders occur, when hands and other portions of the anatomy are used repetitively, forces are set up in the tissues.  This means the tissues are deformed.  They swell, swelling causes pain, and eventually if the swelling does not regress the tissues start to break down, and this causes scar tissue which becomes an irreversible situation.  There are many variables.  This, of course, depends upon the actual work done, the variety of ergonomic stresses, as well as the individual capacity.  Thus, fatigue and tissue breakdown are quite variable, but approximately 20% of all people doing repetitive hand activities are eventually going to come down with some type of a cumulative trauma disorder.

There are certain ergonomic risk factors.  These, of course, include the force applied, localized mechanical stressors, postures of the extremities, exposure to extremes of temperature - especially low temperatures, and the use of vibratory tools.  Ergonomics developed and this is a science concerned with the design of work equipment, procedures and environments so that people can achieve maximal performance without undue risk of injury.

Development Time: Cumulative trauma disorders develop over a minimum of weeks.  They do not develop in days, and in most instances take months or often many years to develop.  There is no data on the actual development time, but by their very name they are not the result of a single traumatic event.  The problems develop insidiously and are usually present for long periods of time before the patient reports the problem.  Many never report the problem for fear of loss of their job, and this has been quite true when major companies such as General Motors and others have left the area, when a plethora of cases suddenly appeared, all of which have been present for many years.  The problem is that abnormal posturing, positioning or movements of the hand, neck and upper extremity result in increased pressure on nerves, shortening of muscles and a variety of compensatory difficulties in which one set of muscles is weakened and another becomes strained or stressed.

Common Cumulative Trauma Disorders: The most common problem encountered is carpal tunnel syndrome.  Pressure develops within the carpal canal when the wrist is moved from a neutral position.  Constant use increased tendonitis and swelling, there is microscopic obliteration of vasculature to the nerve itself, and eventually scar tissue, both microscopic and macroscopic, develops, and this will end up compressing the nerve.  A different etiology is present for cubital tunnel syndrome or ulnar neuropathy at the elbow.  Here elbow flexion decreases the volume within the cubital tunnel, pressure on the nerve increases, and thus the nerve is repetitively stretched and this will eventually cause scarring and nerve compression.

Double Crush Syndrome: When nerves are injured in general, they become hypersensitive at other locations.  Thus, compression of the nerve at one point renders other points, both proximal and distal, less tolerable to pressure.  Cumulative effects of minor compression produce complex problems, usually in the face of normal electrodiagnostic testing.  In terms of nerve testing, the accuracy of the nerve conduction study at the wrist level is probably in the vicinity of 85-90%, but the accuracy of the nerve conduction study at the elbow level is probably only in the vicinity of 65-70%.  This, of course, assumes that the electromyographer is skilled.

Abnormal Posturing: People develop problems not only in their arms, but also in other portions of their anatomy, and this develops from abnormal posturing.  What occurs is that muscles shorten and when an attempt is made to stretch them it results in pain.  When tightened, the muscles can compress neurovascular structures.  Thus, if the scalene and sternocleidomastoid muscles are compressed in the neck, a thoracic outlet problem can occur.  If the pronator teres is compressed in the arm, the median nerve at that level can be compressed.  This muscle imbalance results in compensatory overuse of other sets of muscles.  Thus, a forward flexed position of the shoulders will shorten the serratus anterior and lengthen the trapezium muscle.  This leads to the inability to rotate the scapula, which causes other accessory muscles including the rhomboids, levator scapulae and scalenes to hypertrophy in order to compensate.  Attempts to lengthen the shortened muscles will cause pain.  Thus, when sitting at an unergonomic work station, many workers end up with a self-perpetuating cycle of tight muscles becoming tighter and weak muscles becoming weaker.  Rest alone will not cure this condition and for muscle spasm difficulties physiotherapy is often beneficial to restore muscle balance.  It should be noted, however, that physiotherapy for cumulative trauma problems involving the wrist and elbow, such as nerve compression, is rarely successful and rarely indicated.

Therapeutic Goal: First and foremost, the work station should be corrected.  We should prevent problems before they occur.  If abnormal posturing is prevented, muscles will not go into a state of imbalance and abnormal pressure on the nerves will not occur.  The height of the work station and the position of the neck and the arms when using a keyboard are critical.  If surgery is performed, unless these changes are made, any surgical repair will be doomed to failure.

Patient Management: In diagnosing any condition, it is necessary to exclude non work pathology including old injuries, a variety of metabolic and rheumatologic disorders such as diabetes mellitus, rheumatoid arthritis, systemic lupus, scleroderma, and others.  Conservative treatment should be instituted first, splinting and resting.  In some instances anti-inflammatory agents are beneficial.  Therapy is beneficial for muscle spasm difficulties.  Surgery should be done only when all else fails.  The most common difficulties that will be discussed in greater detail in the second portion of this article are nerve entrapment syndromes.  The nerves can be compressed as they pass through any fixed compartment or muscle group.  Repetitive use causes swelling, edema and scar formation.  Nerves do not like to be compressed and when they are it causes pain, tingling and numbness, muscle dysfunction and weakness.  The median nerve can be compressed not only at the wrist, but also in the forearm.  Similar situations exist for the ulnar nerve and for the radial nerve.  Indications for surgery are failure to improve with conservative care, progression of problems in the case of muscle atrophy, severe symptoms or long duration of symptoms.  Carpal tunnel syndrome can now be corrected endoscopically or open, dependent upon the skills of the surgeon.  My personal preference for primary conditions is an endoscopic correction, however, open approaches are best when there is double nerve involvement including median and ulnar.  De Quervain's tendonitis, first described 150 years ago, is inflammation of the first dorsal compartment tendons.  Trigger fingers is due to inflammation of the tendon sheaths.  These conditions are all due to the same pathophysiologic problem and in approximately one-third of all patients, all three entities, namely carpal tunnel, de Quervain's and trigger fingers, can be found.  Thoracic outlet syndrome, a controversial problem, often results in compression of the C8-Tl roots.  Signs and symptoms are often vague.  Findings are poorly defined.  Testing is difficult and all of the tests are usually ambiguous.  It should be remembered that at least 25% of all normal patients have pulse obliteration on provocative testing.

There are certain psychogenic and sociopolitical factors that are present. 

There is a much higher incidence of disorders and the system can be abused by dishonest workers and malingerers.  Most commonly affected are female employees engaged in low paying, monotonous, low prestige occupations. 

There are also difficulties with treatment rendered.  There seems to be less concern for patient well-being.  There are often unnecessary, often harmful therapies instituted which are too long, the wrong type, and done by unskilled physicians.  There is often too much surgery, too little conservative care, incorrect diagnoses made, there is a cut­now/think-later philosophy, and in many instances large, unnecessary surgery is done when simpler procedures would be sufficient, and in some instances we end up treating iatrogenic problems caused by unnecessary surgery.

Some physicians have become jaded.  They have no concept of the patient's job and simply return them to work, sending them back without any modifications and without any restrictions.  It is best if a modified job can be found for these people.  Others simply rehabilitate everyone, but this is no panacea.  Many people do better if they can be returned to a job, especially if they are in a senior position. on the contrary, some people never rehabilitate anyone.  This, of course, is no solution and unless the work situation is altered a problem is certain to occur.

Conclusion:            There is really nothing new about cumulative trauma disorders.  Only the problems have changed as new industries appear and old ones disappear.  An integrated approach with a well-trained physician orchestrating treatment is necessary.  Work station ergonomics should be corrected and conservative treatment instituted first if possible.  Surgical care should be done only by a well­trained, certified physician with whom the patient can communicate.  The cumulative trauma disorders result when work requirements exceed an individuals capacity.  They are caused, precipitated or aggravated by repeated or sustained exertions of the body in the upper extremity and neck.  They often result in nerve compression, myofascial pain and muscle imbalance.

Click here to go to
The California Injured Worker Advisor's
Home Page