( CASE STUDY J

Electromyographic Biofeedback Evaluation of aComputer Keyboard Operator with

Cumulative Trauma Disorder

Chris Reynolds, PT, CHTClinical Director,Hand Surgery Associates/HandRehabilitation Unit,Phoenix, Arizona

C umulative trauma disorders (CTDs), or ten­dinitis and compression neuropathies in the

upper extremities in particular, are fast reaching ep­idemic proportions in companies manned by key­board operators. The National Institute for Occupa­tional Safety and Health (NIOSH) estimates that in1986 as many as 4% of the work force suffered fromCTDs, many of these keyboard operators in the tele­communications industry. Overall, CTDs accountedfor 56% of all workplace illnesses in 1992, comparedwith just 21% in 1982. Unfortunately, the pathologicagent of these problems is not clear-cut, and typicallyrandom groups of muscles, tendons, and nerves areinvolved in the disorder. Rarely are individual orsingle muscles, tendons, or nerves involved, makingtreatment all the more difficult for medical profes­sionals. When managed in the early stages, though,these problems are relatively easy to reverse becausethe process is not usually as widespread and oftenthe condition is quite localized. The basic goals oftreatment include relieving pain and inflammation,regaining flexibility and strength, and, finally, pre­venting recurrences.

A variety of conservative approaches have provedbeneficial in combating inflammation from anti-in­flammatory medication, steroid injections, splinting,

Correspondence and reprint requests to Chris Reynolds, PT, CHT,Clinical Director, Hand Surgery Associates/Hand RehabilitationUnit, 2610 North 3rd Street, Phoenix, AZ 85004.

ABSTRACT: This articl e descr ibes a rehabilitation approach fora keyboard operator following radial tunnel decompression andrelease of the extensor origin of the right e lbow. Prior to th epati ent's returning to work, a clinical electromyographic (EMG)biofeedback device was used to determine wh ich work activitiesthe patient should avoid or alter to reduce strain on her affectedmuscles. The patient was able to return to work and noticed aco ns ide rable reduction of muscle fatigu e and pain in the involvedmuscles . A relativ ely inexpensive EMG biofeedback devi ce wasemployed to evaluate the patient's mu scles pr ior to return ing towork . The rationale and suggestions for application of the bio­feedback unit are discu ssed .J HAND THER 7:25- 27, 1994.

and physical therapy modalities to deep massage andgentle stretching. When conservative approaches fail,surgical intervention may be appropriate but is usu­ally considered the treatment of last resort.

Preventing recurrence is probably the greatestchallenge to those involved in the care of these pa­tients. Reducing risks through job-station modifica­tion has been suggested as one of the best methodsto ensure against recurrence. Revamping worksta­tions is often costly but in many cases has proved tobe effective .

Preventing recurrence is probably thegreatest challenge.

An electromyographic (EMG) biofeedback eval­uation offers an alternative approach to preventingrecurrence. EMG biofeedback equipment monitorsthe physiologic process of action-potential genera­tion, which results in muscle contraction. Many au­thors have suggested using EMG biofeedback as amethod to evaluate muscle activity in the upper ex­tremity. In our clinic we use EMG biofeedback todetermine which activities and which arm positionsactually promote more muscle fatigue so that thesecan be avoided by the patient. This case study illus­trates a method to evaluate muscle activity in a key­board operator using a simple clinical EMG biofeed­back device during a variety of work-specific tasks.

January-March 1994 25

CASE REPORT

A 45-year-old right-handed female computer keyboardoperator/telephone representative for a cable companywas treated for chronic right lateral epicondylitis andradial tunnel syndrome between June 15 and Decem­ber 28, 1992. A surgical procedure was performed onAugust 26 to decompress the radial nerve and debridethe lateral epicondylar area of scar tissue. Followingthis surgery the patient began a rehabilitation programto regain motion and strength in the right upper ex­tremity. In late December she was released to lightwork by her physician.

EVALUATION

As part of her rehabilitation program the patientwas educated about proper posture and workstationadjustment. However, it was not until days beforeher return to light work that we investigated bio­feedback as a therapeutic tool to identify specific ac­tivities that may have brought on her injury in thefirst place and could potentially aggravate her rightelbow in the future . Theoretically, we were hopingto alter the biomechanics that had produced the wearand tear in the affected area, thus preventing a re­current problem. With this particular patient we usedbiofeedback specifically to see which writing deviceminimized muscular activity of the wrist and fingerextensors. The patient was tested using a standardpen, a pen with gripper, a pencil, and a felt marker.An Amatron (Thought Technology, % Cimetra, NewYork) biofeedback unit was used with electrodeplacement over the motor point of the extensors ofthe wrist ,and fingers at the lateral epicondyle. TheAmatron device has a series of colored lights (fivegreen, one yellow, three red) that indicate increasingmuscular activity. An audible clicking or beeping noiseaccompanies-jhe visual signals. The device was ad­justed (threshold) so that when the patient was usingher usual pen, tJ;1e yellow light was activated. Thiswas our "center pqint" for evaluation of the otherwriting devices. Thepen with gripper and the pencildid not reduce muscular activity into the "green zone,"while the felt marker did. We concluded that becausethe patient did not have to write through carboncopies during her workday, a felt marker would be"safer" for her muscles than would, the usual penand would help reduce muscle fatigue . .

"A felt marker would be safer for thepatient's muscles than would her usualpen.

In a similar manner we tested the patient's rest­ing posture on the keyboard. Normally when thepatient is waiting between phone calls with cus­tomers she "poises" her hands in anticipation of in­itiating keyboard strokes. Unfortunately, this doesnot rest her wrist and finger extensor muscles andtherefore contributes to the repetitive or sustainedmuscular activity leading to early fatigue at the el-

26 JOURNAL OF HAND THERAPY

She could rest adequately betweencalls only if she supinated her rightforearm away from the keyboard orplaced the arm in her lap.

bow. Utilizing the biofeedback unit, we determinedthat she could rest adequately between calls only ifshe supinated her right forearm away from .the key­board or placed the arm in her lap. For this activity,her "center point" or yellow-light threshold was de­termined by asking her to begin keying as if she weretaking a call. Her "poised" posture did not reducemuscular activity and maintained the light in theyellow zone. Only when she supinated her forearmor rested the arm on her lap did muscular activitydiminish and the light subside into the green zone.

Similarly, we evaluated the height of the pa­tient's chair and its impact on the forearm/elbowmuscles . We concluded that there was no differenceor change in muscular activity with different heights.Also, we tested the angle or slant of the keyboardand determined that for this patient a flat keyboardwas preferable to the 3D-degree slant, which createdmore muscle activity during keyboard use.

Finally, we looked at whether a wrist splint deac­tivated or silenced extensor muscles and found thisnot to be the case. With or without the splint, activitywas brisk near or at the elbows.

For this patient a flat keyboard waspreferable.

RESULTS

The patient has returned to work and, despiteoccasional flare-ups is doing better in managing herproblem. She is currently not working full time, butshe has increased her work schedule from four to sixhours per day in the month prior to this writing.

An evaluation using EMG biofeedback was help­ful in this case for assessing work positions and de­vices used to reduce muscular activity. The biofeed­back evaluation became the treatment modality whenthis patient was shown specific methods for dimin­ishing wrist and finger extensor use.

This case differed from previous cases where wedemonstrated to patients using biofeedback how toinhibit muscular activity only by performing key­stroke activity in a gentler fash ion. Unfortunately,this previous method was not as successful becausethe patient required much more training and ulti­mately fell back into habitual forceful key stroking.

The biofeedback evaluation becamethe treatment modality.

A felt marker instead of a ballpoint pen, a flatkeyboard instead of a slanted one, and rolling theforearm into supination to rest are just a few of theways this patient could prevent overuse of her wristand finger extensors.

CONCLUSION

Therapists have developed ergonomically correctpostures and workstations for keyboard operatorsbut have not taken into account the individual needsof these patients. Do all patients have wrist and fin­ger extensor inactivity or reduced activity with feltmarkers, flat keyboards, or even supportive splints?Therapists should evaluate each patient before as­suming that what is ergonomically correct for onepatient is so for another.

Further controlled studies using more sophisti­cated and sensitive EMG biofeedback equipment mayultimately verify these results . Until the findings of

these studies are published, however, hand thera­pists may wish to utilize simple and inexpensive clin­ical surface EMG biofeedback devices and investigatetheir practical applications.

BIBLIOGRAPHY

1. Armstrong T]: Ergonomics and cumulative trauma disorders.Hand Clin 2:553-565, 1986.

2. Fine L], Silverstine BA, Armstrong T], et al: Detection of cu­mulative trauma disorders of upper extremities in the work­place. J Occup Med 28:674-678, 1986.

3. Had ler NM: Plight of directing assistive operators with armpain : A tale of two cities . Occup Probl Med Pract 7(2):1-7,1992.

4. Kelsey J, Postides H, Kriefer N, et al: Upper Extremity Disor ­ders-A Survey of Their Frequency and Cost in the U.S. St.Louis, C.V . Mosby, 1980, pp . 1-70.

5. Keith M: Medical management of cumulative trauma disorders.Orlando, FL, presented at the 14th Annual Meeting of theAmerican Society of Hand Therapists, 1991.

6. Silverstein BA, Fine LJ, Arm strong TJ: Hand/wrist cumulativedisorders in industry. Br J Ind Med 43:779-784, 1986.

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January-March 1994 27