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1 Department of Radiology, Tripler Army Medical Center, 1 Jarrett White Rd.,
Honolulu, HI 96859-5000.
2 Departments of Radiology and Radiological Sciences and Pediatrics, Uniformed
Services University, F. Edward Hébert School of Medicine, Bethesda, MD
20814-4799.
3 Department of Occupational Therapy, Tripler Army Medical Center, Honolulu, HI
96859-5000.
4 Present address: Occupational Therapy Clinic, MCHJ-PMO, Madigan Army Medical
Center, Tacoma, WA 98431-5000.
5 Present address: Department of Radiology, Madigan Army Medical Center, Tacoma,
WA 98431-5000.
6 Department of Design and Environmental Analysis, Human Factors and Ergonomics
Laboratory, Cornell University, MVR Hall, Forest Home Dr., Ithaca, NY
14853-4401.
Received May 28, 2002;
accepted after revision December 17, 2002.
Address correspondence to L. Ruess.
Abstract
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SUBJECTS AND METHODS. Four radiologists with complaints of upper extremity pain, numbness, and weakness or a combination of symptoms were examined by an occupational therapist. The work activities and duties of all 12 staff radiologists in our filmless department were subsequently evaluated. Time working as staff, workday hours, and academic activities were recorded. Nonoccupational activities were also noted. An industrial hygienist evaluated the department work areas and staff offices.
RESULTS. One radiologist had bilateral carpal tunnel syndrome, and all four radiologists had cubital tunnel syndrome (two [50%] unilateral, two [50%] bilateral). The four spent 3.4 ± 0.3 years (mean ± standard error of the mean) as staff radiologists in our filmless department, performing computer keyboard and mouse or trackball image manipulation and work list navigation, typing preliminary reports and telephone notifications, and editing electronically and approving dictated final reports. All four are academically active and had significantly greater workday hours (p < 0.05) and performed more research (p < 0.003) than the asymptomatic radiologists. Three (75%) of four radiologists routinely performed sonography. The industrial hygienist identified hazardous working conditions, especially related to ergonomics, in the reviewing areas and staff offices.
CONCLUSION. Current technology renders staff radiologists at risk for work-related, upper extremity musculoskeletal disorders, including carpal and cubital tunnel syndromes. Proper equipment, ergonomics, and professional consultation should be used in all radiology departments.
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Carpal tunnel and cubital tunnel syndromes are the two most common compressive neuropathies of the upper extremities and represent common causes of referral for electrodiagnostic studies [6]. Both have been linked to computer use. Most experts agree that excessive keyboard use, particularly with the wrist and elbow in awkward positions, probably plays a role in the development of both carpal tunnel and cubital tunnel syndromes [1, 7]. These disorders result in work disability and also affect daily living and sleep.
Carpal tunnel syndrome is the result of median nerve compression from inflammation and thickening of the flexor tendons in the closed space bounded anteriorly by the flexor retinaculum and posteriorly by the bones of the wrist [8]. The symptoms and signs of chronic median nerve compression include pain and paresthesias in the wrist and radial side of the hand, muscle weakness, and abnormal nerve conduction. The incidence of carpal tunnel syndrome has been well documented in several groups, including sales personnel, administrative support, and clerical staff; handlers and laborers; and sonography technologists [3, 9]. Handlers and laborers show a high incidence of these syndromes in approximately 9.9 per 1000 person-years [3].
Cubital tunnel syndrome results from ulnar nerve compression between the medial epicondyle, the olecranon, and the overlying cubital tunnel retinaculum [8]. Chronic irritation results in symptoms and signs of pain in the medial elbow, paresthesias in the ulnar nerve distribution, muscle weakness, and abnormal nerve conduction. Although the incidence of cubital tunnel syndrome is not well reported, it is recognized as the second most common upper extremity compressive neuropathy and represents a major disability in the workforce [7].
During one summer (June through August 2000), one third of our staff radiologists sought medical attention for upper extremity symptoms. Our purpose is to describe the work-related upper extremity musculoskeletal disorders in these four radiologists and to identify possible risk factors in the radiology workplace. Common workplace hazards for the radiologist will be illustrated with suggestions for prevention.
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Provocative maneuvers included Phalen's, Tinel's, and elbow flexion tests. Findings on Phalen's test, also called the wrist-flexion test, are positive if the patient experiences numbness and paresthesias in the first three fingers with complete flexion of the wrist for 1 min with the forearms held vertically. Tinel's test is positive when a nerve is gently tapped and the subject reports pain, numbness, or both, and tingling in the distribution of that nerve [7, 11]. The elbow-flexion test is a positional test used to reproduce symptoms of compressive ulnar neuropathy [7]. The elbow and wrist are placed in the flexed position for 3 min. A test is positive when the subject complains of pain or distal-extremity numbness or tingling in the fourth and fifth fingers. Two radiologists also underwent MR imaging of the cervical spine for evaluation of their symptoms before their occupational health examinations. Carpal tunnel and cubital tunnel syndromes were diagnosed as the result of the presence of one or more symptoms and positive strength, sensation, or provocative tests.
All radiologists in the department completed surveys to estimate computer use. Survey questions included the number of years he or she had worked in the PACS (picture archiving and communication system) environment and an estimate of workday hours performing each of the following activities: PACS workstation operation, administrative duties requiring computer use (such as writing resident evaluations, letters of recommendation, and Joint Commission on Accreditation of Health Care Organizations and hospital administrative correspondence), e-mail, electronic editing and approval of dictated final reports, online time, and time spent performing sonography. PACS workstation operation requires computer keyboard and mouse or trackball image manipulation, work list navigation, and typing preliminary reports. An estimate of weekend hours at the keyboard was also reported. Academic and graduate medical-education–related work was recorded in terms of the number of manuscripts, grant proposals, and electronic lectures completed and the number of institutional review board–approved research projects in progress or completed since working in a PACS environment. Hobbies and other nonoccupational activities were also recorded. The nonparametric Wilcoxon's test was used to compare the survey variables between the symptomatic and asymptomatic radiologists. A binomial test of proportions was used to compare the incidence of carpal tunnel syndrome in our department versus workforce groups reported by others [3]. Differences detected with a p value of less than or equal to 0.05 were considered significant.
An ergonomic assessment of our department was performed as part of a routine survey of the hospital by an industrial hygienist in 1999. Thirty-eight work sites were evaluated, including all radiologists' offices and workstations.
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Radiologist 1 was diagnosed with bilateral carpal tunnel and bilateral cubital tunnel syndromes. Radiologist 2 had bilateral cubital tunnel syndrome, and radiologists 3 and 4 had unilateral right cubital tunnel syndrome.
The incidence rate of carpal tunnel syndrome in our departmental radiologists is 8.3. Comparing this incidence with that in workforce groups of Nordstrom et al., we found the rate of our radiologists to be significantly greater than the incidence rate reported for salesmen (1.5, p < 0.05) and administrative or clerical staff (4.0, p < 0.05) [3]. Our rate is not significantly different from the 9.9 rate reported in handlers and laborers [3]. The incidence rate of cubital tunnel syndrome in our department is 33.3. To our knowledge, no published rates are available for comparison with other workforce groups.
The results of the computer use survey for our department are shown in Table 1. The four symptomatic staff radiologists spent a mean time of 3.4 years working in a PACS environment. Their total time was not significantly different from the time asymptomatic radiologists had been working in the same environment. Symptomatic radiologists were four of the five most academically active staff members, and they routinely worked on academic and teaching activities after hours. The symptomatic radiologists were the only staff members with active institutional review board and grant proposals (p < 0.05). They also spent significantly more time performing sonography (p < 0.05). Three of the four symptomatic radiologists worked in the sonography section. The symptomatic radiologists spent more total workday hours at a keyboard (p = 0.05). These radiologists also had four of the five most demanding administrative jobs.
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Although not statistically significant, most likely because of low sample size, other suggested factors contributed to work-related musculoskeletal disorders, with amount of administrative computer time and the amount of academic writing (manuscripts, abstracts, and electronic lectures) tending to be greater in symptomatic than in asymptomatic radiologists. No radiologist experienced symptoms during any of their nonoccupational activities or while performing sonography.
The industrial hygienist made a total of 93 recommendations for improved ergonomics after evaluating the 38 physician work areas of the department. All equipment is configured for right-handed users. Deficiencies were noted in all areas. All offices and most workstations had standard desks (74 cm) with standard keyboards and a mouse placed on the desktop. Four workstations had adjustable tray tables. A trackball was inconsistently available as an alternative to a mouse at a few workstations. Most chairs had unpadded arms and allowed only seat-height adjustment. All the radiologists' office worktables or desks (12/12, 100%) and most of the reviewing room PC (11/12, 92%) and PACS workstations (10/14, 71%) needed reconfiguration. Recommendations included installation of keyboard holders and mouse trays with adjustable height and tilt as well as the addition of trackballs. The hygienist also recommended chairs with adjustable heights and armrests throughout the department.
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It is generally believed that work-related musculoskeletal disorders are associated primarily with occupational exposures to one or more ergonomic risk factors. One study investigated the role of nonoccupational activities in workers' self-reporting of musculoskeletal symptoms [13]. Home computer use, gardening, crocheting, and needlepoint were associated with increased reporting of musculoskeletal disorders [13]. Vigorous sports (tennis, racquetball, and volleyball) were less often associated with the reporting of these disorders [13]. Golf was not associated with significantly increased reports of musculoskeletal disorders in that study. We believe that nonoccupational activities, including hobbies and sports, were not major contributors to our radiologists' conditions. None of our symptomatic radiologists experienced pain, paresthesias, or both during their nonoccupational activities.
We are not aware of any studies that have looked specifically at handedness and musculoskeletal injuries. Some left-handed people learn to be proficient with their right hands, like our radiologist 3 who uses a right-handed mouse. This left-handed radiologist had only right-sided cubital tunnel syndrome. Likewise, radiologists 1 and 2 had bilateral symptoms suggesting that occupational activities other than mouse operation contribute to these disorders. Radiologist 2, for example, consistently uses his left hand for handheld dictation devices and telephone communication.
We recognize, however, that sleep position may contribute to or aggravate certain musculoskeletal disorders. Compression of the ulnar nerve in the cubital tunnel has been associated with prolonged elbow flexion during sleep. Since the original survey, three of our four symptomatic radiologists have noted symptoms during sleep, suggesting that sleep now aggravates their conditions, which are most severe during PACS workstation and personal computer use.
Typical desk postures found at computer workstations fail to address ergonomic issues (Figs. 1 and 2). An upward (positive) tilt of the keyboard results in wrist dorsiflexion while typing (Fig. 1). The positive tilt may be the result of either improper angulation of an adjustable keyboard tray or the use of commonly available legs found on the undersurface of most computer keyboards, which intentionally create a positive tilt. This should be avoided because sustained and repetitive wrist dorsiflexion can lead to elevated carpal tunnel pressure and resultant median nerve compression [14]. Studies show that wrist posture dramatically alters intracarpal pressure. Pressure changes that detrimentally affect median nerve function occur when the angular excursion of the hand exceeds 15° from neutral [10, 15].
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Work-related activities that require sustained elbow flexion may cause ulnar nerve compression and resultant cubital tunnel syndrome (Table 2). In the radiology department, these activities include use of handheld dictation microphones and telephone receivers, as well as keyboard or mouse operation with these devices positioned too high, typically at or near desktop level (Fig. 2). Leaning on hard surfaces can cause or exacerbate this problem by direct compression of the ulnar nerve.
A computer workstation designed with ergonomic considerations includes correct positioning of the keyboard on a hanging-tray table below desktop level (71–76 cm), which enables extension of the elbows, preferably at an angle slightly greater than 90° [7] (Fig. 3). In addition, the negative tilt of the tray table permits typing with the wrists in a "neutral zone of movement" [16]. Placing a mouse on a negative tilt surface helps to reduce wrist dorsiflexion, but the mouse tends to slide forward when the grasp is released. Modification of the tray table may be required to keep the mouse in place. At our institution, most radiologists prefer the use of a trackball to perform the heavily graphics-dependent tasks of image viewing and to navigate the larger viewing area of workstations with up to four monitors. Use of the trackball on a flat surface can also increase wrist dorsiflexion as the fingers operate the ball. Placement of the trackball on a tilted tray next to the keyboard can improve hand posture, and the device tends to remain in place. Modern ergonomically designed split keyboards primarily reduce ulnar deviation and contribute further to maintaining neutral wrist position.
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In the radiology reviewing room, chairs that permit height adjustment for different users are also necessary. In general, a seat that is positioned too low will require more elbow flexion than a well-positioned seat. Proper positioning of the chair can also avoid lower back pain if the height is such that the feet are positioned on a firm surface with the hips slightly extended beyond 90°. The seat should also be positioned high enough and the monitor low enough that the head and neck can be maintained in neutral position (Fig. 3). Monitors are commonly positioned too high, requiring neck extension, or too low, requiring neck flexion, both of which may result in neck discomfort. Recent studies suggest that the best position for a computer monitor is at approximately one arm's length from the user with the center of the screen located approximately 17–18° and below the horizontal eye line [17, 18].
Although cubital tunnel syndrome is relatively unknown, carpal tunnel syndrome has received considerable coverage in both the medical and lay press. In our experience, surprisingly little attention is paid to the simple measures required to minimize the risk of work-related musculoskeletal disorders. For instance, the adjustable legs found under most computer keyboards provide an additional positive tilt that increases wrist dorsiflexion. These legs are commonly found, and it would be logical to conclude that the manufacturer added the legs because they are advantageous to the user. The design advantage of positive tilt is improved visibility of the keys, but with sustained keyboard use, this advantage is more than offset by the detrimental effect on wrist posture [19]. Even ergonomically designed split keyboards include such legs, thereby inadvertently adding more perceived credence to this poor ergonomic design. Similarly, height-adjustable keyboard trays are most commonly positioned at desktop level, negating their potential advantage. Many radiologists in our department also tend to prefer sitting in a low chair. This results in significant elbow flexion to reach the keyboard and neck extension to view a monitor, potentially causing ulnar nerve compression and neck discomfort. We have found that asymptomatic individuals are reluctant to alter patterns of behavior that place them at risk for these disorders. Education and training of the individuals at risk are probably as important as efforts to provide them with the appropriate work environment.
The National Institute for Occupational Safety and Health has recommended a multifaceted approach consisting of education, ergonomic controls, early reporting, and medical management [4, 5]. Radiology practices should obtain expert advice. Depending on available resources, industrial hygienists or ergonomists may be found in departments of ergonomic or industrial engineering, psychology, industrial hygiene, occupational medicine, physical therapy, or design. These experts can identify existing ergonomic hazards and suggest corrective measures. These factors can also be taken into consideration with future computer system and PACS acquisitions. Expert recommendations are likely to include both expensive and simple inexpensive modifications (Table 2). Costly recommendations include acquisition of ergonomically designed desks and chairs. In addition, keyboard and mouse manipulation can be dramatically and effectively reduced with the use of voice-activated software. Recommendations made by outside consultants may be necessary to justify funding requests for expensive modifications. Simpler and less expensive means include proper adjustment of existing equipment and furniture (Fig. 3) and modification of operator behavior with stretching exercises and frequent breaks from computer-related activities. Studies show that frequent micro-breaks from using the keys and mouse (30 sec to 2 min every 20–30 min) reduce complaints of musculoskeletal discomfort and have no adverse effects on work performance and productivity [20, 21]. Use of headsets and remote microphones can minimize elbow flexion and improve neck posture when radiologists are dictating reports or speaking on the telephone. Use of a headset also reduces neck, shoulder, and upper back muscle tension by as much as 41%, compared with using a handheld telephone receiver [22].
To our knowledge, ours is the first report of radiologists with work-related upper extremity musculoskeletal disorders. Limitations of our report are that it is a retrospective review of a small number of cases, the estimations of computer use reported in a survey of radiologists were highly subjective, and the four symptomatic radiologists may have either made more accurate estimates or overestimated computer use because of a greater awareness of the importance of this issue. Another limitation is that the asymptomatic radiologists did not receive clinical evaluations but did participate in the computer use survey. The disease incidence in our population may be underestimated. Finally, we did not distinguish between mouse and trackball use among radiologists.
In summary, we report an unusually high incidence of work-related musculoskeletal disorders in one department. Given the continued trend toward PACS implementation and the resultant increased demand for computer use, we believe that these injuries are likely to increase. We highly recommend that radiology departments obtain professional consultation from ergonomic experts and aggressively pursue implementation of their recommendations regarding workspace ergonomics. Emphasis must be placed not only on the physical workspace but also on attempts to modify personnel behavior. Education and training regarding risk factors and preventive measures must be performed to effectively minimize the impact of these disorders on our specialty.
Acknowledgments
We thank Catherine F. T. Uyehara for statistical support.
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