Medical Systems recently held a lunch and learn at Lombardi’s Steakhouse in Appleton, Wisconsin at which hand surgery expert Jan Bax, M.D. discussed common hand injuries. During his presentation, Dr. Bax alerted attendees to a recent white paper from the American Academy of Orthopaedic Surgeons (“AAOS”) that reports a moderate level of medical evidence links computer use to the development of carpal tunnel syndrome (see p. 222). As Dr. Bax pointed out, the paper was published in the last couple of months so its ultimate effect in the worker’s compensation arena is undetermined. Nevertheless, Dr. Bax expressed concern that the paper will lead to renewed carpal tunnel syndrome claims based on repetitive computer use (keyboarding and mouse use). He noted this is especially troublesome because the hand surgery section of the AAOS considers it a settled issue that computer use does not cause carpal tunnel syndrome.
The white paper assigns levels of evidence supporting the various factors that are sometimes alleged to cause carpal tunnel syndrome. The highest level of evidence is “strong,” which requires consistent evidence from two or more high quality studies. The second highest level of evidence is “moderate,” which requires consistent evidence from two or more moderate quality studies or evidence from a single high quality study. This is the level of evidence the AAOS finds for the position that computer use causes carpal tunnel syndrome. The second lowest level of evidence is “limited,” which requires consistent evidence from two or more low quality studies, one moderate study, or insufficient/inconsistent evidence recommending for or against the diagnosis. The lowest level of evidence is “consensus,” which requires that there is no reliable evidence but rather is based on unsupported clinical opinion.
As Dr. Bax noted, finding that moderate evidence supports the link between computer use and carpal tunnel syndrome is troubling because it is actually is a high level of evidence and may sway triers of fact despite the nearly uniform position of actual hand surgery specialists that there is no such causal link. This is especially true given the findings in some of the research cited. Coggon, et al., specifically stated that there was an “absence of association with the use of computer keyboards” and noted this “is also consistent with the findings overally from other research.” The researchers concluded that “obesity and diabetes, and the physical stresses to tissues from the use of hand-held vibratory tools and repeated forceful movements of the wrist and hand, all cause impaired function of the median nerve” but that computer keyboard probably only focuses attention on symptoms without being injurious to the tissues of the wrist. Coggon, et al. seem to support a more nuanced relationship between computer keyboard use and carpal tunnel syndrome than is portrayed in the AAOS white paper. Likewise, Eleftheriou, et al. studied the link between computer keyboard use and carpal tunnel syndrome but related the following disclaimer:
One limitation is related to [the study’s] cross-sectional design which does not allow us to conclude if the association between cumulative exposure to key-board use is of causative nature. The study included workers present when the study was formed, which implies a possible selection bias as is the case in all cross-sectional studies, especially if the study population was affected by high turn-over. It’s a limitation of our study that we don’t have data on actual turn-over of the staff…Further, we didn’t control for possible confounding factors like anthropometric characteristics of the wrist…
Eleftheriou, et al. reported only “a possible association between cumulative exposure to keyboard strokes and the development of [carpal tunnel syndrome]…” They specifically noted that additional studies need to be done to verify their results and to address causality.
The AAOS white paper is a troubling development in carpal tunnel syndrome worker’s compensation cases since it potentially throws into question the settled opinion among hand surgery specialists that keyboard use does not cause carpal tunnel syndrome. As Dr. Bax noted at the recent Medical Systems lunch and learn, it is too early to tell exactly what the effects of the paper will be, though they are not likely to be positive. In the event that the AAOS white paper is cited to support work-related carpal tunnel syndrome cases among keyboard users, it will be critical to choose experts who understand and can explain the limitations of the evidence on which the paper relies. Without an expert who will vigorously question and thoroughly refute the evidence, the AAOS white paper is likely to carry more weight in keyboard-related carpal tunnel syndrome claims than it otherwise should.
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