Response

We appreciate the interest of Cappell et al in our research on pinch force and forearm muscle load during colonoscopy. We agree that DeQuervain's tenosynovitis of the left thumb may be caused by the repeated abduction and extension and applied thumb force required to manipulate the turn dials. We also agree with the need to directly measure left thumb forces, but we were unable to do this for technical reasons in this pilot study. In the next phase of our research, we plan to quantify left thumb forces during routine colonoscopy in a larger cohort of gastroenterologists, and to also assess subjective measures of musculoskeletal strain and fatigue. We further plan to videotape the colonoscopies so that the measured forces can be correlated to the subtasks performed. As Dr Cappell suggests, maximal rotation of both dials, which may occur while negotiating flexures or performing polypectomy, may increase left thumb strain. We believe further study will identify the subtasks during colonoscopy that put endoscopists at greatest risk for overuse injury, including DeQuervain's tenosynovitis.