Pinch force and forearm-muscle load during routine colonoscopy: a pilot study

Background and Objective: Overuse injuries of the hand, wrist, forearm, and shoulder are common among endoscopists and may be from repetitive pinching and gripping forces or awkward posturing. In this pilot study, we evaluated distal upper-extremity musculoskeletal load during colonoscopy (1) to confirm the feasibility of performing ergonomic measurements in endoscopists and (2) to identify tasks that may contribute to overuse injuries. Design and Subjects: Three experienced gastroenterologists were evaluated during 3 colonoscopies each Setting: Veterans Affairs Medical Center, San Francisco, California. Main Outcome Measurement: Right-thumb pinch force using a thumb-force sensor and bilateral forearm-muscle activity using electromyography. Results: The mean duration of the 9 colonoscopies was 19.5 minutes. The highest mean (SD) right-thumb peak pinch forces occurred during left (10.4 [4.1] N) and right (10.1 [4.5] N) colon insertion, which exceeded the injury threshold of 10 N. Mean peak forearm-muscle activity was also greatest during left and right colon insertion. Activity of the left abductor pollicis longus, left extensor carpi radialis, and right extensor carpi radialis exceeded the American Conference of industrial Hygienists (ACGIH) hand activity level (HAL) action limit. The left extensor carpi radialis was at the ACGIH HAL threshold limit. Limitations: The small sample size, no force measurement for the left thumb, and all the gastroenterologists were men. Conclusion: The pinch forces and forearm-muscle loads applied during routine colonoscopy may pose a risk for overuse injuries at the elbow and wrist.