Abstract
We developed an in vivo injury model of work related musculoskeletal disease of the upper extremity in the rat in order to determine the extent to which a highly repetitive task causes decrements in motor performance and stimulates inflammation locally and systemically in musculoskeletal tissues. Twenty-two Sprague-Dawley rats were trained to reach for food pellets at a target rate of 4 reaches/min for 2 hours/day, 3 days/week for periods up to 8 weeks. Reach repetition rate and reach success were determined. Observations of reach movement patterns were recorded. The trained and untrained forelimbs of trained rats were examined for macrophages using anti-ED***1 and compared to the forelimbs of control animals. The number of ED***1 immunoreactive macrophages in muscle, tendon and radiocarpal ligaments was quantified. We also examined for proteins indicative of inflammation and injury: IL-1β, COX2 and hsp72. Tissue inflammation was evident by week 3 and increased progressively to weeks 5 and 6. Degradation in reach movement patterns coincided with these tissue changes. Our findings suggest that a high repetition-negligible force task induces inflammatory work related musculoskeletal disease in as few as three weeks.
Get full access to this article
View all access options for this article.