The Effect of Return to Overuse Activity After a Supraspinatus Tear on Joint Function and Biceps Mechanical Properties in a Rat Model

Rotator cuff tendon tears are one of the most common shoulder injuries and are most prevalent in populations performing repetitive overhead activities [1]. In addition, long head of the biceps (LHB) tendon injuries occur secondary to cuff tears and may or may not lead to functional deficits [2]. Previous animal model studies have found that in the presence of a cuff tear, the biceps has decreased mechanical properties at 8 weeks [3]. Such studies, however, did not examine the effect of repetitive overhead activity on biceps properties and shoulder function in the presence of a cuff tear. Therefore, the objective of this study was to evaluate the effect of returning to overuse activity after a supraspinatus tendon tear on shoulder function and biceps structural and mechanical properties. We hypothesized that overuse activity following a supraspinatus tendon tear would not alter shoulder function, when compared to cage activity, but would decrease biceps structural and mechanical properties, particularly at the insertion site.