Conclusion
In this case report, we propose a novel biomechanical source of internal impingement: direct impingement of the biceps tendon on the undersurface of the supraspinatus tendon. We believe that impingement of the LHB can either directly lead to, or potentially aggravate, articular-sided tears of the supraspinatus tendon. This proposed mechanism of impingement may help explain why debridement alone can produce suboptimal results [10,14,13]. In cases where pain persists despite arthroscopic debridement, we recommend performing a biceps tenodesis. In addition, we recommend taking the arm out of traction during arthroscopy and placing it in the 90-90 position. If the biceps tendon can be seen directly abrading the supraspinatus tendon, we recommend primary biceps tenodesis.