Bicipital tendonitis, also called biceps tendonitis, is inflammation in the main tendon that attaches the top of the biceps muscle to the shoulder. It often causes a deep ache directly in the front and top of the shoulder. The ache may spread down into the main part of the biceps muscle and pain usually increases with overhead activities. The most common cause is overuse from certain types of work or sports activities. Biceps tendonitis may develop gradually from the effects of wear and tear, or it can happen suddenly from a direct injury. The tendon may also become inflamed in response to other problems in the shoulder, such as rotator cuff tears, impingement, or instability.