The rotator cuff was divided into three parts according to the arthroscopic discovery: (1) the anterior part which contained the subsacpularis and one third of the suprascapularis forward; (2) the middle part which contained the two thirds of the suprascapularis backward and one third of the subscapularis forward; (3) the posterior part which contained two thirds of subscapularis backward and teres minor. The patients with rotator cuff tear at the anterior part were categorized in the anterior tear group.

The rotator cuff was divided into three parts according to the arthroscopic discovery: (1) the anterior part which contained the subsacpularis and one third of the suprascapularis forward; (2) the middle part which contained the two thirds of the suprascapularis backward and one third of the subscapularis forward; (3) the posterior part which contained two thirds of subscapularis backward and teres minor. The patients with rotator cuff tear at the middle part were categorized in the middle tear group.

The rotator cuff was divided into three parts according to the arthroscopic discovery: (1) the anterior part which contained the subsacpularis and one third of the suprascapularis forward; (2) the middle part which contained the two thirds of the suprascapularis backward and one third of the subscapularis forward; (3) the posterior part which contained two thirds of subscapularis backward and teres minor. The patients with rotator cuff tear at the posterior part were categorized in the posterior tear group.

The rotator cuff tears were repaired under arthroscopy. A subacromial decompression was performed in all patients. Then the long head of the biceps with severe lesions were treated by tenotomy while the others were reserved according to the surgeon's judgment during the surgery.

According to the pre-operative MRI scan, two sites of the long head of biceps tendon were measured by the Image-Pro Plus 6.0 software. One was the plane that passed the center of the glenoid cavity, the other one was the plane that passed the distal border of the glenoid cavity. The contour of the long head of biceps tendon was traced and the area was calculated by the software according to the MRI's scale.

According to the MRI scan 2 months after the surgery, two sites of the long head of biceps tendon were measured by the Image-Pro Plus 6.0 software. One was the plane that passed the center of the glenoid cavity, the other one was the plane that passed the distal border of the glenoid cavity. The contour of the long head of biceps tendon was traced and the area was calculated by the software according to the MRI's scale.