The goal of this clinical trial is to verify the effect of suprascapular nerve block and axillary nerve block in relieving postoperative pain after arthroscopic rotator cuff repair.

Are there differences in visual analog pain scale and patient's satisfaction? Are there differences in mean plasma pain related cytokines? The participants will undergo preemptive ultrasound guided suprascapular nerve block and axillary nerve block using each 0.75% ropivacaine 10mL or each 0.9% saline 10mL.

Inclusion Criteria:

• a definite rotator cuff tear that needed repair seen on preoperative magnetic resonancce imaging (MRI)
• acceptance of arthroscopic surgery including rotator cuff repair
• age same as or more than 20 years
• acceptance of preemptive regional block and PCA, and blood testing

Exclusion Criteria:

• did not undergo arthroscopic rotator cuff repair
• stopped PCA before 48 hours postoperatively because of associated side effects
• a history of previous ipsilateral shoulder operation or fracture
• a concomitant neurologic disorder around the shoulder
• a failure of blood sampling including hemolysis, etc.

We can decide it after the termination of this study.

An independent nurse uses a random number generator and allocates paticipants into the two group. Participant, investigator, and outcome assessor are blinded of the allocation information.