• The purpose of this study is to compare the clinical and anatomical outcomes of rotator cuff repair with Platelet-Rich Plasma(PRP) and conventional rotator cuff repair in treatment of large to massive rotator cuff tears.
• PRP application to arthroscopic rotator cuff repair would accelerate recovery after arthroscopic rotator cuff repair in terms of pain relief, functional outcomes, overall satisfaction, and enhance structural integrity of repaired tendon.

Inclusion Criteria:

large to massive rotator cuff tear as a determined by clinical examination and MR prior to surgery.

Exclusion Criteria:

• previous history of shoulder surgery
• acute trauma
• chronic dislocation
• pyogenic infection
• rotator cuff arthropathy with glenohumeral osteoarthritis and superior migration of the humeral head
• showed abnormal serological test results
• thrombocytopenia (platelets less than 15000 per microliter)
• had been received anti-platelet medication
• psychiatric problems that precludes informed consent or inability to read or write
• other serious problems that preclude participation of the study