Inclusion Criteria:  aged between 18 and 70 years pain in the shoulder region and increase in pain with overhead-throwing activity chronic shoulder pain for more than 3 months partial rotator cuff tear or rotator cuff tendinosis diagnosed by US or magnetic resonance imaging (MRI).  Exclusion Criteria:  a full-thickness rotator cuff tear diagnosed by US or MRI allergic reaction betamethasone or lidocaine contraindications for ozone (O2-O3) injection, such as uncontrolled hyperthyroidism, glucose-6 phosphate dehydrogenase deficiency (G6PDD), pregnancy and platelet level <50 103/µL history of coagulopathy, diabetes, or hepatitis intra-articular/subacromial injections in the last 3 months history of shoulder infection, fracture, trauma, bony lesion, tumor or inflammatory rheumatic diseases history of brachial plexus lesion/cervical radiculopathy.