Chronic musculoskeletal pain (CMP) is a common disease in China, with a high incidence among the elderly, and has a significant impact on patients' quality of life. Shoulder osteoarthritis is a common type of CMP. Currently, both domestic and international studies have confirmed that glucocorticoid injection at myofascial trigger points(MTrPs) can alleviate patients' pain symptoms. MTrPs injection is safe and easy to operate, and can improve the clinical management efficiency of patients with shoulder osteoarthritis. Therefore, we designed a prospective, randomized controlled, blinded outcome, non-inferiority study to compare the long-term clinical efficacy of glucocorticoid injection at myofascial trigger points and complex intra-articular injection in treating shoulder osteoarthritis. Patients will be randomly divided into two groups and receive either glucocorticoid injection at MTrPs or joint cavities. After treatment, patients will be followed up for 2 years. Their NRS scores, WOMAC scores, Patient Global Impression of Change(PGIC) scale, and adverse reactions will be recorded at 2 weeks, 4 weeks, 8 weeks, 12 weeks, and 24 weeks. If the results indicate that the clinical efficacy of myofascial trigger point injection for shoulder osteoarthritis is not inferior to that of injection at intra-articular injection, it will provide a safe and simple treatment option that is easy to promote for patients who do not respond to conservative treatment.

Inclusion Criteria:

• Diagnosis of shoulder osteoarthritis with radiographic evidence of osteoarthritis (Kellgren-Lawrence grade 1-4) confirmed by at least two orthopedic surgeons, pain specialists, or general practitioners, with physical examination confirming at least one myofascial trigger point;
• Disease duration exceeding 3 months;
• Age ≥ 45 years;
• Numerical Rating Scale (NRS) score ≥ 3 points despite prior conservative pharmacological treatment;
• Signed informed consent form.

Exclusion Criteria:

• History of allergy to trial medications such as corticosteroids;
• Alcohol abuse; long-term use of opioids (exceeding 2 weeks or more than 3 days per week for over 1 month); suspected use of sedative or analgesic medications; patients on long-term steroid therapy;
• Severe neurological disorders, significant hepatic or renal dysfunction, heart failure, coagulation abnormalities, gastric ulcer, diabetes, inflammatory rheumatic diseases, etc.;
• Intra-articular injection within the past 6 months or planned joint replacement surgery;
• Inability to use pain assessment scales;
• Presence of local or systemic infection;
• Pregnant or lactating patients.