Comparison of the Analgesic Effect of 2 Shoulder Infiltrations

This study compares two types of shoulder joint injections — one with corticosteroid and one with another substance — for people with moderate-to-severe shoulder osteoarthritis. The goal is to find out which injection provides better and longer-lasting pain relief. You may be eligible if: - You are between 20 and 90 years old - You have been diagnosed with moderate-to-severe primary shoulder osteoarthritis (stage II or higher on the Samilson-Prieto scale) - Your pain is at least 4 out of 10 on the pain scale - You can read and understand French or English You may NOT be eligible if: - You have a full rotator cuff tear on MRI - You are pregnant - You received a cortisone injection in the past 6 months - You received PRP or hyaluronic acid injection in the past 12 months - You have avascular necrosis, active infection, or suspected cancer in or near the shoulder Talk to your doctor to see if this trial is right for you.