My mother was given a splint for osteoarthritis in her upper middle finger when it flared up again. It was very painful for her. The doctor said that it will help relieve the pain and protect it from getting hit by objects. The thing is, it won't help the osteoarthritis itself. Why just give a splint?
Splints are often used to treat mild-to-moderate osteoarthritis in finger joints if they have become painful or difficult to use. As you say, the goal is to relieve the pain and we want to prevent your mother from hitting the joint against objects, such as tables. Treatment of osteoarthritis itself depends on how severe the disease has progressed. It can include medications to reduce inflammation and pain, corticosteroid injections into the joint, physiotherapy, or surgery.