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.