My grandma has these hard bumps forming on her finger joints near the nails. Why is this spreading?

3. How Osteoarthritis Changes the Joints and Creates These Nodules

Osteoarthritis is a chronic condition characterized by the breakdown of cartilage, the flexible tissue that cushions the ends of bones in a joint. When this cartilage deteriorates, the bones begin to rub together, causing  pain, swelling, and stiffness.

In response, the body often forms osteophytes, or bone spurs, as a way to try to repair the damage and increase the surface area of the joint. These osteophytes manifest as the hard nodules