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

The appearance of these nodes on multiple fingers is often due to the progressive nature of osteoarthritis. As the disease advances, it can affect more of the joints in the hands, leading to the formation of nodes on several fingers.

Genetic predisposition also plays a significant role in the spread of these nodes. If a person has a family history of osteoarthritis or joint issues, they may be more likely to develop these nodes on multiple fingers. Additionally, repetitive use or stress on the joints from daily activities can exacerbate the condition and contribute to the spread.