Osteoarthritis is a degenerative condition of the cartilage. There is no clear etiology. Osteoarthritis is not related to tumors, inflammation, infection, gout, or trauma. Osteoarthritis is different from rheumatoid arthritis—which is an inflammatory condition. This distal interphalangeal joint (DIP) is the joint that is most often involved with osteoarthritis. The trapeziometacarpal joint (TM) is the most involved joint with osteoarthritis. When the trapeziometacarpal joint is involved, it causes pain with a weak pinch and grip.
Osteoarthritis of the fingers involves the following:
DIP (Heberden’s Nodes) – Heberden’s nodes are bony swellings (osteophytes) that can 
develop in the distal interphalangeal joints (DIP) due to the effects of osteoarthritis on these joints. Heberden’s nodes are a sign of osteoarthritis caused by osteophyte formation (bony outgrowth) of the articular cartilage in response to repeated microtrauma at the joint. Heberden’s nodes are more common in women then in men.
PIP (Bouchard’s Nodes) – Bouchard’s nodes are also associated 
with osteoarthritis and they are similar bony growths which develop in the proximal interphalangeal (PIP) joints. Bouchard’s nodes, like Heberden’s nodes, may or may not be painful. Swollen, hard, and painful finger joints (Heberden’s and Bouchard’s nodes) is the classical sign of DIP and PIP joint osteoarthritis.
Mucous Cyst– Small, fluid-filled sacs that form between the DIP joint of the finger and the bottom of the fingernail are another sign of osteoarthritis. The best treatment is a surgical excision of the cyst and removal of the underlying osteophyte to decrease the risk of recurrence.
Dr. Nabil Ebraheim's Blog 