How are you? Arthritis can occur due to many reasons like infection, rheumatoid arthritis, gout, psoriasis, trauma, osteoarthritis etc.
More often X-ray images of the affected joint may reveal a narrowing space with in the joint, which indicates that the cartilage is breaking down. An X-ray may also show bone spurs around a joint.
Depending upon the cause, there can be depositions, resorption of bone material etc.
All the best.