Arthritis can be broadly classified into the following groups:-

a) associated with infections for example rheumatic fever arthritis
b) degeneration of joints, often with age and excess body weight for example osteo-arthritis
c) non-infective forms of inflammatory arthritis, often deforming for example rheumatoid arthritis.
d) multiple systemic types (affecting lungs, heart, etc) for example lupus (SLE)
e) Metabolic & miscellaneous causes for example gout, traumatic arthritis.