Arthritis or arthrosis is the degeneration of the joint cartilage. This is a disease process and there are several varieties of them. The commonest of them is Osteo Arthritis. Osteo Arthritis is normal wear and tear of knee joint. This is a type of mechanical arthritis. This process is similar to the wearing off of the car tires. As we age, our cartilage wears off and the bones rub against each other. This causes several problems, the important of them include :-
Pain, stiffness, swelling all of which fluctuate with time. Other two features include instability and deformity i.e. bending of knees.
Osteo Arthritis can be primary or secondary. Primary Osteo Arthritis implies the normal age related wear of the joints.
Secondary Osteo Arthritis implies there is some detectable factor age old injury which has lead to an accelerated wear and tear of joints.
To see these problems we need a weight bearing x rays of the knee.
The second commonest arthritis is the rheumatoid arthritis which is an inflammatory degeneration of the joint. This involves multiple joints simultaneously and is more deforming than pure Osteo Arthritis. Also it is associated with more swelling.
Arthritis can be genetic and can start at much younger age like the juvenile Rheumatoid Arthritis or Ankylosing Spondylitis.