Arthritis is inflammation of the joint. Inflammation is a complex reaction of the body to harmful stimulus such as, infection, injury or irritation. Inflammation is characterized by redness, swelling, warmth, pain and stiffness at the affected site.
A joint consists of ends of the bone held together in a strong ligamentous pouch called capsule. This joint capsule is lined by the synovium which secretes synovial fluid into the joint and keeps the joint nourished and healthy. Synovial fluid is the lubricant and energy drink of the joint. End of the bones are covered by tough highly smooth cap called cartilage. A very thin layer of slimy synovial fluid between the cartilage makes joint movement extremely smooth and efficient.
Knee joint is the most common joint to suffer from arthritis. Knee arthritis can be due to various reasons like, degenerative changes, after injury or fracture of the cartilage, rheumatoid arthritis.
Most common type of knee arthritis is osteoarthritis. Osteoarthritis is continuous and gradual wear and tear of the structures of the joint. There is gradual loss in secretion of quality synovial fluid, wearing of the cartilage cap exposing the bone ends. Further progression of the arthritis leads to bony spurs formation in an attempt by the body to decrease pain. There is also significant change in the load distribution through the knee and biomechanics of weight transmission. In due course there is bone loss after the cartilage is eroded leading to bowing of knee joint.
Knee joint can be roughly divided in to three compartments, the medial, lateral and patella-femoral. It is the medial compartment where osteoarthritis usually starts first.
Causes of knee arthritis
It has not been possible till now to find out the exact reason for arthritis of knee joint, though it can be associated with certain risk factor.
Age- Knee osteoarthritis has been reported in as young as 35 years and there are innumerable people with healthy knee even at the ripe age of 100. Age is definitely the most common risk factor for not only knee arthritis but for arthritis elsewhere.
Sex- A majority of patients with knee osteoarthritis are female up to the extent of about 75-80%.
Weight- higher the weight, the more chances of it causing wear and tear of the already compromised knee joint. Though this is not the rule.
Genetics- it is seen that osteoarthritis runs in the family, and when it does so present at a younger age than general population.
Previous injury especially that has damaged the cartilage or the other stabilizing structures like ligaments in the knee joint cause secondary arthritis.
Whatever may be the cause of arthritis, it is certainly affecting our elderly in epidemic proportions. If not all there are few things like change in lifestyle and weight reduction can certainly delay arthritis and improve quality of life.