OA is the most common type of arthritis. It is also called hypertrophic osteoarthritis & degenerative joint disease. It is thought to be a wear and tear disease of the joints, occurring because of the ageing process. But there are many other risk factors which can accelerate the development of osteoarthritis, most importantly overweight.
What initiates Osteoarthritis?
Osteoarthritis occurs because of the loss of cartilage between bones. Cartilage is a firm rubbery tissue that cushions bony ends at the joints and allows bones to glide over each other smoothly. If the cartilage starts breaking down and wearing away, the cushioning effect reduces. This puts more stress and strain on the structure between cartilage and bone called transitional or subchondral bone, thereby leading to the changes resulting in hardening of this tissue. This reduces the smooth transition of the pressure from the cartilage to bone. Thus cartilage starts degenerating in the process. After some part of the cartilage has worn away, the bony ends start rubbing against each other, which causes pain. In the wearing away process, the cartilage fragments are separated and fall into the joint cavity. The human body tries to remove these fragments through the inflammatory process. This is what causes the joints to swell. If one side of cartilage wears down more than the other, it causes deformities which leads to angulations of the affected joints. Pain and stiffness is also experienced because of deranged biomechanical properties of the joints due to the stretch of the structures around the joints. As there remains no cartilage, the bones try to expand at the bony ends to reduce the pressure per unit area by forming bony spurs or extra bone which are called osteophytes visible on the X-Rays.
What are the risk factors which initiate development of Osteoarthritis?
- It may be familial, running in families.
- Overweight increases the risk of OA in the hip, knee, ankle, and foot joints because extra weight causes more wear and tear.
- Fractures or other joint injuries may start OA later in life
- Jobs involving kneeling or squatting for more than an hour a day put a joints at the highest risk. Jobs that involve lifting, climbing stairs, or walking also put you at risk.
- Sports involving direct impact on the joint (such as football), twisting (such as basketball or soccer), or throwing increase the risk of developing osteoarthritis.
- Bleeding disorders causing bleed in the joint, such as Hemophilia.
- Disorders that block the blood supply to a joint lead to avascular necrosis and thereby OA
- Chronic gout, pseudogout, Rheumatoid arthritis and other autoimmune rheumatic diseases also lead to rapid development of the OA.
- Endocrine disorders like hypothyroidism can accelerate the process of developing the OA
- Hypermobility of the joints, which runs in families, especially when associated with heavy work and overweight tends to cause early osteoarthritis.