What is osteoarthritis? (OA)


Osteoarthritis, referred to as OA in short, is a chronic joint disorder caused by damage to the cartilage in the joint and its surrounding tissues and characterized by symptoms of pain, joint stiffness and loss of its function.

There is inflammation present in the joint between two bones. It is usually progressive with no stops or reverses.

It is important to note that OA is not a disease of just the articular cartilage but of the entire synovial joint in which there is damage to all the tissues of the joint such as the subchondral bone, the ligaments, the tendons, the periarticular muscle, the synovial sac, the sensory nerves, the menisci, and of course the cartilage.

A patient of osteoarthritis is handicapped, physically and mentally, taking painkillers and harboring the knowledge that he has to live with this condition all his life. Daily activities become pain bearing and cumbersome affecting his job performance. It does add to his mental agony.

It is also referred to as degenerative arthritis or  degenerative joint disease because it causes degeneration of the protective cartilage in the joint and the underlying bone. The cartilage is present between the two bones in the joint.

The cartilage is a protein substance present in the joint and acts as a cushion between the two bones of the joint. It allows one bone to slide over another and helps to facilitate various movements. You may develop osteoarthritis of the hip, the knee, spine, of the hands or even of the fingers.

Of the about hundred arthritis conditions, osteoarthritis is the most common form of arthritis and is seen affecting millions of middle age and above people worldwide.

Pathological features of osteoarthritis

  • Softening and later loss of articular cartilage
  • Degeneration of the exposed bone at the site of cartilage loss
  • Remodeling of bone
  • Formation of osteophytes
  • Formation of subchondral cysts
  • Inflammation of the synovial sac called synovitis
  • Thickening of the capsule of the affected joint
  • Degeneration of the menisci
  • Atrophy of the periarticular muscles

Joints affected by osteoarthritis

The joints most often affected in generalized OA include the following:

  • Knee
  • Hip
  • Intervertebral disks and the joints in the cervical and lumbar vertebrae
  • Distal interphalangeal (DIP) and proximal interphalangeal (PIP) joints
  • Thumb carpometacarpal joint
  • First metatarsophalangeal joint


You develop osteoarthritis usually after the age of 45 years and is found more commonly amongst men. Between 55 years to 70 years, it is present equally in men and women. After the age of 70 years, it is more common in women.

This rise in osteoarthritis in women in advanced age is probably due to weight gain due to menopause. According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), osteoarthritis affects about 27 million people in the Unites States.

Half of these cases of osteoarthritis are of the knee, according to the Centers for Disease Control and Prevention (CDC). About 8 million suffer from osteoarthritis in the United Kingdom.

A higher incidence is seen in the Japanese population while it is seen less among the South-African blacks, East Indians, and Southern Chinese.

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