Osteoarthritis of the Knee

Osteoarthritis of the knee (OA Knee) is one of the five leading causes of disability among elderly men and women. The risk for disability from OA Knee is as great as that from cardiovascular disease.

OA Knee usually occurs in knees that have experienced trauma, infection, or injury. A smooth, slippery, fibrous connective tissue called articular cartilage acts as a protective cushion between bones. Arthritis develops as the cartilage begins to deteriorate or is lost.


Several factors may increase the risk of developing osteoarthritis of the knee:

  • There is some evidence that genetic mutations may make an individual more likely to develop OA Knee.
  • Weight increases pressure on joints such as the knee.
  • The ability of cartilage to heal itself decreases as people age.
  • Women who are older than 50 years of age are more likely to develop OA Knee than men.
  • Previous injury to the knee, including sports injuries, can lead to OA Knee.
  • Repetitive stress injuries, such as those associated with certain occupations that involve kneeling or squatting, walking more than two miles a day, or lifting at least 55 pounds regularly. In addition, occupations such as assembly line worker, computer keyboard operator, performing artist, shipyard or dock worker, miner, and carpet or floor layer have shown higher incidence of OA Knee.
  • People who play high impact sports, such as elite players in soccer, long-distance runners, and tennis players have an increased risk of developing OA Knee.
  • Repeated episodes of gout or septic arthritis, metabolic disorders, and some congenital conditions can also increase your risk of developing OA Knee.
  • Other risk factors are being investigated, including the impact of vitamins C and D, poor posture or bone alignment, poor aerobic fitness, and muscle weakness.


Typical symptoms include:

  • Narrowed joint space between the bones.
  • Thinning, grooved, and fragmented cartilage.
  • Thicker surrounding bones that grow outward and form spurs.
  • The synovium—a membrane that produces a thick fluid that helps nourish the cartilage and keep it slippery—becomes inflamed and thickened. It may produce extra fluid, often know as “water on the knee,” that causes additional swelling.
  • In severe cases, when the articular cartilage is gone, the thickened bone ends rub against each other and wear away resulting in a deformity of the joint.
  • Normal activity becomes painful and difficult.


OA Knee can be diagnosed in two ways: patient-reported symptoms such as pain or disability, or actual physical signs, such as the changes in the joint seen on X-rays.

Initial treatment is generally directed at pain management. Because OA Knee pain may have different causes depending on the individual and the stage of the disease, treatment is tailored to the individual. You and your doctor should decide together on the course of treatment that's right for you. In general, treatment options fall into five major groups:

  1. Health and behavior modifications, such as patient education, physical therapy, exercise, weight loss, and bracing.
  2. Drug therapies, including simple pain relievers such as aspirin or nonsteroidal anti-inflammatory drugs, COX-2 specific inhibitors, opiates and stronger drugs for patients who do not respond to other drugs or treatments, and glucosamine and/or chondroitin sulfate.
  3. Intra-articular treatments, including corticosteroid or hyaluronic acid injections.
  4. Surgery, including arthroscopy, osteotomy, and arthroplasty (joint replacement).
  5. Experimental/alternative treatments such as acupuncture, magnetic pulse therapy, vitamin regimes, and topical pain relievers.

Reproduced with permission Fischer S., (interim ed): Your Orthopaedic Connection. Rosemont, Illinois. Copyright American Academy of Orthopaedic Surgeons.