FAQ’s on Knee Pain

Knee pain is a common problem for millions of Americans. The pain is often felt at the front of the joint, or it can radiate up or down the leg. The most common cause of chronic knee pain is osteoarthritis.

The knee joint consists of the femur (upper leg bone), tibia (lower leg bone), and patella (kneecap), as well as ligaments and muscles. The bones are held together by a joint capsule, which has an inner membrane (synovium) that secretes lubricating joint fluid. This joint is the largest joint of the body. The knee moves like a hinge, allowing a person to walk, squat, sit, or jump.

The ends of the bones are covered with a slick, elastic material called cartilage. This substance absorbs shock and allows bones to glide effortlessly against one another. Between the femur and tibia are two small pads of connective tissue, which are crescent-shaped. These structures are the lateral meniscus (on outer side of knee) and the medial meniscus (on the inside of knee).

How common is knee pain?

According to statistics, knee pain affects women more than men. Approximately 18% of men age 60 years and older report knee pain, and the incidence increases with age. For women, the prevalence rate is around 20%. In one study, 23% of women age 60 years and older have reported knee pain at some point during their lives.

What are the risk factors for knee pain?

The most common causes of knee pain are:

  • Ligament strains and sprains – This could mean a torn, stressed, or stretched ligament.
  • Osteoarthritis – Considered degenerative joint disease, this condition is most common among elderly patients. The breakdown of cartilage causes the bone ends to rub together, causing pain and stiffness.
  • Patella-femur syndrome – This causes anterior (front) knee pain.
  • Osgood-Schlatter – This condition occurs during growth, and it involves excessive traction of the tibial tubercle, which attaches to the knee joint.
  • Overuse syndromes – These include bursitis and tendinitis. When the bursa and tendons become inflamed, joint pain occurs.
  • Rheumatoid arthritis – This chronic inflammatory disease causes knee joint pain, stiffness, and loss of function.
  • Juvenile arthritis – When arthritis occurs before the age of 15 years, it is called juvenile arthritis. This causes knee pain, stiffness, and decreased knee range of motion.
  • Gout – This form of arthritis occurs when excessive uric acid collects in the bloodstream. Needle-shaped monosodium urate crystals deposit in the body tissues and joints, which causes serious knee pain.
  • Systematic lupus erythematosus – This chronic autoimmune disease causes release of antibodies that attack healthy tissues, including those of the knee joints.
  • Reactive arthritis – Following an infection, this form of arthritis affects joints, causing serious swelling and inflammation.

How is knee pain treated?

Treatment of knee pain, as with any symptom, involves diagnosing and curing the underlying cause. Some knee pain is chronic, and treatment options include:

  • Hyaluronic acid injections – A substance that mimics synovial joint fluid is hyaluronic acid (HA). These injections can be given weekly for a series of 3-6, or the long-acting form can be given once every 3-6 months. HA injections are widely accepted in the treatment of knee pain. In one study, HA injections worked best for persons age 60 years and older. Viscosupplementation is best for patients who are not candidates for a total knee replacement, or individuals who refuse surgery.
  • Corticosteroid injections – The doctor may inject the knee with a long-acting corticosteroid agent. This medicine decreases inflammation and helps relieve pain.
  • Arthrocentesis – If the knee joint has a buildup of fluid, the doctor may perform an arthrocentesis, which involves aspirating the knee joint. This procedure has a 93% success rate.

Resources

Altman R D, Moskowitz R, Hyalgan Study Group Intraarticular sodium hyaluronate (Hyalgan) in the treatment of patients with osteoarthritis of the knee: a randomized clinical trial. J Rheumatol. 1998;25:2203–2212.

Lohmander L S, Dalén N, Englund G, et al. Hyaluronan Multicentre Trial Group Intra-articular hyaluronan injections in the treatment of osteoarthritis of the knee: a randomised, double blind, placebo controlled multicentre trial. Ann Rheum Dis. 1996;55:424–431.