There are many causes of knee pain and treatment is dependent on determining the exact cause.  The knee has many components including multiple ligaments, tendons, cartilage, bursa, and bones. Because there are so many components, determining the problem is often difficult. Age and activity level can often be a clue to the existing problems.   Younger and more athletic people have injury type problems, while older people develop issues related to degeneration.  Below are four of the most common causes of knee pain:

1. Osteoarthritis is the most common type of degeneration that occurs in the knee.  It is the progressive wear of the joint cartilage that occurs with age and use of the joint.  Read more about Osteoarthritis causes and treatment.
2. Obesity worsens and stresses the joints even more as people age.  The knee becomes chronically swollen, and painful with activity. Treatment is symptomatic – keep the knee moving and strong, and use over the counter medications for the pain as necessary.  If you are obese, try to reduce your weight to relieve additional stress.  When the deterioration is severe, there are orthopedic surgeries that can help including knee replacement.
3. Traumatic injuries to the knee include torn ligaments, meniscus tears, and tendonitis.  Bony injuries also occur to the patellar and the other bones of the joint area.  The anterior cruciate ligament is the most common ligament damaged in sports, caused when there is a sudden change in direction of the body. The side ligaments can also be injured in sports. These are usually treated conservatively.  The meniscus is part of the cartilage in the knee and is a shock absorber.  Injury to the meniscus occurs with twisting while weight bearing, and is fairly common in older active adults. Surgical repair is simple if conservative management is unsuccessful.
4. Bursitis & Tendonitis. Brusitis is inflammation of small sacs of fluid that cushion ligaments and muscles around the knee. This condition often resolves with rest. Tendonitis commonly occurs to the patella tendons in runners, skiers, and cyclists. This condition is also best treated with rest.

Pain in the knees is relatively common.  Traumatic injuries often respond to conservative care.  If not resolving, evaluation by a physician is recommended to determine the cause and best treatment options.  Age related changes, such as osteoarthritis, are usually treated conservatively as long as possible.  If conditions worsen, physicians can prescribe stronger medications, special joint injections, and help determine when surgery may be beneficial.