Have you been told that you have arthritis because you experience knee pain and swelling? Is your pain on the side of your knee rather than within your knee joint? If so, you may actually have pes anserine bursitis or medial or lateral collateral tendonitis.

The knee joint, which links the thigh and shinbone, is stabilized by strong cords called tendons. Strategically placed to prevent the knee from moving side to side, the medial collateral tendon is located on the inner side of the knee to prevent it from collapsing inward, and the lateral collateral tendon, on the outer side, to prevent outward twisting. The pes anserine bursa, a sac-like, protective cushion, is located beneath the tendons on the inner side of the knee.

Medial collateral tendonitis usually occurs as a result of trauma associated with falls with an externally rotated knee such skiing, or football injuries. Lateral collateral tendonitis happens less frequently and heals more easily because it is less vulnerable to injury due to its location on the outer side of the knee. When direct trauma, overuse, or misuse occurs, not only can the tendons become injured, but the bursa can also become inflamed and irritated, meaning bursitis. Long distance runners commonly develop pes anserine bursitis because of stress placed on the knees. Misalignment of the lower extremities, due to osteoarthritis, can stress knee tendons and bursas, causing tendonitis and bursitis.

The most common complaint with medial collateral tendonitis and pes anserine bursitis is constant aching of inner side of the knee with increased pain on rotation of the knee. Activity, especially flexion and external rotation of the knee, increases pain, while resting and heat relieves it. Often, patients wake up at night due to pain and are unable to kneel or walk down stairs. Physical examination may reveal tenderness at the inner aspect of the knee along with pain upon flexion and rotation. Occasionally, an MRI may be helpful.

Treatments for these conditions are similar, but are obviously location specific: analgesics, non-steroidal anti-inflammatory drugs, use of a knee brace to prevent re-injury, physical therapy, and heat application. Local cortisone injection at the exact affected site (anserine bursa or medial or lateral collateral tendon) is crucial to decrease inflammation for a successful outcome. As in many circumstances, other conditions can show similar symptoms that must be differentiated prior to beginning treatment. Knee pain can be caused by arthritis, tendonitis or bursitis. Finally, the coexistence of knee osteoarthritis and tendonitis or bursitis is quite common, particularly in the elderly, which makes diagnosis much more difficult.

Don’t just accept the answer that “You’re getting older and you have arthritis.” Know what the important differences are and get the treatment you need and deserve.