Four Common Causes of Knee Pain: A Primer of Diseases of the Knee Joint

knee pain causes

Knee pain causes

A variety of problems in the Knee can causing pain. Some can be treated conservatively, and some may need surgery.
Individuals that are young or old, active or sedentary may, at some time, suffer from knee pain. Knee pain can be acute or chronic, minor or debilitating. Some causes of knee pain are treatable with conservative, non-surgical methods, while others will require surgery. Four common causes of knee pain are:

Meniscal tear
Ligament tear
Patellar dysfunction/chondromalacia patella

Knee Joint Anatomy

The knee joint is made up of four bones: the femur, the tibia, the fibula and the patella. The main, weight bearing surface of the knee is the articulation of the femur (thigh bone) and tibia (shin bone). The patella (kneecap) provides mechanical support for the extensor muscle group of the knee (the quadriceps group). The fibula helps stabilize the lower leg, but is not a significant weight bearing structure.

The knee joint is stabilized by four ligaments: two crossing central ligaments (the anterior and posterior cruciate ligaments) and two parallel ligaments (the medial and lateral collateral ligaments). The joint is cushioned by two “c”-shaped, disc-like pieces of fibrous cartilage, called menisci. There is one meniscus on the inside of the joint (medical meniscus) and one on the outside of the joint (lateral meniscus). The articulating bone surfaces cover with hyaline cartilage (as in most joints), for further cushioning of movement. The patella aids in knee flexion and extension, providing support and an attachment for the quadriceps muscle group.


Arthritis is inflammation of a joint, characterized by pain, swelling and limited range of motion. There are two main types of arthritis: osteoarthritis, or degenerative arthritis, and inflammatory, or Rheumatoid arthritis. Osteoarthritis is far more common, and is generally a result of long term “wear and tear” of the joint. Factors that increase risk include obesity, weakness of the supporting muscles around the knee, and participation in high risk sports or repetitive activities. Over time, the cartilage of the knee breaks down, until bare bone exposes. The bone on bone motion that occurs after loss of cartilage is painful, and results in swelling and inflammation.

Meniscal Tear

Tears of the inner (medial) or outer (lateral) menisci of the knee cause pain, popping or sticking of the joint. Conservative treatment (“RICE” formula – rest, ice, compression and elevation) does utilize first. If pain persists, it usually requires surgical treatment.

Ligament Tear

The knee stabilize by four ligaments: the two cruciate ligaments, and the two collateral ligaments. Ligament tears usually occur as the result of acute trauma, and are acutely painful. Symptoms include swelling and stiffness, and possibly, instability. Anterior cruciate ligament tears are dramatic, with immediate symptoms of instability following the injury. Posterior cruciate ligament tears are less dramatic, but also result in swelling and instability. Medial collateral ligament tears are painful, but generally, do not cause instability. Lateral collateral ligament tears are rare, but also cause pain without instability.

Patellar dysfunction/Chondromalacia patella

A common form of patellar dysfunction is tendonitis of the patellar tendon. The patellar tendon is a tough band of fibrous tissue that connects the patella (kneecap) to the tibia. Most off all, a tendon can become inflamed  and causing pain with knee flexion/extension, as well as point tenderness over the tendon.
Chondromalacia patella refers to degeneration of the cartilage that lines the kneecap. The loss of cartilage results in knee pain with bending and kneeling, and may cause a grinding sensation behind the kneecap with movement.

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