By: Richard A. Owens, PT, MS, OCS, Cert. SHT, CWcHP, Cert DN
Knee pain is a very common condition affecting both active and sedentary individuals alike. Often, knee pain results from an injury, such as a ruptured ligament or torn cartilage, but can also be attributed to chronic conditions such as arthritis. Depending on the type and severity of damage, knee pain can be minor or it can lead to severe discomfort and disability.
Your knee joint is four bones held together by ligaments. Your thighbone (femur) makes up the top part of the joint, and two lower leg bones, the tibia (shin) and the fibula, comprise the lower part. The fourth bone, the patella or kneecap, slides in a groove on the end of the femur. The ends of these bones, including the underside of the kneecap, are covered with cartilage and lubricated with joint fluid (synovial fluid) to keep friction down during movement.
There are also four main ligaments that link the femur to the tibia. These include the collateral ligaments, the medial collateral ligament (MCL) along the inside, and the lateral collateral ligament (LCL) along the outside of your knee. The cruciate ligaments, the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL), cross diagonally on the inside of your knee. These ligaments help to stabilize the knee throughout its range of motion.
Another important structure within the knee is the meniscus, a C-shaped cartilage ring inside the knee. This also helps to stabilize the knee, but mostly serves as a cushion between the femur and tibia for weight bearing.
A knee injury can affect any of these structures around your knee joint, as well as the bones, cartilage and ligaments that form the joint itself. The pain can come on immediately with injury, or have a gradual onset that you notice with daily activities.
Some of the more common acute knee injuries include ligaments sprains/tears, meniscal tears, and patellar dislocation. Chronic knee pain is ongoing and can result from a previous injury, or another medical condition such as Rheumatoid or Osteoarthritis, patellofemoral pain, or gout.