Common Causes of Knee Pain

Have you ever felt a creak in your knees in the middle of a long run? Or maybe a slight clicking as you squat or walk down a flight of stairs? Well, you're surely not alone: An injured knee is one of the most common reasons people visit the doctor. While there are multiple causes of knee pain, recent research and clinical findings have uncovered methods to help prevent all types of knee joint injuries.

Inside Your Knee

The knee is composed of two joints: one between the thigh bone (femur) and leg bone (tibia) and one between the thigh bone and kneecap (patella). Between the thigh bone and leg bone lie two crescent-shaped pieces of cartilage, called menisci. Adding to the anatomical elegance of the knee are fluid sacs (bursae), tendons, ligaments, and muscles.

The knee functions like a hinge joint, meaning that movement is primarily along one axis: to flex or extend. There is also slight rotational and bending movement.

Common Causes of Knee Pain

Knee pain is often the result of repetitive strain caused by overuse and further induced by improper movement patterns. Let's look at four common knee injuries:

  • Patellar tendinitis (jumper's knee). The patellar tendon connects the kneecap to the leg bone. Accordingly, patellar tendinitis is characterized by inflammation and pain to this region and is most common in athletes who participate in jumping sports. It is caused by repetitive overuse of the tendon and is referred to as tendinopathy if it becomes a chronic condition.
  • Meniscus tears. A meniscus tear is when one or both of the pieces of cartilage between the thigh bone and leg bone tear. The telltale signs of meniscus tears are pain, swelling, an inability to straighten the knee, and/or a feeling of clicking within the knee.
  • Sprained ligaments. Ligaments are fibrous tissue that connect bones together. Their primary purpose is to provide stability. A sprain is a stretch or tear to a ligament. There are four major ligaments in the knee: the anterior cruciate ligament (ACL), the posterior cruciate ligament (PCL), the medial collateral ligament (MCL), and the lateral collateral ligament (LCL). Because each ligament serves a unique function, the potential cause for strain is similarly unique. The commonly torn ACL, for instance, controls rotation and forward movement of the leg bone relative to the thigh bone; the cause of ACL tears is often hyperextension while pivoting. Needless to say, a sprain of any of these four ligaments compromises the stability of the knee joint.
  • Runner's knee. Runner's knee is a catch-all term for overuse injuries that lead to knee pain. Runner's knee may actually refer to patellofemoral pain syndrome (pain in the front of the knee), iliotibial band syndrome (pain derived from lateral motion), or  tarchondromalacia patella (pain and inflammation to the underside of the kneecap).

Preventive Tactics

Despite the complexity of knee joint injuries, there are a few simple actions you can take to prevent injury.

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