Most commonly, the kneecap (patella) dislocates due to a twisting stress to the knee. However, the injury can also occur because of direct contact. If a foot is planted and then a sudden twisting movement or rapid change in direction occurs, the stress to the knee can cause the kneecap to shift out of place.

The most common major knee injury to occur in football is a rupture of the ACL (anterior cruciate ligament). The ACL is the most important structure preventing the tibia bone from moving too far forward of the femur bone. These ruptures are the result of both contact and non-contact injuries.

The knee wears out because all the force of the body’s weight passes through that 3- to 5-inch joint, which is composed of four bones, four ligaments and a couple of cartilage pads that cushion the blows of daily living. For most people, bad knees are just another consequence of the wear and tear of aging.

Common Football Injuries

• Ankle sprains.
• Knee injuries.
• Quad, hamstring, and groin strains.
• Hip pointers.
• Shoulder dislocations.
• Acromioclavicular sprains.
• Wrist and hand injuries.
• Football concussions.

Grade 3 — Considerable pain and tenderness at the inside of the knee; some swelling and marked joint instability. The knee opens up about 1 centimeter (slightly less than half an inch) when the doctor moves your leg around. A grade 3 MCL tear often occurs along with a tear of the anterior cruciate ligament.

Quadruple Knee-Ligament Injury It also seems that the more severe the damage to the knee, or the more ligaments destroyed in the injury, the more pain the player seems to be in. For this reason, the quadruple ligament injury must be one of the most painful football injuries imaginable.

5 Knee Symptoms You Should Not Ignore

• Clicking, locking, or popping in the knee joint.
• Swelling.
• Knee pain when sitting, driving, walking, sleeping, or exercising.
• Instability or a feeling of the knee giving way.
• Pain or stiffness which causes a decreased ability to bend or straighten the knee.

Call your doctor if you:

1. Can’t bear weight on your knee or feel as if your knee is unstable or gives out.
2. Have marked knee swelling.
3. Are unable to fully extend or flex your knee.
4. See an obvious deformity in your leg or knee.
5. Have a fever, in addition to redness, pain and swelling in your knee.

With proper care, the knee pain will become less noticeable in about three weeks, but complete healing from tendinitis may require six weeks, says Stuchin.