Your knee ligaments are a group of strong, fibrous tissues that connect the femur in your upper leg to the tibia in your lower leg. They also provide stability for weight bearing and movement. You can develop minor or severe pain if you stretch or tear one or more of these ligaments, according to KidsHealth.org.
Ligament Basics
Each of your knees contains four ligaments, according to the Nemours Foundation. Your lateral collateral ligament, or LCL, bridges your tibia and femur on the outer border of your knee. Your medial collateral ligament, or MCL, bridges your tibia and femur along the inner border of your knee. Together, your LCL and MCL provide side-to-side knee stability and prevent unwanted inward and outward knee bending.
Your posterior cruciate ligament, or PCL, bridges your tibia and femur at the back border of your knee, while your anterior cruciate ligament, or ACL, bridges your tibia and femur at the center of your knee. Together, these ligaments control backward and forward motion in your knee, as well as knee rotation.
Ligament Injuries
In addition to your four ligaments, the only thing stabilizing your knee is local muscle tissue, according to the American Academy of Orthopaedic Surgeons, or AAOS. As a result, knee injuries occur frequently. Potential sources of knee ligament injury include direct physical trauma and muscle contraction associated with rapid changes of body direction. Technically, tears and stretches of your ligaments are called strains. Depending on your particular circumstances, you may injure a single ligament or two or more ligaments in combination.
Pain and Other Symptoms
If you sprain your knee ligaments, you will feel pain that seems to radiate from inside your knee, the Nemours Foundation explains. This pain will typically worsen if you try to move your knee. Additional potential symptoms include knee looseness or instability, fluid behind your kneecap, swelling, inability to put weight on your injured knee and a popping sound when injury first occurs.
Degrees of Injury
If you only slightly stretch one or more of your ligaments, you could have a grade 1 knee sprain, the AAOS reports. You will typically retain knee stability with this degree of injury. If you develop partial tears in one or more ligaments, you have a grade 2 sprain. This degree of injury causes noticeable knee looseness. If you completely tear one or more knee ligaments, you have a grade 3 sprain. This degree of injury will cause blatant knee instability. If you injure more than one ligament, you can develop complications that include nerve or muscle damage and disruption of your normal blood flow. Frequently, injuries to your LCL also trigger damage to other parts of your knee joint.
Treatment
The Nemours Foundation lists potential treatments for a mild or moderate knee sprain that include rest, ice, compression bandages and elevation---also called the R.I.C.E protocol---and use of a brace, sleeve or cast that temporarily immobilizes your knee joint during healing. You can also reduce pain with nonsteroidal anti-inflammatory medications, according to MedlinePlus. If you have a ligament tear, you may require surgical repair. Multiple tears are more difficult to repair than single tears, the AAOS notes.
