Common Knee Problems and Injuries

Some of the most common knee injuries involve a torn or damaged ligament, though there are a variety of reasons that someone could be experiencing pain in his/her knee.  Below is an outline of common ligament injuries as well as some other potential causes of knee pain.  This is not an exhaustive list, but it’s a great start to become familiar with many of the ways that the knee can become injured.
 
Ligament/Cartilage tears

• ACL – The great majority of knee injuries involve torn ligaments, particularly to the ACL and MCL.  The ACL is most commonly injured from a rapid change in direction, rapid slowing or when landing from a jump.  An ACL tear is not always a contact injury, so almost all athletes (particularly soccer, skiing and football) are at some level of risk for ACL tears. 

• MCL – Sports that involve contact, either as part of the game or as incidental contact, like football and soccer, have a much higher rate of MCL injuries than non-contact sports do.  This is because MCL injuries are most frequently caused by a blow to the outside of the knee, which happens more frequently in contact sports.  For example, a quarterback who gets struck on the right side of their right knee by a 300 lb. lineman would likely suffer a torn MCL.

• Meniscus Tears - Tears in the meniscus can occur during almost any activity that stresses the knee joint in any significant way, however direct contact is typically the cause.  It may feel like a pop at the time of the injury and many patients describe the knee as locking-up.

• PCL/LCL – Other, less common, ligament injuries are PCL tears, caused most frequently by a blow to the front of the knee, or LCL tears, which could be caused by a blow to the inside of the knee in the direction of the outside of the knee, or with high velocity traumatic injuries such as a car accident.

Other knee injuries:

• Plica Syndrome – This is an inflammation of the plica, which are sleeves of tissue located under the patella.  These tissues are formed during the first trimester in the womb to help the knee form properly as a baby develops.  For most people, the plica nearly disappear in the second trimester after its function is no longer necessary. For some, however, the plica remain more prominent and can cause irritation or become inflamed throughout their life.

• Patellar Tendonitis – This can occur when the tendon connecting the patella to the lower leg becomes inflamed.  This will cause irritation and pain in the knee.

• Patellar Dislocation – When the knee is bent beyond approximately 30 degrees, the patella slides up and down in a groove on the end of the femur.  If it becomes dislocated, there can be significant pain associated with it.  A lateral dislocation occurs when the patella dislocates toward the outside of the knee. 

• Patella-Femoral Pain/Syndrome – Pain around the knee cap that worsens/increases with activity.

• Bursitis – Inflammatory disorder of the bursa, the thin walled sac lined with Synovial fluid and tissue.

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