ACL & MCL: Two important knee ligaments
Four key ligaments are responsible for stabilizing the knee. The ACL is located in the middle of the knee. The ligament connects the thigh and shin bones and forms an X with the PCL. The ACL helps with stabilizing the knee and allows twisting movements. The MCL is a band that runs on the knee’s inner edge, also connecting the thigh and shin bones. The LCL is a similar band on the outer edge. MCLs help knees from collapsing inward while bringing added stability. Both are prone to injury, especially in contact sports.
Contact vs. non-contact
Different circumstances can create both ACL and MCL injuries. ACL injuries can happen through contact, like a sports collision or car accident. However, most ACL injuries are non-contact. Landing awkwardly, twisting forcefully, or a sudden change in direction can create ligament damage. MCL injuries, on the other hand, are almost always through contact. A blow to the inner knee, either from sports, a fall, or an accident, can damage the ligament. Keep these factors in mind when assessing the knee.
Did it pop?
The ACL and PCL are strong but flexible bands that stabilize the knee. ACL injuries involve a loud pop that happens at the point of impact. This sound is the band snapping, similar to a rubber band. MCL injuries often occur without the popping sound. In the case of a full MCL tear, a popping sound can be heard. Both ACL and MCL injuries are graded from I to III, with a grade III tear causing the audible pop.
Location of the pain
The location of the pain is a clear indication of the type of ligament damage. An ACL injury is painful directly in the center of the knee. The pain is not close to the skin but instead feels deep inside the knee. An MCL injury will present pain on the knee’s inner part and may feel a bit closer to the surface.
Look for swelling
In the hours following an ACL injury, fluid and inflammation flood the affected knee. This causes the knee to swell, with the swelling based at the center. MCL injuries may not show swelling, depending on the extent of the injury. Full MCL tears will swell at the inner part of the knee.
Do you need surgery?
The need for surgery is another way to differentiate injuries. ACL tears, whether partial or full tears, almost always need surgery, especially if the patient intends to resume physical activity. ACL reconstruction is a minimally invasive surgery. Surgeons remove the damaged ligament and surgically install a replacement. With MCL tears, however, surgery is not always necessary. If the ACL is intact, the MCL can recover with physical therapy, bracing, and rest.
The right assessment means the right treatment
Both ACL and MCL injuries are severe and should not be ignored. These ligaments are critical for movement and present differently in terms of location of pain, swelling, and the cause of injury. More importantly, the type of injury determines the type of treatment needed. Anyone suspecting a knee ligament injury should seek medical attention immediately