The LCL (lateral collateral ligament) is located on the outside of the knee and is one of four main ligaments in the joint. This ligament connects the femur and the fibula and prevents excessive side-to-side movement in your knee joint.
When your knee bends too far inwards, your LCL can stretch or tear. This injury most commonly occurs during sports or as a result of traumatic injuries like a fall. Ligament tears are diagnosed on a graded scale, with grade I being the least severe and grade III being the worst.
- Grade I LCL Tear – With a grade I tear, you will typically feel some pain or pressure on the outside of the knee. The tendon is only slightly torn.
- Grade II LCL Tear – Slightly worse than a grade I, but not a complete tear, the grade II injury may cause some instability in the knee when pivoting. You will also experience more pain and swelling.
- Grade III Tear – A grade III LCL injury is a complete tear of the LCL and typically requires surgery to repair. You will experience pain, swelling, and may have difficulty bending your knee. Injuries to the cruciate ligaments are common in conjunction with a grade III LCL tear.
Diagnosing an LCL Tear
Your doctor will perform a physical exam to determine if the ligament is torn, but an MRI will be needed to determine the grade of the tear. MRIs use magnetic fields to create images of your body, including the ligaments.