A Collateral Ligament Injury is a condition in which one of the side ligaments of the knee joint becomes stretched, partially torn, or completely torn due to trauma, sudden twisting, or direct impact to the knee.
Collateral ligaments help stabilize the knee and control side-to-side movement between the thigh bone (Femur) and the shin bone (Tibia). When these ligaments are damaged, the knee may become painful, swollen, and unstable.
The two main collateral ligaments in the knee are the Medial Collateral Ligament and the Lateral Collateral Ligament.


The MCL is located on the inner side of the knee and prevents the knee from bending inward.
Common causes:
Symptoms:
The LCL is located on the outer side of the knee and prevents the knee from bending outward.
Common causes:
Symptoms:
Common symptoms include:
Immediate medical evaluation is recommended when these symptoms occur.
Grades of Collateral Ligament Injuries
Collateral ligament injuries are classified into three grades based on severity.
Common causes include:
Collateral ligament injuries often occur along with injuries to other structures such as the Anterior Cruciate Ligament, Posterior Cruciate Ligament, or the Meniscus.
Patients with collateral ligament injuries may experience:
Orthopedic specialists diagnose collateral ligament injuries using:
Surgery may be required in severe cases, especially Grade 3 tears or combined ligament injuries.
Performed using Knee Arthroscopy, where a small camera and instruments are inserted through small incisions to repair the ligament.
You should consult an orthopedic specialist if:
Early diagnosis helps prevent complications such as Knee Osteoarthritis or chronic knee instability.
Collateral ligament injuries affect the side ligaments of the knee that provide stability. They may range from mild sprains to complete tears. While many cases heal with conservative treatment, severe injuries may require surgical repair or reconstruction to restore knee stability and function.