Ligaments are strong, dense structures made of connective tissue that stabilize a joint. They connect bone to bone across the joint. The knee joint is located where the end of the thigh bone (femur) meets the top of the shin bone (tibia) and four main ligaments connect these two bones:
- Medial collateral ligament (MCL) runs along the inside of the knee. It prevents the knee from bending in.
- Lateral collateral ligament (LCL) runs along the outside of the knee. It prevents the knee from bending out.
- Anterior cruciate ligament (ACL) is in the middle of the knee. It prevents the shin bone from sliding out in front of the thigh bone.
- Posterior cruciate ligament (PCL) works with the ACL. It prevents the shin bone from sliding backwards under the femur.
Similar to the medial collateral ligament (MCL), the LCL’s primary function is to stabilize the knee as it moves.
Tears to the LCL commonly occur as a result of direct blows to the inside of the knee, which can over-stretch the ligaments on the outside of the knee and, in some cases, cause them to tear.
The tear can occur in the middle or at either end of the ligament. LCL tears often occur while playing sports in which there are violent collisions (such as football or hockey). It is important to note that an LCL tear rarely occurs in isolation — it usually is in conjunction with another knee injury.
Signs & Symptoms
The most common symptoms of an LCL tear are pain, stiffness, swelling and tenderness along the outside part of the knee. The knee may feel loose, as though it will give way under stress, or it may lock.
More severe tears can cause numbness or weakness in the foot, which occurs in the peroneal nerve (located near the LCL) if it is stretched at the time of injury or squeezed by swelling of the surrounding tissues.
The doctor will check for pain or tenderness along the inside of the knee. In order to determine the severity of the injury, he or she will apply pressure to the outside of the knee while the leg is both bent and straight.
In some cases, the immediate pain and swelling may make it too difficult to accurately gauge the severity of the injury. If this occurs, the patient may be asked to wear a light splint and ice and elevate the knee until the swelling and pain lessen, so that an accurate diagnosis can be made.
In addition, the following tests may be ordered:
- X-ray – These are usually ordered to evaluate the bones and alignment around the knee.
- Magnetic Resonance Imaging (MRI) – This test is more than 90 percent accurate in assessing the severity of LCL injuries, and it is commonly used if the physical examination does not yield a satisfactory diagnosis.
If the torn ligament does not heal sufficiently, instability in the joint may be experienced, making it more susceptible to re-injury. Although more severe injuries often require surgery, lesser damage to the LCL usually responds very well to non-surgical treatment. Recovery time depends on the severity of the injury.
Rehabilitation for an LCL tear consists of:
- A period of rest
- Physical therapy
Once pain and swelling have subsided, physical therapy begins to restore strength and normal range of motion to the knee.
Surgical repair of a torn LCL usually takes about one to two hours but can be longer if there are other injuries to the knee that also require treatment, such as an ACL tear. General anesthesia or a spinal or epidural anesthetic is used. An incision is made on the outside of the knee to gain access to the torn ligament. The ligament is re-attached to the bone using screws, sutures or both. The skin is sewn back together using sutures or staples.
It is important to note that an LCL tear rarely occurs in isolation — it usually is in conjunction with other major knee injuries — and therefore overall treatment and recovery depends on the extent of the other damage.