Multi-Ligament Knee Injuries
There are four major ligaments that help stabilize the knee joint so it can function normally. When the knee is pushed beyond its normal limit an injury, such as a tear, can occur. When two or more ligaments are torn, it is known as a multi-ligament knee injury.
Anatomy of the Knee
The ligaments within the knee joint fall into two categories: cruciate ligaments and collateral ligaments.
Cruciate ligaments are what control the back and forth motion of your knee. They include the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL), which cross each other to form an “X” inside the knee joint.
Figure 1: MRI image of a normal, uninjured knee. Arrows point to the normal appearance of the ACL, PCL, MCL, medial meniscus and lateral meniscus.
Figure 2: MRI image of a patient with a high-energy multi-ligament knee injury. Arrows point to the severe soft tissue edema (white fluid) that surrounds the knee, a torn MCL, a torn medial meniscus (it has lost the normal triangular appearance), a sprained or partially torn PCL, a torn ACL, and a bone bruise along the outside aspect of the knee.
Collateral ligaments are what control the sideways motion of your knee and brace it against unusual movement. They include the medial (inside) collateral ligament (MCL), which connects the femur to the tibia, and the lateral (outside) collateral ligament (LCL), which connects the femur to the fibula.
In addition to the four major ligaments that surround the knee, there are multiple other ligament structures in the knee such as the posteromedial corner, posterolateral corner, medial patellofemoral ligament (MPFL) and the anterolateral ligament (ALL) which help provide stability to the knee. The ALL helps the knee pivot and provides additional stability. Until recently, doctors were unaware of this ligament and its importance to the anatomy of the knee.
You can learn more about the anatomy of the knee by reading our document A Patient’s Guide to Knee Anatomy.
How Multi-Ligament Knee Injuries Occur
Multi-ligament knee injuries usually occur when the lower leg is forced sideways, either toward the other knee (medially) or away from the other knee (laterally). Knee ligament damage typically occurs in high-energy trauma such as a car accidents, falls from height, or sports injuries. In more rare cases, smaller falls that can happen at work or during everyday activity can result in multi-ligament injuries.
The most common combined ligament injury is a tear of the MCL and ACL. MCL tears are more common than LCL tears, but a torn LCL has a higher chance of causing knee instability. MCL tears typically cause less instability than an LCL tears because MCL tears typically heal without surgery. The top of the shinbone (called the tibial plateau) forms a deeper socket on the side nearest the MCL. On the other side, near the LCL, the surface of the tibia is flatter, and the end of the shinbone can potentially slide around more.
Injured ligaments are classified as sprains and are graded on a severity scale:
- Grade 1: Ligament has been slightly stretched, but is still able to help keep the knee joint stable.
- Grade 2: The ligament has been stretched to the point where it becomes loose. This is often referred to as a partial tear of the ligament.
- Grade 3: Most commonly referred to as a complete tear of the ligament. The ligament has been split into two pieces, and the knee joint is unstable.
Symptoms of Multi-Ligament Knee Injuries
An injury violent enough to result in tears of multiple ligaments of the knee causes significant damage to the soft tissues around the knee, which can result in:
- A loud “popping” sound and/or sensation at the time of the injury
- Pain at the sides of your knee, especially when putting weight on that leg
- Swelling throughout the knee which makes it difficult to bend the knee
- Instability or the feeling that your knee is giving way and not supporting your body weight
Diagnosing Multi-Ligament Knee Injuries
Our team of surgeons at Sterling Ridge Orthopaedics will start with a thorough history and physical exam of your injured knee so that we can understand of the exact mechanism of injury. Typically, x-rays of your knee are obtained in clinic can help determine if a bone fracture is present or if the injury involves only the soft tissue ligaments. An MRI scan is typically obtained to define the number of injured ligaments and to find damage to bone, cartilage, meniscus, tendons, and muscles of the knee. In many cases, special x-rays called stress x-rays can help your surgeon quantitatively examine which ligaments are loose and may require repair or reconstruction.
Treatment Options
An isolated injury to the LCL or MCL doesn’t usually require surgical repair or reconstruction. If other structures in the knee are injured, however, surgery may be required.
When the sprain is less than a Grade 3, non-surgical treatment approaches may be an option. This might include things such as:
- Reducing activity
- Resting
- Wearing a brace
- Icing the injury
- Taking anti-inflammatory medications, such as aspirin
- Physical therapy
In regards to surgery, repair may be performed where the ligaments are stitched back together. However, most cases require the ligaments to be reconstructed by using a graft to make a new ligament. The graft may be taken from the patient (autograft method) or from donor tissue (allograft method). Our orthopedic surgeons are experts in multi-ligament knee injuries and will talk with you about your treatment options.
After surgery, you will meet with the SROSM physical therapy team to begin your rehabilitation program, which could include standard physical therapy and/or aquatic therapy. Rehabilitation starts out slowly and treatments will vary depending on the type of surgical procedure that was used. The first few physical therapy treatments are designed to help control the pain and swelling from the surgery. There are many goals of physical therapy, which include protecting the post-surgical knee, reducing inflammation and pain, and restoring strength, proprioception (body’s sense of positioning), and the natural range of motion.
You can learn more about multi-ligament knee injuries by downloading our educational documents A Patient's Guide to Collateral Ligament Injuries. Information specific to the ACL can be found in the related document A Patient’s Guide to Anterior Cruciate Ligament Injuries.
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