Anatomy of the Knee

The knee is the largest joint in your body and one of the most complex. Three bones meet to form the knee joint: the thighbone (femur), shinbone (tibia), and kneecap (patella). The kneecap sits in front of the joint to provide some protection. Knee ligaments connect the thighbone to the lower leg. The four primary ligaments in the knee act like strong ropes, holding the bones together and keeping the knee stable.

  • Collateral ligaments—Found on the inside (the medial collateral ligament or MCL) and on the outside (lateral collateral ligament or LCL) of the knee, these ligaments control the sideways motion of the knee and brace it against unusual movement.
  • Cruciate ligaments—Found inside your knee joint, these ligaments cross each other to form an “X” with the anterior cruciate ligament in front and the posterior cruciate ligament in back. The cruciate ligaments control the knee’s back and forth motion.

What Are Combined Knee Ligament Injuries?

It is possible to injure two or more ligaments at the same time. Multiple injuries can have serious complications, such as disrupting blood supply to the leg or affecting nerves that supply the limb’s muscles. In severe cases, multiple ligament injuries may lead to amputation if major blood vessels or nerves are also damaged. Although the MCL is injured more often, an injury to the LCL usually includes injury to other structures in the joint, as well.

An injured ligament is considered a sprain, and is graded on following severity scale:

  • Grade 1 sprain—The ligament is mildly damaged. It has been slightly stretched but is still able to help keep the knee joint stable.
  • Grade 2 sprain—The ligament is stretched to the point where it becomes loose. This is often referred to as a partial tear of the ligament.
  • Grade 3 sprain—The ligament has been split into two pieces and the knee joint is unstable. This is commonly referred to as a complete tear of the ligament.

What Causes Combined Knee Ligament Injuries

Because the knee joint relies just on ligaments and surrounding muscles for stability, it is easily injured. Direct contact to the knee or hard muscle contraction, such as changing direction rapidly while running, can injure a knee ligament.

Diagnosis

A suspected multiple ligament injury needs a thorough examination by an experienced physician. Depending on the injury, the orthopaedic surgeon may call in other specialists such as a vascular surgeon or microsurgeon.

Treatment

In contrast to treatment for single ligament tears, surgery for combined ligament tears is often performed soon after the injury. This is done even though early surgery, before inflammation has resolved, poses an increased risk of arthrofibrosis (a scar forming in the joint). More than one operation may be required when treating multiple ligament injuries.

Recovery

Results of surgery are typically more consistent for a single ligament injury than for an injury to multiple ligaments. Knee ligament sprains and tears are a common sports injury that, in the past, often put an end to the patient’s sports activities. Today, advances in treatment have made it possible for many athletes to return to high-level sports, even after multiple ligament injuries, however each case is unique and there is no certainty of this. A knee conditioning program can help in preventing injury.

VIDEO: Knee Injuries with Kirk Cousins & Dr. Bruce Stewart, Holland Hospital Sports Medicine

VIDEO: Dr. Bruce Stewart Knee Injuries in Athletes, Holland Hospital Physician Lecture Series, May 2015