Knee Ligament Sprains

Knee Ligament Sprain Definition and Anatomy

Knee ligament sprains are defined as an injury or disruption to the ligamentous tissue. There are a variety of reasons that the ligament fails, but it is usually due to overloading the tissue due to poor movement mechanics or blunt force. The primary ligaments that provide support for your knee are the anterior crucial ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and the lateral collateral ligament (LCL). The ACL and PCL cross from the front to back and back to front of the knee respectively: This is why they are given the name of cruciate (or cross) ligaments. The MCL and PCL help to support the inner and outer parts of your knee. 

There is a spectrum of sprains from very minor disruptions in the tissue (grade 1) to full thickness tears (grade 3). Grade one and two tears can generally be treated conservatively, but full thickness repairs often require surgical repair, especially if the patient wants to return to higher level activities including running etc. 

Injury Mechanism and Diagnosis

ACL sprains

ACL sprains are more common in athletics that require running and cutting like soccer, field hockey, lacrosse, and football. The ACL is an important structure for promoting stability within the knee. Injuries to this structure usually leads to a long term recovery, especially with full thickness tears requiring surgery.

Hallmark signs and symptoms

  • Often occur when cutting, pivoting, or planting 
  • Knee usually collapses inwards when performing provoking movement
  • Audible pop usually reported with full thickness tears
  • Swelling of the knee occurs quickly
  • Knee feels loose and unstable with most movements

MCL sprains

MCL sprains is one of the most common knee sprain injuries. It may usually occurs in a similar fashion to an ACL injury during cutting, pivoting, or planting with poor form. It can also occur with a force to the outside of the knee. The outside of the knee is much more vulnerable to insults during sport than the inside, making this ligament particularly vulnerable.

Hallmark signs and symptoms

  • Occurs with a force to the outside of the knee or with a cutting/ pivoting movement
  • Pain and tenderness located on the inside of the knee
  • Swelling and/or bruising may occur on the inside of the knee
  • Feelings of instability or weakness around the knee

PCL sprains

PCL sprains tend to be more rare and are usually caused by blunt forces to the front of the knee. One common way of injuring the PCL is someones knee hitting the dashboard during a motor vehicle accident. This movement forces the tibia backwards on the femur causing the injury. The biggest difference in diagnosis between an ACL and a PCL sprain is the injury mechanism.

Hallmark signs and symptoms

  • Often due to a blunt force to the front of the knee (hitting knee on dashboard during car accident)
  • Swelling in knee occurs quickly 
  • Knee feels unstable like it may give our

LCL sprains

LCL sprains are another relatively rare occurrence in sport and everyday life. They usually occur when there is a force to the inside of the knee. This may occur during sport when a player falls and hits the inside of another players knee.

Hallmark signs and symptoms

  • Occur with a force to the inside of the knee 
  • Pain and tenderness on the outside of the knee
  • Sitting with leg crossed is uncomfortable 
  • Swelling and/or bruising may occur on the outside of the knee

Treatment For Knee Ligament Sprains

Conservative treatment depends on the severity of the injury. Since most ligaments have a poor blood supply, they generally take longer to heal than other tissues in the body. Progression will be based on your response to treatment and your tissues irritability level. With grade one and two sprains, knees will generally heel over time with targeted manual therapy, therapeutic exercise, and neuromuscular reeducation.

  • Manual Therapy: Manual therapy can be effective for reducing pain, decreasing swelling, and improving range of motion with this type of an injury. Regaining full motion is critical with this type of injuries. Small losses in extension motion can lead to significant difficulties returning to normal activities like walking and running.
  • Therapeutic Exercise: Effective for improving range of motion, promotion muscle activation, and improving strength and endurance. With this type of injury, muscles surrounding the knee joint may become inhibited. Ther-ex can be used to train these muscles to activate properly again. Strength and endurance improvements are usually targeted both at the knee and the hips. Since some of these injuries occur due to faulty movement mechanics, special attention must be paid to hip musculature. The hips have a large role in form and function at the knee and ankle.
  • Neuromuscular reeducation: Effective for improving muscle activation and proprioception around the joint. Proprioception is your bodies sense of that joint. With an injury, your brains internal picture of your joint is skewed. Improving this joint sense is essential to preventing future injuries. Neuro re-ed for this type of injury usually includes series of exercises that may include balance, motor control, agility, and plyometric movements. It is used to ensure that all of the muscles around the joint are doing what they’re supposed to to help stabilize the knee.


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