Knee Sprain Diagnosis and Treatment

woman putting ice on sprained knee
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A knee sprain means that you have injured one of the ligaments around the knee joint. There are four major ligaments that contribute to the stability of the knee. In addition, there are many smaller ligaments that can cause pain after injury.

Sprain vs. Strain

A sprain is an injury to a ligament, and a strain is an injury to a muscle.  Ligaments are structures that connect two bones.

  Ligaments are important in allowing joint stability, while at the same time allowing the joint to move.  In the case of the knee, the ligaments allow the knee joint to bend back and forth but control excessive movements.  The collateral ligaments of the knee prevent excessive side-to-side motion, while the cruciate ligaments are important in both rotational and forward/backward stability.


Saying someone has a "knee sprain" is not a terribly useful diagnosis for two reasons:

  1. It does not tell you which ligament is injured. This is important because different ligaments are treated very differently. For example, ACL (anterior cruciate ligament) injuries often need surgical reconstruction. On the other hand, MCL (medial collateral ligament) injuries seldom require surgery.
  2. It does not tell you how badly the ligament is injured. The reason this is important is that minor injuries usually require minor treatment. More severe injuries may require more substantial treatment, rehabilitation, and possibly surgery.

    Despite this, patients are often told they have a knee sprain. If you are diagnosed with a knee sprain, try to get more information. Find out which ligaments are injured, and then you will be able to understand more about what possible treatments and rehabilitation are necessary. 

    Severity of Injury

    Often knee ligament injuries are graded to define the severity of the injury.

      A grade of injury is meant to give an indication of the extent of damage to the ligament.  In general, most physicians grade on a scale of 1 to 3. The grades of a ligament tear are:

    • Grade I: A minor injury that will likely recover with rest and activity modifications over the course of 1-2 weeks.
    • Grade II: A moderate injury with partial tearing of the ligament that will require more limitations in activities and may take 4-6 weeks for recovery.
    • Grade III: A complete or near-complete tear of the ligament. Depending on the ligament damaged, this may require either more prolonged rehabilitation or surgical intervention.

    It is important to keep in mind that these general classifications are somewhat arbitrary, and the truth is a ligament can be damaged in many ways across a spectrum from no injury to a complete tear. Therefore, these categories are used most notably to give athletes a sense of the severity of the injury and a timeline for an expected return to their athletic endeavors.


    As stated, the primary problem with calling an injury a knee sprain is that these words do little to convey much useful information. Knowing the specific ligament injured will help your doctor and you team up to find the best treatment to ensure you return to your normal activities as soon as possible.

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