A Quick Guide To Knee Sprains

By:    Published: January 30, 2012

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Knee sprains are a common injury, caused by anything from a simple misstep on a staircase to a one-on-one collision in a competitive sporting event. Read this article to find out what classifies as a sprain, what can cause it and if you may be at a greater risk for this type of injury.

What is a Knee Sprain?

Sprains occur when a ligament (a band of tough tissue which connects bones together) in the body is torn or stretched too far. There are four ligaments which support the knee, each of which is susceptible to a sprain: the anterior cruciate ligament (ACL), the posterior cruciate ligament (PCL), the medial collateral ligament (MCL) and the lateral collateral ligament (LCL). These ligaments are integral to keeping the knee joint stable, so a sprain will compromise the knee's ability to function properly.

There are different levels that classify the severity of a sprain.

  • Grade 1: minor stretching or very tiny tears to the ligament tissue. Home treatments are usually sufficient for these types of sprains.
  • Grade 2: the ligament is partially torn and the joint becomes mildly unstable. Some individuals with this type of sprain may need to wear a brace to stabilize the injured area while it heals.
  • Grade 3: severe or complete tearing of the ligament tissue and serious instability of the knee joint. In many cases, surgery or serious physical therapy is needed to repair this type of sprain.

A sprain should not be confused with a strain, which affects either a muscle or a tendon, not a ligament. The most common place for a sprain to occur is in the ankle or the knee.

Common Causes of Knee Sprains

In general, there are two basic incidents that cause most knee sprains. The first is any movement that places stress on the knee, such as twisting, sudden stops or changes in direction, shifting your weight, jumping or landing. The second cause is a direct hit to the knee, whether it is caused by the person's knee hitting the ground after a fall or something striking the individual from the front, sides or back of the knee.

Sports are one of the most common causes of a knee sprain. Soccer, tennis, basketball, volleyball and running are just a few of the many sports that could potentially lead to a sprain in the knee. In many cases, these sports-related injuries are caused when the person receives a blow to the knee or lands incorrectly after jumping. Shifting your weight, as is often done in downhill skiing, is another way that knee sprains commonly occur.

Falls are another common cause of knee sprains. Falling a great distance almost always results in some type of injury, and when the person tries to land on their feet, a knee sprain may likely occur. Even small falls, like those that may result from tripping over something on the ground, could potentially lead to a knee sprain if the person lands awkwardly or falls onto their knees.

How to Tell if You Have a Knee Sprain

Many people know right away that something is wrong after an injury occurs. However, they may not know for sure whether the injury is a knee sprain or not. The most common symptoms of a knee sprain include:

  • A "pop" feeling or noise at the moment of injury
  • Pain and tenderness in the knee area
  • Swelling
  • Bruising or redness
  • Decreased range of motion in the knee joint
  • Stiffness in the knee
  • An inability to place weight on the knee

In most cases, knee sprains do not require emergency medical treatment. However, if you find that your knee becomes severely painful or swollen, see a doctor about your injury immediately. In most cases, it's a good idea to have a doctor inspect you after a knee sprain to determine the severity of the injury and whether physical therapy is necessary.

Risk Factors for Sprains

While many knee sprains can occur from just a simple accident like a fall or tripping over something, there are certain risk factors that may increase an individual's chances of spraining their knee. Those risk factors include:

  • Playing sports
  • Previous injuries in the knee area
  • Poor coordination or balance
  • Poor flexibility in the joints and muscles
  • Loose or weak joints
  • Obesity or being overweight
  • Failing to wear the correct protective gear for certain sports and activities
  • Improperly fitted shoes

Talk to your doctor if you have any of these risk factors to find out what you can do to help prevent knee sprains in the future.

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