Knee sprain occurs when one of the knee ligaments is stretched and laceration of the fibers occurs. 
Symptoms: pain in the injured knee ligament, swelling , instability, limitation of flexion movements and knee extension. 
Cause: An indirect force in the knee as a sudden twist. 
Treatment: rest, elevation, ice , bandage, exercises. Surgery is rarely needed.


What is a knee sprain?

There are four ligaments in the knee joint. At the center of the joint are the two cruciate ligaments – anterior and posterior (ACL and LCP). On the sides of the joint are the two collateral ligaments – the medial and lateral (LCM and LCL). These fibrous cables work together to keep the knee joint stable and protect it from injury.

knee sprain simply means that at least one of the ligaments has been stretched beyond the physiological limit and that some or all of the fibers have been damaged. 
This occurs by a force applied on the joint, such as a sudden twist of the knee, such as when you fall awkwardly or during sports. 
Rarely do children have a sprained knee.


There are 3 types of sprain in the knee:

  • 1st Grade – some fibers (less than 10%) are damaged and / or torn, usually heals naturally
  • 2nd Degree – many fibers are torn, but the ligament is still intact
  • 3rd Degree – when the ligament is completely broken . In this case there is an indication for surgery.

The knee joint is stabilized by four major ligaments, the anterior cruciate ligament, the posterior cruciate ligament, the medial collateral ligament and the lateral collateral ligament. Each ligament prevents excessive movement of the knee. The anterior crusader prevents excessive advancement of the tibia on the femur, the posterior crusade prevents the posterior displacement of the tibia on the femur beyond the natural limit. 
The medial collateral prevents excessive abduction of the tibia and the lateral collateral ligament prevents excessive adduction of the tibia. 
When the knee becomes unstable it deforms in the direction of the injured ligament. There are four specific tests to evaluate each of the four ligaments.


Causes of Sprain in the Knee

Knee sprains can be caused by:

  • A forced knee twist,
  • Move weight while running a race
  • An ugly stop after a jump
  • A  trauma on the outside or inside of the knee.

A trauma to the front of the knee when the knee is bent and the foot is firmly planted on the ground.


Risk Factors for Knee Sprain

These factors increase the chance of developing a sprained knee:

  • Practicing some types of sports, for example soccer, volleyball, skiing and basketball, rarely occurs with a bicycle
  • Bad coordination
  • Loss of balance
  • Insufficient flexibility or strength of muscles and ligaments
  • There is the same chance of a right or left knee sprain
  • Ligament looseness.

The signs and symptoms

The most common symptoms of a sprained knee are: pain, swelling and bruising. If the injury is severe, there may be instability of the joint and the patient feels that the knee gives in. 
The injury can cause crack-like noise, in which case there may be meniscus or ligament injuries. 
Symptoms can be felt immediately or after the accident, but sometimes occur two days later.

The symptoms are as follows:

  • The knee is sore.
  • Swelling, redness, heat or bruising can be found around the knee.
  • The range of motion of the knee is reduced,  the patient feels pain even in movements of hyper-reflection or passive hyperextension .
  • The person is not able to lean over the injured leg, also can not fully stretch or bend the knee when standing
  • If you feel stiffness in the knee joint
  • Usually the patient does not have a fever


Diagnosis of Knee Sprain

The doctor asks the patient about the symptoms and how the injury happened. 
The knee should be monitored during the consultation to assess whether the joint is stable and how severe the pain is. 
The location of the pain can help determine which knee ligament is stretched. 
If knee pain is medial (inner side of the knee) indicates the medial collateral ligament (MCL), this is the most common. 
Pain on the outer side of the knee indicates a stretch of the lateral collateral ligament.


The tests that are performed:

Anterior drawer test for anterior cruciate injury

The anterior drawer test is used to evaluate the anterior cruciate ligament. To perform this test, the patient should lie down in the dorsal position, the knee should be bent to ninety degrees, and the foot should be stabilized in the bed. The examiner should grasp the back of the tibia above the calf muscle, then pull forward with a constant force. If the tibia moves forward more than usual, the test is positive. It is necessary to make the comparison with the healthy knee because some people have a ligament laxity. If the test is positive, it indicates injury to the anterior cruciate ligament .


Rear drawer test for posterior cruciate injury

The posterior drawer test is used to evaluate the posterior cruciate ligament. To perform this test, the patient should be lying supine on the bed, the knees should be bent at 90 degrees and the foot should stand and rest on the bed. You should rely on the frontal area of ​​the tibia above the tuberosity of the tibia and push forward (later passing the tibia) with a constant force. If the posterior tibial displacement is greater than normal, the test is positive. This is indicative of a rupture of the posterior cruciate ligament.

this stress valgus or adduction of the tibia is used to assess the medial collateral ligament. To perform this test, place the knee in a bending of about thirty degrees. Stabilize the knee, hold the ankle and push the tibia outwards. If knee adduction is greater than normal (compared to uninjured leg), the test is positive. This is indicative of a tear of the medial collateral ligament .

The varus stress test or abduction of the tibia is used to see if the lateral collateral ligament is intact. This test is performed with the knee bent at 30 degrees of flexion. Stabilize the knee and ankle. If the adduction is greater than normal, the test is positive. This is indicative of a lateral collateral ligament tear. 
If the ligament is affected by a sprain, the meniscus will also be damaged .

McMurray test, the starting position

One of the main tests for meniscus rupture is the McMurray test. With the patient lying on his back and the lower extremity elevated, the physician bends the knee and then extends the leg while rotating the knee. This test causes meniscus elongation. In the presence of an injury to the meniscus, this movement causes a ticking. The knee must “click” every time the doctor performs the test.

Laboratory Tests

  • The x-ray  is a test that uses radiation to create images of structures inside the body, especially the bones (to evaluate possible fractures).
  • An ultrasound  is not very useful because it can only assess the collateral ligaments.
  • The MRI is a test that uses a magnetic field to print the images inside the body to see if a ligament has completely torn, or if it is worn.
  • Arthroscopy is a surgical procedure that uses a small endoscope to look inside the knee, is the most reliable, but it is an invasive examination.


What to do ? The Treatment for Knee Sprain

1) RICE protocol generally the best treatment in the first two days is to follow the principles of treatment of acute inflammation: protection, rest, ice , compression, elevation. 
This treatment is used to reduce pain , swelling and speed healing.

For pain the patient may take anti-inflammatory tablets (eg, Advil, Voltaren ) or may apply an ointment with arnica or montana montana.

2) Physiotherapy and rehabilitation : as soon as possible, the patient must perform certain exercises to regain the strength, movement and function of the knee. For information about exercises and how to properly promote them to return to full functionality, follow the advice of an experienced physiotherapist. 
Pool rehabilitation is indicated if the patient has difficulty standing upright. 
There are some instruments that help to recover faster, for example ultrasound , laser treatment  and magnetic therapy  are useful if the knee is swollen and to reduce pain.

3) The doctor may recommend a knee brace to reduce pain and have greater stability after a knee sprain. Usually the knee is fairly simple, the price is low. If the patient needs more support, the advanced knee pads are helpful. 
If the doctor thinks that the problem is a simple knee sprain and does not require tests to assess the case better, almost certainly, the injury is not too serious and is probably a degree sprain 1 or 2. 
The third degree tear ( complete rupture) can often be treated in the same way as a first and second degree sprain, even if it takes longer to heal. However, surgery is recommended if the knee tends to become unstable  after performing a rehabilitation exercise program.

What is the recovery time? The prognosis

In case of injury to the meniscus or ligaments, the specific healing time should be considered, especially in the case of surgery .
Generally, in the case of a first-degree sprain, within 7/10 days the pain disappears, while the duration of swelling varies. In some cases, the knee becomes  swollen while in others the joint  (fluid) effusion may remain for a few weeks.

The patient can walk, but should not overdo it so as not to lengthen recovery time.

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