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Knee is one of the largest joints of the body. Connecting the upper and lower legs, it moves like a hinge providing back and forth, and to some extent, pivoting and twisting motion. 

However, it is quite susceptible to injury. Sudden jerk, accidents or falling traumatizes the supporting structure of the knee joint, leading to pain, swelling and temporary or long term loss of movement. 

Knee sprain is a type of knee injury that occurs when the ligaments or supporting structures in the knee joint gets torn or overstretched.

Human knee is composed of four ligaments that connect the bones on either side of the knee to the joint. These include:

  • Anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL): Anterior cruciate ligament and posterior cruciate ligaments stabilize the knee joint from front and back respectively in an "X” shaped pattern. Stopping suddenly, over-straightening or direct injury to the knee from the front could injure these ligaments. ACL and PCL knee sprain are often witnessed by players of football, basketball, soccer, rugby, wrestling, gymnastics and skiing.
  • Medial collateral ligament (MCL) and Lateral collateral ligament (LCL): MCL cushions the knee from medial or inner side and LCL supports the knee from the lateral or outer side. When trauma hits from the outer side, MCL injury can occur, alternatively, if the trauma hits from the inner side of the knee, LCL injury might occur - although it is rarely encountered.

According to Harvard Medical School, a sprained joint severely restricts movements. However, if the ligament is severely torn it may lead to loosening of the joint, which is not able to support and stabilise the attached bones. Bones attached to such joints then start to extend beyond their normal range of motion making it difficult to perform everyday tasks. 

  1. Types of Knee Sprain
  2. Symptoms of Knee Sprain
  3. Causes of Knee Sprain
  4. Diagnosis for Knee Sprain
  5. Treatment of Knee Sprain
  6. Prognosis of Knee Sprain
  7. Prevention of Knee Sprain
Doctors for Knee Sprain

Depending upon the severity of ligament injury, knee sprain is divided into three types:

  • Grade I (mild): This type of sprain occurs when an injury only results in microscopic tearing of the ligament. Mild knee sprain does not alter the weight-bearing capacity of the knee joint.
  • Grade II (moderate): A grade II sprain involves partial tearing of the knee ligament. It alters the weight-bearing capacity of the knee joint to a certain extent, the person is unable to walk or stand for a longer period of time.
  • Grade III (severe): This is kind of sprain is caused due to complete separation of the ligament from the bone. Severe knee sprain makes the person unable to walk or even stand properly.

Symptoms of a sprained knee would vary depending on the injured ligaments. In other words, each ligament has its own characteristic symptoms. The specific symptoms help a doctor locate the injury and give treatment accordingly. 

Symptoms of an ACL Sprain 

  • Popping sound of the knee every time you move the joint
  • Knee joint swells like a bump just in few hours
  • Severe knee pain on movement
  • Discolouration (blackish to bluish) of the overlying skin of the knee
  • The person often becomes unstable. Upon standing, he or she might feel that the knee will distort or twist

Symptoms of PCL Sprain

  • Usually results in mild to moderate swelling of the knee
  • A person may or may not become unstable, although standing or walking becomes demanding
  • Constant feeling of pain at the backside of joint. Pain aggravates on bending the knee

Symptoms of MCL and LCL Sprain

  • In both cases, pain and swelling is present  though in MCL this swelling is localised on the inside of the knee and in LCL it is mostly present on the outside of the knee
  • In case of MCL the knee gives out in the outside direction, however, in case of LCL, the knee joint gives out in the inside direction

High impact accidents that twist or injure the knee are one of the most common causes of knee sprain. Knee sprain can occur due to: 

  • Movement of a knee joint beyond its natural limit: For example, if a person flexes (bends) and extends (outstretch), twists or rotates knee joint too much, it can cause knee sprain.
  • Sudden, forceful strain or pull on knee ligament - separating the ligament into two: For example, if a person suddenly stops after a fast pace run, it creates a sudden tension in the muscle leading to tearing and separation of a knee ligament into two, often accompanied by a popping sound.
  • Forceful impact directly on the joint or on the bones in closure: For example when a player hits against the ground or another player against the knee joint.

Few sports are relatively risky for the knee and are associated with most cases of sprains such as football, basketball, soccer, rugby, wrestling, gymnastics or skiing. Footballers have to take cutting moves and sharp turns to defend and goal - these are detrimental for knee ligament health. 

To make a correct diagnosis, a doctor uses few tools. These include:

Patient history: Your doctor will want to know the whole story behind the knee injury, right from the activity which caused injury to the time taken by the knee to show a full-blown swelling. 

Clinical examination: After taking a detailed history of a sprained knee, the doctor will examine your knee. He will look for pain on touching, swelling, bulge, deformity or discolouration of the knee joint. Range of motion is also evaluated in most of the patients.

To confirm a ligament injury and evaluate the extent of the injury he/she may ask to run a few mandatory tests such as:

  • Knee X-ray: It is done to elicit deformity in the ligament and bone attachment site or bone fracture.
  • Magnetic resonance imaging (MRI): An MRI helps evaluate tiny details of the soft tissue changes in the knee joint.
  • CT Scan: It is done to get a more precise evaluation of bone injuries if they appear in an X-ray.
  • Arthroscopy: Arthroscopy is both a diagnostic as well as a therapeutic test. It involves the insertion of an arthroscope - a type of endoscope - inside the joint through a minimally invasive procedure. The instrument has a tiny camera attached to it which takes pictures of the inside of the joint helping find the exact location of the injury and assess the extent of the damage.

Treatment of sprained knee varies according to the severity of the ligament injury, however, the basic treatment remains the same for every case.

It incorporates four steps:

  • Rest: Give adequate rest to the injured joint to avoid further complications and pain
  • Ice pack: Cold compression helps in alleviating pain. Apply an ice pack for at least four times a day for 20 minutes
  • Compression bandage: Wrap the joint with a compression bandage to support and seize the movement of joint, thereby reducing swelling 
  • Elevate: Elevate the knee above heart level, if feasible, to reduce swelling in the joint. 

To relieve pain and discomfort, your doctor may prescribe painkillers such as ibuprofen.

In most cases, the above-mentioned modalities help in managing mild to moderate case of the sprained knee when accompanied by a rehabilitation programme to strengthen the muscles attached to the knee joint.

However, for grade III (severe knee sprain) or in case of multiple ligament injuries, multidirectional management is required.

  • In case of grade III ACL or PCL sprain, the injured ligament is repaired through joint reconstruction surgery, usually through arthroscopy. Repairing can be done by using or adjusting the torn ligament itself - autograft, or by using someone else's tissue - allograft.
  • In case of grade III MCL sprain, the injured ligament is successfully managed by RICE, painkillers rehabilitation programme. Rarely, surgery remains the only choice to fix the damage.
  • In most of the cases of grade III LCL sprain, surgery is the recommended option to repair ligament damage.

(Read more: Anterior Cruciate Ligament (ACL) Reconstruction Surgery)

Rehabilitation of joint and muscles: Knee sprain is followed by a period of immobilization and loss of muscle strength, which makes the joint weak, inelastic or firm. The longer the duration of immobilisation, the longer will it take to achieve normal range of motion. And without muscle strengthening, the knee joint is unable to perform any physical activity. 

Early movement of joint helps in getting an optimum range of motion easily along with strengthening the attached muscles to the knee joint. 

During the initial phase of recovery, a person walks with crutches and is asked to slowly put his or her weight to the knee joint. This is usually followed by stretching and heavy exercises with elastic bands and weight machines.

The healing time of sprained knee depends on the injured ligament, cause of injury, the severity of injury and management techniques used. Usually, mild to moderate MCL or LCL sprain takes nearly 2 to 4 weeks to heal, however, any other type or grade of knee sprain takes 4 to 12 months to achieve normal function.

Almost 90% of patients with ACL injury and 80% of patients with PCL injury live fully functional life after the right treatment and rehabilitation.

On the other hand, most of the MCL and LCL sprain show excellent prognosis.

Knee sprain can be prevented, if you keep a few things in mind and follow some precautions, such as:

  • Always warm-up before taking part in any sports or physical activity. Stretching should be an important part of your exercise or sports regime 
  • Exercise regularly to strengthen muscles attached to knee or leg muscles
  • Don’t increase or decrease the intensity of your workout routine suddenly, instead, follow a gradual process
  • Wear comfortable clothes to avoid any restricted movement of the knee
  • If you are an athlete or soccer player, talk to your trainer or sports doctor for recommended shoe cleats in order to reduce risk to knee ligaments
Dr. Narendran Dasaraju

Dr. Narendran Dasaraju

8 Years of Experience

Dr. Ashwani Maichand

Dr. Ashwani Maichand

32 Years of Experience

Dr. Gaurav Gupta

Dr. Gaurav Gupta

8 Years of Experience

Dr. VP Raman

Dr. VP Raman

30 Years of Experience


  1. Health Harvard Publishing, Updated: April 3, 2019. Harvard Medical School [Internet]. Sprain (Overview). Harvard University, Cambridge, Massachusetts.
  2. Health Harvard Publishing. Harvard Medical School [Internet]. Knee Sprain. Harvard University, Cambridge, Massachusetts.
  3. Parag Sancheti, Mohammed Razi, E B S Ramanathan and Patrick Yung. Injuries around the knee – Symposium. British Journal of Sports Medicine; Volume 44, Issue Suppl 1
  4. Aaron M. Gray and William L. Buford. Incidence of Patients With Knee Strain and Sprain Occurring at Sports or Recreation Venues and Presenting to United States Emergency Departments . J Athl Train. 2015 Nov; 50(11): 1190–1198. PMID: 26523662
  5. Johns Hopkins Medicine [Internet]. The Johns Hopkins University, The Johns Hopkins Hospital, and Johns Hopkins Health System; Knee Ligament Repair
  6. University of California; Berkeley. Knee Sprains and Strains. [internet]
  7. American Academy of Orthopaedic Surgeons [Internet] Rosemont, Illinois, United States; ACL Injury: Does It Require Surgery?.
  8. American Academy of Orthopaedic Surgeons [Internet] Rosemont, Illinois, United States; Combined Knee Ligament Injuries.

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