Pain in Back of Knee When Straightening Leg: Causes, Relief and Prevention Methods 

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Photo by Nathan Dumlao on Unsplash

In the human body, the knee is the biggest joint and is prone to injury.  Several people have pain not only in their knees but at the back of the knee, especially when straightening their legs.

Pain behind knee is caused by a lot of conditions, some treatable at home while others require more intense medical procedures to correct. So, what are the causes of the sharp pain behind knee, and how do you find a long-lasting solution that leaves you pain-free?

What is Back of Knee Pain?

Pain at the back of your knee (scientifically known as popliteal fossa) is also identified as posterior knee pain. It ranges from slight pain to intense pain that results in:

  • Difficulty in walking
  • Swelling of the entire knee joint

The sharp pain behind knee is common, and you feel the pain more intensely while straightening or stretching your leg. Many causes of this pain should not be left untreated because you might be suppressing an urgent medical condition.

The most significant step after the identification of pain in back of knee when straightening leg is finding out what caused it. As a result, you get to understand why you are feeling what you’re feeling.

Causes of Back of Knee Pain

Photo by Nathan Dumlao on Unsplash

There is a long list of knee pain causes. These causes range from mild to severe, and if left untreated, your knee might suffer irreversible damage.

Back of knee pain causes include:

1.     Leg Cramps

Most people often experience leg cramps. Cramps in the leg cause a sudden muscle spasm or contraction. The pain from a muscular contraction lasts a few seconds, but in extreme cases, it goes on for about ten minutes. The result is a muscle cramp that may last a few hours.

Causes of leg cramps are:

  • Nerve issues in your legs
  • Dehydration
  • Tetanus infection
  • Toxins in the blood, for example, contamination by mercury
  • Liver disease

Any of these conditions may be the reason why you get leg cramps, consequently leading to back of knee pain when you stretch your leg.  Narrow down to the specific source of pain, and visit a doctor to get it checked and sorted out.

2.     Injury to the Posterior Cruciate Ligament (PCL)

The PCL- Posterior Cruciate Ligament is located at the posterior of your knee. This ligament works to hold your knee in place. It also provides stability by preventing your shinbone from overextending backward.

Injury to the PCL comes about if:

  • You experience trauma to the front of your knee
  • You land heavily on your knees during a fall
  • Twisting of the leg occurs
  • You overextend your knee joint

Following PCL injury, you will have difficulty walking, experience stiffness in your knee, and have instability at the knee joint.

Treatment involves resting your leg, placing ice on the affected area, compression, and elevation. You might end up getting knee braces to stop knee movement or getting physical therapy to correct the injury. Extreme cases call for reconstruction of the ligament through surgery.

3.     Tendinopathy

Ever had a swollen tendon?

Tendinopathy is the medical term that describes swelling of the tendon. This condition comes about by straining the knee joint and repetitively moving the knee. You will experience feelings of tenderness at the back of your knee, sharp pain behind knee, and ultimately the range of motion around your knee reduces.

For treatment, apply the following measures:

  • Rest
  • Physical therapy
  • Flexibility training
  • Anti-inflammatory medicine

However, you should visit a professional to avoid further injury to your tendon.

4.     Arthritis

overhead shot of a man putting a kinesio tape on a woman s injured knee
Photo by cottonbro on

Arthritis comes in many forms. They include; osteoarthritis (breakdown of the cartilage around your joints), rheumatoid arthritis (autoimmune disease affecting joints), lupus (autoimmune disease-causing knee inflammation), and psoriatic arthritis (joint pain and scaly skin).

23% of adults, representing more than 54 million people in the United States, have arthritis. This statistic indicates the number of people suffering from pain in back of knee when straightening leg because arthritis causes your joints to swell, making them feel stiff and painful.

Unfortunately, arthritis has no cure. Some patients have undergone surgery to alleviate symptoms, while others have modified their lifestyle to reduce the pain.

These are some of the treatment measures to alleviate arthritis symptoms:

  • Switch to low-impact exercise, for instance, swimming.
  • Get physical therapy to strengthen the legs.
  • Take prescribed pain medicationsuch as corticosteroids to reduce pain and swelling.
  • Maintain a healthy weight to relieve pressure on the bones and joints.

5.     Baker’s Cyst

Baker’s cyst is a sac full of synovial fluid (knee joint lubricant), forming at the back of the knee. Injury or conditions like arthritis cause overproduction of synovial fluid. As expected, the extra fluid builds up to form a cyst.

Baker’s cyst symptoms are:

  • Pain inside and at the back of your knee
  • Severe swelling behind your knee
  • Stiffness of the knee joint and trouble stretching your leg

Being active worsens these symptoms and can lead to cyst bursting. If this happens, you will experience sharp pain behind knee.

Baker’s cysts can go away without treatment. However, severe cases need injections with steroids and or physical therapy.  

The above are a few examples of conditions that would contribute to back of knee pain. However, numerous other causes lead to knee pain. It is necessary to visit a medical practitioner to get to the root of your pain and follow up with treatment.

Tips for Back of Knee Pain Relief

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If you happen to experience sharp pain behind knee, don’t panic. Observe the symptoms and get medical attention.  In addition to this, it is vital to practice the following:

  • Keep off your leg until your knee heals by minimizing movement and using crutches or a cane.
  • Hold ice on your knee for 20 minutes at a time, daily.
  • Wear a bandage for compression to provide support to the knee. It should not be loose or too tight.
  • Keep the injured knee elevated.
  • Take medicine (non-steroids) to alleviate the pain.

Do not hesitate to see a doctor if the affected leg is red or swollen. The moment you start running a fever and experience warmth in your affected leg, it means your condition is getting worse. Moreover, if you have a history of blood clots, don’t think twice about calling your doctor.

Knee pain relief measures are not enough to cure you of the sharp pain behind knee. Consider visiting a hospital as soon as possible.

How to Prevent Pain in Back of Knee

Pain in back of knee when straightening leg can be a menace because it alters and inhibits movement.

More often than not, you can avoid pain behind the knee. Unless you are suffering from a medical condition, a lifestyle change can reduce and eliminate symptoms. 

You must get checked at the slightest appearance of symptoms. However, to keep knee joint pain at bay, practice the following:

1.     Keep an Active Lifestyle

The more active you are, the better for your entire body. However, based on your body type and size, ensure you do not do any activities that strain or stress your knee joint. Take part in low-impact exercises like swimming and cycling.

2.     Consume a Healthy Diet

Whatever you eat has a significant impact on your joint and bone health. Consumption of well-balanced foods, especially those rich in calcium, will help you avoid pain behind knee.   

3.     Get Regular Health Checkups

If you experience any discomfort around your knee joint or any other joint in your body, visit the doctor. Early diagnosis will curb any knee pain causes that might be building up in your body. Prevention is better than cure in this case.


a woman having a knee pain
Photo by Kindel Media on

It is undeniably uncomfortable to experience pain in back of knee when straightening leg. This pain hinders your movement and generally reduces your quality of life.

So, how do you deal with such pain?

Get to the root cause of your knee pain and get the necessary treatment, as advised by your doctor. There are quick treatments to get you back to health, but some conditions may require surgery. However, it is important to catch it in time before acute knee pain morphs into anything that’s irreversible.

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