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Pain in Back of Knee: Symptoms, Causes & Treatments

When you move, sit, stand, or run, your body relies heavily on the knee joint. Your knee not only contains the largest joint in your body, but it is also one of the most injury-prone areas.

The knee joint is made up of bones that can easily dislocate or fracture. It also has ligaments, tendons, and cartilage that can tear or strain when put under stress.

Pain in the back of the knee when straightening the leg can occur for a variety of reasons. Some causes of back or knee pain may necessitate medical attention, while the majority do not.

Does experiencing pain in back of your knee cause concern?

 Not all back of the knee pain when straightening the leg necessitates medical attention. Some injuries that cause knee pain eventually heal on their own if you rest and care for your knee.

Some knee injuries, however, may necessitate medical intervention, such as surgery.

In other cases, you may experience pain in the back of the knee when straightening the leg as a result of conditions such as arthritis, which gradually deteriorates the knee over time.

This article will discuss various conditions that can cause pain in the back of your knee. Furthermore, the paper will assist you in understanding what to expect if you experience any of these conditions.

Jumper's Knee

The condition Jumper's knee is caused by a tendon injury in the knee. The tendon is the cord that runs from the shinbone to the patella (kneecap).

Jumper's knee, also known as patellar tendonitis, can occur when changing the direction of your movement or jumping. When playing basketball or volleyball, for example, you can easily sustain a Jumper's knee injury.

When the tendon is injured, it tears into tiny pieces, causing swelling and weakness in the knee joint area.

If you have Jumper's knee, you will most likely experience pain below your kneecap, which will worsen over time.

A jumper's knee can also cause pain in the back of the knee when straightening the leg, stiffness, difficulty straightening and bending the knee, and weakness.

Baker's Cyst

Baker's cysts are fluid-filled sacs that can form behind your knee. The synovial fluid contained within the sac normally lubricates the knee joint, allowing for flexibility and ease of movement.

However, in some cases, such as when you have a knee injury or arthritis, your knee can produce an abnormally large amount of synovial fluid.

When there is an excess of synovial fluid produced, it can accumulate around the knee joint and form a cyst.

The following are some of the most common symptoms of a baker's cyst:

  • Pain in back of knee when straightening leg
  • Experiencing sharp pain behind and in your knee
  • Development of swells behind the knee
  • A feeling of stiffness, causing trouble in flexing the knee

If you are physically active, especially athletes and sportspeople, your symptoms of a baker's cyst may worsen.

In some cases, the cyst will burst, causing a sharp pain behind your knee.
Fortunately, most baker's cyst symptoms go away on their own if you rest and take care of your knee.

Physical therapy, cyst drain, or steroid injections are all options for treating a large cyst that is causing pain.

Notably, it is critical to consult a medical specialist to determine the underlying cause of cysts such as arthritis. If such causes are not treated promptly, they can lead to additional complications.

Meniscus Tear

The meniscus is wedge-shaped cartilage found in the knee joint that helps cushion and stabilizes the knee joint. Each of a human's two knee joints contains two menisci (each on either side of your knee).

When you twist your knee or squat (which is common among athletes and sportspeople), you are likely to injure one or more of your menisci.

With age, the menisci also weaken and degenerate. As a result, older people are more likely to develop meniscus tears with even minor twisting movements.

When a meniscus tear occurs, people may hear a popping sound, and the injury may not hurt at first.

However, as you continue walking on your feet for a few days, the intensity of the pain in the back of the knee when straightening the leg may increase. As the pain worsens, the knee may swell.

Some of the most common symptoms of a meniscus tear are as follows:

  • Weakness
  • Pain in back of knee when straightening leg
  • Swelling
  • Stiffness in the back of the knee
  • Giving away or locking of your knee

When you have a meniscus tear, you can relieve the pain and other symptoms by applying ice, resting, or elevating the knee. Rest, icing, and elevation can also help your knee heal faster.

When the tear is too complex, the doctor may recommend a surgical procedure to treat the symptoms on the knee.


Injuries, particularly fatal accidents, can cause the cartilage inside your knee joint to deteriorate. Chondromalacia refers to the breakdown of the cartilage piece.

Cartilage, the rubbery material attached to bones and joints, cushions your bones so they don't scrape against each other when you move.

Chondromalacia can be caused by conditions such as arthritis, overuse of the knee, gradual wear-off, and knee injuries.

In most cases, cartilage breakdown occurs beneath your kneecap, also known as the patella.

When the cartilage in your knees wears down, it causes pain from the bones scraping against each other.

An ache in the back of your kneecap is one of the primary symptoms of Chondromalacia.

Going up the stairs or sitting for an extended period of time may cause you to feel more pain.

Other common Chondromalacia symptoms include the following:

  • Pain in back of knee when straightening leg
  • Buckling or weakness of the knee
  • Griding or cracking sounds at the back of your knee when you straighten or bend your leg.
  • Experiencing challenges/troubles when you try to move your knee behold a particular point.

Chondromalacia pain can be relieved with ice, physical therapy, and over-the-counter pain relievers.

The doctor, on the other hand, can only replace the already damaged cartilage through a surgical procedure. Otherwise, the pain will continue because the Chondromalacia conditions do not resolve.

Deep Vein Thrombosis (DVT)

When you are injured, blood can clot in a vein deep within your knee, resulting in Deep Vein Thrombosis (DVT).

When the DVT condition strikes, your leg suffers from pain, particularly at the back of the knee.

The pain worsens when you stand up, move, twist, squat, or run.

To determine if you have a DVT, look for the following symptoms:

  • Having a swollen leg or knee
  • Development of red skin around the knee
  • Feeling of warmth in the knee joint area
  • Pain in back of knee when straightening leg

If you have any symptoms or signs of DVT, seek medical attention as soon as possible.

A clot in a deep vein inside your leg can become dislodged and travel to your heart or lungs. If a clot becomes lodged inside a pulmonary artery, you can develop pulmonary embolism (PE). The PE condition can endanger a person's life.

Blood thinners are used by doctors to treat DVT. Thinners keep blood from clotting further inside the deep vein and keep the already formed clot from growing in size.

The human body eventually breaks up the formed clot after being given thinners, relieving you of DVT.

Other drugs are available to help doctors break up larger clots more quickly in order to get the patient out of danger.


Arthritis is a knee joint disease that causes the cartilage in the joint to degenerate over time. The cushioning and support cartilages provide to the joint deteriorate as they age.

As a result, you begin to experience pain in the back of your knee when straightening your leg, among other symptoms. The following are some of the most common types of arthritis that can affect your knee joint:

  • Lupus is an autoimmune arthritis disease that causes joint inflammation, particularly in the knee.
  • Rheumatoid arthritis is another autoimmune arthritis disease that causes your immune system to mistakenly attack your knee joint.
  • The most common type of arthritis affecting knee joints is osteoarthritis. As you get older, the disease causes a gradual breakdown of the cartilage in your knee joints.
  • Psoriatic arthritis is a type of arthritis that causes severe joint pain as well as scaly patches on the skin around the knee.

Injections, pain relievers, and exercise can help patients manage their arthritis. Some types of arthritis, such as Rheumatoid, can, however, be treated with disease-modifying medication.

The drugs help to reduce inflammation by dampening your immune system's responses.

Depending on the complexities of the situation, your medical officer may recommend other treatment methods for arthritis diseases, such as surgery.

Posterior Cruciate Ligament (PCL) Injury

The posterior cruciate ligament (PCL) works with the anterior cruciate ligament (ACL) to connect the thighbone to the shinbone in humans. More specifically, the two partner ligaments provide support to the knees.

Despite being partners, the ACL is more likely than the PLC to be injured.

The PCL can be injured in situations such as a hard hit to the front of the knee, such as in a car accident.

However, twisting the knee can injure the PCL in some cases. If you miss a step while walking, you can also injure your PCL.

When patients stretch their PCL too far, especially during athletics and sporting activities, they may experience strain.

Under enough pressure, the PCL can tear into parts in rare cases.

The following are the symptoms of a PCL injury:

  • Pain in back of knee when straightening leg
  • Stiffness
  • Experiencing troubles while walking
  • Swelling at the knee joint region
  • Increasing weaknesses of the knee joint

Rest, icing, and elevating the knee can all help to speed up healing from a PCL injury.

When the PCL injury is too complex, particularly if you have injured more than one ligament in the knee, the doctor may recommend surgery.

Furthermore, if you have symptoms of instability or cartilage damage, surgical procedures may be an option.

Gastrocnemius Tendonitis (Calf Strain)

Another cause of pain in the back of the knee when straightening the leg is Gastrocnemius tendonitis, also known as Calf strain.

The soleus and gastrocnemius muscles combine to form the human calf, which is located at the back of the leg—the two muscles that make up the calf aid in knee flexion and toe pointing.

Your calf, or the back of your lower leg, is made up of the gastrocnemius and soleus muscles. These muscles assist you in bending your knees and pointing your toes.

When participating in any sporting or athletic activity that requires you to suddenly change from a standing posture to a run, such as squash or tennis, the gastrocnemius muscle can tear or strain.

If you strain the gastrocnemius muscle, you may experience sharp pain behind the knee. If the injury is severe, the pain may spread to other areas of the back of your leg.

The following are the primary symptoms of a calf strain:

  • Pain in back of knee when straightening leg
  • Bruises in your calf
  • Experiencing trouble when standing on the tiptoes
  • Intense pain as well as swelling in the calf area

Depending on the severity of the sprain or tear, the pain may go away with time. Icing, elevating, and resting the injured area can all help to speed up healing. 

Leg Cramps

A leg cramp is a condition in which muscles tighten as a result of an injury. Muscles in the calf region are more susceptible to cramping than other leg muscles.

Under pressure, muscles located beneath the thigh and close to the knee can also cramp.

Leg cramps are more common in pregnant women and athletes.

Other common causes of leg cramps are as follows:

  • Continued dehydration
  • Infections and diseases like tetanus and liver diseases
  • Problems of the nerves in the legs
  • Having toxins such as mercury and lead in your blood

Symptoms of leg cramps include:

  • Contraction or spasm of the muscle
  • Sharp pain behind the knee lasting for up to 10 minutes
  • Experience muscle soreness for a few hours
  • Pain in back of knee when straightening leg

When dehydrated, pregnant, or suffering from diseases such as tetanus or liver disease, you should avoid walking long distances.

When you are about to exercise or participate in strenuous activity, drink more water.

Biceps Femoris Tendonitis

Biceps femoris tendonitis, also known as a hamstring injury, is another common cause of pain in the back of the knee when straightening the leg.

The hamstring is made up of three muscles that run down the back of the thigh. These three muscles are as follows:

  1. Biceps femoris muscle
  2. Semimembranosus muscle
  3. Semitendinosus muscle

The three hamstring muscles allow you to bend your knee.

A hamstring strain or a pulled hamstring occurs when one or more of these three muscles sustains an injury.

Hamstring strain usually occurs when your hamstring muscles stretch too far beyond a certain point.

If the muscle completely tears, it can take several months to heal. When you injure the hamstring muscle, you will experience a sudden sharp pain behind the knee.

If you injure the biceps femoris, you will develop biceps femoris tendinopathy, which will cause pain in the back of your knee.

Other signs of biceps femoris tendonitis include the following: 

  • Pain in back of knee when straightening leg
  • Swelling at the knee region and behind the leg
  • Bruises around the injured region
  • Weakness and stiffness in the back of the leg

Hamstring injuries are common among athletes participating in fast sports and video games such as basketball, soccer, track, and tennis.

To avoid hamstring injuries, sports specialists, physical therapists, and other specialists recommend stretching muscles before engaging in athletic activities. 

Anterior Cruciate Ligament (ACL) Injury

The anterior cruciate ligament (ACL), a partner of the posterior cruciate ligament (PCL), is a band of tissues that runs through the front of the knee joint.

The ACL, along with the PCL, connects the shinbone to the thighbone. The tissue cushions, supports, and stabilizes the knee's movement.

If you come to a sudden stop, change direction, or slow down suddenly while sprinting, you are more likely to injure your ACL.

People also choose ACL tears or strains when they land a jump incorrectly or are hit in a player contact sport, such as football.

When an injury occurs, some patients hear a pop sound. The occurrence of an ACL injury is followed by a painful and swollen knee.

A complex ACL injury causes knee pain, difficulty moving the leg, and sharp pain behind the knee when walking.

This article suggests that you rest your knee and seek physical therapy to allow for the steady healing of an ACL injury.

In more severe cases, the ligament can completely tear, necessitating surgical procedures to repair the damage.

Instances That You May Need to See a Doctor

Most injuries that cause pain in the back of the knee when straightening the leg can be treated. However, it is critical not to put your knee in jeopardy, especially if you have any of the following symptoms:

  • If your leg is unusually swollen
  • The pain is intensifying even after trying several pain-relieving techniques
  • You start running a fever
  • If you the injured area turning red
  • Your medical record shows a history of blood clotting
  • Trouble when breathing
  • Sudden warmth and swelling of your leg
  • Increasing and unbearable pain
  • Changes in the shape and appearance of the knee joint
  • If you notice that your leg unusually can't hold the weight of your body

Your doctor can determine the underlying cause of pain in the back of the knee when straightening the leg and provide effective treatment, relief, and healing techniques. 

Tips to Help You Attain Quick Relief

Use the following tips to get quick relief if you have pain in the back of your knee when straightening your leg:

  • Let your knee rest until it heals
  • Wear a bandage at the point of injury to support your knee. Ensure the dressing is not too tight to prevent blood circulation
  • Use a cane or crutches to relieve the knee some burden of your weight
  • Elevate the knee using one or more pillows
  • Icing your injured leg severally a day for about 20 minutes each round
  • Get over-the-counter medications such as nonsteroidal anti-inflammatory drugs for pain-relieving.


We are pleased that this article has provided you with information about pain behind the knee that you were unaware of.

When straightening your leg, you may experience pain in the back of your knee due to normal twisting or turning of the knee joint. However, if you experience sudden sharp pain, unusual swelling, your skin begins to turn reddish, or the appearance of your knee changes, you should seek medical attention.

Long-term aching at the back of the knee, especially if accompanied by arthritis symptoms, should be taken more seriously.


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