Pain Behind Knee: Common Causes and Treatment

Pain behind the knee suggests muscle strain or tear, or an underlying medical condition.

The body’s biggest joint is the knee, which makes it one of the areas most prone to injury. While pain behind the knee may suggest muscle strain or a ligament tear, it may signal an underlying medical condition. Here are the usual causes of pain behind knee, its symptoms, and appropriate treatment.

Causes & Treatment

Patellar Tendonitis

This condition is also called a jumper’s knee which occurs when the tendon is injured, particularly the tendon that connects the shinbone to the patella (kneecap). Patellar tendonitis is an injury common in basketball or volleyball players. Due to the sudden changes in direction or quick jumps, these movements cause little tears that may cause inflammation and weakening of the tendon.

The pain is felt below the patella and may worsen over time. Some of the other signs associated with this type of injury include the following.

  • Stiffness
  • Difficulty Straightening or Bending the Knee
  • Weakness

Leg Cramps

The tightening of the muscles is indicative of cramps which usually occur in the calves. However, cramps are also felt in the legs, particularly behind the thigh close to the knee. Cramps are often felt during an exercise. Pregnant women are most likely to experience leg cramps as well.

During a cramp, an individual will feel a sudden contraction of the muscles or a muscle spasm. The pain persists from as short as a few seconds to as long as ten minutes. Once the cramp subsides, the muscles feel sore which extends for several hours. Other causes that lead to leg cramps include the following.

  1. Dehydration
  2. Toxins in the Blood
  3. Nerve Problems in the Legs
  4. Liver Disease
  5. Infections

Baker’s Cyst

When a sac filled with fluid forms behind the knee, this is a condition known as baker’s cyst. The fluid contained in the pouch is a synovial fluid which generally acts as a lubricant for the knee joint. However, in cases of a knee injury or arthritis, there is an overproduction of synovial fluid which results in the formation of a cyst. Symptoms of such conditions include the following.

  1. Difficulty Flexing the Knee
  2. Knee Stiffness
  3. Swelling Behind the Knee
  4. Pain Behind and in the Knee

Symptoms worsen when an individual is active, and once the cyst erupts, the pain is characterized as sharp and stabbing. While small cysts usually subside, large and painful cysts require drainage, steroid injections, or physical therapy. Moreover, diagnosing the underlying disorder causing the formation of the cyst is vital before treatment is given.

Hamstring Injury

Also known as biceps femoris tendonitis, a hamstring injury involves three muscles that are located at the back of the thigh. These muscles include the following.

  • Biceps Femoris Muscle
  • Semimembranosus Muscle
  • Semitendinosus Muscle

The muscles mentioned above aid in knee movement, particularly bending. If one of the muscles are injured, then it is called a hamstring strain or a pulled hamstring. It usually occurs if the muscle is overstretched and may result in a tear. This condition takes months before an individual fully recovers. Apart from the pain felt behind the knee, other associated symptoms include the following.

  • Bruising
  • Swelling
  • Weakness Felt Behind the Back of Leg

Calf Strain

A calf strain, also known as gastrocnemius tendonitis, occurs when there is a tear or stress to the gastrocnemius muscle. This injury often occurs when an individual performs a sudden change of movement. In addition to the pain felt at the back of the leg, symptoms of a calf strain include the following.

  • Difficulty Standing on Tiptoes
  • Bruising, Swelling, and Pain in the Calf
  • Deep Vein Thrombosis (DVT)

Blood clots that form in the deep vein located in the leg are known as deep vein thrombosis. Pain is often felt in the leg with the blood clot, specifically when an individual is standing up. Symptoms associated with a DVT include the following.

  • Red and Warm Skin on Affected Leg
  • Swollen Leg

A DVT should be treated immediately because the clot may break free. Once a blood clot breaks loose from the vein, it may travel to the lungs and clog an artery. This may result in pulmonary embolism, which is fatal.

Treatment for DVT includes blood thinners which are medications that prevent new clots from forming and prevent the existing clots from growing bigger. For bigger and more dangerous clots, thrombolytics are prescribed which help break down clumps faster.

Meniscus Tear

The wedge-shaped cartilage that stabilizes and cushions the knee joint is called the meniscus. There are two menisci for both knees. As an individual age, the meniscus degenerates and weakens; thus, it is most likely to tear with any activity or movement that requires twisting.

A meniscus tear is characterized by a “popping” sound. While the injury does not hurt initially, the pain is felt after a few days. Symptoms related to this condition include the following.

  • Giving Way or Locking of the Knee
  • Weakness
  • Swelling
  • Stiffness in the Knee

Resting, applying ice, and elevating the affected knee ease the symptoms and facilitate healing. However, if the injury persists despite home remedies, then surgery is needed.

Anterior Cruciate Ligament Injury

A group of tissue that runs through the front of the knee joint is called the anterior cruciate ligament (ACL). These ligaments connect the shinbone to the thighbone. Furthermore, these ligaments provide and stabilize knee movements. The rapid change in movements may cause an ACL injury, such as suddenly changing direction when running. An ACL tear may also occur if an individual land wrongly after a jump.

When an ACL injury occurs, there is a “popping” sound and is followed by immediate pain. After a while, the knee swells and an individual may find it difficult to move the knee. Physical therapy and rest ease the pain and facilitate healing. However, for a torn ACL, surgery is recommended.

Posterior Cruciate Ligament Injury

Another group of tissue that connects the shinbone to the thighbone and offers knee support is the posterior cruciate ligament. However, unlike the ACL, the PCL is not as likely to suffer an injury. An individual may injure the PCL if the front of the knee receives a hard blow, much like in a car accident. Missing a step while walking or twisting the knee may also lead to a PCL injury.

Overstretching the ligament can also cause a strain. On the other hand, excessive stretching accompanied by pressure may cause a ligament tear. A PCL injury is associated with the following symptoms.

  • Pain
  • A weakness of the Knee
  • Trouble Walking
  • Stiffness
  • Swelling of the Knee


The rubbery material that serves as a cushion between bones is called cartilage. It prevents scraping between the bones, especially during movement. When the cartilage inside the joint degenerates or breaks down, it leads to a condition known as chondromalacia. Injury to the knee, overuse of the knee, arthritis, or gradual wear associated with age are common causes of chondromalacia.

With the cartilage gone, bones in the knee scrape against one another resulting in pain. The primary sign associated with this injury is a dull ache felt behind the patella. Pain worsens when an individual has been sitting for a while or when climbing the stairs. Other signs associated with chondromalacia include the following.

  • Grinding or Cracking Feeling When Straightening or Bending the Knee
  • Buckling or Weakness of the Knee
  • Difficulty Moving the Knee Past a Specific Point

For alleviating pain, physical therapy, over-the-counter pain medications, and ice may help. However, with the cartilage damaged and gone, surgery is the only option to treat chondromalacia.


This is a degenerative disorder where the cartilage in the knee gradually wears down. There are various types of arthritis affecting the knee. These include the following.

  • Psoriatic Arthritis: results in scaly patches on the skin and joint pain.
  • Lupus: which is an autoimmune disorder leading to inflammation of joints and the knee.
  • Rheumatoid Arthritis: is another autoimmune disorder resulting in the immune system attacking the joints.
  • Osteoarthritis: which is the most prevalent type of arthritis. It is the gradual collapse of the cartilage as an individual age.

Pain associated with arthritis is treated with pain medications, injections, and physical therapy. On the other hand, rheumatoid arthritis is treated with disease-modifying medications that reduce inflammation and inhibit the immune system response in the body.

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