What causes pain behind the knee? Related conditions and treatments

Overview: What does pain behind the knee feel like?

The knee is a complex joint in the human body. It has many moving parts, including bones, cartilage, tendons, and ligaments, so there’s potential for pain if any parts move out of place. Pain behind the knee is called posterior knee pain. It can occur for several reasons, such as an injury, chronic condition, or blood clot. Some causes may resolve on their own, while others require treatment. 

Read on to learn more about different causes of pain behind the knee.

What causes pain behind the knee?

Pain behind the knee has many causes. Common causes include injury and arthritis. Other less common causes include a blood clot or tumor. Here are some of the causes of pain behind the knee. 

1. Anterior cruciate ligament or posterior cruciate ligament injury

The anterior cruciate ligament (ACL) is one of the main ligaments of the knee. It runs in the front of the knee and connects the thigh and shin bones. The posterior cruciate ligament (PCL) runs along the back of the knee and connects the thigh and lower leg bones. These ligaments prevent the knee from bending or rotating out of place. 

Injuries to the ACL or PCL occur when the ligament is overstretching or tearing. This can cause symptoms such as loss of range of motion, swelling, and pain around or behind the knee. 

2. Meniscus tear

The meniscus is a C-shaped piece of cartilage between the thigh and shin bone. It plays an important role in knee stability and helps cushion the knee joint. The meniscus can tear during an injury or deterioration over time. A torn meniscus can cause symptoms such as stiffness, swelling, locking of the knee, and pain behind the knee. 

3. Jumper’s knee

Jumper’s knee, also known as patellar tendonitis, is typically a sports-related injury that occurs when there has been overuse of the knee joint, such as frequent jumping on hard surfaces. This causes inflammation in the patellar tendon, a piece of tissue connecting the kneecap to the shin (tibia) bone. Jumper’s knee weakens this tendon, which, if left untreated, can lead to a tear. Symptoms of jumper’s knee include swelling, tenderness, and pain behind the knee. 

4. Baker’s cyst

Baker’s cysts, also known as popliteal cysts, are among the most common causes of knee pain. They occur when fluid-filled cysts form behind the knee. Typically, Baker’s cysts form due to an injury or condition that causes swelling inside the knee joint, including osteoarthritis, rheumatoid arthritis, meniscus tear, and ACL tear. This swelling causes the knee to make excess synovial fluid, accumulating behind the knee and forming a cyst. This can lead to a lump behind the knee, stiffness at the back of the knee, swelling, and pain around or behind the knee. 

5. Arthritis 

Arthritis is inflammation or joint swelling that causes mild to severe pain or stiffness. A joint is where two bones meet. Different types of arthritis can cause pain behind the knee. These can include:

• Osteoarthritis: A degenerative disease where the cartilage in the joint breaks down over time 

• Rheumatoid arthritis: An autoimmune disorder where the immune system attacks the joints, causing pain and inflammation 

• Psoriatic arthritis: An inflammatory disease that affects the joints and where tendons or ligaments attach to bones 

6. Leg cramps

Cramps occur when muscles tighten up. This can happen when the muscle is overworked, if dehydrated, or if nerve problems exist. Cramps can occur in any muscle in the body, but leg cramps, especially in the muscles in the back of the leg, can result in pain behind the knee. 

7. Deep vein thrombosis (DVT)

A DVT is a type of blood clot that forms in a deep vein in the leg. They typically occur in the lower leg, thigh, or pelvis. Symptoms of a DVT include swelling, pain, and redness of the skin. Almost anyone can experience a DVT, but certain factors may increase the risk of having one. Examples include: 

• Injury to a vein

• Slow blood flow

• Increased estrogen intake

• Older age

• Obesity

• Heart disease

• Lung disease

• Cancer 

If any symptoms of a DVT occur, it’s a good idea to see a healthcare provider as soon as possible. 

8. Tumor

Although rare, tumors may grow near the knee, leading to pain behind the knee. These tumors can be benign or malignant. Examples of cancers that may cause pain behind the knee include:

• Liposarcoma

• Osteosarcoma

• Synovial sarcoma

Should I be worried about pain behind the knee?

Pain behind the knee has many possible causes, most related to injuries, such as an ACL tear, meniscus tear, or Jumper’s knee. In rare cases, it can be caused by serious conditions such as a blood clot or tumor. Some pain behind the knee, such as a leg cramp or Baker’s cyst, may resolve independently over time. However, others, such as an ACL tear or DVT, may require medical treatment from a healthcare professional. If persistent, worsening swelling or pain, redness on the skin behind the knee, a fever, or a lump behind the knee exists, see a healthcare provider. Go to the emergency room if there is a history of blood clots or trouble breathing.

How is the cause of pain behind the knee diagnosed?

A doctor will need to perform a physical exam to diagnose pain behind the knee. They will move the knee around to test the range of motion and see which movements cause pain. They will ask about the location of knee pain and any medical history. They may also order imaging tests, such as magnetic resonance imaging (MRI), arthrography, ultrasound, X-ray, and computed tomography (CT) scans. Other tests may include blood tests or synovial fluid analysis, where fluid is drawn from the knee and tested in a laboratory to determine the cause of joint inflammation. 

How long does pain behind the knee last?

Non-severe causes of pain behind the knee, including leg cramps, may resolve on their own over time. If the pain is caused by a chronic condition, such as arthritis, it may come and go for years. Because arthritis is a degenerative disease, pain behind the knee may worsen as time goes on, so it’s important to consult a healthcare provider to discuss pain management options. If a DVT or tumor causes pain behind the knee, it will likely only resolve with medical treatment. 

How to stop pain behind the knee

Pain behind the knee treatment depends on the cause. Some causes of pain behind the knee can be treated at home. For example, pain from a Baker’s cyst or Jumper’s knee may improve with rest, ice, or over-the-counter painkillers, such as Advil (ibuprofen) or Tylenol (acetaminophen). How to treat pain behind the knee may also include surgery for causes such as an ACL, PCL, or meniscus tear. DVTs are treated with blood thinners, such as Coumadin (warfarin), and compression stockings. While tumors may be treated with surgery or chemotherapy. 

Living with pain behind the knee

In some cases, pain behind the knee can last a long time, so it’s important to know how to manage it. Pain behind the knee may be managed with rest, ice, physical therapy, or support, such as knee braces, wraps, or taping. Medications to relieve pain, such as Naprosyn (naproxen) or Motrin (ibuprofen) may also help. However, these medications aren’t right for everyone. Discuss pain management with a doctor if there is pain behind the knee. 

What’s next? Additional resources for people with pain behind the knee

Test and diagnostics

• Baker’s cyst (popliteal cyst), OrthoInfo

Treatments

• ACL tear, Cleveland Clinic

Scientific studies and clinical trials

• Thrombosis of the popliteal vein, Cardiovascular Intervention Radiology

More information on related health conditions

• Osteoarthritis vs. rheumatoid arthritis: which one do I have? SingleCare

• Patellar tendonitis (Jumper’s Knee), Johns Hopkins Medicine