Pain behind or in the back of the knee is fairly common. The pain can be sharp and severe or mild and dull. In some of you, the pain in the back of the knee started after a sports injury. For others pain behind the knee began after bending down, or even occurred at rest. Pain in the back of the knee can occur with or without swelling or a feeling of fullness. Most causes of pain in the back of your knee are straightforward and others might need urgent attention. In this post, we will review some of the most common causes of pain in this region of your knee.
Behind our knee, we have the calf and hamstring muscles, the popliteal artery and the nerve to the leg. We also have bones and cartilage in the back of our knee as well a portion of the medial and lateral meniscus. Many of these structures are capable of causing pain in the back of your knee. Because of the complicated anatomy a good examination, xrays and perhaps an MRI will be useful in determining which structure is the cause of your pain. Once the cause of the pain is determined, the best possible treatment can be recommended.
Common causes of pain in the back of the knee:
- Swelling due to a Bakers cyst: A Bakers cyst is a common cause of swelling and pain behind your knee.
- Root tears of the meniscus
- Hamstring injury: usually occur higher in the thigh.
- Tears of the posterior horn of the medial meniscus
- Deep vein thrombosis — or a blood clot in the back of your leg
- Overuse syndromes in runners and athletes.- usually causing a grinding or snapping in the back of the knee.
- Osteoarthritis: probably the most common cause of pain. Often due to swelling and inflammation.
DVT: Deep vein thrombosis can cause pain in the back of your knee and calf
Deep vein thrombosis (DVT) can cause pain in the back of your knee. Usually the pain will also occur in the back of your calf or your thigh. While not impossible, the pain is rarely isolated to just the back of your knee. Most people with a DVT will also have swelling in their calf or leg. People who are risk for DVT include people with cancer, other chronic diseases, and those of you who recently traveled and sat still for a while (recovering from illness, injury or surgery). People who recently had surgery, regardless of how short the surgery was are at an increased risk for a DVT. If your calf is tender and swollen and the back of your knee hurts you need to see your doctor urgently or go to an emergency room.
Meniscus tears and pain behind your knee
Root tears of the meniscus are very common. The root of a meniscus is where the meniscus attaches to the shin bone or tibia. Much like a tree roots into the ground, the meniscus has a firm deep attachment to your bones as well. Sadly, over the years, these attachment points can weaken. The most common story is that you bent down or knelt down and felt a pop in the back of the knee. Later that day or two days later your knee is swollen and the pain is very severe. The root of the meniscus tore in this situation because it had degenerated from decades of activity. The pain from root tears usually subsides over the next few weeks. By the time you see a doctor and they order an MRI the pain is usually starting to improve. This post below goes into far more detail about root tears as the cause of pain in the back of your knee. The meniscus is a shock absorber. When the root of the meniscus tears it no longer works as a shock absorber. Therefore, following a root tear you may develop stress fractures or stress reactions. That is why the pain worsens a fews days after you felt the pop. This post goes into detail about how root tears cause these stress fractures and how they can be treated. This is usually a situation where you have very severe pain and require crutches for support. As I have talked about elsewhere, root tears will often cause a significant stress reaction or stress fracture. When root tears lead to a stress reaction the pain will often move from behind the knee to the inner side.
On some occasions we need to consider surgery to repair these root tears… but this is not usually necessary.
Pain behind the knee in runners
Overuse syndromes are very common in runners. The most common cause of pain behind the knee in runners is due to a hamstring strain. Shortening your stride and increasing your cadence, as well as avoiding hills for a few weeks should enable a painful hamstring to settle down.
A less common cause of pain in the back of the knee in a runner is bursitis that occurs where a few tendons cross over each other. The pain is usually associated with a grinding or snapping sensation as you squat down. This is usually related to the hamstring tendons being irritated. Some believe it might be due to one of your calf muscles rubbing along one of the hamstring muscles in the back of the knee. This has also occurred in some patients after a hamstring ACL reconstruction. Surgical treatment is rarely necessary for this situation. In runners, the pain in the back of the knee will usually subside with a change in their running style (shorter stride, higher cadence) and workout schedule. Physical therapy may be effective as well.
Bakers cyst and pain in the back of the knee
A Bakers cysts, or a fluid filled pocket in the back of the knee is a common cause of painful swelling. When the cysts are small they do not create much discomfort. As the cyst grows larger it puts pressure on the surrounding muscles, blood vessels and nerves and will cause discomfort. Most people with a Bakers Cyst will also have osteoarthritis. In most instances treatments to diminish the pain and swelling of arthritis will help diminish the pain and swelling from the cyst. In the majority of cases these cysts are not dangerous. An ultrasound can usually tell if you have a simple cyst versus something more complex that warrants further evaluation. If the Bakers cysts is very large, then one treatment alternative is to have the fluid drained. While that will result in relief of pain, the fluid might come back again.
Osteoarthritis and pain in the back of the knee
Osteoarthritis is very common cause of pain behind your knee. Some of you might also note that you have a loss of motion and can not fully bend the knee. The pain from arthritis can be due to inflammation. That irritates the lining or inside of the knee joint and makes the joint stiff and painful. Many people with osteoarthritis and pain in the back of the knee will note that the pain can refer up the back of the thigh, or down into the calf. Many of you with arthritic knee pain will benefit from wearing a compression sleeve or brace. You will also find that gentle stretching, an ice pack, or a warm compress can help calm arthritic pain. If the pain does not improve over a few days consider seeing your doctor to be sure of the reason why the back of your knee hurts.
Hamstring injuries are a very common injury in sports. Hamstring injuries usually occur higher and in the back of the thigh near the pelvis. We discuss hamstring injuries and some of the difficulties in managing them here and here. It is possible to injure the hamstring near the back of your knee. Usually the pain will occur about 4-6 inches above your knee. The pain from a lower hamstring injury will be most severe immediately after the injury and start to improve within a week. It is important to start stretching the hamstrings as soon as you tolerate it to prevent stiffness.
Pain in the back of the knee is common, but can be non specific. There are many reasons why the back of your knee might be bothering you. I hope you find this short guide useful in determining the possible causes of your pain.
Disclaimer: this information is for your education and should not be considered medical advice regarding diagnosis or treatment recommendations. Some links on this page may be affiliate links. Read the full disclaimer.