Pain Behind the Knee / In Back of Knee

What Causes Pain Behind the Knee? Why Does it Hurt in the Back of my Knee or Knee Cap?

Back of knee pain, also known as posterior knee pain, can come in varied forms ranging from slight to sharp pain behind knee to pain in the back of knee when bending to back of knee pain after sitting. As you might imagine, these types of pain can stem from a wide variety of causes, not all of which involve damage to the knee joint.

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Degenerative joint disease, namely the various forms of arthritis, can directly and indirectly contribute to pain behind the knee. As the protective tissues of the knee erode (via wear, disease or injury), the bone on bone rubbing that results creates friction and inflammation that often leads to joint pain. Thankfully, there are a number of arthritis knee braces for easing discomfort associated with the various forms of arthritis.


#1 - Pain Behind Knee Joint from Popliteal Cysts or Baker's Cyst


The Anatomy of the Knee

One of the more common causes of pain in the back of the knee joint, specifically, is a popliteal synovial cyst, which is also known as a baker’s cyst. This fluid-filled cyst at the back of the leg often forms in response to arthritis or other cartilage damage. The bulge creates a feeling of tightness behind the knee as well as stiffness and swelling and pain behind the knee and calf. For many, this pain intensifies when flexing or fully extending the leg. 

Often, these cysts go away without any treatment. But if that is not the case, the first course of treatment would usually involve addressing the underlying condition. Only treating the cyst means another one may well form in response to the underlying condition.

Conservative treatment methods for relieving this behind the knee pain may involve using ice, compression, crutches and engaging in physical therapy. DeRoyal offers a compression knee brace designed to ease the pain associated with osteoarthritis as well as Baker’s cysts. Alternatively, a professional may recommend use of corticosteroid medication, fluid drainage and, in rare cases, surgery.

A tear to the cartilage-like meniscus can also result in pain in the back of the knee, depending upon what sort of tear occurs. Pain and swelling behind the knee is common with a meniscus tear; the severity of the pain and whether the stability of the knee is compromised depends upon the extent of the tear. This pain behind the knee when it’s bent will often intensify during a deep knee flex or when getting up after sitting.

Treatment for a meniscus tear or other meniscal injury often involves physical therapy, meniscus bracing and possibly surgery, again depending upon the severity of the tear.

Cartilage in the Knee Joint


Another cause of leg pain behind the knee is calcium pyrophosphate dihydrade disease (CPPD). This mouthful of a condition is used synonymously with the term pseudogout or chondrocalcinosis (though the

One’s risk of developing CPPD increases with age; 50% of those over the age of 85 experience CPPD. Other risk factors include joint trauma, mineral imbalances and certain medical conditions, such as an underactive thyroid.  latter is actually a generic term referring to visible calcification of cartilage). As you can likely infer, this disease mimics the symptoms of gout, though it is actually a form of arthritis, and it often settles in the knees. The hallmarks of CPPD are sudden flare ups of sharp pain behind the knee and swelling that may be accompanied by redness and warmth. This is due to the formation of crystal deposits in one’s joints. 

There is no cure for CPPD, so treatment revolves around reducing pain and maintaining full joint movement and muscle strength. As is the case with a number of knee injuries, rest and ice are one mode of treatment, followed by physical therapy.  A doctor may also prescribe medications or draining excess fluid from the knee for reducing inflammation and swelling and, in rare cases, surgery.


#2 - Back of Knee Pain from Athletic Hamstring or PCL Injury


Hamstring Exercises for Knee Pain

A number of injuries causing pain in back of knee stems from athletic activity. For instance, one can pull a hamstring muscle via a sudden stretch of the muscle fibers of the hamstring. Generally, a “pulled hamstring” refers to a strain to one of the three muscles of the hamstring. Failing to stretch or warm up, tired or imbalanced muscles, inadequate footwear or a prior injury can contribute to a sudden injury, or this hamstring pain behind the knee can develop gradually over time due to overuse. Check out our Hamstring Support Shorts, a great solution for hamstring pain.

Besides this muscle pain behind the knee that may become more prominent when suddenly accelerating or decelerating, the symptoms of a hamstring injury may also include swelling, bruising, muscle spasms and limited range of motion and knee flexion. In cases of a major pull, an audible “pop” might accompany the injury.

Treatment of this type of pain in back of leg above the knee is also influenced by the extent of the damage. Following the steps of RICE (rest, ice, compression and elevation) is usually advised, along with use of medication and possibly crutches. Physical therapy is sometimes recommended to improve one’s range of motion, flexibility and strength following such an injury. In rare cases, surgery may be needed to repair the damaged muscle(s). Click here for some post-operation knee braces

A popliteus tendon injury is another possible cause of pain at the back of the knee stemming from athletic activity. More specifically, damage to this tendon is often caused by running downhill, though it can result from trauma to the knees or overuse.  

This pain in tendon behind the knee can usually be eased by following the steps of RICE and massaging the affected area. Stretching and engaging in some strength exercises can help prevent a repeat of the injury. 

Injury to the popliteus tendon sometimes coincides with a tear to the posterior cruciate ligament (PCL) as the two have similar functions—preventing the tibia from sliding too far back relative to the femur. This ligament is located deep in the knee and it usually takes quite a bit of trauma to be torn.

A PCL tear resulting in back of the knee pain can be caused by a fall on the knees when they are bent, a blow to the front of the knee or a major twisting motion, such as during a skiing wipeout. Physical therapy and surgery are the usual PCL tear treatment methods, likely with use of a ligament tear knee brace



#3 - Pain Behind Knee Caused by Blood Clot or Tumor


Pain Behind Knee in Back of Femur

A tumor in the soft tissue or bone of the knee joint can also cause pain in the back of the knee. In addition to discomfort, a tumor will likely include the appearance of a palpable mass, trouble

 bending the knee and pain even when no weight is being placed on the legs. Treatment for a tumor in the knee joint is dependent on the grade and stage of the tumor and might involve such things as radiation, chemotherapy, resection or amputation.

Another thing that can cause pain behind the knee and is characterized by symptoms quite similar to those of a baker’s cyst is deep vein thrombosis (DVT), which is basically a blood clot or clots in the leg. One with DVT will likely experience swelling, pain behind knee when walking or standing, warm and/or discolored skin, fatigue in the leg and visible surface veins.

This pain behind the knee blood clot is not something to fool around with. If the clot breaks loose, it can result in a heart attack, pulmonary embolism (blockage of an artery) in the lung or a stroke. Risk factors for deep vein thrombosis include advanced age, being overweight, smoking and sitting for long periods of time.

A doctor will likely recommend one of a number of medications or blood thinners to treat DVT. If these do not work, a doctor may recommend use of a small metal devise to capture blood clots, elevation and compression (sometimes via use of a compression knee wrap or compression stockings) and in rare cases surgery. For more, see “Preventing Deep Vein Thrombosis.”

#4 - Back of Knee Pain from Nerve or Artery Compression 


Knee Pain - Popliteal Entrapment

Compression of nerves or arteries can also result in knee pain in the back of the knee. For instance, the popliteal artery can become compressed as it moves through the popliteal fossa due to an abnormality of the artery’s position relative to its surrounding structures. When this occurs, it is known as popliteal artery entrapment syndrome.  

The result is restricted blood flow to the tissues of the leg, causing back of leg pain behind the knee and swelling, cramping, and a sensation of coldness, tingling or prickling in the area below the knee. Over time this can result in vascular damage or complete blockage or lesion of the artery that can threaten the vitality of the limb.

This popliteal artery entrapment phenomenon is not common, but when it does occur, it is more likely to affect young, athletic people, especially sportsmen or soldiers due to their enlarged muscles in the vicinity of the popliteal artery. Treatment for a compressed popliteal artery typically involves surgery.

Another relatively rare condition is peroneal nerve entrapment. This is when the peroneal nerve gets trapped in the popliteal space, usually while one is walking or running. This causes shooting, severe pain behind the knee that is constant. Treatment typically involves a period of immobilization, followed by range of motion and strength exercises. In some cases, surgery may be needed.

This is not the only nerve of the knee or in fact the body that can result in  leg pain behind the knee, as well as numbness, tingling, weakness and a sensation of tingling, pins and needles or burning. Indeed, several levels of the vertebrae contain nerves that send fibers to the knee. (View a nerve function chart.) Thus, a disc that is compressed in these regions can cause both lower back and knee pain.

Treatment for pinched or compressed nerves typically involves use of anti-inflammatory drugs, steroid injections or oral corticosteroids, narcotics for the pain, physical therapy, splinting or bracing and possibly surgery.

As you can see, though there is a wide variety of causes of pain behind the knee (and those covered in this article are by no means an exhaustive list), a number of the symptoms are similar. Therefore, it is important to get the advice of a professional before getting started on a mode of treatment.

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