Pain in the back of the knee can be an indication of various injuries or diseases of the knee joint: After a fall or an accident, pain in the back of the knee can indicate damage to the knee ligaments or a meniscus, for example. However, if the back of the knee hurts, especially after sports, an overload or incorrect load is often the cause.
Pain in the back of the knee: Causes in the overview
More rarely, thrombosis of the leg veins can also cause pain in the back of the knee. A painful, palpable swelling in the back of the knee, on the other hand, is often indicative of a so-called Baker’s cyst: this is a mostly harmless bulge in the joint capsule, which is filled with synovial fluid. We have compiled an overview for you, which causes can be behind pain in the back of the knee.
Injuries to the knee joint as a cause
A fall, accident or twisting of the knee joint can cause damage to a meniscus or to the knee ligaments – such as a torn cruciate ligament. Depending on the exact location of the injury, pain may also be localized in or radiate to the back of the knee. For pain after a fall, the PECH rule generally applies first:
- Pause (avoid stress on the affected leg).
- Ice (cooling)
- Compression (light pressure to reduce swelling and bruising, such as taping with an elastic bandage).
- Elevation
If the pain does not improve after a few days, you’d better see a doctor – an MRI can usually confirm the diagnosis.
Painful back of the knee after exercise
If the back of the knee hurts, especially during exertion or after sports, the cause may be overuse of the popliteus muscle or the posterior thigh muscles (ischiocrural muscles). These muscles are located at the back of the thigh and run past the back of the knee to the calf. Too intensive or incorrect training – for example, jogging or cycling – can lead to irritation or inflammation of the tendons of these muscles. This then becomes noticeable through pain on the inside or outside of the back of the knee, which mainly occurs when bending the knee or when pressure is applied to the tendon. Under certain circumstances, the affected tendon may also be thickened or overheated. It is then advisable to take a break from sport for a few days. If the muscles are overstrained, heat – for example in the form of red light or warm compresses – is good. In the case of inflammation, on the other hand, cooling makes more sense: the affected back of the knee is then usually overheated and swollen. The preventive effect of stretching before or after sports is controversial, however: a light stretching, however, at least does not seem to hurt.
Baker’s cyst: swelling in the back of the knee
A Baker’s cyst is an outpouching of the knee joint capsule that occurs when there is increased production of synovial fluid due to increased pressure in the joint. The cause is usually irritation of the knee joint – such as osteoarthritis, meniscus damage, or joint inflammation. More rarely, a Baker cyst occurs after knee injuries. A Baker’s cyst is noticeable as a palpable swelling or bump in the back of the knee. When stretching or bending the knee sharply, there may also be pain or a pulling sensation in the back of the knee. Rarely, the cyst can rupture – in which case there is sudden, severe pain as well as redness and overheating of the back of the knee. Learn what to do about a Baker cyst here.
Thrombosis as a rare cause
In rare cases, pain in the back of the knee can be a sign of thrombosis in a leg vein. To assess the likelihood of thrombosis, it is important to know its risk factors:
Immobilization of the legs, such as during bed rest, and after surgery or injury, where relief with crutches is necessary.
- Sitting for long periods of time, such as during long-haul flights or long trips by train or car
- Excess weight
- Age over 60 years
- Cancer
- Thrombosis in the past
- Diseases with a tendency to clot (thrombophilia).
- Pregnancy and puerperium (up to six weeks after birth).
- Smoking
- Taking birth control pills or hormone treatment with estrogen.
In the case of thrombosis, other symptoms may include swelling of the back of the knee or calf and a bluish discoloration or clearly visible veins (as in varicose veins). In addition, pain when the calf is squeezed or pressure is applied to the sole of the foot may reinforce the suspicion of thrombosis. If you suspect that you may have a thrombosis, you should see a doctor as soon as possible, because in the worst case a life-threatening pulmonary embolism can be the result. Read all the details about thrombosis here.
Nerve irritation: pain when stretching
The tibial nerve runs through the back of the knee, allowing the foot to be extended, among other things. Rapid muscle growth during intense weight training, a knee joint effusion, or a Baker’s cyst can constrict the nerve and cause pain in the popliteal fossa. The pain then occurs preferentially when the knee is stretched or after long periods of walking or running. Additionally, if the tibial nerve is irritated, there may be a burning or tingling sensation in the calf.
Pain in the back of the knee in children
In children, pain in the back of the knee or calf that occurs without a previous fall is often due to growth: Such growing pains usually occur at kindergarten and elementary school age and usually disappear on their own after some time. However, if the pain persists for a longer period of time or is unusually severe, it should be clarified by a doctor – this applies in particular if the child has fallen or had an accident. In rare cases, a detachment of the growth plate (epiphysolysis) can be the cause of a painful back of the knee in children. This condition can occur for no apparent reason or due to an injury. Prompt treatment is then important, otherwise growth disturbances may occur.
