Pain behind the knee is also called posterior knee pain and often occurs alongside swelling at the back of your knee, which may spread to the back of your leg (calf). Severe swelling can prevent you from bending your leg.
There are many different causes for pain at the back of your knee, with symptoms varying accordingly. Depending on the cause, symptoms include:
There are many different causes of posterior knee pain, including injury, inflammation or infection of the knee joint, overuse, wear and tear with age, osteoarthritis, rheumatoid arthritis, cysts or in very rare cases, cancer.
Leg cramps occur when your leg muscles tighten up. Symptoms include a sudden muscle spasm, with pain lasting from several seconds up to 10 minutes. After the spasm, your muscles may feel sore for several hours.
Leg cramps are most common during exercise and pregnancy. However, they can also be caused by:
This is also known as patellar tendonitis and occurs when a tendon in your knee is injured, often while playing sport. The tendon develops tiny tears that cause swelling stiffness, weakness and difficulty bending and straightening your knee.
Biceps femoris tendonitis (hamstring injury)
Your hamstrings are three muscles that run along the back of your thigh and help you bend your knee. Hamstring injuries most often occur when playing sports, usually when the hamstring is overstretched (strained or pulled hamstring). However, the hamstrings can also be torn, which can take several months to heal.
In addition to posterior knee pain, symptoms include swelling, stiffness and difficulty bending or straightening your leg. Symptoms often worsen on activity and if the cyst bursts, you will feel a sudden, sharp pain.
Symptoms include sudden pain and swelling, bruising and weakness in your leg.
Gastrocnemius tendonitis (calf strain)
Your calf muscles include the gastrocnemius muscle and the soleus muscle in the back of your lower leg. They help you bend your knee and point your toes. If you take part in sports where you suddenly have to go from standing to running (eg during tennis or squash), the gastrocnemius muscle can tear or become strained.
Symptoms include bruising, pain and swelling in your calf, and difficulty standing on your tiptoes.
The meniscus cartilage sits in your knee joint and acts as a cushion to stabilise it. Each of your knees has two menisci, one on each side. If you play sports that involve squatting or twisting your knee, you may tear this cartilage. With age, this cartilage weakens and can more easily tear with any twisting motion during everyday activities.
You may hear a popping noise when it tears but have no immediate pain. However, over the next few days, knee pain will develop, as well as stiffness, swelling, weakness and/or locking or giving way of your knee.
Anterior cruciate ligament injury
The anterior cruciate ligament (ACL) is a ligament that runs along the front of your knee and connects your thigh bone to your shinbone. It helps stabilise your knee so you can move it smoothly.
ACL injuries are common when playing sports where you suddenly slow down, stop or change direction when running (eg football). You can also damage your ACL if you land badly after a jump or your knee is hit by a blunt object. You may hear a popping noise on injury followed by immediate pain and swelling. You may find it difficult to bend your knee and/or walk.
Posterior cruciate ligament injury (knee sprain)
The posterior cruciate ligament (PCL) is a ligament that runs along the back of your knee and connects your thigh bone to your shinbone. It helps stabilise your knee so you can move it smoothly. It is less likely than the ACL to be damaged, however, it can become damaged if your knee is hit by a blunt object (eg during a car accident). Occasionally, the PCL can be damaged by twisting your knee or missing a step when walking. It can be strained if it is overstretched and if enough pressure is applied it can tear in two.
Alongside posterior knee pain, symptoms include swelling, stiffness and weakness of the knee, as well as difficulty walking.
Chondromalacia occurs when the cartilage in your knee wears down, so your bones rub against each other. Common causes include injuries, wear and tear with age, overuse and arthritis. Symptoms include a dull ache behind your kneecap (patella) that may worsen when climbing the stairs or after sitting for a long time, difficulty moving your knee along its full range, weakness or giving way of your knee, and a cracking or grinding feeling when bending or straightening your knee.
Arthritis causes inflammation of your joints due to the cartilage in your knee wearing away. There are several different types of arthritis that can affect your knee and cause posterior knee pain:
Lupus, an autoimmune condition related to arthritis, can also cause knee pain due to inflammation of your joints.
Deep vein thrombosis (DVT)
DVT is a blood clot that develops in a deep vein in your leg. This causes leg pain, especially when you stand up. If this occurs in a vein behind your knee (popliteal vein thrombosis) you can experience posterior knee pain. Other symptoms of a DVT include redness, swelling and warmth of your leg.
Hyperextension refers to bending your knee too far backwards, which often occurs when playing sports. In addition to posterior knee pain, symptoms include weakness in your knee and unsteadiness.
If you have pain behind your knee, it is important to see your doctor to rule out anything serious such as a DVT.
For posterior knee pain caused by a minor injury or arthritis, you can treat this at home with rest and pain relief. However, you should see a doctor if
Your doctor will perform a physical examination of your knee and ask you questions about your symptoms and your medical history. This includes:
If you have symptoms of a Baker’s cyst your doctor may recommend an ultrasound scan.
You should seek urgent medical attention if you:
Rest, applying ice packs, taking painkillers and physiotherapy can all be used to treat posterior knee pain. Depending on the severity and underlying cause of your knee pain, your doctor may also prescribe medication and/or recommend surgery.
Treatment for Baker’s cysts
Baker’s cysts can go away on their own or with treatment of the underlying condition causing your cyst (eg arthritis). However, if you have a large or painful cyst, your doctor may recommend steroid injections, physiotherapy or drainage of the cyst.
Treatment for gastrocnemius tendonitis
Your knee pain should subside with rest, elevation of your leg and applying ice packs. How long this takes will depend on the size of the tear.
Treatment for meniscus tear
Rest, elevation of your leg and applying ice packs may be enough to treat your tear. However, if your tear doesn’t improve on its own, your doctor may recommend surgery.
Treatment for ACL injury
Rest and physiotherapy can treat an ACL injury. However, if your ACL is torn, you may need surgery.
Treatment for PCL injury
Your knee pain should subside with rest, elevation of your leg and applying ice packs. However, your doctor may recommend surgery if you have injured more than one ligament, are unsteady on your feet or have also damaged cartilage in your knee.
Treatment for chondromalacia
Applying ice packs, taking over-the-counter painkillers and physiotherapy can treat chondromalacia. However, if the cartilage in your knee is damaged, you will need surgery.
Treatment for arthritis
Arthritis can’t be cured but it can be managed with exercise, painkillers and medications, including injections.
Rheumatoid arthritis can be treated with disease-modifying drugs that suppress your immune system and reduce inflammation.
Treatment for DVT
DVT is treated with blood thinners, which prevent the clot growing and new clots forming. Eventually, your body will break down the DVT.
There are different complications from rear knee pain, depending on the underlying cause.
A DVT should always be treated urgently as it can travel to your lungs and cause a pulmonary embolism, which is life-threatening.
To avoid complications from rear knee pain, you should see a doctor if:
You should also see a doctor if your knee:
Why do I have pain in the back of my knee when straightening my leg?
There are many different causes for pain behind the knee when straightening the leg, including jumper’s knee (patellar tendonitis), a Baker’s cyst and chondromalacia.
Why do I have pain behind my knee when bending my leg?
You may have damaged a ligament, tendon or cartilage, which prevents full range of motion in your knee without pain.
Why do I have pain behind my knee when walking and after/during running?
There are many different causes for pain behind the knee on activity, such as arthritis or a Baker’s cyst, as well as injuries, such as a meniscus tear, anterior or posterior cruciate ligament injury or hamstring injury.
Why do I have pain in the back of my knee after sitting?
There are several conditions that can cause pain in the back of your knee after sitting for a long time, including arthritis and chondromalacia.
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