Pain Behind the Knee

Pain behind the knee aka posterior knee pain is a common problem with multiple possible causes. It may develop gradually over time due to an underlying knee condition, or it may develop suddenly, which is usually due to an injury.

Here we will look at the most common causes of pain behind the knee. By thinking about how your pain started, the common symptoms and how your pain behaves, you can work out what is causing your pain.

There may be a general achy back of knee pain, leg movements may be restricted by swelling or there may be a sharp pain at the back of the knee. 

As you read through each summary, you can decide whether it sounds like your problem or not. If it does, read the full article to find out everything you need to know about the causes, symptoms, diagnosis and best treatment options. If it doesn't sound quite like your pain, simply move on to the next one.

Finally, we will look at some of the most frequently asked questions about pain at the back of the knee.

1) Bakers Cyst

What is it: Inflammation of the popliteal bursa (fluid filled sac) at the back of the knee. It is the most common cause of pain behind the knee.
Symptoms: Swelling (like a small water balloon), tightness and pain behind the knee
Aggravating Activities: Bending and straightening the knee, walking, kneeling
Onset: Can come on after a blow to the back of the knee but usually comes on gradually. Often associated with arthritis - fluid from the arthritis leaks back into the bursa causing it to swell
Treatment: Ice, exercises, aspiration, injection, electrotherapy and occasionally surgery
Recovery: Can take a few months for the pain behind knee to settle down and they have a tendency to recur if not treated properly
Read Full Article: Bakers Cyst: Causes, Symptoms & Treatment

2) Posterior Cartilage/Meniscus Tear

What is it: Tear at the back of the cartilage lining the joint
Symptoms: Pain behind the knee, swelling, locking, instability, difficulty straightening the knee
Aggravating Activities: Walking, running, squatting, stairs esp going up
Onset: Can occur suddenly with a force through the knee, sudden twisting of the knee or gradually through wear and tear
Treatment: PRICE, exercises, tubigrip, knee brace and occasionally surgery
Recovery: Can take months to recover as the meniscus has a poor blood supply, which slows healing 
Read Full Article: Meniscus Tear: Symptoms, Diagnosis & Treatment

3) Calf Strain/Tear

What is it: Overstretching or tearing of part of the calf muscle
Symptoms:  Pain in the back of the knee or calf, bruising, swelling & difficulty walking
Aggravating Activities: Walking, running, pushing down through toes
Onset: Can occur suddenly when changing speed or direction or gradually from repetitive running or jumping
Treatment: rest, PRICE, heel pads, massage, ultrasound and exercises (but not too soon)
Recovery: Usually takes 6-12 weeks to recover
Read Full Article: Calf Strains - Treatment & Recovery 

4) Knee Arthritis

What is it: Changes in the bone usually caused by wear and tear (osteoarthritis) or sometimes by inflammation (rheumatoid)
Symptoms: Morning stiffness, pain, swelling, clicking/grinding, reduced leg movements
Aggravating Activities: Worse after prolonged rest, activity, cold weather
Onset: Symptoms gradually come on over time. Most common over the age of 50
Treatment: Exercises, knee brace, heat, ice, acupuncture, weight loss, walking aids, gel knee pads, cushioned footwear, medication, injections
Recovery: The changes in the bone from arthritis cannot be undone, but treatment aims to reduce pain, improve function and prevent deterioration
Read Full Article: Knee Arthritis - Take Back Control

5) Knee Sprain

What is it: Overstretching or tearing one of the ligaments in the knee
Symptoms: General pain, swelling, bruising, occasional giving way and/or decreased movement
Aggravating Activities: Depends on the severity but can be any physical activity or movement of the knee
Onset: Sudden twisting movements or a force through the knee
Treatment: PRICE, exercises, tubigrip, knee brace
Recovery: There are three grades of knee sprain depending on how much damage there is. It can take anything from 2 weeks to 3 months to fully recover, depending on the severity of the injury
Read Full Article: Knee Sprains - How To Make A Full Recovery

6) Hamstring Injury

What is it: A tear in one of the hamstring muscles on the back of the thigh
Symptoms: General achy pain in back of knee where hamstring tendon attaches to the bone. Sharp pain behind knee with sudden movements
Aggravating Activities: Bending the leg, sudden acceleration or deceleration when moving
Onset: Sudden onset with an injury
Treatment: PRICE, exercises, massage, tubigrip
Recovery: Usually takes 6-12 weeks to fully recover

7) Deep Vein Thrombosis (DVT)

What is it: A blood clot in one of the deep veins of the leg
Symptoms: Pain behind the knee or in the calf, swelling, redness, warmth, usually only on one leg 
Aggravating Activities: Dorsiflexion - pulling your toes up towards you (your foot doing the work not your hands) will increase the pain behind the knee/calf pain
Onset: Can start gradually or suddenly, due to periods of inactivity, certain medical conditions, pregnancy, obesity or genetics
Treatment: Blood thinning medication (anticoagulants), compression stockings, exercises
Recovery: Can take several weeks/months to fully recover and you may need long term treatment

NB A DVT is a potentially life threatening condition. If you are showing symptoms of a DVT seek immediate medical attention

What Causes Pain Behind The Knee When Straightening The Leg?

The most common cause of knee pain when you straighten the leg is a meniscus tear, particularly if you've been sitting down or squatting for a while. As the knee straightens out from a bent position, the torn, inflamed portion of cartilage gets squashed in the joint, causing pain in the back of the knee.

What Causes Pain Behind The Knee When Bending

The most common cause of pain behind the knee when bending is a Bakers Cyst. This is when there is inflammation of the semimembranosus bursa, a small sac filled with fluid that sits at the back of the knee. If it gets inflamed then any time you bend your knee, the bursa gets squashed, causing posterior knee pain.

What Causes Tightness Behind The Knee?

Tightness behind the knee is often caused by tightness in the hamstring or calf muscles. The hamstring muscles run down the back of the thigh attaching behind the knee, and one of the calf muscles, gastrocnemius, arises from the back of the knee and travels down to the heel. Tightness in these muscles is a common problem, particularly in men, and makes the back of the knee feel very tight. Simple knee stretches are the best way to treat the tightness.

What Causes Pain Behind The Kneecap?

Pain behind the kneecap is usually caused by a problem with the cartilage that lines the back of the kneecap. It may be Runners Knee, where  a problem with how the kneecap glides causes friction and pain behind the kneecap. In teenages, pain behind the kneecap is often caused by Chondromalacia Patella, a condition where there is thinning of the cartilage on the back of the kneecap.

What Causes Swelling Behind The Knee?

Swelling behind the knee is most commonly caused by a Baker's Cyst. Excess fluid in the knee joint, usually from an injury or knee arthritis, leaks out of the back of the joint filling the semimembranosus bursa and causing swelling behind the knee. It often feels like there is a squashy orange behind the knee.

What Causes Pain Behind The Knee After Sitting?

Pain behind the knee after sitting for prolonged periods is often caused by arthritis. When we sit still, the fluid that lubricates the knee joint dries out slightly so when we then stand up, there is less cushioning. The wear and tear associated with arthritis means you can end up with the knee bones rubbing together, causing pain. Once you are up and moving about, the joint produces more synovial fluid so after a few minutes of moving around, the pain eases off.

What Causes Sharp Pain Behind The Knee?

If you are a runner, then sharp pain at the back of the knee often indicates a problem with the hamstring tendons, such as tendonitis. If you do a lot of cycling, then a sharp pain behind your knee is usually caused by tendonitis in one of the calf muscles, gastrocnemius. If you have recently twisted your knee or had a fall, then a meniscus tear is probably causing the sharp pain.

To find out more about these common causes of pain behind knee, click on the links above. People often have lots more questions such as what are the best exercises for treating pain in the back of your knee? What is the muscle behind the knee called? How do I know if I've got a DVT? You can find answers to these and other questions in the back of knee FAQ's section.

However, just because there is pain in the back of the knee, doesn’t necessarily mean the problem is there. Pain can refer to different places so a problem round the front of the knee can produce a feeling of posterior knee pain.

If you would prefer to diagnose your pain using other specific symptoms such as how the pain started or the specific location of the pain, go to the diagnose your pain section for help working out was is causing your posterior knee pain and to learn what you can do about it. Remember, the best way to accurately diagnose the cause of your pain behind the knee is to see your doctor.

Go to Diagnosis Section or Knee Pain Guide