Pain at the back of the knee, or posterior knee pain, can be a sign of any of five or six possible conditions, some of which are mild and easily treatable (or even ignorable). Others are potentially serious maladies requiring urgent medical attention.
In this article, we shall examine the 5 or 6 most common possible reasons for pain behind the knee and the treatments that doctors might adopt to resolve each possible cause.
One cause that we will not describe in detail for obvious reasons is a phenomenon described as “referred pain”. This is a situation in which you feel pain behind your knee but it actually originates somewhere else in your body, e.g. the front of the knee or even the lower back.
The accompanying symptoms of referred pain can span a wide range. With this type of pain, you will need to consult a doctor who can conduct tests to identify and treat the underlying cause.
Possible Causes of Pain At The Back Of The Knee
One possible commonly experienced cause of pain behind the knee is a Baker’s cyst. This is a cyst that may be produced by an accumulation of synovial fluid in the “popliteal’ area behind the kneecap. Another name for this cyst is a “popliteal cyst”.
Synovial fluid actually occurs naturally in the knee (and other joints) and is required as a “lubricant” of the knee joint so that you can easily extend and flex the joint. A Baker’s cyst due to synovial fluid may cause some pain and discomfort. However, although these symptoms may vary over time and cause you some alarm, the condition is not inherently harmful. You can rest assured that you are not in danger of suffering long term damage to your knee.
In other cases, however, a Baker’s cyst may be an accumulation of inflammation behind the knee that is due to the effects of either arthritis or a knee injury such as a torn meniscus.
In either of the latter two cases, a Baker’s cyst will need to be addressed by treating its underlying cause, whether this is arthritis or a knee soft tissue injury.
In addition to treating its underlying causes, doctors may attempt to remove the cyst itself by one or more of the following methods:
Aspirating (or draining) it with a needle, a process that should be carried out in a doctor’s office;
Corticosteroid injections to combat the inflammation that may be causing the cyst;
Over the counter pain relief medication such as Tylenol;
Non steroidal anti inflammatory medications such as Ibuprofen or Naproxen.
Application of the R.I.C.E. protocol by resting, icing , compressing and elevating the knee; and
Referral to a physical therapist who can recommend an exercise program to strengthen the knee and allow it to recover its normal range of motion.
Treatment of a Baker’s cyst that is due to an arthritic condition such as osteoarthritis or rheumatoid arthritis will likely continue for the rest of your life. These (and other) forms of arthritis do not have any fundamental cures that will halt or reverse the underlying knee damage. Instead, doctors will try to manage the condition by slowing its rate of progression and preserving as much of your quality of life as they can.
The pain at the back of your knee may also be due to an infection there.If an infection is present, the posterior knee pain would be accompanied by redness, warmth and possible swelling.
An infection could be one of three possible types:
Knee bursitis, which is an infection of the fluid filled sacs inside the knee joint that assist tendons to move smoothly and frictionlessly over the bones in the joint.
Doctors can deploy a wide range of antibiotics to treat a possible infection. Your first step should be to contact one and schedule an appointment for medical advice, diagnosis and treatment.
Infections should be treated as matters for urgent medical attention. If they are not attended to in a timely fashion, various complications can develop up to and including sepsis, which is a life threatening medical condition.
Another possible cause of pain at the back of the knee is a soft tissue injury in that reqion. The most common knee injuries that might result in this type of pain would be a ligament strain, a muscle or tendon strain or a torn meniscus.
Accompanying symptoms (in addition to pain behind the knee) would be one or more of the following:
You may hear a pop or snap at the time the injury is sustained;
A feeling or weakness of the joint, and reduced range of motion;
Possible contusions at the back of the knee, as well as a “tender to the touch” feeling.
A severe hamstring strain may be accompanied by occasional muscle spasms.
If you have experienced either a ligament sprain or meniscus tear, you may have difficulty walking without feeling knee instability, i.e. that the joint may give way beneath you.
The symptoms will likely be at their most severe during a period of activity, and will tend to recede during periods of rest.
In the main, doctors will treat these types of knee soft tissue injuries using the R.I.C.E. protocol:
Rest the knee and take as much stress off it as possible. Use a knee brace for additional support of the injured ligaments (if any) or, if the condition is severe, consider using crutches to keep weight off the knee entirely;
Apply a cold compress or ice pack to the knee at intervals of 2-3 hours and for 20 minutes or so at a time. This will help to reduce pain and swelling;
Use an over the counter pain relief medication such as Tylenol if the pain is severe. If inflammation is also a problem, a non steroidal anti inflammatory drug like Naproxen or Ibuprofen can be considered;
Elevate the knee above heart level as much as possible, e.g. when lying or sitting down.
In addition to these treatments, doctors will probably refer you to a therapist who can devise a physical therapy exercise program for your knee to help you return to activity as soon as possible and with as little risk of re-injury as possible.
We mentioned knee arthritis above as a possible cause of a Baker’s cyst behind the knee.
However, if the posterior knee pain and cyst are due to arthritis of the knee, that will need to be managed separately. There are several types of knee arthritis, and the more likely ones are:
Knee osteoarthritis, a wear and tear form or arthritis that causes wearing down of the tough but slick cartilage covering the bone ends in the joint;
Rheumatoid arthritis of the knee, caused by an aggressive immune system starting to attack the synovial joint lining of the knee
Psoriatic arthritis, in which arthritis develops from psoriasis, a condition that produces red patches on the skin with silvery scales over it.
Arthritis typically causes knee pain and stiffness that may be worse upon awakening in the morning or after a period of inactivity (e.g. a daytime nap).You may also suffer from swelling and inflammation because of the condition.
If you think your pain behind the knee is due to arthritis, you should see a doctor who can make a formal diagnosis and rule out the other potential causes mentioned in this article.
Once arthritis has been positively identified, doctors can recommend a range of drugs depending on the type of arthritis that you have.
They can also refer you to an occupational therapist who can advise on home modifications to reduce the pain of performing daily activities like cooking, bathing and toileting. A physical therapist can devise an exercise program that will help you maintain knee joint function and range of motion.
As far as surgery is concerned, doctors once again have a range of options up to and including knee replacement.
For additional information on the treatment and management of knee arthritis, please read this article.
These (whether malignant or benign) are another potential cause of pain behind the knee. Clearly, this is a very serious problem and you should consult a doctor as soon as possible for a complete examination, diagnosis and treatment.
To say any more on this subject would be beyond the scope of this article.
Deep Vein Thrombosis
This is a condition caused by the appearance of a blood clot in a deep vein, typically in one of your legs.Although deep vein thrombosis (DVT) can occur with pain behind the knee (typically the calf area) it is important to note that it can also occur with no symptoms at all.
DVT can be a serious and potentially life threatening condition, since the blood clot can break off and travel in your bloodstream to your lungs. There it can block blood flow and cause what is called a pulmonary embolism.
The symptoms that accompany the posterior knee pain may include swelling of the leg with the clot, red or discolored skin and a “warm to the touch” feeling in the leg. As mentioned though, in some cases, DVT can be present with no noticeable symptoms.
If you think that your pain at the back of your knee may be a result of Deep Vein Thrombosis, you should consult a doctor without delay for a proper diagnosis.
If your doctor confirms your suspicion, the goals will be to prevent the blot clot from expanding or breaking loose. Treatment will also be aimed at preventing the formation of another clot.
Your doctor can prescribe blood thinning medication to achieve these goals, such as Heparin, Warfarin or dabigatran. These won’t break up the clots you already have, but they will help to prevent them expanding or increasing in number.
If your clot presents an immediate risk, clot busting drugs can be injected directly via IV or even directly into the clot. As an alternative, a surgeon can inject a filter into a large abdominal vein to prevent the blood clot reaching your lungs even if it does break off.
To manage the risk of a blood clot developing, you can wear compression stockings. Choose stockings that apply graduated compression between your feet and your knees as that is the portion of your legs where DVT is most likely to develop.