Why Do I Have Pain In The Back Of Knee When Straightening Leg?

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Why Do I Have Pain In The Back Of Knee When Straightening Leg?

Why Do I Have Pain In The Back Of Knee When Straightening Leg? On the corner of Ripon Street, the taxi stops!

You are back home after a hectic day. The moment you open the door and get down straight on your legs, you start to feel severe pain in the back of your knee.

And this is not the first time!

You often feel this pain these days, once in the morning, just while you stand up from bed, and then again when you get up from your chair after many hours of work while sitting in that same position.

Perhaps, it’s a sharp one, and you feel it gradually intensifying over time!

This time, I request you please see a doctor! This pain in the back of the knee you have when straightening the leg is not a positive sign. It means you have an underlying health abnormality that needs a fix!

Wondering, what can that be? Discover now!

Why Do I Have Pain In The Back Of Knee When Straightening Leg?

Baker’s Cyst

Do you know the most common cause of your pain in the knee when straightening your leg is a Baker’s cyst? That’s right!

A cyst that develops due to the seepage of excess fluids from your knee joints, the Baker’s cyst causes tightness and pain in the knee, especially when walking, kneeling, or bending the knee. These are most common among people above the age of 40; and also women.

A wear and tear in the knee bone or cartilage triggers this excess fluid collection in the knee joint, which then makes its way to the popliteal bursa, causing it to swell.  In fact, knee injuries or inflammation like gout can bring this cyst to the stage!

So, your doctor may have to drain this fluid to give you relief, both from the cyst and your knee pain!

Ligament Injury

Another plausible cause of pain in the back of your knee while you straighten your legs is certainly a ligament injury or sprain. Yes. Your knee ligaments, anterior, posterior, medial, or lateral, might have been overstretched and torn due to a sudden heavy force through your knee, like in the case of a car accident or hitting a dashboard.

It can also be a result of a twisted movement when running in cleats and changing direction in the way.

Your doctor will decide on the treatment depending on how severe the injury is! Sometimes, you may even require surgery to fetch a long-term cure. But mostly, a knee brace, accompanied by a few knee-strengthening exercises, works effectively.


The medical term referring to a swollen tendon, tendinopathy, is bound to appear in the list of diseases causing pain in the back of the knee. Such a condition occurs from repetitive knee movements or persistent strain on your joints.

Swelling in the patella tendons and the hamstring tendons is most common, especially in the case of athletes.

Your doctor shall typically prescribe anti-inflammatory medicines and bracings and suggest appropriate exercises and physical therapies to treat this condition.  If the swelling is severe, they may also consider surgery as a suitable treatment option.

Posterior Cartilage Tear

If your posterior cartilage, the one at the back of your knee, gets a tear, you are likely to experience pain therein every time you straighten your legs.

This tear can be sudden and can even develop gradually with time. It can happen to the outer edge of your meniscus (the cartilage lining the knee joint) or along its length. Sometimes, this cartilage may turn brittle and thin.

Alas! It takes a long time for posterior cartilage tears to heal, as blood supply to this area of your body is usually poor.

Your doctor may ask you to apply ice, keep the area compressed with tubigrip or knee braces, and exercise regularly.  In some cases, your doctor may have to opt for meniscus surgery.

Knee Arthritis

Are you above 50? If so, the pain in the back of the knee you experience while straightening your leg can be a sign of knee arthritis ( i.e., swelling or inflammation in the joints). This pain is common, especially when arthritis starts to affect your joints and one bone gets rubbed with another.

Not just your age; your weight, gender, genes, previous knee injury, previous knee surgery, and flat feet can be the reason behind such a health abnormality.

There are multiple options to treat this common disease, nearly 15 of them! It can be exercise, knee braces, footwear, or heat and ice. It can be natural remedies, such as glucosamine supplements. It can be a weight management and diet course, knee pads with gel, or simply moving around. Also, oral medications, injections, and joint replacement surgeries!

Deep Vein Thrombosis

You have pain in the back when straightening your leg if there is a hidden deep vein thrombosis, i.e., a blood clot formed within a deep vein in your leg. When these blood clots break, you have a chance of experiencing a heart attack or stroke.


The Centers for Disease Control and Prevention says that it is an underdiagnosed disease, and in about 50% of the cases, there isn’t any symptom.

So, when it does show up, do consult a doctor. You shall need blood-thinning medications and sometimes even a catheter-based surgery to remove the blood clot.

Hamstring Injuries

If and when your hamstring muscles get overstretched beyond the elastic limit, they have, leading the muscle fibers to tear, you are likely to feel pain in the back of your knee when straightening the leg.

Are you actively into sports, actively? If yes, this injury is common, you know. If not, you may also get it from a sudden, fast movement, like jumping, sprinting, lunging, etc.

Doctors shall ask you to rest and keep applying cold packs! Compression, elevation, and anti-inflammatory painkillers may also apply to the treatment course. But, it may need around eight weeks to recover.

Knock! Knock! I see you’re wondering which one is the cause of your knee pain!

Trust me,

Only your doctor can find it out and offer you the right remedy. Early diagnosis and treatment of the knee problem can help stop further complications and life threats. Make a move now. Go, see the doctor!


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About author
Hi, I’m Alka Tiwari, healthcare marketer at HealthFinder. I started this blog to help you provide better healthcare information directly from the doctors.
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Alka Tiwari

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