Pain behind the knee when you bend it can stem from a variety of issues, ranging from minor muscle strains to more serious conditions.
Here's a breakdown of potential causes:
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Muscle Strain: Overexertion or sudden movements can strain the hamstring muscles (located at the back of the thigh) or the calf muscles, leading to pain when bending the knee.
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Ligament Injury: A tear in one of the knee ligaments, such as the posterior cruciate ligament (PCL), can cause significant pain, especially with bending or weight-bearing.
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Tendonitis: Inflammation of the tendons around the knee, such as the hamstring tendon or the popliteal tendon, can result in pain that worsens with knee flexion.
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Baker's Cyst: This fluid-filled sac behind the knee can cause pain and stiffness, particularly when bending or straightening the leg. The cyst often arises from an underlying knee problem, like arthritis or a meniscus tear.
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Arthritis: Osteoarthritis or rheumatoid arthritis in the knee can lead to pain and stiffness, especially when bending the knee.
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Deep Vein Thrombosis (DVT): Though less common, a blood clot in a deep vein of the leg (DVT) can cause pain, swelling, and warmth behind the knee and in the calf. This is a serious condition requiring immediate medical attention.
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Meniscus Tear: Tears in the cartilage of the knee (meniscus) can sometimes cause pain referred to the back of the knee, especially during movements like bending and twisting.
When to Seek Medical Attention:
While some causes of pain behind the knee are minor and can be treated with rest and ice, you should see a doctor if:
- The pain is severe.
- You cannot put weight on your leg.
- Your knee is swollen or deformed.
- You have numbness or tingling in your leg or foot.
- You suspect you have a DVT (pain, swelling, warmth, redness).
- The pain doesn't improve with rest and ice after a few days.
Ignoring the pain can potentially lead to serious complications if the underlying cause is not treated.
