Imagine climbing the stairs, and a sharp pain shoots through your knee. Or sitting for a while, then standing up and feeling a dull ache or even a burning pain in your knee joint.
If that sounds like you, you’re not alone.
Knee pain when bending and straightening is a common issue that affects people of all ages, from athletes to desk workers.
There are many reasons for knee pain, from patellofemoral pain syndrome (runner’s knee) to meniscus tears, patellar tendinitis, ligament injuries, and even rheumatoid arthritis. Body weight, previous knee injuries, and overuse can also play a role.
Knowing what’s causing your pain is the first step to finding relief and preventing long-term issues.
According to the CDC, nearly one in four adults in the US experience knee pain at some point, making it one of the most common musculoskeletal complaints.
Whether you’re dealing with a sore knee from exercise, an unstable knee with torn cartilage, or knee bursitis causing fluid-filled swelling, getting the correct diagnosis and treatment is key.
In this article, we’ll cover the common causes of knee pain when bending and straightening, signs to look out for that indicate a serious injury that needs medical attention, and treatment options to relieve pain and reduce swelling.
Why Does My Knee Hurt When I Bend and Straighten?
If you’re experiencing knee pain when bending or straightening your leg, several things could be happening.
From overuse injuries to degenerative diseases, knowing the cause is key to finding the proper treatment and reducing knee pain effectively.
Here are the most common causes:
Patellofemoral Pain Syndrome (Runner’s Knee)
Patellofemoral pain syndrome occurs when the kneecap (patella) doesn’t track properly along the thigh bone during movement. This can cause pain around the kneecap, especially when climbing stairs, squatting, or sitting for long periods.
Overuse, muscle imbalances, and flat feet can all contribute to this condition.
Related: Learn more about Patellofemoral Pain Syndrome
Tendonitis (Patellar or Quadriceps Tendonitis)
Tendonitis is inflammation of the tendons around the knee, often due to repetitive strain.
Patellar tendonitis (jumper’s knee) is the tendon connecting the kneecap to the shin bone, and quadriceps tendonitis is the tendon above the kneecap.
Symptoms include burning pain and tenderness, especially after activity.
Ligament Injuries (ACL, MCL, PCL Tears)
Ligaments support the knee joint, and injuries like ACL tears, MCL sprains, or PCL damage can cause severe pain, knee buckling, and instability.
These injuries often occur from sudden twisting, high-impact sports, or falls.
Meniscus Tears
The meniscus is a cartilage shock absorber in the knee.
A meniscus tear can happen from sudden twisting or age-related degeneration.
Symptoms are sharp pain, swelling, and difficulty bearing weight on the knee.
Arthritis (Osteoarthritis and Rheumatoid Arthritis)
Arthritis is the leading cause of chronic knee pain.
Osteoarthritis causes joint stiffness, swelling, and a dull ache from cartilage breakdown.
Rheumatoid arthritis is an autoimmune condition that can cause severe knee pain, joint deformities, and mobility issues over time.
Related: Arthritis Knee Pain Relief – What You Need to Know
Muscle Weakness and Knee Instability
Weak muscles, especially in the quadriceps and hamstrings, can cause joint instability, poor knee function, and knee pain when bending.
Strengthening these muscles is key to joint stability and preventing future injuries.
This is where Motive Knee can be a game changer—helping to strengthen the muscles around the knee for better mobility and less pain.
Bursitis (Inflamed Bursae in the Knee)
Bursae are small fluid-filled sacs that reduce friction in the knee joint.
Knee bursitis occurs when these sacs become inflamed from repeated pressure or trauma.
Symptoms are fluid-filled swelling, soreness, and pain relief when the knee is rested.
Pro-Tip: If your knee pain persists, worsens, or is accompanied by very sharp pain, knee buckling, or difficulty bearing weight, you must see a doctor to prevent further damage.
Symptoms to Watch For
The symptoms of knee pain when bending and straightening will vary depending on the condition.
Some people will experience a dull ache, while others will feel sharp or burning pain that worsens with activity.
Knowing your symptoms will help you determine the best way to relieve pain and improve knee function.
Here are some common signs to watch for:
1. Pain in Different Areas of the Knee
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Front of the knee: Often linked to patellofemoral pain syndrome (runner’s knee) or patellar tendonitis
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Side of the knee: Could indicate meniscus tears, ligament injuries, or IT band syndrome
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Back of the knee: May be due to hamstring tendonitis, Baker’s cyst, or knee bursitis
2. Swelling
Swelling can be due to fluid-filled swelling, inflammation, or serious injury like a torn ligament or bone fractures.
The swelling may be a more serious issue if it is persistent or severe.
3. Stiffness
If your knee movement feels restricted or stiff, it could be arthritis, bursitis, tendinitis, or other forms of injury. Stiffness is often worse after prolonged sitting or in the morning.
4. Clicking or Popping Sounds
Hearing clicking, popping, or grinding when moving your knee could be a sign of chondromalacia patella, meniscus tears, or patellofemoral pain.
Occasional sounds are normal, but if they’re accompanied by pain or swelling, they may indicate a problem.
5. Instability
A knee that buckles or feels unstable could be due to anterior cruciate ligament injuries, torn cartilage, or muscle weakness.
If your knee keeps giving out, you may need physical therapy or medical intervention to restore joint stability.
6. Limited Range of Motion
Struggling with a limited range of motion for your knee?
Knee injuries, arthritis, bursitis, or meniscus tears can limit movement, making everyday activities more difficult.
If this is persistent, you may need a professional evaluation.
Pro-Tip: If you notice any of these symptoms—especially severe pain, knee buckling, or swelling that won’t go away—you should seek medical advice. Early diagnosis and treating knee pain proactively can help reduce knee pain and prevent further damage.
What Can I Do About It?
Conditions like meniscus tears, ligament injuries, or patellofemoral pain syndrome may require specialized treatment.
However, for mild discomfort or minor injuries, there are several self-care strategies that can help reduce pain and improve knee function.
1. Follow the RICE Method
The RICE method is a first-line approach for treating knee injuries and reducing swelling:
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Rest – Don’t put excessive strain on your knee joint and give it time to heal.
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Ice – Apply an ice pack for 15-20 minutes every few hours to reduce swelling and pain.
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Compression – Wrap your knee with an elastic bandage to provide support and minimize inflammation.
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Elevation – Keep your knee raised above your heart level to help reduce swelling.
2. Take Over-the-Counter Pain Relief
Medications like ibuprofen or naproxen can ease pain and reduce inflammation in the patellar tendon, quadriceps tendon, and knee joint.
Always follow instructions and consult a doctor if you use it long-term.
3. Try Gentle Stretching and Strengthening Exercises
Weak muscles around the knee can cause knee problems and lead to more discomfort. Strengthening knee exercises can improve joint stability and prevent knee pain.
Exercises to try:
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Quadriceps Stretch: Stand, grab one of your ankles, and pull your foot towards your glutes. Hold for 30 seconds and switch sides.
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Hamstring Stretch: Sit with one leg extended, reach for your toes, and hold for 30 seconds. Repeat on the opposite side.
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Straight Leg Raises: Lie down, keep one leg straight, and slowly lift it up to strengthen your thigh bone muscles.
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Wall Sits: Sit against a wall with knees bent at 90 degrees to build knee joint strength.
For individuals who find traditional strengthening exercises challenging or painful, Motive offers a therapy system designed to fortify the muscles surrounding the knee. This can provide a valuable alternative or supplement to traditional exercises, helping to improve knee stability and reduce discomfort.
4. Avoid Activities That Increase Your Pain
If certain movements cause sharp pain or burning pain, stop doing them.
Activities like running, jumping, and deep squats can make knee patellofemoral syndrome pain, patellar tendonitis, or unstable knee conditions worse. Try low-impact exercises like swimming or cycling that don’t trigger knee problems.
If your knee pain persists, worsens, or is accompanied by severe swelling or instability, see a sports medicine doctor or physical therapist to have a physical exam done and discuss further treatment options, including physical therapy, knee pads, or special shoe inserts, which are proven to help.
Take Control of Your Knee Pain with Motive
Knee pain when bending and straightening is a common issue, but that doesn’t mean you have to live with it.
Whether it’s patellofemoral pain syndrome, tendonitis, or arthritis, understanding the cause is the first step to relief.
Self-care, physical therapy, and strengthening exercises can reduce pain and improve knee function over time.
For those looking for an at-home solution, Motive is here to support your journey to recovery.
By targeting muscle weakness, the major contributor to knee pain, Motive strengthens the muscles around your knee joint, improving joint stability and mobility.
Don’t let knee pain hold you back. Start your journey today!
Learn more about Motive Knee and how it can get you back to doing what you love.
