There are several reasons why your knee feels tight when bending. However, most of them are benign and you may be able to solve them at home.
More often than not, having a stiff knee is your body’s way of asking you for more movement, like in the case of a moviegoer’s knee.
But, depending on your associated symptoms, knee stiffness can also be a sign of a more challenging condition. Like rheumatoid arthritis or arthrofibrosis, for example.
Below is a list detailing 7 common causes of knee tightness when bending, including:
- Sitting for too long
- Runner’s knee
- Sprained ligaments
- Torn menisci
- Rheumatoid arthritis
- Stiff knee syndrome
7 causes of knee stiffness while bending
1) Too much sitting
In most healthy people, knee stiffness while bending is often due to a lack of movement.
Think about it. If you keep a door closed for a long time, the hinges get rusty. They will creak and get even stiffer over time.
But it’s not the hinges’ fault. They just haven’t been used for quite a while. After some oil, they’ll be as good as new.
A similar thing happens to our knees.
If we sit most of the day, the fluid within our joints stagnates. It becomes stiff, reducing our range of motion. Over time, this can make us prone to knee problems.
And, it’s so easy to reverse! Because, unlike hinges, our bodies have their own “oil”.
Doing movement breaks throughout the day will increase the blood flow in our joints. Thus, keeping them “oiled”. We left some tips on the “treatments” section to help you with this.
For further reading: 5 reasons why your knee hurts when sitting
2) Patellofemoral pain syndrome (PFPS)
Patellofemoral pain syndrome is a term that describes pain and stiffness around the kneecap. The symptoms tend to get worse with sitting, climbing stairs, or standing. (1)
This syndrome is also called “runner’s knee,” but don’t let that nickname deceive you. It’s also common in people that don’t play sports.
For example, does your knee feel stiff after going to the movies? That may be a sign of PFPS, as its other nickname is “moviegoer’s knee”.
There isn’t a clear consensus on what causes PFPS, but it’s believed to be a multifactorial issue.
In active people, the root cause is often inappropriate training. Your leg muscles may not be strong enough for your athletic discipline yet.
In sedentary people, the cause can be quadriceps muscle weakness due to lack of movement. Adding more physical activity to your day is like a magical solution to this.
This can help: Best exercises for treating runner’s knee
3) Ligament injuries
Ligaments connect bones to each other. They are strong, thick bands of tissue responsible for keeping our joints stable.
If they get sprained, the surrounding muscles will make the joint stiffer. This is a normal protective response to prevent further damage to the ligaments.
Here, the level of stiffness is often proportional to the severity of the injury. The healing time of a sprain depends on a few factors, but it can take from a few days to months.
If your stiffness is due to a sprain, it will improve once the ligament heals.
After a sprain, it’s normal to feel unstable. Wearing a knee brace on the affected leg can give you extra support and prevent future joint problems.
You’ll probably experience swelling or difficulty moving as well. The best thing you can do is have some patience and follow these 7 tips to heal a sprain as quickly as possible.
4) Meniscus tears
A meniscus is a C-shaped cartilage inside the knee and it helps cushion the joint. We have two in each knee – the medial and lateral menisci.
Now, a meniscal tear happens when a meniscus gets injured. This is common in athletes, people that squat or kneel frequently, and people with a history of ACL injuries. (2)
The stiffness comes from the same protective response described above. Our muscles restrict the mobility of the knee after a fresh meniscus tear. This avoids worsening the injury.
And also, the stiffness will improve once the meniscus tear heals.
Some meniscal tears can heal on their own. But whether yours can heal at home or not depends on the severity of the tear and which part of the meniscus is affected.
For some people, walking can promote the healing of meniscal tears. Others may have to rest and wear a knee brace to protect the meniscus.
In this case, it’s wise to see a doctor. They’ll perform a physical exam and request imaging tests to see the size and location of the tear. That way, you’ll know the best treatment plan for you.
5) Knee osteoarthritis
Knee osteoarthritis is an overuse injury that’s often diagnosed in people over 50 years old. (3)
This wear and tear of the knee joints can lead to severe pain, swelling, and a gradual loss of range of motion. One of the early symptoms is knee stiffness, mostly in the few hours after waking up.
Although it’s common in the elderly, recent studies have found other risk factors such as previous knee injuries and obesity. (3)
Meniscus tears have also been found to accelerate knee osteoarthritis.
Another risk factor is obesity.
Having a BMI >30 can increase the risk of developing knee osteoarthritis by 2–10 fold. (4)
And, according to research, several factors are responsible for this (4):
- The added weight accelerates the degeneration of the joints.
- The low-grade inflammation caused by obesity makes the joints prone to injury.
- If there’s any genetic predisposition to osteoarthritis, it will be accelerated due to obesity.
But, a 10% reduction in baseline body weight can have immense benefits on knee health.
This will help: Our evidence-based guide on knee osteoarthritis
6) Rheumatoid arthritis
Rheumatoid arthritis (RA) is a disease of the immune system.
The main symptom is joint swelling, stiffness, and pain. It can happen in any joint, but the most commonly affected are the hands, fingers, and one or both knees.
It’s more common in women than men. Having a family member with RA, cigarette smoking, and obesity are strong risk factors for developing this disease. (5)
Seeking treatment is key to preventing flare-ups and avoiding potential physical disability.
The treatment focuses on taking certain medications and doing physical therapy.
Early diagnosis is vital in rheumatoid arthritis. So, if you have joint swelling that comes and goes without apparent reason, please visit a rheumatologist.
7) Stiff knee syndrome
This is another name for “knee arthrofibrosis.” This joint condition happens when the body creates too much scar tissue after a knee injury or surgery.
It causes knee stiffness and pain, which sometimes can be worse than the symptoms from the original injury. Walking and standing make the symptoms worse. (6)
Most cases of arthrofibrosis occur after knee surgery.
Studies estimate it happens in ~10% of total knee joint replacement surgeries and up to 35% of ACL reconstruction surgeries. (6)
Some people have a genetic predisposition for this. But, there are ways to decrease the risk of developing this syndrome.
First, a good surgical technique. The surgeon must perform the surgery properly to reduce the risk of stiff knee syndrome. (6)
The second is physical therapy compliance. This will promote healing and prevent knee joint problems. (6)
Finally, have a healthy lifestyle after surgery. Focus on eating nutritious foods, sleeping, and reducing stress. They can prevent complications and boost recovery. (6)
Treatments to alleviate knee stiffness
Add more movement to your day with these ideas
- Walk a little more. This free app from the NHS, “Active 10,” can get you started.
- Choose one or two of these 12 home exercises. Do 2-3 sets of 10 reps a few times per week.
- If you take the elevator often, get off one floor up or down your destination. Use the stairs for the remaining floor.
Wear a knee brace
Knee braces are effective in moderate or severe soft tissue injuries, like ligament or meniscus tears. If your stiffness is due to a sprain or tear, wearing a knee brace may reduce some stiffness.
For further reading: What type of knee brace does your injury need?
Go to physical therapy
A physio will identify the cause of your stiffness and treat it with therapeutic exercises and other methods. They will help you recover from your knee injuries, too.
Need help finding a physical therapist in your area? We got you.
Why does my knee feel tight when I bend it?
Knee tightness when bending could be a sign that you need to move more. Or, it could be an early symptom of runner’s knee, osteoarthritis, or rheumatoid arthritis.
It could also be one of your body’s protective mechanisms to help heal a meniscus or ligament tear.
What causes a stiff knee after sitting?
Often, it’s a sign that you’ve been in the same position for too long. It can be a sign of patellofemoral pain syndrome as well.
How to ease pain and stiffness?
Identify the underlying cause of the symptoms first.
If you’re healthy, it could be a lack of movement. So, try adding more physical activity to your day.
But if you do physical activity, are injured, or have a health condition, visit a physical therapist. They’ll identify the root cause to ease the knee joint stiffness and pain.
Conclusion: Knee stiffness while bending
Knee joint stiffness can be due to several things. Most of them can improve with some movement and physical therapy.
But, if you have knee pain around the knee or other symptoms, visit a doctor. It’s key to identify the root cause of your symptoms to treat them properly.
- Bump JM, Lewis L. Patellofemoral Syndrome. [Updated 2021 May 8]. Statpearls. Retrieved on November, 2021 from: https://www.ncbi.nlm.nih.gov/books/NBK557657/
- Raj MA, Bubnis MA. Knee Meniscal Tears. [Updated 2021 Jul 21]. Statpearls. Retrieved on November, 2021 from: https://www.ncbi.nlm.nih.gov/books/NBK431067/
- Losina, Elena et al. “Lifetime risk and age at diagnosis of symptomatic knee osteoarthritis in the US.” Arthritis care & research vol. 65,5 (2013): 703-11. doi: 10.1002/acr.21898
- Griffin, Timothy M, and Farshid Guilak. “Why is obesity associated with osteoarthritis? Insights from mouse models of obesity.” Biorheology vol. 45,3-4 (2008): 387-98.
- Chauhan K, Jandu JS, Goyal A, et al. Rheumatoid Arthritis. [Updated 2021 Oct 7]. Statpearls. Retrieved on November, 2021 from: https://www.ncbi.nlm.nih.gov/books/NBK441999/
- Usher, Kayley M et al. “Pathological mechanisms and therapeutic outlooks for arthrofibrosis.” Bone research vol. 7 9. 26 Mar. 2019, doi: 10.1038/s41413-019-0047-x