Why Does Your Knee Pain? 12 Common Causes and When to See a Doctor

Why Does Your Knee Hurt? 12 Common Causes and When to See a Doctor

Knee pain can turn simple everyday actions—like walking, climbing stairs, or just standing up—into a real struggle. Sometimes it comes on suddenly after a fall or injury, and other times it creeps in slowly from wear and tear, arthritis, or other health issues. While resting might ease the discomfort for some, ongoing pain, swelling, or stiffness could be a sign of something more serious that needs a doctor’s attention. In this blog, we’ll walk you through 12 common reasons why your knee might be hurting, the symptoms to watch for, and when it’s time to get professional help.

Common Causes of Knee Pain

1. Ligament Injuries

Your knee is held together by four main ligaments that keep it stable. When one of these ligaments gets injured, it can cause pain, swelling, and make it hard to walk. These injuries often happen suddenly—especially during sports that involve a lot of jumping, twisting, or quick direction changes like football, basketball, or skiing.

ACL (Anterior Cruciate Ligament) Tear:

This is one of the most common and painful knee injuries. It usually happens when you suddenly stop or change direction, often during high-energy sports. You might hear a “pop” at the moment it happens, followed by swelling and a feeling that your knee can’t hold you up properly.

MCL (Medial Collateral Ligament) Tear:

This injury tends to occur when there's a direct blow to the outside of the knee, pushing it inward. It causes pain and swelling on the inner side of your knee and is common in contact sports like football or hockey.

PCL (Posterior Cruciate Ligament) Tear:

Less common than ACL injuries, this one often results from falling hard on a bent knee or a front-on collision, like when your knee hits the dashboard in a car accident. You may feel stiffness, swelling, and some difficulty moving your knee.

LCL (Lateral Collateral Ligament) Tear:

This type of injury is rare but can happen if your inner knee takes a hard hit. It usually causes pain on the outer side of the knee and may make your knee feel unstable, like it could give way.

2. Meniscus Tear

The meniscus is like a soft cushion in your knee—it helps absorb shocks and keeps things moving smoothly. But sometimes, a sudden twist, deep squat, or lifting something heavy can tear this cushion. When that happens, you might feel pain, notice swelling, or find it hard to bend or straighten your knee. Some people even say their knee feels like it’s locking or catching, which can make everyday movement really uncomfortable. Meniscus tears are pretty common, especially among athletes and older adults whose knees have seen a lot of wear and tear over time.

3. Tendonitis

Tendonitis happens when the tendons—those strong cords that connect your muscles to your bones—get irritated or inflamed from overuse. It’s a common issue for people who do a lot of running, jumping, or cycling, especially without proper rest or stretching.

• Patellar Tendonitis (Jumper’s Knee): This type usually causes pain just below the kneecap. It's common in athletes who jump a lot, like basketball or volleyball players. Even simple things like going up stairs or kneeling can start to hurt.
  

• Quadriceps Tendonitis: This affects the tendon just above the kneecap. It can be caused by overdoing leg exercises, skipping warm-ups, or having muscle imbalances. The pain tends to flare up during physical activity and ease off when you're resting.

4. Bursitis

Bursitis happens when the small, fluid-filled cushions in your knee—called bursae—get irritated or swollen. These little sacs help reduce friction between your bones, muscles, and tendons, making movement smoother. But if you kneel a lot, put pressure on your knees for long periods, or take a hard hit to the area, those sacs can become inflamed.

You might notice swelling, warmth, or tenderness around the knee, and it could hurt more when you move. This condition is especially common in people who kneel often for work—like plumbers, carpet installers, or gardeners.

5. Osteoarthritis

Osteoarthritis is the most common type of arthritis that affects the knee. It happens when the smooth cartilage that cushions your knee joint slowly wears down over time. As a result, you might feel pain, stiffness, and find it harder to move your knee like you used to.

This condition usually gets worse gradually, especially for people over 50, those who’ve had knee injuries before, or anyone carrying extra weight. You might notice your knee feels stiff in the morning, swells up sometimes, and simple activities like walking or climbing stairs become more difficult. Cold weather or doing more physical activity can make the pain feel even worse.

6. Rheumatoid Arthritis

Rheumatoid arthritis is different from osteoarthritis because it’s an autoimmune condition. This means your body’s immune system mistakenly attacks the lining of your knee joint, causing ongoing inflammation. This leads to pain, stiffness, and over time, the joint can become deformed.

Usually, rheumatoid arthritis affects both knees, and people often go through flare-ups where the pain and swelling suddenly get worse. If it’s not treated, the damage to the knee can become serious, making it hard to move around comfortably.

7. Gout and Pseudogout

Gout happens when too much uric acid builds up in the knee joint, forming tiny crystals. This causes sudden, intense pain, along with redness and swelling. Gout attacks can come out of nowhere and often get worse at night, making it hard to sleep.

Pseudogout is similar but happens because of calcium crystals collecting in the knee. It usually affects older people and causes knee pain and stiffness that comes on more slowly, not as suddenly as gout does.

8. Knee Infections (Septic Arthritis)

Sometimes, bacteria can get into the knee joint, causing a serious infection called septic arthritis. This leads to intense pain, swelling, warmth, and makes it hard to move your knee. Infections can happen if you have an open wound near the knee, after surgery, or if bacteria travel through your bloodstream. This condition needs urgent medical care because if left untreated, it can cause permanent damage to the joint. You might also have a fever and chills, which are signs that the infection is serious.

9. Obesity and Excess Weight

Carrying extra weight can really put a lot of strain on your knees. This added pressure wears down the cartilage that cushions your joints, increasing the chance of developing osteoarthritis. The good news is that even losing a little weight can take a big load off your knees, easing the pain and helping protect your joints from further damage. Plus, being overweight can cause inflammation that makes your knees hurt, even if you don’t have arthritis.

10. Flat Feet and Poor Alignment

If your feet don’t have the right arch—like flat feet or very high arches—it can throw off the way your knees line up. Over time, this misalignment puts extra strain on your knees. The way you stand or walk also plays a role; poor posture or walking habits can add uneven pressure on your knee joints. People with flat feet often feel pain not just in their knees, but sometimes in their hips and lower back too, especially after standing or walking for a long time.

11. Muscle Weakness and Lack of Flexibility

Your knee relies a lot on the muscles around it—like those in your thighs and calves—to keep it stable and supported. When these muscles are weak, your knee has to work harder, which can lead to pain or even injuries. On the other hand, tight muscles can tug on your knee and cause discomfort too. Doing regular stretches and exercises to strengthen these muscles can go a long way in keeping your knees steady and pain-free, especially if you stay active.

12. Overuse and Repetitive Strain

When you use your knees a lot—like kneeling for long periods, standing all day, or doing the same movements repeatedly (think running or cycling)—it can wear down the knee joint over time. This kind of strain often causes ongoing pain, swelling, and issues like runner’s knee. Overuse injuries happen a lot in athletes and people whose work involves constant knee movement. That’s why giving your knees enough rest and taking care of them with proper exercises is really important to keep them healthy.

Symptoms That Often Come Along with Knee Pain

Knee pain usually doesn’t come alone—it often brings other signs that can help figure out what’s going on. Here are some common symptoms to watch for:

• Swelling and Redness: This can mean there’s inflammation from things like arthritis, bursitis, or an injury. If your knee suddenly swells up, it might be a sign of something more serious, like a ligament tear or an infection.
  

• Stiffness and Trouble Moving: If you find it hard to bend or straighten your knee, it could be because of arthritis, a meniscus injury, or just not moving enough.
  

• Popping or Clicking Sounds: Sometimes your knee might pop with a ligament injury, or make grinding noises if the cartilage is wearing down or if arthritis is present.
  

• Weakness or Feeling Like Your Knee Could Give Out: If your knee feels unstable or wobbly, it might be due to ligament damage, weak muscles, or nerve problems.
  

• Locking or Catching Sensation: If your knee gets stuck in a bent position or feels like it’s catching, it could be a torn meniscus or loose cartilage causing the problem.
  

• Sharp or Dull Pain: Sharp pain usually comes from sudden injuries like ligament tears or fractures. On the other hand, dull and ongoing pain might point to arthritis or overuse injuries.

When Should You See a Doctor for Knee Pain?

If your knee pain is ongoing, really bad, or comes with other worrying signs, it’s a good idea to check in with a doctor. Here are some situations when you should definitely see a healthcare professional:

• If your knee suddenly swells up a lot without any clear injury.
  

• If you can’t put weight on your leg or feel like your knee might give out.
  

• If your knee looks misshapen or has big bruises after an accident.
  

• If the pain and stiffness don’t get better even after resting or trying home remedies.
  

• If you notice signs of infection like fever, warmth, or redness around your knee.
  

• If the pain gets worse slowly over time and starts to interfere with your everyday life—this might mean arthritis or another long-term problem.

Consult Today

Knee pain can make even the simplest tasks feel difficult, but the right care can help you find relief and regain mobility. If your symptoms are persistent, worsening, or affecting your daily routine, seeking medical attention is the next step. Dr. Anil Arora provides thorough evaluations and treatment options suited to your condition, from managing joint inflammation to addressing injuries and long-term concerns. Schedule a consultation with Dr. Anil Arora to discuss your knee pain and take a step toward better movement and comfort.