Knees are like the body’s Swiss Army knife – they help us sit, stand, walk, run, jump and dance. But when they hurt, it’s hard to think about anything else.

Feeling a constant ache? Dealing with painful stiffness? Surprised by shooting pain? Each type of knee pain is unique, with a range of possible causes and treatment options.

But we’re here to walk you through the most common causes of knee pain, how your knee pain symptoms and pain location can help with a diagnosis, and when to see a doctor so you can find answers and get back to the activities you enjoy.

Causes of knee pain

Many adults will experience knee pain at some point in their lives. Generally, there are two types of knee pain: acute knee pain and chronic knee pain.

While there is some overlap, different types of knee pain are often associated with different underlying conditions.

Common causes of acute knee pain

Staying active is one of the best things you can do for your body, but sometimes unexpected knee injuries happen. Common causes of knee pain from injuries or overuse include:

  • Sprained or strained ligaments
  • Tendonitis
  • Tendon or meniscus tears
  • Stress fractures
  • Dislocations
  • Runner's or jumper’s knee

Common causes of chronic knee pain

Chronic knee pain is long-term discomfort, swelling or sensitivity in one or both knees. Pain is considered chronic if it’s been around 12 weeks or longer. It can be a constant ache or recurrent, meaning the pain may go away at times but regularly comeback.

The most common cause of chronic knee pain in adults is osteoarthritis, which is the arthritis due to normal age-related changes. Other chronic knee pain causes can include gout and rheumatoid arthritis. Very rarely, chronic knee pain may be caused by an infection in the knee bones or joints, or a tumor.

Knee pain symptoms by location

Being able to pinpoint the location of your knee pain is helpful for diagnosis and treatment, but first let’s look at what makes up the knee itself. The knee joint is formed by three main bones:

  • Tibia (shin bone)
  • Femur (thigh bone)
  • Patella (kneecap)

Each bone end is covered with a layer of cartilage that absorbs shock and protects the knee, allowing it to glide and slide in a smooth motion. And the bones are held together by muscles, ligaments and tendons.

As we mentioned earlier, osteoarthritis is one of the most common causes of chronic knee pain – and people can feel pain virtually anywhere in the joint. It’s a low-grade joint inflammation that is most common in people over 50 years old. Oftentimes, X-rays will show reduced cartilage and a person will experience less range of motion.

Aside from possible arthritis, there are some conditions that are commonly associated with pain in specific areas of the knee.

Pain on top or over your kneecap

Pain at the top of your knee near the thigh bone or over your kneecap, which can often be felt when walking down a flight of stairs, could be the result of:

  • Bursitis – Inflammation of the bursae (a fluid-filled sac that helps cushion joints) is often caused by repetitive motion or overuse, but an injury or an inflammatory condition like rheumatoid arthritis or gout can also cause bursitis.
  • Quadriceps tendonitis – Inflammation of the tendon that connects the quadriceps muscles in the front of the thigh to the top of the kneecap. This is typically related to repetitive use or a ligament strain.

Pain at the bottom of the knee

Pain at the bottom part of the knee can often be associated with the following conditions:

  • Osgood-Schlatter disease – A condition common in children in which the patellar tendons of the knee pull on the knee's growth plate during rapid growth spurts.
  • Patellar tendonitis – Inflammation of the tendon below the kneecap, also known as “jumper's knee”, that commonly occurs in athletes who jump or run.
  • Patellofemoral instability – A condition, once known as traumatic patellar dislocation. The patella rests in a groove formed by the femur. But it can shift partially (sublex) or completely (dislocate) out of the groove.

Pain on the inside of the knee (medial knee pain)

Pain on the inside of your knee, which is the portion of your knee closer to the center of your body, can occur for a number of different reasons, including:

  • Medial collateral ligament injury – Also known as an MCL tear, this type of knee injury is often caused by sudden turning or twisting motions in sports like skiing or basketball. It can also be caused by a direct blow to the outside of the knee or a severe inward bowing of the knee.
  • Medial meniscus tears – Usually a sport-related injury that happens when you forcefully twist or rotate your knee.

Pain on the outside of the knee (lateral knee pain)

Pain on the outside, or hip side, of your knee may be caused by:

  • Iliotibial band syndrome – A condition common in distance runners and cyclists where the strong band of tissues called the iliotibial band, or IT band, is injured.
  • Lateral collateral ligament injury – Also known as an LCL tear, this type of injury is most commonly caused by a direct blow to the inside of the knee or excessive outward bowing of the knee.
  • Lateral meniscus tear – When the cartilage on the knee is torn, often the result of excessive weight bearing and twisting knee motions.

Pain deep in the middle of the knee

Pain in the middle of your knee, including behind the kneecap, may be the result of the following conditions:

  • Anterior cruciate ligament tear – Also known as an ACL tear, this is an injury that can occur during sports, severe falls, a sharp pivot motion and work-related injuries.

Pain at the back of the knee

Pain at the back of your knee is commonly caused by things like:

  • Baker's cyst – A fluid-filled sac that occurs when excess synovial fluid flows through the back of the knee capsule (due to things like osteoarthritis or an injury of the meniscus).
  • Posterior cruciate ligament injury – Also known as a PCL tear, this usually occurs when the knee is directly hit during contact sports like football or rugby, or being in a car accident.

How to know if knee pain is serious

It is never a good idea to ignore knee pain that is severe or persistent. Make an appointment with a knee specialist or find an orthopedic urgent care near you if:

  • You can’t bear weight on your knee
  • Your knee buckles, clicks or locks
  • Your knee is deformed or swollen
  • You cannot flex your knee or have trouble straightening it
  • You have a fever, redness or warmth around the knee, or a lot of swelling
  • You have pain, swelling, numbness, tingling or discoloration below the knee
  • You have pain after three days of home treatment

Diagnosing knee pain

Scheduling an appointment with an orthopedic doctor is the best way to find out the underlying cause of your knee pain. During your appointment, your doctor will likely ask you questions about past injuries and your medical history to look for clues to what is causing your knee pain. They’ll also perform an exam by bending, straightening, rotating or pressing on the knee to feel for injury, and find out how well the knee moves and where the pain is. Your doctor may also request that you get an X-ray, MRI or other imaging tests to get a better picture of what’s going on inside your knee.

Knee pain relief and treatment options

If nagging knee pain has become an unwelcome part of your life. There are nonsurgical knee treatment options you can try to help you find relief from pain, including:

  • Staying active keeps your joints moving, which reduces stiffness and helps with weight loss to take pressure off your knees.
  • Over-the-counter pain relievers and injections for knee pain can be recommended by your doctor to help manage knee pain and reduce swelling.
  • Physical therapy to strengthen muscles and joints, and improve mobility. The best part is that you typically don’t need a doctor’s referral to start physical therapy, but it’s a good idea to talk with your insurance company to understand your coverage.
  • Orthobiologics is a treatment option that may help improve pain and restore function.

Knee replacement surgery

When other treatments have stopped working well or chronic knee pain has begun to impact your daily life, a knee replacement surgery can be a life-changing option to get you back to doing what you love.

It’s generally considered a safe procedure and has a high rate of success. The American Academy of Orthopedic Surgeons reports that more than 90% of modern knee replacements are still functioning well 15 years after surgery. But getting a knee replacement is a big decision. A good first step is to review the signs you might need a knee replacement and discuss options with an orthopedist.

Get help with knee pain

If your knee pain symptoms seem serious or are worsening, make an appointment with a knee specialist or find an orthopedic urgent care near you.

If you’ve been using home remedies to manage nagging knee pain, but it’s not improving, a great first step is making an appointment with a physical therapist. They’re experts in helping people heal after acute injuries, as well as those who’ve been dealing with chronic pain for weeks, months or even years.

Your physical therapist can work with you to create a personalized treatment plan based on your unique needs to help you get back to your favorite activities as soon as possible.