Pain is the first symptom of patellar tendinitis, usually between your kneecap and where the tendon attaches to your shinbone (tibia).

Initially, you may only feel pain in your knee as you begin physical activity or just after an intense workout. Over time, the pain worsens and starts to interfere with playing your sport. Eventually, the pain interferes with daily movements such as climbing stairs or rising from a chair.

For knee pain, try self-care measures first, such as icing the area and temporarily reducing or avoiding activities that trigger your symptoms.

Call your doctor if your pain:

• Continues or worsens
• Interferes with your ability to perform routine daily activities
• Is associated with swelling or redness about the joint

Patellar tendinitis is a common overuse injury, caused by repeated stress on your patellar tendon. The stress results in tiny tears in the tendon, which your body attempts to repair.

But as the tears in the tendon multiply, they cause pain from inflammation and weakening of the tendon. When this tendon damage persists for more than a few weeks, it's called tendinopathy.

A combination of factors may contribute to the development of patellar tendinitis, including:

• Physical activity. Running and jumping are most commonly associated with patellar tendinitis. Sudden increases in how hard or how often you engage in the activity also add stress to the tendon, as can changing your running shoes.
• Tight leg muscles. Tight thigh muscles (quadriceps) and hamstrings, which run up the back of your thighs, can increase strain on your patellar tendon.
• Muscular imbalance. If some muscles in your legs are much stronger than others, the stronger muscles could pull harder on your patellar tendon. This uneven pull could cause tendinitis.
• Chronic illness. Some illnesses disrupt blood flow to the knee, which weakens the tendon. Examples include kidney failure, autoimmune diseases such as lupus or rheumatoid arthritis and metabolic diseases such as diabetes.

If you try to work through your pain, ignoring your body's warning signs, you could cause increasingly larger tears in the patellar tendon. Knee pain and reduced function can persist if you don't tend to the problem, and you may progress to the more serious patellar tendinopathy.

To reduce your risk of developing patellar tendinitis, take these steps:

• Don't play through pain. As soon as you notice exercise-related knee pain, ice the area and rest. Until your knee is pain-free, avoid activities that put stress on your patellar tendon.
• Strengthen your muscles. Strong thigh muscles are better able to handle the stresses that can cause patellar tendinitis. Eccentric exercises, which involve lowering your leg very slowly after extending your knee, are particularly helpful.
• Improve your technique. To be sure you're using your body correctly, consider taking lessons or getting professional instructions when starting a new sport or using exercise equipment.

During the exam, your doctor may apply pressure to parts of your knee to determine where you hurt. Usually, pain from patellar tendinitis is on the front part of your knee, just below your kneecap.

Imaging tests

Your doctor may suggest one or more of the following imaging tests:

• X-rays. X-rays help to exclude other bone problems that can cause knee pain.
• Ultrasound. This test uses sound waves to create an image of your knee, revealing tears in your patellar tendon.
• Magnetic resonance imaging (MRI). MRI uses a magnetic field and radio waves to create detailed images that can reveal subtle changes in the patellar tendon.

Doctors typically begin with less invasive treatments before considering other options, such as surgery.

Medications

Pain relievers such as ibuprofen (Advil, Motrin IB, others) or naproxen sodium (Aleve, others) may provide short-term relief from pain associated with patellar tendinitis.

Therapy

A variety of physical therapy techniques can help reduce the symptoms associated with patellar tendinitis, including:

• Stretching exercises. Regular, steady stretching exercises can reduce muscle spasm and help lengthen the muscle-tendon unit. Don't bounce during your stretch.
• Strengthening exercises. Weak thigh muscles contribute to the strain on your patellar tendon. Exercises that involve lowering your leg very slowly after extending it can be particularly helpful, as can exercises that strengthen all of the leg muscles in combination, such as a leg press.
• Patellar tendon strap. A strap that applies pressure to your patellar tendon can help to distribute force away from the tendon and direct it through the strap instead. This may help relieve pain.
• Iontophoresis. This therapy involves spreading a corticosteroid medicine on your skin and then using a device that delivers a low electrical charge to push the medication through your skin.

Surgical and other procedures

If conservative treatments don't help, your doctor may suggest other therapies, such as:

• Corticosteroid injection. An ultrasound-guided corticosteroid injection into the sheath around the patellar tendon may help relieve pain. But these types of drugs can also weaken tendons and make them more likely to rupture.
• Platelet-rich plasma injection. This type of injection has been tried in some people with chronic patellar tendon problems. Studies are ongoing. It is hoped the injections might promote new tissue formation and help heal tendon damage.
• Oscillating needle procedure. This outpatient procedure is performed using local anesthesia. Your doctor uses ultrasound imaging to guide a small oscillating needle that cuts away the damaged area while sparing healthy tendon. This is a relatively new procedure, but results have shown promise.
• Surgery. In rare cases, if other treatments fail, your doctor might suggest surgical debridement of the patellar tendon. Some procedures can be done through small incisions around your knee.

If your knee hurts, consider the following:

• Pain relievers. Over-the-counter medications such as ibuprofen and naproxen sodium may provide short-term pain relief.
• Avoid activity that causes pain. You may need to practice your sport less often or temporarily switch to a lower impact sport. Working through pain can further damage your patellar tendon.
• Ice. Apply ice after activity that causes pain. Place ice in a plastic bag and wrap the bag in a towel. Or try an ice massage. Freeze water in a plastic foam cup and hold the cup as you apply the ice directly to your skin.

If you have knee pain during or after physical activity that doesn't improve with ice or rest, see your doctor. After an exam, your doctor may refer you to a sports medicine specialist.

Here's information to help you get ready for your appointment.

What you can do

• List your symptoms and when they began.
• Write down key medical information, including other conditions you have and medications and supplements you take.
• Log your typical daily activity, including the length and intensity of sports practice or other exercise. Note if you've recently changed your activity, how hard or often you work out, or your equipment, such as running shoes.
• Note any recent injuries that may have damaged your knee joint.
• Write down questions to ask your doctor to help you make the most of your time together.

Below are some basic questions to ask a doctor who is examining you for possible patellar tendinitis. If additional questions occur to you, don't hesitate to ask.

• What is the most likely cause of my signs and symptoms?
• Do I need tests?
• What treatment do you recommend?
• With treatment, will I be able to play my sport and how long will treatment take?
• What exercise can I safely do while healing, if any?
• What self-care measures should I take?
• Should I see a specialist?

What to expect from your doctor

Your doctor is likely to ask you questions, including:

• Are your symptoms getting worse?
• How severe is your pain?
• Does your pain occur before, during or after your workouts — or is it constant?
• Is the pain associated with knee swelling, locking or buckling?
• Are your symptoms affecting your ability to exercise or to walk up stairs or do other activities?
• Have you tried at-home treatments? Has anything helped?