Runner’s Knee: Symptoms, Causes, Treatment

Runner’s knee, or patellofemoral pain (PFP) syndrome, causes pain around and behind your kneecap from repeated knee movements. It commonly affects runners who frequently stress their knees.

Runner’s knee is an overuse injury that causes pain around and behind your kneecap (patella). People who jog or run frequently often get PFP syndrome, hence its nickname. Still, anyone who repeatedly bends and straightens their knee can develop runner’s knee.

Runner’s knee is a common cause of knee pain and usually improves with self-care and physical therapy. However, nearly 40% of people with this condition may still have persistent symptoms.

Traumatic knee injuries, like banging your knee or tearing a ligament, happen suddenly. However, runner’s knee develops slowly. You might first notice discomfort around or behind your knee that worsens with activities such as climbing stairs, running, or squatting.

Other runner’s knee symptoms include:

• Cracking or popping sounds from your knees
• Pain in the front of your knee after sitting for prolonged periods with bent knees (e.g., on an airplane)
• Pain that occurs when you change your activity level or intensity, equipment, or surface (e.g., running on grass instead of the road)

Your kneecap glides freely, moving back and forth as you bend your leg, unlike many other bones.

PFP syndrome happens if something throws your kneecap off its track. A misaligned kneecap then rubs against your thigh bone (femur), resulting in pain.

Overuse is one of the most common causes of runner’s knee. Repeatedly making the same movements, like bending and straightening your legs while running, places stress on your knees.

Several other factors, such as imbalance, muscle weakness, and tightness, can drive the kneecap off your track, said Kevin Vincent, MD, PhD, chair of the Department of Physical Medicine and Rehabilitation at the University of Florida.

In other cases, the issue starts from the ground up. Flat feet affect how your foot strikes the ground, which might throw your knee off its track. Weak muscles that stabilize your lower leg can also contribute to knee pain.

Risk Factors

People who run competitively or long distances, which places a lot of stress on the knees, have a high rate of PFP syndrome.

Running is essentially a series of around 1,700 one-legged squats per mile, said Dr. Vincent. This is a lot of bone-on-bone contact if your knee is misaligned.

People who play sports that involve running and jumping, such as basketball and soccer, have a high risk of runner’s knee. Certain exercises, like deep squats, might also contribute to this type of knee pain, said Kevin Plancher, MD, an orthopedic surgeon based in New York.

Women are twice as likely to develop runner’s knee as men. The shape of the pelvis and the angle at which the quad muscles and knees align might be the culprits, said Christopher Ka​eding, MD, an orthopedic surgeon at The Ohio State University Wexner Medical Center.

Still, the exact causes are not entirely clear.

See a doctor if you have knee pain that interferes with how you walk or run or worsens with exercise. Early diagnosis and treatment help ease runner’s knee as quickly as possible.

Although rare, untreated runner’s knee can permanently damage knee cartilage.

There’s no single test that diagnoses PFP syndrome. A doctor will likely ask about your symptoms and perform a physical exam. They might press on your knee to check for tenderness and watch as you move your legs.

A doctor may order imaging tests to rule out other knee injuries, such as:

• CT scan: Uses multiple X-rays to create detailed bone images
• MRI: Provides images of ligaments, muscles, and tendons
• X-rays: Show pictures of your knee to rule out bone damage

Other illnesses and injuries may cause knee pain, such as a kneecap fracture or osteoarthritis. Some people, especially older adults, can have osteoarthritis and runner’s knee at the same time.

Treatment helps relieve pain and improve your range of motion and strength. 

At-home treatments can ease mild cases of runner’s knee. These include taking non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen, and using the RICE method.

The RICE method includes:

• Rest: Limit how much weight you place on your knee.
• Ice: Apply an ice pack to your knee for 20 minutes. Repeat several times daily.
• Compression: Some people use knee braces or tape to stabilize their knee.
• Elevation: Keep your knee raised higher than your heart while lying down.

Most people, even runners, with PFP syndrome can safely keep moving, said Dr. Vincent. You might just have to cut back a little until your alignment and strength improve. You can try inserting orthotics into your shoes to temporarily relieve pain.

Runner’s Knee Exercises

Physical therapy is usually the first line of treatment for runner’s knee if self-care is not enough, said Dr. Kaeding.

A physical therapist will assess your strength and alignment. They will then tailor a program of exercises to improve your range of motion and strengthen your muscles.

Try these exercises to strengthen your hip and thigh muscles:

• Leg extensions: Sit on a chair with your legs bent at 90 degrees. Stretch one leg and lift it in front of you, then slowly bend and lower it. Repeat 10–20 times, then switch sides. Aim for three sets on each leg.
• Side leg raises: Lie on your side with legs stretched out. Place one hand on the ground for stability and the other under your head. Lift your top leg upward, hold for a few seconds, then lower it. Repeat 10–20 times, switch sides, and do three sets on each leg.
• Wall sits: Stand with your back against a wall, feet shoulder-width apart and about two feet in front. Slide down the wall until your legs form a 90-degree angle. Hold for 20–30 seconds and repeat three times.

Other physical therapy exercises for runner’s knee include stretching and gait retraining. Stretching helps improve alignment and ease knee pain. You can try stretching your calves, glutes, and thighs.

Gait retraining changes how you run or walk to decrease the load on your knees. Take shorter, faster steps to take pressure off your knees. You can count the number of steps you take per minute while you run. It’s best to speed your gait up 5-10% if you get a number below 160, said Dr. Vincent.

It typically takes several months or longer to treat runner’s knee. Physical therapy is rarely ineffective. In these cases, surgery can realign your kneecap or remove damaged tissue to lessen knee pain.

Runner’s knee can return if you resume normal activity without regularly strengthening and stretching muscles. It’s best to protect your knees from overuse injuries by taking preventive measures.

Here are some ways to prevent runner’s knee:

• Cross-train: These are low-intensity activities other than running, like swimming or yoga, that help strengthen your muscles, said Dr. Plancher.
• Exercise and stretch: Consider working some core and hip exercises into your routine, especially if you regularly run or play other sports. Make sure that you stretch before and after the activity.
• Invest in your shoes: Pick up a good pair of shoes specifically designed for your sport, said Dr. Kaeding.
• Maintain your body weight: Excess body weight places stress on your joints, including your knees.
• Start slowly: Be careful about starting any new exercise program or ramping up an existing one to protect your knees. Increase your mileage or time spent doing any single activity by no more than 10% per week.
• Warm-up: Take time to warm your body up before activity. This helps activate and engage your muscles.