Patellofemoral Pain Syndrome (Runner's Knee): Symptoms, Causes, and Treatment
Updated: 14 hours ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 30, 2026
Patellofemoral pain syndrome, commonly called runner's knee, is pain at the front of the knee around the kneecap (patella) [1]. It is most common in runners and athletes who play running-and-jumping sports, and in teens and young adults [1]. Pain typically worsens with stairs, kneeling, squatting, or sitting long with a bent knee [1]. It is linked to overuse, muscle imbalances, knee injury, and knee surgery [1]. Most cases improve with rest, ice, over-the-counter pain relievers, and physical therapy [1] [2]; persistent cases may need braces, taping, orthotics, or rarely arthroscopy or realignment surgery.
Quick Answer
Patellofemoral pain syndrome is pain at the front of the knee, around the kneecap, sometimes called runner's knee because it is common in people who run or jump [1]. The dull ache worsens with stairs, kneeling, squatting or prolonged sitting [1]. Most cases improve with rest, ice and pain relievers, while persistent cases often respond to physical therapy [1]. Surgery is rarely needed.
What the research says
Hip plus knee strengthening reduces pain and improves activity. A 2018 systematic review and meta-analysis of 14 trials with 673 participants found that hip and knee strengthening lowered pain (mean difference, −3.3; 95% CI, −5.6 to −1.1) and improved activity compared with no training or placebo, and reduced pain more than knee strengthening alone (mean difference, −1.5), with results maintained beyond the treatment period (Nascimento et al., J Orthop Sports Phys Ther, 2018).
Adding hip exercises beats knee exercises alone. A 2025 meta-analysis of 6 randomized trials with 241 patients (96.3% women) found that hip and knee strengthening improved pain (SMD −1.29) and functional activity (SMD 0.99) more than knee strengthening alone, with no significant difference in muscle strength (Halabi et al., Musculoskeletal Care, 2025).
Stick with rehabilitation even if early progress is slow. In 151 adolescents aged 10-14 with patellofemoral pain, those who felt improved at 4 weeks were more likely to be improved at 52 weeks (RR 1.26, 95% CI 1.06-1.50), yet 73% of those with no improvement at 4 weeks reported improvement by 52 weeks (Rathleff et al., Orthop J Sports Med, 2024).
Research summaries are based on article abstracts retrieved from PubMed.
What Is Patellofemoral Pain Syndrome?
Patellofemoral pain syndrome is pain at the front of the knee, around the kneecap [1]. The kneecap is also known as the patella [1].
The name refers to the joint where the kneecap (patella) meets the thigh bone (femur). In a healthy knee, the kneecap sits in a groove in the thigh bone and slides as the knee moves; in patellofemoral pain syndrome, something affects how the kneecap moves [5]. It usually develops over time and can affect one knee or both [5].
The condition is sometimes called runner's knee. It is more common in people who run and who play sports that involve running and jumping [1].
The knee pain often increases when running, walking up or down stairs, sitting for long periods, or squatting [1]. Simple treatments, such as rest and ice, often help [1]. But sometimes patellofemoral pain needs physical therapy [1].
Key fact | Detail |
|---|---|
What it is | Pain at the front of the knee, around the kneecap (patella) |
Common name | Runner's knee |
Typical pain | A dull, aching pain in the front of the knee |
Who gets it | More common in runners and athletes who run and jump; typically affects teens and young adults |
First-line treatment | Rest, ice, and simple pain relievers; physical therapy when needed |
What Are the Symptoms?
Patellofemoral pain syndrome usually causes a dull, aching pain in the front of the knee [1]. The condition tends to flare during activities that load the kneecap.
The ache can turn sharp or stabbing, and pain is especially common when going downhill or down stairs [5]. Some people also hear or feel cracking or popping in the knee [5].
Pain trigger | Why it matters |
|---|---|
Walking up or down stairs | Stair climbing loads the patellofemoral joint and increases the pain |
Kneeling or squatting | Bending the knee under load irritates the area under the kneecap |
Sitting with a bent knee for long periods | Prolonged flexion increases discomfort; sometimes called the "theater sign" pattern |
Running | The activity most associated with this condition |
Symptoms can also flare after changing the playing or training surface or wearing new or different shoes during activity [5].
When should you see a doctor about runner's knee?
Call your healthcare provider if the knee pain doesn't improve within a few days or if it gets harder to move the knee [1].
Pain that persists beyond a few days despite rest, or knee pain that limits your ability to move the joint, deserves a professional evaluation to identify the true cause and guide treatment.
Sign | Action |
|---|---|
Knee pain not improving within a few days | Call your healthcare provider |
Increasing difficulty moving the knee | Call your healthcare provider promptly |
What Causes Patellofemoral Pain Syndrome?
Patellofemoral pain syndrome can have several causes. The medical literature links it with four main factors.
Overuse. Running or jumping sports put repeated stress on the knee joint, which can cause irritation under the kneecap [1].
Muscle imbalances or weaknesses. Patellofemoral pain can occur when the muscles around the hip and knee don't keep the kneecap in line [1]. Moving the knee inward during a squat has been linked to patellofemoral pain [1].
Injury. Trauma to the kneecap, such as when the kneecap gets out of place or breaks, has been linked to patellofemoral pain syndrome.
Surgery. Knee surgery can increase the risk of patellofemoral pain [1]. This is especially true of repair to the anterior cruciate ligament (ACL) using one's own patellar tendon as a graft [1].
Other possible causes include weak or tight muscles around the knee, a sudden increase in activity level or training intensity, running or jumping with a hard strike pattern, and the natural shape of the knee [5].
Cause | Mechanism |
|---|---|
Overuse | Repeated stress on the knee joint from running or jumping causes irritation under the kneecap |
Muscle imbalances or weaknesses | Hip and knee muscles don't keep the kneecap in line; inward knee movement during squats is linked to the pain |
Injury | Trauma such as a kneecap that gets out of place or breaks |
Surgery | Knee surgery raises risk, especially ACL repair using the person's own patellar tendon as a graft |
What Are the Risk Factors?
Three factors raise the risk of developing patellofemoral pain.
Risk factor | Details |
|---|---|
Age | Typically affects teens and young adults; arthritis is more often to blame for knee problems in older people [1] |
Sex | Women are twice as likely as men to develop patellofemoral pain, possibly because women have wider pelvises, which increases the angle at which the bones in the knee joint meet [1] |
Certain sports | Running and jumping sports put extra stress on the knees, especially when adding more training [1] |
People who do physical work and adults ages 20 to 40 are also more likely to develop it [5]. Without diagnosis and treatment, it usually gets worse over time and can put extra stress on joints such as the hips and ankles [5].
Can It Be Prevented?
Sometimes knee pain just happens. But certain steps may help prevent the pain [1].
Prevention step | How it helps |
|---|---|
Build strength | Strong leg and hip muscles help keep the knee balanced during activity; avoid deep squatting during weight training [1] |
Move safely | Ask a physical therapist about exercises to jump, run, and turn correctly; strengthening the outer hip muscles helps keep the knee from caving inward when squatting, landing from a jump, or stepping down [1] |
Lose excess pounds | Losing weight relieves stress on the knees [1] |
Warm up | Warm up with about five minutes of light activity before running or other exercise [1] |
Stretch | Gentle stretching promotes flexibility [1] |
Build up slowly | Don't suddenly increase your workouts [1] |
Mind your shoes | Wear shoes that fit well and are designed for the activity [1] |
It also helps not to play through knee pain, to give your body time to rest and recover, and to cool down and stretch after activity [5].
How Is Patellofemoral Pain Syndrome Diagnosed?
Your healthcare provider might ask about your history of knee problems, press on your knee, and move your leg into a variety of positions [2]. This physical exam is the foundation of diagnosis [2].
The provider may also watch you walk, run, jump or squat [5].
Sometimes imaging tests can help find the cause of knee pain [2].
Imaging test | What it shows | Limitations |
|---|---|---|
X-rays | Show bones well [2] | Not as good for viewing soft tissues [2] |
CT scans | Show bones and soft tissues | Much higher dose of radiation than plain X-rays |
MRI | Detailed images of bones and soft tissues, such as the knee ligaments and cartilage, using radio waves and a strong magnetic field [2] | Costs much more than X-rays, CT scans, or ultrasounds [2] |
Ultrasound | Uses soundwaves to show images of muscles and tendons [2] | Less detail on bone structure |
How Is Patellofemoral Pain Syndrome Treated?
Treatment of patellofemoral pain often begins with simple measures [2]. Rest the knee as much as possible, and try not to do things that increase the pain, such as climbing stairs, kneeling, or squatting [2].
Most people need a month or two to recover [5].
Medicines
If needed, take over-the-counter pain relievers. These include acetaminophen (Tylenol, others), ibuprofen (Advil, Motrin IB, others), and naproxen sodium (Aleve) [2]. Do not take them for more than 2 to 3 weeks [2].
Another trusted source advises not taking them for more than 10 days in a row without talking to your provider [5].
Physical Therapy
A physical therapist might suggest several approaches.
Therapy | How it helps |
|---|---|
Rehabilitation exercises | Strengthen the muscles that support the knees and keep parts of the leg in line; a main goal is keeping the knee from moving inward while squatting [2] |
Supportive braces | Knee braces or arch supports may improve pain [2] |
Taping | A physical therapist may show you how to tape your knee to reduce pain and make it easier to exercise [2] |
Icing | Icing your knee after exercise might be helpful [2] |
Orthotics | Custom-made or ready-made shoe inserts might take stress off the knee [2] |
Knee-friendly sports | During recovery, stick to sports easier on the knees, such as bicycling or swimming [2] |
Surgical and Other Procedures
If simple treatments don't relieve pain, a healthcare provider might suggest one of two procedures.
Arthroscopy. During this procedure, a surgeon inserts a pencil-thin device into the knee through a tiny cut in the skin. The device, called an arthroscope, contains a camera lens and a light [2]. Tools to repair the problem can be inserted through other small cuts in the skin [2].
Realignment. In more-severe cases, a surgeon may need to operate on the knee to fix the angle of the kneecap or relieve pressure on the cartilage [2].
Procedure | What happens | When it's considered |
|---|---|---|
Arthroscopy | A pencil-thin camera and light (arthroscope) inserted through a tiny cut; repair tools inserted through other small cuts [2] | If simple treatments don't relieve pain |
Realignment | Surgery to fix the angle of the kneecap or relieve pressure on the cartilage [2] | More-severe cases |
How should you prepare for a runner's knee appointment?
You might start by seeing your primary care provider. Or you might be referred to a physical medicine and rehabilitation specialist (also known as a physiatrist), a physical therapist, an orthopedic surgeon, or a sports medicine specialist [2].
Because appointments can be brief, it's a good idea to be prepared.
What You Can Do
Before your appointment, make a list of the following.
Take a family member or friend along, if possible, to help you remember the information you're given [2]. Also, if you've had X-rays or other imaging tests of your knees, try to bring copies of them to your appointment [2].
Questions to Ask
Question | What it helps you understand |
|---|---|
What's likely causing my knee pain? | Your most probable diagnosis |
What are other possible causes? | Alternative explanations |
What tests do I need? | Next diagnostic steps |
Is my condition likely temporary or chronic? | Expected course of the condition |
What's the best course of action? | The treatment plan |
Do I need to restrict my activities? | Activity limits during recovery |
Should I see a specialist? | Referral needs |
Are there brochures or other printed material I can have? What websites do you recommend? | Reliable educational materials |
Ask any other questions you have.
What to Expect From Your Doctor
Your doctor is likely to ask how you would describe your knee pain, where exactly it hurts, what activities improve or worsen your symptoms, whether you've recently started exercising or exercising more, and what home treatments you've tried and whether they helped [2].
Conclusion
Patellofemoral pain syndrome, or runner's knee, is a dull ache at the front of the knee around the kneecap, most often seen in runners, jumpers, and young adults. It is linked to overuse, muscle imbalances, kneecap injury, and some knee surgeries, and it flares with stairs, squatting, kneeling, and long stretches of sitting. The good news is that most cases respond to simple measures: rest, ice, short courses of over-the-counter pain relievers, and physical therapy focused on strengthening the leg and hip muscles and keeping the knee from caving inward. If pain persists despite these steps, procedures such as arthroscopy or realignment surgery are available options.
Your next step: If your knee pain isn't improving within a few days or it's getting harder to move your knee, call your healthcare provider, and bring the question list in this guide to make the most of the visit.
Frequently Asked Questions
What is patellofemoral pain syndrome?
Patellofemoral pain syndrome is pain at the front of the knee, around the kneecap (patella). It is sometimes called runner's knee because it is more common in people who run or play sports involving running and jumping.
What does patellofemoral pain feel like?
Patellofemoral pain usually causes a dull, aching pain in the front of the knee that increases when running, walking up or down stairs, kneeling, squatting, or sitting for long periods with a bent knee.
Why is it called runner's knee?
The condition is more common in people who run and who play sports that involve running and jumping, so it became known as runner's knee.
What causes patellofemoral pain syndrome?
Patellofemoral pain syndrome is linked with overuse (repeated stress irritating the area under the kneecap), muscle imbalances or weaknesses that let the kneecap drift out of line, trauma to the kneecap, and knee surgery, especially ACL repair using the person's own patellar tendon as a graft.
Who is most at risk?
Patellofemoral pain typically affects teens and young adults. Women are twice as likely as men to develop it, possibly because a wider pelvis increases the angle at which the knee bones meet. Running and jumping sports also raise the risk.
When should I see a doctor for knee pain?
Call your healthcare provider if the knee pain doesn't improve within a few days or if it gets harder to move the knee.
How is patellofemoral pain syndrome diagnosed?
Your provider asks about your knee history, presses on the knee, and moves your leg into different positions. X-rays, CT scans, MRI, or ultrasound may be used to help find the cause.
What is the first-line treatment?
Rest the knee as much as possible and avoid activities that increase the pain, such as climbing stairs, kneeling, or squatting. Over-the-counter pain relievers (acetaminophen, ibuprofen, naproxen) can help, but shouldn't be taken for more than 2 to 3 weeks.
What does physical therapy involve?
A physical therapist may suggest rehabilitation exercises to strengthen knee-supporting muscles (keeping the knee from moving inward while squatting is a main goal), supportive braces or arch supports, knee taping, icing after exercise, orthotics, and knee-friendly sports like bicycling or swimming during recovery.
Is surgery ever needed?
Yes, if simple treatments don't relieve pain. Options include arthroscopy, a camera-guided procedure done through small cuts, and realignment surgery to fix the angle of the kneecap or relieve pressure on the cartilage in more-severe cases.
Can patellofemoral pain be prevented?
Some knee pain just happens, but prevention steps include building leg and hip strength, learning to jump, run, and turn safely, losing excess weight, warming up for about five minutes, stretching, increasing workouts gradually, and wearing well-fitting shoes designed for the activity.
Related Resources
Related reading on Rinnit:
External resources for deeper reading:
References
Mayo Clinic Staff. Patellofemoral pain syndrome: Symptoms and causes. Mayo Clinic. Sept. 17, 2026. https://www.mayoclinic.org/diseases-conditions/patellofemoral-pain-syndrome/symptoms-causes/syc-20350792
Mayo Clinic Staff. Patellofemoral pain syndrome: Diagnosis and treatment. Mayo Clinic. Sept. 17, 2026. https://www.mayoclinic.org/diseases-conditions/patellofemoral-pain-syndrome/diagnosis-treatment/drc-20350797
Nascimento LR, Teixeira-Salmela LF, Souza RB, et al. Hip and knee strengthening is more effective than knee strengthening alone for reducing pain and improving activity in individuals with patellofemoral pain: a systematic review with meta-analysis. J Orthop Sports Phys Ther. 2018;48(1):19-31. PMID: 29034800. https://doi.org/10.2519/jospt.2018.7365
Halabi MH, Alturkistani BA, Abuhadi RH, et al. The efficacy of hip and knee muscles strengthening versus knee muscle strengthening alone in managing patellofemoral pain syndrome: a systematic review and meta-analysis. Musculoskeletal Care. 2025;23(1):e70059. PMID: 39934098. https://doi.org/10.1002/msc.70059
Cleveland Clinic. Patellofemoral Pain Syndrome (PFPS). Cleveland Clinic. Last updated April 13, 2026. https://my.clevelandclinic.org/health/diseases/17914-patellofemoral-pain-syndrome-pfps
Rathleff MS, Thorborg K, Andreucci A, et al. Association of self-reported improvement after 4 weeks and outcomes after 52 weeks among adolescents with patellofemoral pain and Osgood-Schlatter disease. Orthop J Sports Med. 2024;12(10):23259671241280581. PMID: 39430112. https://doi.org/10.1177/23259671241280581
Medical disclaimer
This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have about a medical condition.
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