Anterior Knee Pain (Patellofemoral Pain) – Causes, Symptoms, and Modern Treatment

Anterior knee pain—also known as patellofemoral pain—is the most common cause of knee problems in young and active people. The condition is a symptom, not a single disease, and can be caused by many different mechanical or anatomical factors in the knee.

This page provides a comprehensive overview of symptoms, causes, diagnostic tests, treatment, and modern surgical options if you have been experiencing long-term discomfort.

This page is especially for those who have had long-term problems with pain around or behind the kneecap.

What is anterior knee pain?

Anterior knee pain is pain around or behind the kneecap. This condition is commonly seen in teenagers and in adults who are active in sports. Since the pain can originate from several different structures, a proper evaluation requires experience and specialized knowledge.

Typical symptoms

• Pain behind or around the kneecap when going up or down stairs
• Pain after sitting for a long time with the leg bent (e.g., while driving or at the movie theater)
• Pain when squatting, running or jumping
• Pain in the back of the knee
• Stiffness or a feeling of weakness

Medical Disclaimer: The information on this page is general in nature and cannot replace a personal examination. Diagnoses and treatment options for anterior knee pain should always be based on an individual assessment by a qualified orthopedic surgeon. Contact a doctor if you have persistent pain, instability, or limited function.

Right to an Investigation

HUSK – Right to be examined within 30 days
Many doctors do not know that in Denmark there is a legal right to be examined within 30 days. If this cannot be met, you can be treated at a private hospital – click here to see your right

The most common causes

Anterior knee pain is often caused by mechanical factors in the patellofemoral joint, such as:

• The kneecap slips out of place 
• The kneecap is positioned too high (patella alta)
• The tissue around the kneecap is too tight – Hyperpressure
• Rotation of the thighbone or lower leg – Inward-pointing kneecaps
• flat groove (trochlear dysplasia)
• hyperpronation of the foot
• mucosal fold – Plica
• Osteoarthritis of the kneecap 

Cross-section of the knee and kneecap

The image illustrates how pressure in the joint between the kneecap and the groove can increase if there is a slight misalignment. The dots illustrate the pressure.

How to examine anterior knee pain

A proper examination covers the entire leg—from the pelvis to the foot:

• the axis of the leg
• inward-facing kneecaps
• “Camel knee” associated with patella alta
• foot position
• muscles around the hip and thigh
• tenderness of the plica

Additional X-rays, MRIs, or CT scans may be necessary.

MRI scan and anterior knee pain

An MRI may appear normal even in cases of significant mechanical causes. An MRI scan may reveal:

• High patella
• Trochlear Dysplasia
• Tilted Patella—Many Causes
• Cartilage damage
• Rotation of the femur or tibia (requires a specialized MRI or CT scan)

Mucosal folds are rarely seen on MRI.

Treatment options

Most people find relief from pain with:

• physical therapy
• Strength training for the hips, thighs, and glutes
• stretching
• balance exercises
• shoe inserts
• knee brace or tape

Surgery is a last resort and is only appropriate once the cause has been determined.

Exercises that can help

First and foremost, it’s important to strengthen your glutes and thigh muscles

Here are links to some knee exercises

When to see a specialist

• if the pain affects quality of life
• if physical therapy and rest don’t help
• if mechanical causes are suspected
• if there are any deadlocks or failures

Common Misconceptions

Patellofemoral Pain Syndrome (PFPS)

This is not a syndrome, but a symptom with many causes.

When I was a young doctor, I conducted one of my first scientific articles on this topic, and it wasn’t until several years later that I realized there is no such syndrome.

“It’s psychological”

No. The pain is real and is often caused by mechanical factors.

Chondromalacia

An old term for damaged cartilage behind the kneecap. It is not always painful.

Growing Pains

Some young people outgrow it, but if the pain persists, the cause must be identified.

Anatomical Causes of Chronic Anterior Knee Pain

1. Plica – mucosal fold
2. Trochlear dysplasia – flat groove
3. Patella alta – high-riding kneecap
4. Hyperpressure – tight outer ligaments
5. Inward-turning kneecaps – rotated hip/lower leg
6. Peripheral patellar tendon attachment (rare)
7. Valgus – bowlegs
8. Chondromalacia – Diseased Cartilage
9. Patellofemoral osteoarthritis

Surgical treatment options for chronic anterior knee pain

• Plica – Mucosal foldcan can be easily removed during arthroscopic surgery, and uneven cartilage can be smoothed out. 
• Extension of the lateral retinaculum. Here the outer ligament is extended to the kneecap if you have hyperpressure.
• Distalization of tibial tuberosity involves moving the patella attachment downwards if your kneecap is too high (Patella alta).
• Arthroscopic trocheoplasty where your patellar groove is deepened if the groove is too shallow.
• Cartilage transplantation. This is if you have major cartilage damage caused by an injury.
• Femur derotation osteotomy where you rotate the femur outwards. That is if you have kneecaps pointing towards each other.
• Tibial derotation osteotomy where you rotate your tibia inwards. That is if you have Chaplin feet when you point your kneecaps forward.
• Patellofemoral Prosthesis – Osteoarthritis of the patella involves replacing the cartilage in the joint between the patella and the patellar groove with artificial material.
• Smoothing of Irregular Cartilage Using Binocular Surgery

Rare Opportunities

• Lateral patellar facetectomy
• Fulkerson osteotomy
• Elmslie–Trillat procedure
• Varus Osteotomies
• Reconstruction of the lateral collateral ligament following a surgical error

Risks Associated with Surgery

Surgery can make the pain worse if the cause has not been correctly identified. The surgeon must be able to explain exactly what the suspected cause is and why.

Frequently asked questions (FAQ)

Can the MRI scan come back normal even though I’m in pain?

Yes. Many mechanical causes of anterior knee pain—such as a plica, patella alta, dysplasia, or rotational misalignment of the femur and tibia—are not clearly visible on an MRI. A normal scan therefore does not rule out an actual cause.

Can pain in the front of the knee be congenital?

Yes. Some anatomical conditions may be congenital, such as trochlear dysplasia, patella alta, or femoral rotation. Others develop during growth.

Is pain in the front of the knee dangerous?

Not usually. However, if there is a significant imbalance in the knee’s mechanics, it can increase the risk of early patellofemoral osteoarthritis over time. Therefore, mechanical causes should be thoroughly evaluated.

Could the pain be psychological?

No. The pain is real and is often caused by mechanical or anatomical factors. Many patients have not been examined thoroughly enough before being told that “there is nothing wrong.”

My legs are crooked—should I have them corrected?

Only if you have symptoms. Misalignments without symptoms do not require treatment.

My knees crack—is that dangerous?

No. Noises from the knee are common and rarely mean anything. It’s the pain, not the noises, that matters.

Is chondromalacia the same thing as anterior knee pain?

No. Chondromalacia refers to irregular or damaged cartilage behind the kneecap. It can cause pain, but it is only one of many possible causes.

…everything you can see on an MRI scan.

Frustration

Many people get frustrated when they suffer from anterior knee pain. It’s hard to explain to those around you that it hurts inside or around the kneecap. There is nothing to see! Pull yourself together! Stop whining! Yes, you have to listen a lot. It’s much easier to explain that it hurts if you’ve broken your leg or have a meniscus injury or something else more tangible in your knee. Sometimes the knee may also lock a little or there may be discomfort that is interpreted as the meniscus being the cause of the clicking and pain, If you haven’t had a major knee twist, a meniscus injury is rarely the cause of your anterior knee pain.

Anterior knee pain

My particular interest and area of expertise is problems around the kneecap. Partly loose kneecap, but also anterior knee pain (patellofemoral pain) and kneecap osteoarthritis.

Research & Development

It all began in 1998, when I conducted a research project involving 250 patients with anterior knee pain. It turned out that about half of the patients still had mild to moderate anterior knee pain after 6 years. Unfortunately, 10% still had severe pain. You can download the article as a PDF  here. Other studies have since confirmed this.

Causes of the pain

Today, we know that there can be some mechanical causes for the pain. For example, the kneecap can drive crookedly or the kneecap can sit too high or sit too tight. These conditions can stress the cartilage (chondromalacia patella). This leads to an inflammatory condition or it can cause wear and tear and pain.

Bandage and shoe inserts for anterior knee pain

There are countless different types of knee braces, and while some people find them helpful, others do not.

For those who are particularly severely affected, there is a very specialspring bandage that can reduce the forces acting on the kneecap when walking up stairs. I don’t have any experience with this brace, and I don’t know if it helps, but the idea is good. Here’s a link to a website where you can buy it Click herehere

If you overpronate at the ankles, it might be a good idea to try some arch-supporting insoles. These standard anti-pronation insoles are available at most sporting goods stores. If that solves your problem, you might want to invest in custom-made insoles tailored specifically to you—though they’re relatively expensive, so feel free to try the standard ones first.

Chondromalacia

The image on the left is taken during a telescopic operation. At the top is the kneecap and at the bottom is the furrow to the kneecap. The cartilage on the back of the kneecap is irregular and diseased and this is called chondromalacia (diseased cartilage). Chondromalacia is a common finding in arthroscopic surgery. However, it is far from always associated with pain. However, some people do experience anterior knee pain and a grinding and clicking behind the kneecap as a result. In rare cases where the only symptom is locking ligaments, the cartilage can be smoothed out in an arthroscopic surgery.

MRI image

On the left is a cross-section of a normal knee. At the top, you can see the kneecap (patella) and the groove (trochlea) in which the kneecap slides.

X-ray

Above is an X-ray of a patient with inward-turning kneecaps and anterior knee pain. It looks as if the knee is crooked. This appearance is called the “winking sign.”

When Should You Have Surgery for Anterior Knee Pain?

You should have surgery when your pain affects your quality of life to such an extent that you feel you can no longer live with it, and you are willing to take the risks associated with surgery. First, try to see if simply reducing your activity level can lessen the pain. In most cases, this is a better option than surgery.

Why Surgery Isn’t Necessary for Anterior Knee Pain

There’s no such thing as a surgery that can’t go wrong—partly because there are risks, and partly because we, as surgeons, aren’t 100% infallible. Many surgeons will typically advise against surgery because, over the years, there have been so many unsuccessful knee surgeries for anterior knee pain. Thankfully, we’ve become much more skilled and now know that there are many causes of anterior knee pain. If we identify the cause and perform the correct surgery for it, there’s a good success rate—but never a 100% success rate. I also have patients who are dissatisfied. On the other hand, some of the most grateful patients are those who have been suffering for many years and are now healthy.

Conclusion

As you can see, there are many surgical treatment options for chronic anterior knee pain, and it is absolutely crucial that the true cause of the pain be determined before you undergo surgery. All surgeries carry a risk, and there is a chance that surgery could make your pain worse. Thankfully, the results after surgery are very good—provided, of course, that the true cause of the pain has been identified.  

Click here for E-Book “Anterior Knee Pain”

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