Knee Cap Pain

Kneecap pain, aka patellofemoral pain, often feels like a dull aching or burning sensation at the front of the knee or behind the kneecap.

Here we will look at the common causes of knee cap pain, how they present and how to treat patellofemoral pain.

Knee Cap Anatomy

The kneecap aka patella is a small triangle shape bone that sits inside the joint tendon of the quadriceps muscles. It rests in a groove on the femur (thigh bone) known as the patellar/trochlear groove and glides up and down in this groove as the knee moves.

The back surface of the kneecap is lined with the thickest layer of cartilage in the whole body. This is because such large forces go through it. For example when you squat, a force equivalent to eight times your body weight goes through the kneecap.  

But why do we have kneecaps? The knee cap is functionally important because it increases the leverage at the knee joint. This increases the strength of the knee by approximately 30% with extension activities like kicking. 

Causes Of Knee Cap Pain

The eight most common causes of knee cap pain are:

1. Chondromalacia Patella

2. Runner's Knee

Runner's knee is a very common cause of knee cap pain. It can affect anyone from athletes to office workers - don't be fooled by the name!

Patellofemoral pain syndrome tends to be worse after prolonged activity and people often complain of knee cap pain when coming down stairs.

Find Out More: Runner's Knee - Causes & Treatment

3. Patellar Tendonitis

More commonly known as Jumper's Knee, patellar tendonitis usually results in kneecap pain just below the patella.

Patellofemoral pain associated with patellar tendonitis tends to get gradually worse over time as the tendon weakens and if left untreated, the tendon may tear completely.

Find Out More: Jumper's Knee - Causes & Treatment

4. Quadriceps Tendonitis

Another possible cause of knee cap pain is quadriceps tendonitis. Quadriceps Tendonitis typically affects people who do activities with lots of sprinting, jumping and quick changes in direction, particularly if they have recently upped their training.

It can also affect non-athletes, particularly those with tight leg muscles, altered foot biomechanics and obesity.

Quadriceps tendinopathy causes pain and tenderness just above the knee cap. There may be swelling on top of the knee and the knee may feel stiff and weak.

It is really important to rest from all aggravating activities with quads tendonitis otherwise the knee cap pain will get gradually worse. When caught early, recovery may only take a few weeks, whereas if treatment is delayed, it can take months.

Find Out More: Quadriceps Tendonitis - Causes & Treatment

5. Knee Bursitis

Inflammation in any of these can limit knee movement and affect daily activities due to pain and swelling.

Find out More: Knee Bursitis - Causes & Treatment

6. Dislocated Patella

One of the more serious causes of knee cap pain is a dislocated kneecap. A patella dislocation occurs when the knee cap is forced out of the patellar groove, usually after a knee injury, or from twisting awkwardly.

When the patella dislocates there is a visible deformity with a large bulge to the side of the knee, most commonly the outer side. There also tends to be lots of swelling if the kneecap dislocates, and, obviously, knee cap pain.

A patellar dislocation is a medical emergency and the knee cap needs relocating, putting back in place, by a doctor as soon as possible.

Kneecap dislocation is usually accompanied by damage to the ligaments that hold the knee cap in place which can make you prone to dislocating again in the future. Treatment consists of a rehab program and in some cases surgery may be necessary.

Find out More: Kneecap Dislocation - Causes & Treatment

7. Patella Fractures

8. Patella Alta

Patella alta, aka high riding patella, is a rare but potentially serious cause of knee cap pain.

With patella alta, the kneecap sits higher than normal in a shallower part of the patellofemoral groove on the thigh bone. This means that the kneecap is less well supported and thus moves excessively which can lead to secondary knee problems.

Instability and kneecap dislocation is common with patella alta. Kneecap pain from high riding patella is worse after prolonged periods of sitting, on stairs, walking up and down slopes and squatting.

Find Out More: Patella Alta: Causes & Treatment

9. Patellofemoral Arthritis

Patellofemoral arthritis is a common cause of chronic knee cap pain in people over the age of 60. Arthritis is when there is wear and tear in the bones and cartilage, which can affect any of the knee bones.

Patellofemoral arthritis leads to a narrowing of the space between the kneecap and the groove it sits in on the femur.

Anterior knee pain from patellofemoral arthritis is usually worse with any activities that put pressure through the patella such as squatting, climbing stairs and kneeling. It also sometimes produces a cracking or grating noise/sensation when you move your knee. 

Find Out More: Patellofemoral Arthritis

Knee Cap Pain FAQs

What Causes Pain Under The Knee Cap? Pain under the kneecap can be due to a number of problems. If the pain is felt on the back of the kneecap it is usually a problem with the cartilage on the back of the patella, most typically Chondromalacia Patella or Runners Knee. The pain tends to come on gradually and gets worse after sitting for a while or doing lots of exercise.

If there is pain below the knee cap, the most common causes are patellar tendonitis or infrapatellar bursitis.

What Causes Pain Above The Knee Cap? When knee cap pain is felt just above or at the top of the kneecap, the most likely cause is Quadriceps Tendonitis. The top of the patella is usually tender to touch and the knee pain gets worse with activity. If there is a localised pocket of swelling, it is likely due to suprapatellar tendonitis.

If there is also marked weakness and swelling, it may indicate a complete quads tendon rupture which will likely need surgery.

What Causes Sharp Pain In The Knee Cap? Sharp knee cap pain is usually caused by either damage to the cartilage on the back of the kneecap, or a patella fracture - a break in the bone. Sharp knee pain is usually worse with movement and may be intense. 

What Causes Knee Cap Swelling? There are a number of things that can cause swelling at the knee cap. A defined pocket of swelling that resembles a squashy orange is usually caused by knee bursitis. If there is a lump in the tendon it usually indicated tendonitis. Severe swelling all around the front of the knee is usually due to a kneecap injury

How Do You Treat Kneecap Pain? Treatment for patellofemoral pain will depend on the type of knee injury. In most cases, knee cap pain can be treated with a combination of exercises and physical therapy, knee ice wraps, painkillers and a knee brace. You can find out everything you need to know in the knee joint pain treatment section.

Knee Cap Pain Summary

Knee cap pain may caused by strains or tears of the muscle tendons surrounding the knee, overexertion of muscles, tendons or ligaments around the knee, a misalignment of the patella, or a fracture of the knee cap.

Symptoms may include patellofemoral pain during activities such as running, climbing stairs, kneeling, or squatting; swelling of the knee or a grinding sensation in the joint; tenderness in the knee cap area; or difficulty moving the knee.

Knee cap pain treatment options usually include rest and ice, over-the-counter anti-inflammatory medications, physical therapy, corticosteroid injections, or surgery depending on the severity of the injury.

You might also be interested in the following articles:

• Knee Pain & Popping
• Swollen Knee Treatment
• Front Knee Pain
• Pain Below Knee
• Side Knee Pain
• Pain Behind The Knee
• Burning Knee Pain
• Knee Pain On Stairs

Page Last Updated: 04/10/23
Next Review Due: 04/10/25

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