Knee cap pain can be due to a number of factors. It may be that the problem is with the kneecap itself, with the cartilage that lines it, or tightness and/or weakness in the surrounding muscles causing it to move incorrectly.
The kneecap aka patella is a small triangle shape bone that sits inside the quadriceps tendon. It sits in a groove on the femur (thigh bone) known as the patellar/trochlear groove. It 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 8 times your body weight goes through the kneecap.
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.
Problems with the patella tend to cause pain at the front of the knee joint. Here you will find a summary of the most common causes of knee cap pain. To find out more about each one, including detailed information on symptoms, causes, diagnosis and treatment options, click on the relevant links below:
Chondromalacia is a common cause of knee cap pain,
especially in young adults and adolescents. Thinning of the cartilage that lines the back of the knee cap results in pain at the front. It
tends to be worse when you first get up from sitting or when climbing
stairs. It can also cause a
grinding/grating sensation. It is
usually caused by muscle tightness and weakness, overuse or altered
biomechanics in the leg
Find out More: Chondromalacia
Runner's knee is a very common cause of patellar pain. It can affect anyone from athletes to office workers, despite the name! It is caused by patella maltracking, a problem with how the kneecap moves, usually due to muscle tightness, weakness or abnormal biomechanics eg foot position.
Symptoms tend to come on gradually over time. Typically people experience an achy pain around the front and under the patella. It tends to be worse after prolonged activity or inactivity and when coming down stairs. It is also known as anterior knee pain or patellofemoral pain syndrome.
Find out More: Runner's Knee
More commonly known as Jumper's Knee, this usually results in knee cap pain just below the patella. It is caused by damage to the patella tendon from repetitive activities like jumping and kicking. The most defining symptom is pain when pressure is applied just below the knee on the tendon. The knee cap pain also tends to be worse with and after activity and first thing in the morning.
Find out More: Jumper's Knee
A patella dislocation occurs when the knee cap is forced out of the patellar groove, usually after a fall, car accident, or less commonly after twisting the knee awkwardly. There is usually a visibly deformity with a large bulge to the side of the knee, most commonly the outer side. There tends to also be lots of swelling. It is a medical emergency and needs relocating (putting back in place) by a doctor as soon as possible. It 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.
Find out More: Kneecap Dislocation
This is when the kneecap gets broken. This tends to occur due to a fall
from a height or a massive force through the bone. Depending on the severity of the injury, the
leg may be put in a brace/cast to prevent movement for a few weeks while the
bone heals, or surgery may be required to fix the fragments back together. If the injury is severe, part or all of the
kneecap may be removed.
Find out More: Patella Fractures
Arthritis often causes knee cap pain. Osteoarthritis 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 (thigh bone). The knee cap
pain 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: Arthritis
To find out more about these common causes of knee cap pain, including causes, symptoms, diagnosis and treatment options, click on the links above. If none of these are sounding quite like your pain, visit the diagnosis section for help working out what is wrong with your knee.
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Updated 5th December 2013
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