There are numerous causes of knee cap pain. It may be due to the knee cap bone itself, softening of the knee cap cartilage or tightness or weakness of the surrounding musculature are among the common causes. The knee cap named as patella, is a small triangle shape bone that sits inside the j tendon of the quadriceps muscles. It rests in a groove on the femur (thigh bone) known as the patellar/trochlear groove and slides 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 enormous high forces passes through it with certain movements. For example, during squat, a force equivalent to 3-4 times of body weight passes through the kneecap.

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.

Common Knee Cap Pain Problems

Problems with the patella tend to cause pain in front of the knee joint. Here we look at the 8 most common causes of kneecap pain. To find out more about each one, including detailed information on symptoms, causes, diagnosis and treatment options, visit the relevant articles.

1. Chondromalacia Patella

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 anterior knee pain. Chondromalacia patella causes anterior knee pain that tend to be worse when you first get up from sitting or when climbing stairs. It can also cause a grinding/grating sensation. Chondromalacia patella is usually caused by muscle tightness and weakness, overuse or altered biomechanics in the leg.

2. Runner's Knee

Runner's knee is a very common cause of patellofemoral pain. It can affect anyone from athletes to office workers, despite the name! Runner's Knee is caused by patella maltracking problem. This is usually due to muscle tightness, weakness or abnormal biomechanics e.g. foot position. Runner's Knee is also known as anterior knee pain or patellofemoral pain syndrome and is a common cause of chronic knee pain. The symptoms of Runner's Knee tend to come on gradually over time and people typically experience an aching pain around the front part of the knee and under patella. Patellofemoral pain syndrome tends to be worse after prolonged activity or inactivity and when using stairs.

3. Patellar Tendonitis

More commonly known as Jumper's Knee, patellar tendonitis usually results in kneecap pain just below the patella. The most defining symptom of jumper's knee is anterior knee pain when pressure is applied just below the knee on the tendon. Knee cap pain from patellar tendonitis also tends to be worse with and after activity and first steps in the morning. Patellar tendonitis is a common cause of chronic knee pain in runners. Patellofemoral pain associated with Patellar Tendonitis tends to get gradually worse over time as it is left untreated.

4. Quadriceps Tendonitis

Quadriceps Tendonitis typically affects people who do activities like sprinting, jumping and quick changes in direction. 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 in the tendon above the kneecap and the knee may feel stiff and weak. It is really important to rest from all aggravating activities otherwise the knee cap pain will get gradually worse. When caught early, recovery may only take few weeks, whereas if treatment is delayed, it can take months.

5. Dislocated Patella

Patella dislocation occurs when the knee cap is forced out of the patellar groove, usually after a knee injury or due to a sudden twisting activity.. When the patella dislocates, there is a visible deformity with a large bulge to the side of the knee, most commonly at the outer side. There also tends to be lots of swelling if the kneecap dislocates. A patellar dislocation is a medical emergency and needs relocation by putting it back in place. Kneecap dislocation is usually accompanied by damage to the ligaments that hold the knee cap in place which increases the risk of re-dislocation. Treatment consists of a rehab program and in some cases surgery may be necessary.

6. Patella Fractures

Patella fracture may occur due to a fall from a height or exposing to a massive force directly to the bone. There may be one clean break or in most cases, the patella will break into several pieces. 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 knee injury is severe, part or all of the kneecap may need to be removed.

7. Patella Alta

Patella alta is high location of patella and 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 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.

8. Patellofemoral Arthritis

Patellofemoral arthritis is a common cause of chronic knee cap pain in people over the age of 60. Arthritis is erosion of the cartilage which can affect any of the knee bones. Patellofemoral arthritis leads to 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.