Anterior knee pain is a pain at the front of the knee. It includes the patella (kneecap) pain. Here we outline the causes of pain at the front of the knee.
Did your anterior knee pain develop gradually or occur suddenly?
Gradual onset anterior knee pain
Most causes of pain at the front of the knee occur gradually over time through overuse. You will most likely not be aware of a specific incident which caused your injury:
Patellofemoral pain syndrome
Also known as runners knee, patellofemoral pain syndrome is a generic term used to describe anterior knee pain that is patella related. Symptoms include:
- Tenderness on the inside of the kneecap.
- Swelling may sometimes occur.
- Pain may get worse when walking up and down hills or after long periods of sitting.
More on Patellofemoral pain syndrome
Jumper’s knee or patellar tendonitis is an overuse injury that results in pain at the front of the knee, specifically at the bottom of the kneecap. Overuse from running or jumping causes inflammation, or more likely, degeneration of the patella tendon.
- The bottom of the kneecap will feel very tender and may seem larger than the other knee.
- It is likely to ache and feel stiff after exercise.
- If neglected this injury can cause it to become worse and a chronic problem.
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Osgood Schlatter’s disease
Osgood Schlatter’s disease is a very common cause of anterior knee pain in children between the ages of 10 and 15 years old. Pain at the top of the shin (tibial tuberosity), just below the kneecap, is the main symptom becoming swollen and inflamed. Symptoms will worsen with exercise and improve with rest.
It is something children will usually grow out of, but treatment and ‘management’ of this injury are essential.
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Sinding-Larsen-Johansson lesion (syndrome) also affects young athletes and children causing pain at the front of the knee, at the lowest point of the patella or kneecap. The bottom of the kneecap may feel tender and the pain will get worse during and after exercise. Symptoms are very similar to Jumper’s knee, but the injury is more like Osgood Schlatter’s disease in that the point where the tendon attaches to the bone reacts as tendons and soft tissue have not adjusted to new bone growth.
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Chondromalacia patella (CMP) involves damage to the articular cartilage under the patella. Symptoms are similar to patellofemoral pain at the front of the knee. The kneecap rubs on the bone underneath causing swelling and pain. Pain can worsen when walking downstairs or after sitting for long periods. A grinding or clicking feeling may be felt when moving the knee.
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Housemaid’s knee & knee bursitis
Housemaid’s knee, also known as prepatellar bursitis or knee bursitis, is a swelling of the bursa at the front of the knee. A bursa is a small sac of fluid whose function is to lubricate the movement between tendons and bone. Symptoms include:
- Pain and tenderness at the front of the kneecap.
- Local swelling in the form of a lump over the patella.
- Your kneecap may be warm to touch.
- Kneeling will often be painful.
Infrapatellar bursitis occurs when the infrapatellar bursa below the kneecap becomes inflamed. Pain at the front of the knee and swelling are the main symptoms. The symptoms are similar to those of Jumper’s knee.
More on knee bursitis.
The synovial plica is a synovial fold found along the inside of the kneecap causing pain and discomfort. It is sometimes be confused or misdiagnosed as patellofemoral pain syndrome as the symptoms can be similar. Symptoms include:
- Sharp anterior knee pain, specifically at the front inside edge of the kneecap.
- Pain may also be towards the back of the patella.
- Sharp pain when squatting.
- A synovial plica may sometimes feel like a thickened band under the inside of the kneecap.
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Patellofemoral instability can occur through a number of anatomical or genetic causes, or it can result from a previous patella dislocation injury. The injury usually involves the patient having a sensation of their kneecap ‘slipping away’ or feeling loose on a movement of the knee. The front of the knee may be painful and swollen.
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Overuse causes pain and inflammation of the quadriceps (thigh muscle) tendon to the point where it attaches to the top of the kneecap or patella. Over time this can lead to degeneration of the tendon resulting in:
- Pain around the top of the kneecap that increases during and after exercise.
- Symptoms may also be reproduced when standing up from a crouched position or simply contracting the quadriceps muscles.
- Pressing in at the top of the knee will be tender.
More on Quadriceps tendinopathy
Fat pad impingement
The infrapatellar fat pad is also sometimes known as Hoffa’s pad. It is a soft tissue that lies beneath the kneecap which can get impinged, causing knee pain. This knee injury can be caused by a severe impact which traps the pad between the patella and femoral condyle. Tenderness at the bottom and under the kneecap can suggest this injury, and sometimes the kneecap seems to tilt outwards, because of swelling.
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Sudden onset (acute) anterior knee pain
The following are causes of sudden onset or acute pain at the front of the knee:
Patella tendon rupture
This is a tear of the patella tendon (sometimes called patella ligament) which connects the kneecap (patella) to the front of the shin.
- It is often caused by jumping or an explosive load.
- Patella tendon ruptures are very painful.
- A pop may be heard at the time of injury and there may be swelling, particularly at the bottom of the patella.
- Putting weight on the knee or straightening the leg will probably be impossible.
Read more on Patella tendon rupture.
Other causes of anterior knee pain
Other causes of pain at the front of the kneecap which always be considered include:
- Pain referred from the hip or lumbar spine.
- Osteochondritis dissecans.
- Slipped capital femoral epiphysis.
- Tumors (especially in young athletes).