Try our Knee Pain Symptom Checker if you are not sure what might be causing your knee pain. Simply tick the symptoms that apply to you to view the knee injuries which match your symptoms.
Knee injuries are either acute which means they happened suddenly and are acutely painful or they are chronic or overuse knee injuries which have come on gradually over time. An acute knee injury can become chronic if it is not treated properly, likewise a chronic injury can be classed as acute if it flares up or becomes acutely painful.
Back of knee pain
Common causes of pain behind the knee include Bakers Cyst 
which is a specific swelling behind the knee caused by another knee injury. Hamstring Tendinitis causes pain behind the knee where the hamstring tendons insert. This is usually an overuse knee injury where the symptoms come on gradually. One knee joint injury which may cause pain in the knee joint as well as pain at the back of the knee is a Posterior Cruciate Ligament injury and is caused by the knee being bent the wrong way through impact or twisting.
Kneecap pain
Kneecap pain or patella pain occurs at the front of the knee and is also known as anterior knee pain. Pain behind the kneecap could be patella pain syndrome or runners knee as some people call it. In younger female athletes Chondramalacia patella is a common cause of pain under the kneecap.
Pain below the kneecap is 
usually patella tendonitis or jumpers knee. This and most other causes of anterior knee pain are over use injuries which come on gradually.
Swollen knee
A swollen knee is usually a sign of a knee joint injury or knee sprain resulting in damage to knee ligaments and other structures in the knee. The most common knee joint injury is an anterior cruciate ligament sprain or acl injury. A medial knee ligament injury on the inside of the knee can also occur with knee cartilage meniscus injury. A lateral knee ligament injury causes pain on the outside of the knee.
If the swollen knee occurs gradually then arthritis is the most common cause along with Bakers cyst if the swelling is at the back of the knee, although knee synovitis or loose bodies within the knee joint can also occur.
Outside knee pain
The most common cause or lateral knee pain or pain on the outside of the knee is Iliotibial Band Syndrome which is also known as runners knee as it is an overuse injury that comes on during a run.
A lateral ligament sprain and cartilage meniscus injury are both examples of acute knee injuries resulting in lateral knee pain. Knee cartilage inflammation can also cause pain on the outside of the knee and comes on gradually.
Inside knee pain
The most common cause of pain on the inside of the knee or medial knee pain is a medial knee ligament sprain. A bad medial knee sprain can also occur in conjunction with knee cartilage injury or acl sprain. Cartilage inflammation can come on gradually and also be a cause of medial knee pain.
Knee pain in children
Knee pain in children often happens as they grow. Osgood schlatters disease is a painful condition causing pain at the front of the knee where the patella tendon (or patella ligament) attaches to the bumpy bit at the top of the shin bone or tibia.
Running Knee pain
If you run regularly on the roads then you are probably going to suffer knee pain from running at some time or other. Running knee injuries are mostly overuse injuries which develop over time as a result of over training, poor foot biomechanics or incorrect running shoes.
Runners knee is a term used to describe either patella pain syndrome where the kneecap tracks wrongly against the bone underneath causing kneecap pain or Iliotibial band syndrome which causes pain on the outside of the knee as the long tendon rubs over the bone on the outside of the knee. These two over use running injuries are most common along with patella tendinitis or jumpers knee which causes pain at the bottom of the kneecap.
Anterior Cruciate Injury
A tear or rupture of the ACL deep within the knee joint.
The cruciate ligaments cross over front to back in the joint and can be injured by twisting or from impact in contact sports.
Medial Ligament Injury
A tear or rupture of the MCL on the inner side of the knee joint.
Symptoms include pain on the inside of the knee joint, often resulting from an impact on the outside of the knee.
Medial Meniscus Injury
A tear of one of the rings of cartilage within the knee joint.
The cartilage meniscus provide cushioning and support to the joint. The medial meniscus on the inside of the knee joint is often injured when the medial ligement is torn.
Patella Pain Syndrome
Excess movement of the knee cap causing pain and inflammation.
Symptoms include pain or aching under or around the knee cap, often the result of over use or poor knee biomechanics.
Housemaids Knee
Also known as prepatella bursitis, an inflammatory condition of the bursa often caused by pressure or kneeling.
A bursa is a small sac of fluid which lubricates a joint between the bone and the tendon.
Jumpers Knee
Also called patella tendonitis, causing pain in the tendon below the knee cap.
This is an overuse knee injury causing inflammation or degeneration of the patella tendon or ligament which connects the knee cap to the shin bone.
Bakers Cyst
An enlarged cyst or swelling at the back of the knee joint causing pain behind the knee.
A Bakers Cyst may have many causes and to cure the problem the original cause should be found.
Posterior Cruciate Ligament
A tear or rupture of the PCL, deep within the knee joint. This is an important ligament for stabilizing the knee joint and prevents the joint from bending back the wrong way.
PCL injury is usually caused by an impact to the front of the leg or a hyperextension force injuring the knee ligament.
Biceps Femoris Tendinopathy
An overuse injury causing pain on the outer back of the knee. The biceps femoris tendon is one of the hamstring tendons.
It can become inflammed as it inserts into the back of the joint.
Medial ligament sprain
A tear or rupture of the MCL on the inner knee joint is usually caused by an impact to the outside of the knee.
More severe injuries may involve damage to the cartilage meniscus causing pain on the inside of the knee joint.
Medial meniscus injury
A tear of the inner ring of cartilage within the knee joint. The cartilage menisus provide support and cushioning to the knee joint.
There are a number of different types of tear which may require surgery.
Knee plica
Inflammation of a synovial fold found along the inside border of the knee cap is one of the less common knee injuries.
The knee joint is surrounded by a capsule which contains synovial fluid. This fluid acts as a lubricant for the joint.
Iliotibial band syndrome
An overuse injury also known as runners knee. Pain is felt out the outside of the joint which may come on gradually during a run.
The pain goes after a period of rest only to return again when running starts.
Lateral cartilage tear
A tear of the outer ring of cartilage within the knee joint. The cartilage meniscus provide cushioning and support to the knee.
Pain is felt on the outside of the joint and often worse when squatting.
Lateral ligament sprain
A tear or rupture of the LCL on the outer side of the knee. The lateral knee ligament provides support to the joint.
It may be injured by an impact to inside of the joint causing pain on the outside where the ligament is torn.
