Lateral knee pain, or pain on outside of knee, is the least common that may be caused by a number of factors. Symptoms will vary depending on the cause, and outer knee pain can come on gradually or happen suddenly. The pain usually ranges from a general ache to sharp pains with restricted movement. Common causes are different for adults and children.

Outer Knee Pain in Adults

There are 4 possible causes of pain on outside of knee in adults. This pain should be tended timly and if it's severe, you should visit a doctor.

1. Iliotibial Band Syndrome

When the iliotibial band (ITB), a thick, fibrous band of muscle on the outer knee, is irritated, injured or overused, too much friction occurs and you will experience pain. The pain will usually be felt most when your heel hits the ground while walking, running or squatting. It is a common injury among cyclists.

Treatments include:

• Rest. Your ITB will need time to heal so avoid excessive or heavy exercise where extra strain and friction will be put on your iliotibial band.
• Ice. Cold compresses and ice are efficient for reducing inflammation. Hold an ice pack to your knee for about 15 minutes.
• Anti-inflammatory Drugs. Medications like ibuprofen help alleviate pain, swelling and inflammation.
• Exercises. Strengthening your glutes, quads and hamstrings will help improve your hip and knee function, which will reduce friction on the ITB. Stretching is as vital as strengthening. Keeping your muscles lose will promote better joint mobility.
• Knee Straps and Taping. Knee braces with straps around the top and bottom of the knee forces friction and tension away from the iliotibial band. Wear a brace during exercise or active tasks. Taping works like knee straps do to reduce tension on the ITB, but tape can be less restrictive than a knee brace.
• Massage. Deep tissue massage on the ITB can reduce tightness. Be sure to have it done by a trained specialist.
• Injections. Cortisone injections can be given to reduce pain, irritation and inflammation, but this should only be used after other treatments have failed. Accompany the injections with stretching and strengthening exercises to avoid a recurrence of the problem.
• Orthotics. Special insoles can be worn in your shoes in order to correct foot positions, like a flat foot, that can contribute to this condition. See and orthotist to determine what you need.
• Surgery. This is an extremely rare treatment and is only done after all others have failed and the condition worsens. The surgery is done arthroscopically to break down scarring on the tissues and extend the ITB if needed.

2. Lateral Collateral Ligament Injury

Damage to some or all of the fibers in this ligament causes bruising, instability, lateral knee pain, swelling and stiffness. Any activity that causes bending or force in the knee will bring pain and it is usually a sudden pain.

Treatments include:

• PRICE. It stands for protect, rest, ice, compress, and elevate. It is effective in reducing pain and swelling as well as promoting fast healing.
• Rehab. After a few days of PRICE you will be able to do some strengthening exercises to regain movement and function in your knee. There are exercises you can do on your own, or, in more serious cases, you may need to work with a rehab specialist.
• Knee Brace. A knee brace will help reduce pain and instability from a ligament injury. You can get a basic knee brace at most pharmacies.

3. Lateral Meniscus Tear

The outer side of the joint in your knee has a cartilage lining that can be torn if bent or moved with enough force in the wrong way. A lateral meniscus tear will cause difficulty straightening your leg, swelling in the knee, locking of the joints, instability and pain.

You can use the treatments of the two above to combat this condition.

4. Rare Causes

Nerve abnormalities peroneal nerve compressions can also cause lateral knee pain. Pain from areas like the back or hips can travel down your nerves and be felt on the outside of the knee even if the injury did not originate there. This is referred pain and is usually a sign of a muscle or nerve condition.

It is very unlikely that bone tumors cause knee pain but there were 2,400 bone sarcomas diagnosed in the U.S. in 2007. Cancer can metastasize to the knee so it is not impossible.

If the knee becomes unbearably painful and swollen, beware. Redness, fever and excessive swelling could be a sign of infection so seek medical help immediately. Types of arthritis like gout and pseudogout cause very sudden and painful swelling in the knees, requiring medical attention.

Lyme disease can also be a cause of knee swelling and lateral knee pain. Those who live in areas with deer populations are at risk for contracting the disease.

Outer Knee Pain in Children

Children have a different bone structure than adults. Their femur, tibia and fibula all develop from growth plates at the knee. Outer knee pain in a child can be caused by metabolic diseases that lead to abnormal growth plate development and fractures in different parts of the bones. If a child's meniscus has not completely developed they will also experience outer knee pain, but it is very rare for children under 10 to have any meniscal tears. Overweight children with knee pain must have their hips examined as they could be suffering from capital femoral epiphysis, a fracture in the growth plate on top of the developing femur.

It is very uncommon and unusual for children to have gradual onset pain on outside of knee. However, if they do have pain and it persists for 6 weeks or more it could be a sign that they have juvenile arthritis.