Most sports injuries which cause pain on the outside of the knee are gradual onset, overuse injuries rather than sudden onset, acute injuries such as sprains and strains. Here we outline the most common causes of acute pain on the outside of the knee, as well as overuse injuries.
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Iliotibial band syndrome
One of the most common causes of pain on the outside of the knee is Iliotibial band syndrome. It is also known as ITBFS or runners knee and is common in runners, cyclists and soldiers. Symptoms consist of:
- Pain and inflammation on the outside of your knee.
- Symptoms develop gradually, often occuring at roughly the same time into a run.
- The pain usually eases with rest, only to return again when training resumes.
Read more on Iliotibial band friction syndrome.
Lateral cartilage meniscus injury
A lateral meniscus tear is an injury to the cartilage meniscus. These are semi circular discs found in the joint. They provide cushioning and support to the knee joint. A torn meniscus can be a sudden onset, acute knee injury, or it can develop gradually from wear and tear. Symptoms include:
- Pain on the outside of your knee, along the joint line.
- Pain may be worse when squatting, especially deep squats.
- More often than not your knee will be swollen and may also lock or give way.
- Read more on Lateral cartilage meniscus injury.
Patellofemoral Pain Syndrome (PFPS) is better known for causing pain at the front of your knee and around your patella (kneecap). It occurs when the patella is out of alignment and rubs on the femur bone underneath. Symptoms include:
- An aching pain in the knee.
- Tenderness and swelling which is mostly at the front of your knee around the patella.
- Symptoms can also occur over the outside of your knee.
- Pain is often worse when walking up and down hills, or when sitting for long periods.
Read more on Patellofemoral Pain Syndrome
Osteoarthritis is wear and tear of the knee joint. This results in degeneration of cartilage which lines and protects the ends of your bones. Eventually the bone will begin to wear away. Symptoms include:
- A deep aching pain is felt, usually on the inside of the knee but can also affect the outside of the knee.
- Symptoms are worse after exercise.
- Joint swelling and/or joint stiffness is common.
Read more on Osteoarthritis in the knee.
Biceps femoris tendinopathy/tendinitis
Biceps femoris tendonitis is inflammation of the hamstring tendon at the point where it inserts into the back of the knee. The term Biceps femoris tendinopathy is probably a more accurate description of most injuries which tend to be chronic, long term degeneration of the tendon through overuse rather than sudden onset acute inflammation.
Symptoms include tenderness and swelling at the back of the knee where the tendon attaches. The back of the knee may feel still first thing in the morning, or after sitting for a long periods of time.
Read more on Biceps femoris tendinopathy.
Superior (proximal) tibiofibular joint sprain
The tibiofibular joint is the point in the knee where the tops of the shin bones (tibia and fibula) join. Dislocation of this joint is likely to have been caused by an impact or fall onto the knee, particularly when it is in a fully bent position. Symptoms include:
- Pain and swelling on the outer surface of your shin.
- In addition the top of the fibula bone may appear more prominent than normal on the outside of your knee.
Read more on Tibiofibular joint sprain.
Synovitis is inflammation of the synovial membrane in the knee joint. The synovial membrane contains the synovial fluid which helps lubricate the knee. Symptoms include:
Read more on Synovitis.
Referred knee pain
Pain on the outside of the knee may result from injuries and problems elsewhere in the body, particularly sciatic pain from the lower back and hip.
Read more on: Sciatica
Important: Causes of lateral knee pain not to be missed:
Although not paticularly common causes of pain on the outside of the knee, it is essentail to consider the following as more serious complications may occur if they are missed and go untreated.
Peroneal nerve injury
Peroneal nerve injury is caused by a direct impact to the outside of the knee which damages the peroneal nerve. Symptoms which might distinguish a Peroneal nerve injury from a straightforward contusion include numbness or tingling in the front or side of the lower leg. As a result the patient will also have weakness lifting the foot up, and in severe cases, a sign known as ‘foot drop‘ will occur. A patient with foot drop will be unable to lift the foot up properly when walking and may tend to drag the toes.
Read more on Peroneal nerve injury.
Slipped capital femoral epiphysis
A Slipped capital femoral epiphysis is a hip injury more common in boys aged 11 to 16 years old. A fracture occurs of the growth plate in the thigh bone (femur) develops gradually causing pain in the hip, which may radiate to the outside of the knee.
Read more on Slipped capital femoral epiphysis.
Perthes’ disease is a hip condition which affects children, most commonly aged between four and eight. Symptoms of tiredness and groin pain are common and the patient may also have a noticeable limp. If Perthes’ disease is suspected then seek medical advice as soon as possible because early intervention is neccessary to prevent future problems.
Read more on Perthes’ disease.
When should I see a doctor?
The majority of knee injuries, especially minor ones, can be treated at home. However, if you have any of the following symptoms you should seek professional medical assistance.
- Severe pain in or around the knee, especially during walking.
- Severe swelling (oedema) in the knee.
- An audible “pop” or “crack” in the knee joint that is painful.
- A “giving way” feeling in the knee during walking or going up/downstairs.
- A feeling when the knee “locks” whilst bending or straightening it.
- Altered sensation in the foot – such as a feeling of “pins and needles” (paresthesia) or a “loss of feeling” (anesthesia) in the lower leg.
- Inability to complete your normal daily activities after the initial 72 hours.
Read more on when to seek professional advice for knee injuries.
- Baker RL, Fredericson M. Iliotibial Band Syndrome in Runners: Biomechanical Implications and Exercise Interventions. Phys Med Rehabil Clin N Am 2016;27(1):53–77.
- Andrish JT1. Meniscal Injuries in Children and Adolescents: Diagnosis and Management. J Am Acad Orthop Surg. 1996 Oct;4(5):231-237.
- Kocher MS, Klingele K, Rassman SO. Meniscal disorders: normal, discoid, and cysts. Orthop Clin North Am 2003;34(3):329–40.