Most sports injuries which cause pain on the outside of the knee are gradual onset, overuse injuries rather than sudden onset. Here we outline the most common causes of pain on the outside of the knee.
Most common causes of lateral knee pain
The following are some of the more common knee injuries causing pain on the outside of the knee:
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.
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.
Lateral ligament sprain
A lateral ligament sprain is a knee injury involving a tear to the ligament on the outside of the knee. Symptoms include:
- Pain on the outside of the knee.
- Swelling over the outside of the joint.
- Symptoms can vary from being very mild to a complete rupture.
More on Lateral ligament sprains
Less common causes of pain on the outside of the knee
The following are some of the less common knee injuries which result in lateral knee pain:
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.
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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 or degeneration of the hamstring tendon at the point where it inserts into the back of the knee. 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.
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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.
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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:
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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.
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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.
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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.
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.
More on Perthes’ disease
References & further reading
- 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.