Pain on the outer side of the knee is also known as lateral knee pain. This knee area contains many structures that cross the joint, such as tendons, ligaments, and capsules. So, getting to the bottom of pain in this area can be frustrating. So, what are the causes of pain on the outside of the knee, and how do you make a diagnosis?
Common causes of pain on the outside of the knee
Common causes of pain on the lateral side of the knee include:
Knee osteoarthritis
Along with medial arthritis, arthritis can also affect the outer or lateral compartment. For example, osteoarthritis is one of the most common causes of pain in the outer part of the knee.
Symptoms include pain outside the knee, swelling and restricted movement, noises such as crepitations, and occasional giving way.
Generally, osteoarthritis affects people over the age of 50, although younger people with a history of knee injury (such as an ACL tear) can also develop this condition early.
Torn lateral meniscus
The outer or lateral meniscus can tear during an acute injury, such as a twist, or secondary to degeneration. Symptoms often include pain on the outer side of the knee, swelling, locking, and giving way.
LCL sprain
The lateral collateral ligament is a tissue band connecting the top of the outer femur to the tip of the fibula. It provides stability and prevents the knee from falling outwards.
Generally, LCL injuries are secondary to a direct blow to the inside of the knee, forcing the knee outwards. This force can stretch and tear the LCL. Symptoms include a pop, pain, swelling, and instability or giving way. Sometimes, as this ligament is close to the common peroneal nerve near the knee, injury can also lead to numbness, tingling, and weakness of the lower leg.
IT band friction syndrome
The IT Band is a long, thin connective tissue outside the leg. It starts from the pelvis and crosses the knee to connect to the outer part of the tibia.
Pain occurs when the bottom part of the IT band rubs against the femur, causing pain and focal swelling. This condition commonly occurs in runners, although cyclists and walkers are also prone. Ususally, pain from the IT Band starts within minutes of activity and worsens as you continue. Pain can sometimes be so bad that you need to stop.
Less common causes of pain on the outer side of the knee
Less common causes of pain on the outside of the knee include:
Common peroneal nerve injury
This nerve passes from the back of the lower thigh and crosses the lateral knee before supplying the lower leg muscles.
Similar to LCL injury, common peroneal nerve damage can occur from a blow to the inside of the knee, stretching the knee outwards. This injury can pull or tear the nerve.
Generally, symptoms include pain, numbness, and tingling in the outer part of the lower leg and the top of the foot.
Proximal tibiofibular joint injury
The proximal tibiofibular joint is a small joint that connects the top of the shin bone (tibia) with the fibula. Ususally, injury to this joint occurs acutely after a high-force injury such as a fall or gradually due to degeneration.
Symptoms usually include pain on the outside of the knee and a feeling of instability when deep squatting. In addition, moving the joint with your fingers is often painful and sometimes looser.
Biceps femoris tendonitis
The large biceps femoris hamstring muscle forms a tendon in the lower part of the thigh. This tendon crosses the lateral knee and attaches to the tip of the fibula.
Generally, biceps femoris tendonitis occurs from excessive activity, such as repetitive running and jumping. The pain is usually on the outer side of the knee, which is worse at the start of the movement and getting better as you continue. Also, the tendon is tender to the touch, and contracting the hamstring muscles reproduces the pain.
Making a diagnosis of pain in the outer side of the knee
You should see a specialist sports medicine doctor for a diagnosis and management plan.
Your doctor will ask you questions about your condition. Next, they will examine limb alignment, the knee’s range of movement, and the ligaments’ stability related to lateral knee pain. In addition, careful palpation of all the relevant anatomy, such as the joints and tendons, is vital. Finally, your doctor may want to perform investigations to confirm a diagnosis. Weight-bearing X-rays will assess the degree of arthritis. MRI scans use strong magnets to examine joint, tendon, and ligament structures. Sometimes, we use ultrasound to view the structure of tendons in more detail.
When to see a doctor about pain in the outer side of the knee
We recommend you see a doctor if you have any of the following:
- Outer knee pain after trauma
- Pain that has not settled after a few weeks with simple treatments such as ice and oral NSAIDs (ibuprofen)
- mechanical symptoms such as locking or giving way
- nerve symptoms such as numbness or tingling suggestive of nerve damage
Final word from Sportdoctorlondon about pain on the outer side of the knee
Pain on the outside of the knee is common in sportspeople and runners. You should see a sports doctor for an early diagnosis and management plan tailored to the cause.
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