Pain on the outer side of the knee is also known as lateral knee pain. The knee area contains many structures that cross the joint, including tendons, ligaments, and the capsule. So, getting to the bottom of pain in this area can be frustrating. So, what causes 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, restricted movement, and noises such as crepitations, as well as 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 a feeling of the knee 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, causing the knee to be forced outward. This force can stretch and tear the LCL. Symptoms include a pop, pain, swelling, and instability or giving way. Sometimes, as this ligament is located near the common peroneal nerve at the knee, injury can also cause numbness, tingling, and weakness in 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 originates from the back of the lower thigh and crosses the lateral aspect of the knee before supplying the muscles of the lower leg.
Similar to LCL injury, damage to the common peroneal nerve can occur from a blow to the inside of the knee, causing the knee to stretch outward. This injury can cause the nerve to be pulled or torn.
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. Usually, injury to this joint occurs acutely after a high-force injury, such as a fall, or gradually due to degeneration.
Symptoms typically include pain on the outside of the knee and a sensation of instability when performing deep squats. 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 typically located on the outer side of the knee, worsening at the beginning of movement and improving as you continue. The tendon is tender to the touch, and contracting the hamstring muscles reproduces the pain. Sometimes, biceps femoris tendonitis can lead to snapping or popping, a condition called biceps femoris snapping tendon.
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 motion, and the stability of the ligaments related to lateral knee pain. Additionally, careful palpation of all relevant anatomy, including joints and tendons, is crucial. Finally, your doctor may want to conduct further investigations to confirm the 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 consult a sports doctor for an early diagnosis and a management plan tailored to the specific cause.
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