Pain on the outside of the knee, known as lateral knee pain, is a frequent complaint, especially among active individuals. The discomfort is typically aggravated by dynamic movements like walking, running, or cycling, which require constantly bending and straightening the leg. This type of pain often suggests a mechanical issue in the joint, the surrounding soft tissues, or a combination of both.
Understanding Iliotibial Band Syndrome
The most common cause of lateral knee pain in active individuals is Iliotibial Band Syndrome (ITBS). The iliotibial (IT) band is a long, thick strip of connective tissue running along the outside of the thigh, from the hip down to just below the knee. Its primary function is to stabilize the hip and knee joints during movement, such as walking or running.
ITBS is an overuse injury, frequently seen in runners and cyclists due to the repetitive flexing and extending of the knee. The injury involves friction or compression where the IT band passes over the lateral femoral epicondyle, a bony prominence on the outside of the knee. This repeated rubbing irritates the band or the underlying bursa, causing inflammation and pain.
A distinctive symptom of ITBS is a sharp or burning pain on the outer side of the knee that appears only after a certain period of activity. The pain is often noticeable when the knee is bent at roughly a 30-degree angle, where the band exerts maximal stress. Risk factors include sudden increases in training volume, running downhill, improper footwear, or weakness in the hip abductor muscles.
Other Structural Injuries Causing Lateral Pain
Other structural issues besides ITBS can cause lateral knee pain aggravated by bending and straightening. A lateral meniscus tear affects the C-shaped cartilage on the outside of the knee that acts as a shock absorber. Pain from a tear is often accompanied by mechanical symptoms, such as catching, clicking, or locking sensation within the joint.
A meniscus tear is typically caused by a sudden, twisting movement while the foot is planted, unlike the gradual onset of overuse injuries. Individuals with this injury may find it difficult to fully bend or straighten the leg and might experience the knee giving way. Immediate pain and swelling, although sometimes delayed, help differentiate a meniscal injury from friction-based pain.
Another possibility is an injury to the Lateral Collateral Ligament (LCL), which stabilizes the outer side of the knee joint. LCL injuries result from a direct blow to the inside of the knee or significant varus (outward) stress. A sprain or tear usually causes immediate pain and swelling. The acute, trauma-related nature and feeling of joint instability distinguish LCL issues from chronic overuse patterns.
Immediate Steps for Pain Relief
For immediate relief of lateral knee pain, the R.I.C.E. protocol is a helpful initial strategy, especially for acute overuse injuries. Rest involves temporarily avoiding activities that provoke pain, such as running or cycling, to prevent further tissue irritation. Applying ice to the outer knee for 15 to 20 minutes every few hours helps reduce local inflammation and discomfort.
Compression using a bandage or sleeve minimizes swelling, and elevating the leg assists in reducing fluid accumulation. Over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs) can manage pain and swelling, but their use should be discussed with a healthcare provider. Gentle movement and stretching of the hip and leg muscles, such as the glutes and hip flexors, can help maintain mobility and reduce tightness.
Warning Signs Requiring Medical Evaluation
While many cases of lateral knee pain are manageable with self-care, certain symptoms indicate a more serious injury requiring prompt medical evaluation. A healthcare professional should be consulted if the knee pain persists for more than 48 to 72 hours despite rest and home treatment. Severe, sudden pain, especially following a specific injury or trauma, requires immediate attention to rule out fractures or significant ligament tears.
Other critical warning signs include:
- Inability to bear weight on the leg or difficulty walking without a severe limp.
- A feeling of the knee locking, catching, or giving way, suggesting instability or mechanical damage.
- Visible deformity of the joint or severe swelling that does not improve.
- Signs of infection, such as warmth, redness, or fever accompanying the pain.