Lateral Knee Pain in Runners: Causes, Symptoms, and Prevention

Why does the side of my knee hurt when I run?

Lateral knee pain, often experienced by runners, typically stems from overuse injuries or biomechanical imbalances that place excessive stress on the structures on the outside of the knee joint. Identifying the specific cause is crucial for effective treatment and prevention.

Understanding Lateral Knee Pain in Runners

The knee is a complex hinge joint, crucial for locomotion, absorbing shock, and transmitting forces. The "side" of the knee refers to its lateral aspect, encompassing a network of muscles, tendons, ligaments, and cartilage. When pain arises in this region during running, it's often a signal that one or more of these structures is being overloaded or irritated. While various conditions can cause lateral knee pain, some are far more common in the running population due to the repetitive, high-impact nature of the sport.

Common Causes of Lateral Knee Pain in Runners

Several conditions can manifest as pain on the side of the knee during running. Understanding the primary culprits is the first step toward diagnosis and recovery.

• Iliotibial Band Syndrome (ITBS) ITBS is arguably the most common cause of lateral knee pain in runners. The iliotibial band (IT band) is a thick, fibrous band of connective tissue that runs along the outside of the thigh, from the hip to just below the knee. It helps stabilize the knee and hip. ITBS occurs when the IT band becomes inflamed and irritated, typically where it crosses the lateral femoral epicondyle (the bony prominence on the outside of the knee) during repetitive knee flexion and extension.

  • Symptoms: Sharp, burning pain on the outside of the knee, often worse when running downhill or after a certain distance, and may subside with rest but return upon resuming activity.
  • Causes: Weak hip abductors (especially gluteus medius), excessive pronation, sudden increase in mileage, inadequate warm-up, running on cambered surfaces, or worn-out shoes.

• Lateral Meniscus Injury The menisci are C-shaped pieces of cartilage that act as shock absorbers and help stabilize the knee joint. The lateral meniscus is on the outer side of the knee. While acute meniscal tears can occur from sudden twisting motions, runners can develop degenerative tears or irritation from repetitive stress.

  • Symptoms: Pain on the outside of the knee, sometimes accompanied by clicking, popping, or a feeling of the knee "giving way." Pain may worsen with squatting, twisting, or deep knee flexion.

• Lateral Collateral Ligament (LCL) Sprain The LCL is a strong ligament on the outside of the knee that connects the femur (thigh bone) to the fibula (smaller lower leg bone), providing stability against varus stress (force pushing the knee inward). While less common in runners than ITBS, an LCL sprain can occur from a sudden impact or an awkward landing that forces the knee outward.

  • Symptoms: Localized pain on the outside of the knee, tenderness directly over the LCL, swelling, and sometimes instability. Pain may worsen with side-to-side movements or when putting weight on the affected leg.

• Patellofemoral Pain Syndrome (PFPS) - Lateral Component While PFPS typically causes pain around or behind the kneecap, imbalances in quadriceps strength or tracking issues of the patella can lead to excessive pressure on the lateral facet of the patella, causing pain on the outer side.

  • Symptoms: Dull, aching pain, often worse with stairs, squatting, or prolonged sitting with bent knees. Pain can be felt on the outside if there's lateral patellar tilt or compression.

• Biceps Femoris Tendinopathy The biceps femoris is one of the hamstring muscles, and its tendon inserts on the fibular head on the outside of the knee. Overuse or repetitive stress can lead to inflammation or degeneration of this tendon.

  • Symptoms: Localized pain and tenderness directly where the hamstring inserts on the outside of the knee, often worse with hamstring activation (e.g., knee flexion against resistance) or stretching.

• Proximal Tibiofibular Joint Dysfunction The proximal tibiofibular joint is a small joint just below the knee, connecting the tibia and fibula. Dysfunction here, such as hypermobility or hypomobility, can cause localized pain on the outside of the knee.

  • Symptoms: Localized pain and tenderness just below the knee on the outer side, sometimes radiating down the leg. Pain may worsen with specific movements or palpation.

• Referred Pain Less commonly, pain felt on the side of the knee can be referred from other areas, such as the lumbar spine (lower back) or hip. Nerve impingement or muscle imbalances higher up the kinetic chain can manifest as knee pain.

Contributing Factors and Biomechanical Considerations

Understanding why these conditions develop often involves examining a runner's training habits and individual biomechanics.

• Training Errors:

  • Sudden Increase in Mileage or Intensity: Rapidly increasing weekly distance, pace, or hill training without adequate adaptation.
  • Inadequate Warm-up/Cool-down: Skipping essential preparation and recovery routines.
  • Insufficient Rest: Not allowing muscles and connective tissues enough time to recover and adapt.

• Biomechanical Imbalances:

  • Weak Hip Abductors and External Rotators (especially Gluteus Medius): This is a primary driver for ITBS. Weakness here allows the thigh to adduct and internally rotate excessively during running, increasing tension on the IT band.
  • Foot Pronation or Supination Issues: Overpronation (foot rolling inward excessively) or oversupination (foot rolling outward excessively) can alter the mechanics of the lower leg and knee, placing undue stress on lateral structures.
  • Leg Length Discrepancy: Can lead to compensatory movements that stress one side of the body more than the other.
  • Q-Angle: The angle formed by the quadriceps muscle and the patellar tendon; a larger Q-angle can increase lateral stress on the knee.
  • Core Weakness: A weak core can lead to instability throughout the kinetic chain, affecting running form and increasing stress on the lower limbs.

• Footwear:

  • Worn-Out Shoes: Loss of cushioning and support can increase impact forces and alter running mechanics.
  • Improper Shoe Type: Shoes that don't match your foot strike or pronation pattern can exacerbate biomechanical issues.

• Running Surface:

  • Cambered Roads: Running consistently on the same side of a sloped road forces one leg to be lower than the other, creating uneven stress.
  • Hard Surfaces: Concrete or asphalt can increase impact forces compared to softer trails or tracks.

When to Seek Professional Help

While many running-related pains can be managed with self-care, it's crucial to know when to consult a healthcare professional. Seek medical advice if:

• The pain is severe or debilitating.
• The pain does not improve with rest and self-management within a few days.
• You experience significant swelling, redness, or warmth around the knee.
• You hear a "pop" at the time of injury or experience instability (feeling your knee "give way").
• You have difficulty bearing weight on the affected leg.
• The pain persists or worsens despite modifying your training.

A sports medicine physician, physical therapist, or kinesiologist can provide an accurate diagnosis and develop a tailored rehabilitation plan.

Initial Self-Management Strategies

If your pain is mild and you suspect an overuse injury, these initial steps can help alleviate symptoms.

• Relative Rest and Activity Modification: Reduce or temporarily stop running. Engage in cross-training activities that don't aggravate the knee, such as swimming or cycling (if pain-free).
• Ice Application: Apply ice packs to the painful area for 15-20 minutes, several times a day, especially after activity, to reduce inflammation and pain.
• Gentle Mobility and Stretching:
  • IT Band Stretch: Cross the affected leg behind the other, lean away from the painful side, feeling a stretch along the outer thigh.
  • Gluteal Stretches: Piriformis stretch or figure-four stretch to target hip external rotators.
  • Hamstring Stretches: Gentle stretches to improve flexibility.
• Strengthening Exercises (Pain-Free):
  • Hip Abduction: Side-lying leg lifts or clam shells (with resistance band) to strengthen gluteus medius.
  • Glute Bridges: To activate gluteus maximus.
  • Core Stability: Planks, bird-dog exercises to improve trunk stability.
  • Eccentric Exercises: If pain allows, eccentric lowering exercises for the affected muscle groups can be beneficial under guidance.

Prevention Strategies

Proactive measures are key to keeping lateral knee pain at bay and ensuring a long, healthy running career.

• Progressive Overload: Increase your running mileage, intensity, or duration gradually – typically no more than 10% per week.
• Strength and Conditioning: Incorporate a regular strength training routine focusing on the entire kinetic chain:
  • Hip Abductors and External Rotators: Crucial for knee stability.
  • Glutes: Power generators for running.
  • Core Muscles: Essential for maintaining proper running form.
  • Hamstrings and Quads: Balanced strength helps protect the knee.
• Proper Footwear: Replace running shoes every 300-500 miles or every 6 months, whichever comes first. Consult a specialist running store to ensure your shoes are appropriate for your foot type and running gait.
• Dynamic Warm-up and Cool-down:
  • Warm-up: Include dynamic stretches (leg swings, walking lunges, butt kicks) before each run.
  • Cool-down: Perform static stretches (holding stretches for 20-30 seconds) after your run.
• Listen to Your Body: Pay attention to early signs of discomfort. Minor aches and pains are signals; ignoring them can lead to more significant injuries. Incorporate rest days into your training schedule.
• Vary Running Surfaces: Mix up your routes to include softer surfaces like trails or grass, and be mindful of cambered roads.

Conclusion

Lateral knee pain in runners is a common but often preventable issue. While Iliotibial Band Syndrome (ITBS) is the most frequent culprit, a thorough understanding of potential causes, contributing biomechanical factors, and proactive prevention strategies is essential. By addressing training errors, strengthening key muscle groups, and paying attention to your body's signals, you can significantly reduce your risk of lateral knee pain and continue to enjoy your running journey. When in doubt, always consult with a qualified healthcare professional for an accurate diagnosis and personalized treatment plan.