Can repetitive stress cause knee strain?

Repetitive Stress Can Cause Knee Strain and Injury

Yes, repetitive stress definitely causes knee strain and can lead to more serious injuries including bone stress injuries (BSIs) and stress fractures. 1, 2

Mechanism of Knee Strain from Repetitive Stress

• Biomechanical Overload: Repetitive loading leads to increased osteoclastic activity that exceeds the rate of osteoblastic new bone formation, resulting in bone weakening and microtrabecular disruption 1
• Progression of Damage: Initially causes tissue strain, which can progress to stress injury and eventually to stress fracture if the repetitive stress continues 1
• Two Types of Stress Injuries:
  • Fatigue fractures: Result from repetitive submaximal stress on normal bone
  • Insufficiency fractures: Occur due to normal activity on bones with deficient microstructure/mineralization 1

Risk Factors for Knee Strain from Repetitive Stress

• Athletic Activities: Running, jumping, and other high-impact activities significantly increase risk 1
• Biomechanical Factors:
  • Greater peak hip adduction and rearfoot eversion angles 1
  • Increased tibial accelerations 1
  • Varus or valgus knee alignment affects stress distribution (varus alignment increases medial compartment stress) 3
• Muscle Weakness: Reduced lower extremity muscle size and strength are associated with higher risk of bone stress injuries 1
• Training Errors:
  • Excessive volume (pitch counts in baseball correlate with shoulder injuries, similar principles apply to knee) 1
  • Training while fatigued significantly increases injury risk 1

Prevention Strategies

1. Load Management:

   • Gradual progression of activity intensity and duration
   • Adequate rest periods between training sessions 1
   • Avoid training through fatigue 1

2. Biomechanical Optimization:

   • Address running gait abnormalities
   • Consider reducing stride length or increasing cadence to reduce tibial stresses 1

3. Strength Training:

   • Focus on lower extremity and core strengthening
   • Address hip and proximal strength to control biomechanical variables 1
   • Incorporate plyometric training in advanced stages of conditioning 1

4. Supportive Equipment:

   • Appropriate footwear with adequate support and cushioning 4
   • Custom orthotics when indicated for biomechanical issues 4

Early Warning Signs of Knee Strain

• Pain during or after activity
• Decreased performance
• Localized tenderness
• Pain that progressively worsens with continued activity 2

Common Knee Overuse Injuries

• Patellofemoral pain syndrome
• Patellar tendinitis (jumper's knee)
• Iliotibial band friction syndrome (runner's knee)
• Bone stress injuries (BSIs) 5, 2

Pitfalls and Caveats

• Delayed Recognition: Early recognition of symptoms is critical to prevent progression to more serious injury 6
• Inadequate Rest: Continuing activity despite early symptoms can lead to chronic conditions 6
• Ignoring Biomechanical Factors: Failure to address underlying biomechanical issues can lead to recurrent injuries 1
• Premature Return to Activity: Returning to full activity before complete healing increases risk of recurrence or more serious injury 1

Repetitive stress injuries of the knee are common but preventable with proper attention to biomechanics, training load management, and early intervention when symptoms first appear.