Knocking Knees: Understanding Genu Valgum, Valgus Collapse, Causes, and Corrective Strategies

What Does Knocking in My Knees Mean?

When your knees appear to "knock" or move inward towards each other, particularly during movement or when standing, it typically refers to a condition known as genu valgum (commonly called "knock knees") or, more dynamically, valgus collapse, indicating a misalignment of the lower limb.

Understanding "Knocking Knees" (Genu Valgum)

Genu valgum is an anatomical alignment where the knees touch or nearly touch while the ankles remain separated when standing with the feet together. This creates an inward angle at the knees. While a mild degree of valgus is normal, especially in young children (often resolving by age 7-8), excessive or persistent genu valgum in adults can indicate underlying issues and contribute to various musculoskeletal problems.

Why Do My Knees Knock? Understanding the Causes

The inward deviation of the knees can stem from a complex interplay of anatomical predispositions and biomechanical imbalances.

• Anatomical Factors:

  • Femoral Anteversion: An increased inward twist of the femur (thigh bone), causing the knee and foot to turn inward.
  • Tibial Torsion: An inward twist of the tibia (shin bone).
  • Pelvic Width: A wider pelvis can naturally angle the femurs inward to meet the knees.
  • Developmental Factors: Persistent genu valgum from childhood that didn't self-correct.
  • Bone Deformities: Rickets or other bone diseases can lead to structural changes.

• Biomechanical Factors (Often more prevalent in dynamic valgus):

  • Muscle Imbalances:
    • Weak Hip Abductors and External Rotators: Muscles like the gluteus medius and gluteus maximus are crucial for stabilizing the pelvis and preventing the femur from rotating inward. Weakness here is a primary contributor to valgus collapse.
    • Overactive or Tight Hip Adductors: Muscles on the inner thigh that pull the legs together can exacerbate inward knee movement.
    • Weak Vastus Medialis Obliquus (VMO): A quadriceps muscle important for patellar tracking and knee stability.
  • Foot Pronation: Excessive flattening of the arch of the foot (overpronation) can cause the lower leg to rotate inward, subsequently leading to inward knee collapse.
  • Limited Ankle Dorsiflexion: Restricted ankle mobility can force the knees to compensate by moving inward during movements like squats.
  • Poor Neuromuscular Control: Inefficient communication between the brain and muscles, leading to improper activation patterns during movement.

• Injury or Condition-Related Factors:

  • Osteoarthritis: Degenerative changes in the knee joint can lead to altered alignment.
  • Ligamentous Laxity: Weak or stretched knee ligaments can contribute to instability.
  • Previous Trauma: Fractures or injuries that healed with altered alignment.

The Biomechanics of Valgus Collapse During Movement

While genu valgum describes a static alignment, "valgus collapse" refers to the dynamic inward movement of the knee during activities like squatting, lunging, jumping, or landing. This dynamic movement is a common compensatory pattern and is characterized by:

• Hip Adduction and Internal Rotation: The thigh bone rotates inward and moves towards the midline.
• Knee Abduction: The lower leg moves outward relative to the thigh, causing the knee to buckle inward.
• Ankle Pronation: The foot flattens and rolls inward, often contributing to the chain reaction up the kinetic chain.

This chain reaction of movement often begins at the hip due to insufficient strength or control of the hip abductors and external rotators, leading to the knee falling inward.

Potential Implications and Risks

Persistent genu valgum or recurrent dynamic valgus collapse can place undue stress on various structures of the knee and surrounding joints, increasing the risk of:

• Patellofemoral Pain Syndrome (Runner's Knee): Pain around or behind the kneecap due to improper tracking.
• Anterior Cruciate Ligament (ACL) Injury: Valgus collapse is a significant risk factor for non-contact ACL tears, especially during landing or cutting movements.
• Medial Collateral Ligament (MCL) Strain: Increased stress on the inner knee ligament.
• Meniscus Tears: Increased compressive forces on the lateral meniscus.
• Iliotibial (IT) Band Syndrome: Friction and irritation of the IT band on the outside of the knee.
• Osteoarthritis Progression: Long-term altered mechanics can accelerate wear and tear on the knee joint.
• Altered Gait Mechanics: Can lead to compensatory movements in the hips, ankles, and spine.

Assessing and Diagnosing Knocking Knees

• Static Assessment: Observe standing posture from the front. Do the knees touch while the ankles are apart?
• Dynamic Assessment:
  • Squat Test: Observe knee alignment during a bodyweight squat. Do the knees track over the second or third toe, or do they collapse inward?
  • Single-Leg Squat/Balance: Assess stability and alignment during unilateral movements.
• Professional Evaluation: A physical therapist, orthopedist, or exercise physiologist can perform a comprehensive assessment, including muscle strength testing, range of motion evaluation, gait analysis, and functional movement screens. Imaging (X-rays) may be used to assess bone alignment if a structural issue is suspected.

Corrective Strategies and Management

Addressing "knocking knees" primarily involves improving strength, mobility, and neuromuscular control to optimize lower limb alignment.

• Strengthening Key Muscle Groups:
  • Hip Abductors: Exercises like side-lying leg raises, clam shells, band walks (lateral walks), and hip hikes.
  • Hip External Rotators: Exercises such as external rotation with a resistance band, pigeon pose variations.
  • Gluteus Maximus: Glute bridges, hip thrusts, deadlifts, squats (with proper form).
  • Vastus Medialis Obliquus (VMO): Terminal knee extensions, leg extensions with focus on VMO activation.
• Improving Mobility and Flexibility:
  • Hip Flexors: Stretches like the kneeling hip flexor stretch.
  • Hip Adductors: Butterfly stretch, wide-leg forward fold.
  • IT Band: Foam rolling, IT band stretches.
  • Ankle Dorsiflexion: Calf stretches, ankle mobilizations.
• Neuromuscular Control and Motor Pattern Retraining:
  • Conscious Correction: Practice movements like squats and lunges in front of a mirror, focusing on keeping the knees aligned over the feet.
  • Proprioceptive Training: Single-leg balance exercises, unstable surface training to improve body awareness.
  • Feedback: Use resistance bands around the knees during squats to provide external feedback to push against.
• Footwear and Orthotics: For individuals with significant foot overpronation, supportive footwear or custom orthotics may help correct the foundation of the kinetic chain.
• Activity Modification: Temporarily reducing or modifying activities that exacerbate knee valgus or cause pain.
• Professional Guidance: Working with a qualified physical therapist or exercise professional is highly recommended to develop an individualized corrective exercise program.

When to Seek Professional Help

While many cases of mild "knocking knees" or dynamic valgus can be managed with targeted exercise, it's important to seek professional medical advice if you experience:

• Persistent pain in your knees, hips, or ankles.
• Instability or a feeling of the knee "giving way."
• Worsening alignment or increased difficulty with daily activities.
• Significant impact on your ability to exercise or participate in sports.
• Unilateral "knocking" (only one knee affected) which could indicate a specific injury or underlying condition.

Understanding what "knocking in your knees" means—whether it's a static alignment or a dynamic movement pattern—is the first step towards addressing it. With a structured approach focusing on strength, mobility, and neuromuscular control, significant improvements in lower limb mechanics and a reduction in associated risks are often achievable.