Knee Valgus and Varus: Understanding Knock-Knees, Bow-Legs, Causes, and Implications

What is the opposite of knee valgus?

The opposite of knee valgus, commonly known as "knock-knees," is knee varus, often referred to as "bow-legs," where the knees angle outward, causing the lower legs to bow inward.

Understanding Knee Valgus

Knee valgus is a biomechanical alignment issue where the knees collapse inward towards the midline of the body, creating an "X" shape with the legs. This position is particularly noticeable during dynamic movements such as squats, lunges, jumping, or landing, but can also be present as a static postural deviation.

From an anatomical and biomechanical perspective, knee valgus typically involves a combination of movements at the hip, knee, and ankle:

• Hip Adduction: The thigh bone (femur) moves inward towards the center of the body.
• Hip Internal Rotation: The femur rotates inward.
• Knee Abduction: The knee joint collapses medially.
• Ankle Pronation: The foot flattens, and the ankle rolls inward.

Common Contributing Factors to Knee Valgus:

• Weak Hip Abductors: Muscles like the gluteus medius and gluteus minimus are crucial for stabilizing the pelvis and preventing the femur from adducting.
• Weak Hip External Rotators: Muscles such as the gluteus maximus and the deep six external rotators (e.g., piriformis) help prevent internal rotation of the femur.
• Tight Hip Adductors: Overly tight inner thigh muscles can pull the femur inward.
• Limited Ankle Dorsiflexion: Inadequate ankle mobility can force the knee into a valgus position to achieve depth during squats or landings.
• Structural Factors: In some cases, the skeletal structure itself (e.g., excessive femoral anteversion) can predispose an individual to knee valgus.

Implications of Knee Valgus:

Chronic or excessive knee valgus can place undue stress on various structures of the knee and surrounding joints, increasing the risk of:

• Anterior Cruciate Ligament (ACL) tears
• Patellofemoral pain syndrome (runner's knee)
• Iliotibial (IT) band friction syndrome
• Medial meniscus injuries
• General knee pain and instability

The Opposite: Knee Varus

Knee varus, often called "bow-legs" or genu varum, is the direct opposite of knee valgus. In this alignment, the knees angle outward, away from the midline of the body, creating a "bowed" appearance. When standing with the feet together, there is a noticeable gap between the knees.

Biomechanically, knee varus is characterized by:

• Hip Abduction (relative): The femur appears to move outward.
• Hip External Rotation (relative): The femur may rotate outward.
• Knee Adduction: The knee joint deviates laterally.
• Ankle Supination: The foot rolls outward, and the arch may be excessively high.

Common Contributing Factors to Knee Varus:

• Structural Conditions: Varus alignment can be physiological in infants and toddlers, often correcting naturally. However, persistent or severe varus can be due to conditions like Blount's disease (a growth disorder affecting the shinbone), rickets (vitamin D deficiency), or osteoarthritis causing cartilage loss in the medial compartment of the knee.
• Muscle Imbalances: While less common than in valgus, imbalances such as weak hip adductors or overly strong hip abductors could contribute.
• Occupational or Athletic Stress: Repetitive stress in certain activities can exacerbate a tendency towards varus.

Implications of Knee Varus:

Knee varus can place excessive compressive forces on the medial (inner) compartment of the knee joint, potentially leading to:

• Medial compartment osteoarthritis, particularly in older adults.
• Lateral collateral ligament (LCL) strain due to stretching on the outside of the knee.
• Lateral meniscus issues.
• Increased stress on the ankle and foot due to compensatory supination.

Key Differences Between Valgus and Varus

Why Understanding These Conditions Matters

For fitness enthusiasts, athletes, and anyone concerned with musculoskeletal health, understanding knee valgus and varus is critical for several reasons:

• Injury Prevention: Recognizing these alignment issues allows for targeted interventions to reduce the risk of common knee injuries, especially during dynamic movements.
• Performance Enhancement: Correcting malalignment can improve movement efficiency, power transfer, and overall athletic performance by optimizing joint mechanics.
• Long-Term Joint Health: Addressing these deviations can help mitigate the progression of degenerative joint conditions like osteoarthritis.
• Effective Program Design: For personal trainers and kinesiologists, identifying valgus or varus patterns informs the design of more effective and safer exercise programs.

Addressing Malalignment: General Principles

Correcting knee valgus or varus requires a comprehensive approach, often involving a combination of mobility work, strengthening exercises, and movement pattern re-education.

1. Assessment:

• Visual Observation: Observe static posture (standing) and dynamic movements (squats, lunges, single-leg balance, jumping/landing).
• Functional Movement Screens: Specific tests can help identify underlying muscular weaknesses or imbalances.

2. Corrective Exercise Strategies:

• For Knee Valgus:

  • Strengthen Hip Abductors and External Rotators: Exercises like banded side walks, clam shells, glute bridges, and single-leg Romanian deadlifts help improve hip stability and control.
  • Improve Ankle Dorsiflexion: Calf stretches and ankle mobility drills can ensure adequate range of motion.
  • Release Tight Muscles: Foam rolling or stretching for the hip adductors, TFL (tensor fascia latae), and quadriceps can be beneficial.
  • Movement Pattern Retraining: Consciously focus on maintaining knee alignment over the second toe during squats and lunges.

• For Knee Varus:

  • Strengthen Hip Adductors: Exercises such as Copenhagen planks, adductor squeezes with a ball, and Cossack squats can help strengthen the inner thigh muscles.
  • Release Tight Hip Abductors/External Rotators: Stretching the gluteus medius, piriformis, and TFL can alleviate excessive outward pull.
  • Address Ankle Supination: Work on improving ankle eversion and overall foot mobility.

3. Professional Guidance: It is highly recommended to consult with a qualified healthcare professional, such as a physical therapist, orthopedic specialist, or certified kinesiologist, especially if you experience pain, persistent discomfort, or suspect a structural issue. They can provide an accurate diagnosis, guide appropriate interventions, and ensure exercises are performed safely and effectively.

Conclusion

While knee valgus and varus represent opposite biomechanical deviations of the knee, both highlight the critical importance of balanced musculoskeletal function. Understanding these conditions, their underlying causes, and their potential implications empowers individuals to take proactive steps towards better joint health, injury prevention, and optimized movement performance. Prioritizing proper alignment through targeted exercise and professional guidance is key to maintaining a healthy and functional kinetic chain.