04/01/2026
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🧍♂️ Biomechanics of Frontal-Plane Postural Asymmetry
This image illustrates how pelvic obliquity and spinal side-bending create visible asymmetry in the shoulders, trunk, and lower limbs. What we see externally is the result of force distribution and compensation throughout the kinetic chain.
🔹 1. Pelvic Obliquity – The Base of the Problem
One side of the pelvis sits higher than the other
This alters the position of the hip joints
Creates an apparent leg-length difference
📌 The body prioritizes keeping the eyes level, so compensations travel upward.
🔹 2. Lumbar Spine Side-Bending & Rotation
The lumbar spine side-bends toward the high pelvis
Rotates to maintain balance
Produces asymmetric loading of discs and facet joints
➡️ Over time, this increases stress on one side of the lumbar spine.
🔹 3. Shoulder Girdle Compensation
To keep the head and eyes level, the thoracic spine counter-bends
One shoulder appears higher
Scapular resting position changes
📌 This often leads to unilateral neck and shoulder pain.
🔹 4. Force Transmission Through the Lower Limb
On the lower side:
Increased hip adduction
Greater knee valgus tendency
Increased foot pronation
On the higher side:
Reduced load acceptance
Relative hip abduction bias
🔹 5. Muscular Imbalance Pattern
Common findings include:
Tight quadratus lumborum on the elevated side
Inhibited gluteus medius on the lower side
Asymmetric trunk stabilizer activation
These imbalances maintain the asymmetry, even at rest.
🧠 Why This Matters
This is not a static “posture problem” — it is a dynamic control issue.
If unaddressed, it can contribute to:
Low back pain
SI joint dysfunction
Hip and knee overuse injuries
Gait inefficiency
✅ Key Biomechanical Takeaway
✔ Asymmetry is a compensation strategy
✔ The spine adapts to pelvic position
✔ Treating symptoms without addressing pelvic control fails
📌 Clinical Insight:
Correction requires restoring frontal-plane control, not forcing symmetry.