Time to Take Off Our ‘Spasticity Goggles’

Why Spasticity is Not the Main Cause of Body Shape Distortion

For decades, the management of spasticity has dominated discussions around body shape distortion in children with cerebral palsy (CP). The assumption has been that high muscle tone pulls the body into deformity and that reducing spasticity will, in turn, prevent skeletal changes. However, the evidence tells a very different story—spasticity is not the primary cause of body shape distortion. Instead, prolonged passive positioning, gravity, and lack of movement play the biggest role. It is time to take off our ‘spasticity goggles’ and shift our focus toward early, proactive postural care before body shape distortions become severe and irreversible.

Spasticity is Not the Root Cause—Here’s Why

1. Body Shape Distortions Occur Across All CP Types—Not Just Spastic CP

If spasticity were the main cause of skeletal deformities, then children with low tone (hypotonia) or dystonia would not experience them. Yet, we see severe body shape distortions across all types of CP, including in children with little to no spasticity.

• Children with hypotonia (low tone, GMFCS IV-V) often develop the most severe body shape changes, despite their muscles being too weak to exert high forces on the bones .
• Dystonic CP, where muscle tone fluctuates unpredictably, also leads to major skeletal deformities—showing that it is not just spasticity that causes these changes.

If spasticity were the primary driver, these groups would be spared from severe deformities—but they are not.

2. Body Shape Distortions Develop Before Spasticity Becomes a Major Issue

Children with CP are born with symmetrical bodies and full range of motion. The distortions of the ribcage, spine, pelvis, and limbs develop over time—long before spasticity becomes a major limiting factor.

• Plagiocephaly (head flattening), ribcage asymmetry, and hip misalignment appear early in infancy, when children spend most of their time lying down, not actively moving.
• At this stage, the child is not yet engaging in high-force movements, but gravity is already acting on their body.
• If spasticity were the main cause, we would expect to see distortions only once the child is older and has developed high muscle tone—but we see clear skeletal changes in the first months of life, often before spasticity is severe.

3. Gravity and Asymmetrical Positioning Are the Primary Forces Driving Distortion

The human body adapts to the forces placed upon it—this is well understood in biomechanics.

• Wolff’s Law (Bone Adaptation): Bones change shape in response to mechanical stress. If a child lies in one position for hours each day, their bones will twist and reshape under that constant force.
• Davis’s Law (Soft Tissue Adaptation): Soft tissues lengthen or shorten depending on the forces acting upon them. If a child is habitually placed in an asymmetrical posture, their muscles and ligaments will permanently adjust to that shape.

Spasticity does not need to be present for these forces to act on the body. Lying still in one position for long periods is enough to distort body shape over time.

4. Spasticity is Absent or Greatly Reduced During Sleep—Yet Distortions Progress

If spasticity were the main cause, we would expect children to develop fewer deformities while they sleep, when muscle tone is naturally reduced. Yet, we see severe body shape changes progressing during sleep because gravity is still acting on the body.

• Many children with severe CP sleep in one position all night because they lack the ability to reposition themselves.
• Over time, this leads to flattening of the ribcage, pelvic obliquity, and spinal curvature—even though spasticity is not active during sleep.
• This confirms that passive positioning—not active muscle tone—is the main driver of skeletal change.

Taking Off Our ‘Spasticity Goggles’—A New Approach

For too long, we have focused on reducing spasticity, hoping it would prevent deformities. But when we take a step back and remove our ‘spasticity goggles’, the real cause of body shape distortion becomes clear:

• Gravity is acting 24/7, while spasticity is not.
• Children who lack movement—even without spasticity—develop severe distortions.
• Bones and soft tissues adapt to habitual positioning, whether spasticity is present or not.

Instead of waiting until skeletal changes appear on X-rays, we must act early with proactive 24-hour postural care.

A Call to Action: Stop Waiting, Start Supporting

• Educate caregivers and families from the start—not just about spasticity but about how body shape changes when a child is left in unsupported positions.
• Provide early, effective 24-hour postural care in lying, sitting, and standing to prevent rather than react to distortions.
• Ensure safe, comfortable positioning without neglecting alignment and symmetry.
• Recognize that spasticity is only one piece of the puzzle. Addressing positioning, gravity, and movement is far more impactful in the long run.

Conclusion

Body shape distortions in CP are predictable, progressive, and preventable. It is time to shift our focus away from just spasticity management and instead prioritize postural care, movement, and early intervention. Let’s take off our ‘spasticity goggles’ and start seeing the full picture—before it’s too late.