Cerebral Palsy and Lower Leg Movement
Sep 30, 2025
Two Bone System & Weight Transfer Work
In cerebral palsy, we often observe that the two-bone systems of the limbs (the radius/ulna in the arm, and the tibia/fibula in the leg) frequently lose their articulation. Instead of working as a shifting mechanism, they behave like a single-bone unit.
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Two-bone system → shift.
Allows automatic weight transfer (like the micro-adjustments of an airplane’s wings correcting lift).
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One-bone system → lift.
Forces the body to lift instead of shift, which disrupts smooth balance and coordination.
That’s why, early on, you can often see CP in the radius/ulna or tibia/fibula, because they stop articulating and instead act as one unit.
Why This Matters
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Without shifting, weight transfer is blocked.
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Movements that should be automatic (standing balance, step initiation, transitions) become forced lifts.
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The body loses its “absolute horizon” — that natural lying reference point where shifting begins. This is one reason the Moro reflex is often misinterpreted as a startle response.
How I Work With This
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One hand under the foot, the other under the knee crease.
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As I weight shift down, I want the foot to press into my lower hand, not away from it. This gives the body a chance to feel the transfer into the ground.
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Then, as I rotate the foot and push slightly upward, the knee should press into my upper hand. That completes the loop — foot to knee, knee back to foot.
This is the missing transitional skill: the ability to transfer weight down and back, side to side, instead of lifting as one block.
Once this is built, the body is better able to:
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Bring the knee into line under standing.
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Shift smoothly in and out of squats.