A detailed gait analysis is a fundamental tool in rehabilitation. Step length asymmetry is a key indicator: it reflects a constraint or strategy implemented by the patient. But what is the real origin of this asymmetry?
This article offers a dual perspective:
The limitation of ankle dorsiflexion (on the pathological side) during stance limits the ability to pass over this support. The recurvatum associated with this equinus pushes the body backward when it should be moving forward.
The patient cannot advance on their affected leg: the good leg must take a large step.
The limitation of hip extension (on the pathological side) will restrict passage over the support and will limit the “posterior step”. Limited posterior step = limited anterior step on the opposite side.
The short posterior step on the pathological side prevents the good leg from advancing normally.
Pain is a frequent and very powerful cause of gait modification. The patient adopts an “antalgic” gait to avoid pain.
To avoid pain, the patient shortens the support on the affected leg.
This lack of knee flexion can have several origins: triple flexion pattern, quadriceps hypertonia, Rectus Femoris retraction… The asymmetry allows limiting foot catching on the ground (we keep the ascending phase of the swing of the bad leg).
The asymmetry allows compensating for a flexion defect by keeping the leg in the ascending phase.
Recurvatum is a classic and useful compensation for weakness of the knee extensors. The risk? Knee unlocking and falling. The “bowing” gait (forward trunk inclination) associated with step length asymmetry allows locking this recurvatum.
The asymmetric step stabilizes the pathological knee by locking it.
The three-point gait is adopted by people who seek to always have two supports for stability. Always in their search for balance optimization, they stop in double support to move their cane, with one foot next to the other. The step length on the good side will be shorter…
The Wheeleo® eliminates the three-point gait and allows a significant improvement in the asymmetry associated with this approach.
The need for security related to moving a cane disrupts step symmetry.
Ankle instability, knee instability, fear of knee collapse, loss of sensation… The limitation of support time and weight-bearing will cause asymmetry.
Less support on the unstable leg = compensatory asymmetry.
The classic compensation to avoid knee “hyperextension”, strongly encouraged by physiotherapists, is to place the knee in hyperflexion. The resulting forces cancel each other out and the knee can be stable. A symmetric step would decrease this hyperflexion and lead to a new imbalance and recurvatum at the end of the stance phase.
The asymmetry preserves knee stability (limits recurvatum).
Knee flexion contracture limits the amplitude of the anterior step despite correct hip flexion.
The pathological leg cannot lengthen its step.
When pressure is applied to the weak lower limb, without compensation in recurvatum, the body collapses. The patient must then recover from this collapse, which propels them forward. They take a large step with their good leg.
The asymmetry is a reaction to the imbalance caused by weakness.
This weakness prevents the patient from moving their bad leg forward while the good leg advances well.
The pathological leg lags behind and doesn’t follow.
For various reasons, the foot can catch on the ground and be slowed down when advancing the bad leg forward.
A catching of the pathological foot slows its forward movement.
The patient may neglect their hemibody and “drag” it behind them. The entire hemibody is in a retroposition.
The asymmetry is due to partial non-use of the body.
To avoid heel pain, the step length will be reduced to put weight on the forefoot.
The pain avoidance strategy shortens the step.
The asymmetry in step length can be:
For the therapist, the goal is to decode these strategies to better guide the patient towards functional walking.
The Wheeleo®, by allowing smooth and secure weight-bearing, can help reduce unnecessary asymmetries while respecting necessary adaptations.
What about you? What causes of asymmetry have you encountered in your practice?
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