Neuromotor reprogramming of functional ankle instability ?
Ankle instability: definition
LFunctional ankle instability to use Yves Tourmé's classification, is defined by :
- a proprioception deficit, a direct consequence of the sensory deafferentation of ligament receptors during ankle sprains, hence the importance of re-establishing muscular pre-activation (retrocontrol) which will be the main element in regaining joint stability.
- a functional muscular deficit essentially based on the fibulars but also the gastrocnemius or anterior tibial, as a direct consequence of the inhibitions put in place after ankle sprains, i.e. a muscular mechanical defect.
- Postural instability, mainly varus of the hindfoot, claw toes, equinus, genu varum, adductus foot or pronatus forefoot.
The neuromotor reprogramming method for ankle instability
For proprioception and muscle function deficits, new procedures allow us to reprogram the neuromotor of the ankle in a very short period of time with a high degree of durability. These procedures exploit recent discoveries in neuroscience on brain plasticity based on proprioceptive identification, mental imagery and multi-sensory stimulation using a low frequency sound generator. Indeed, certain low frequency sounds, while stimulating the motor areas, make the patients enter the alpha mode. This state of cerebral activity is essential for neurosensory visualisation and allows optimal visualisation.
Ankle instability is characterised according to Hopkins et al (2009) and Menacho et al (2010) in their meta-analysis by :
- A later activation of the fibulars
- A significantly lower activitý of the fibulars in pre-landing and higher in post-landing
- Altered motor patterns. Subjects with an unstable ankle would tend to activate fibulars, gastrocnemius and tibialis anterior simultaneously in contrast to normality where the tibialis anterior is activated after the fibularis longus and after the gastrocnemius.
How does neuromotor reprogramming work?
Neuromotor reprogramming proposes to fill the proprioceptive deficit by :
- An improvement in the recruitment of the fibulars and an increase in the basic muscle tone of this group,
- A relearning of motor patterns based on the temporal dissociation of muscle activations during the unipodal jump of the fibular, gastrocnemius and tibialis anterior, in that order.
Initially, the subject, working on the healthy limb, learns to identify the specific recruitment of the fibulars against resistance. This work is done either in mirror image of the healthy limb, or in perceptive analysis. Once the mental image of these proprioceptive sensations has been acquired, the neuromotor reprogramming of the unstable ankle can be envisaged.
To do this, the patient first performs a mental deprogramming task by imagining a contraction of the fibulars on the pathological side with a small amplitude, then virtually erases the ankle as if he or she saw himself or herself without a foot.
It then reprograms a powerful and explosive fibular contraction corresponding to the fibre type of this muscle group.
In a second step, on the same scheme, he reprograms a dissociative work of the fibulars, gastrocnemius and tibialis anterior, in this order when receiving the unipodal jump.
Proprioceptive identification work is done on an unstable plane, such as a Bosu or mini trampoline. The subject learns to identify the muscular contractions during the reception of the unipodal jump on the healthy limb. Once acquired, these sensations are induced thanks to low frequency sounds by visualization work on the pathological limb.
This type of reprogramming allows the subject to automate the muscular pre-activations necessary for functional stability in a subconscious way and not to clutter the cognitive part of his motor skills with conscious-voluntary. This is known as liberated motricity.