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Le cycle de la marche : phases, paramètres à évaluer et technologie
Qu'est-ce que la marche ?
Pour bien comprendre les pathologies ou les blessures de la locomotion humaine, il faut commencer par comprendre la façon de se mouvoir du sujet, patient ou athlète. La marche (ou course) est communément considérée comme la méthode par laquelle est parcouru le déplacement d'un point A à un point B. L'analyse de la marche permet d'appréhender les asymétries spécifiques liées au mode de déplacement. Une évaluation de la marche peut être réalisée à partir d'informations cinétiques (force) et cinématiques (spatiales/temporelles).
L'examen standard de la marche nécessite la prise en compte d'au moins un cycle de marche complet, démarrant au premier contact d'un pied au sol, suivi d'un appui l'autre pied et se terminant au nouveau contact avec le sol du premier pied. Bien entendu, plus le nombre de pas analysés est élevé, plus il est facile d'obtenir un ensemble cohérent de pas naturels malgré leur variabilité inévitable.
La marche humaine peut être définie comme une série de mouvements alternés des membres inférieurs dans un mouvement rythmique qui entraîne une progression du corps vers l'avant avec une dépense énergétique minimale. Afin de déterminer les troubles de la marche, les cliniciens et chercheurs ont souvent recours à une analyse biomécanique afin d'examiner et traiter les personnes présentant différentes affections, pathologies ou blessures susceptibles de perturber leur capacité à marcher ou à courir. Une bonne compréhension du cycle de la marche et de ses phases est nécessaire pour assurer une prise en considération adaptée de la situation individuelle de chaque patient ou athlète.
Quelles sont les phases de la marche ?
Looking at the gait cycle from a temporal perspective, it can be broken down into two distinct global phases: the stance phase and the swing phase.
The stance phase of gait begins when the foot first touches the ground and ends when the same foot leaves the ground. The stance phase makes up approximately 60% of the gait cycle.
The swing phase of gait begins when the foot first leaves the ground and ends when the same foot touches the ground again. The swing phase makes up the other 40% of the gait cycle.
There are also important support phases known as:
Single support phase
Initial double support phase
Terminal double support phase
Single support phase is also known as the swing phase where only one limb in in contact with the ground. In normal gait, this phase comprises between 60-72% of the stance phase.
Initial double support phase is the sub-phase between heel contact of the phase to contralateral foot-off. This phase makes up approximately 14-20% of the stance phase.
Terminal double support phase is the sub-phase from contralateral foot-on to the toe-off. This phase makes up approximately 14-20% of the stance phase. Total double support phase is defined as the sum of the initial and terminal double support phase. This makes up approximately 28-40% of the stance phase.
Typically, gait problems/pathologies will appear during the stance phase of gait when the foot is loaded, which will ultimately impact the swing phase as well. In order to gain a better understanding of how the foot functions, the stance phase can be further broken down to more refined sub-phases to enable a more in depth look. These phases are called:
-Contact phase (heel contact or heelstrike)
-Propulsive phase (active and passive)
The contact phase is the first heel contact of the lead leg and end at “toe-off” of the contralateral leg. The contact phase makes up 14-20% of the stance phase.
The foot-flat phase or “loading response” phase has an important function since body weight is transferred to the lead leg at this point and thus must absorb this weight while maintaining forward momentum. This phase is defined by the first heel contact of the lead leg to the first contact of the first metatarsal head of the lead leg. The foot-flat phase makes up 16-22% of the stance phase.
The mid-stance phase is the point where the support limb moves from shock absorption to more of a stability function. This phase is defined from the toe-off point of the contralateral leg to the first point the heel comes off the ground of the lead leg. The mid-stance phase makes up 29-37% of the stance phase.
The final phase of stance is called the propulsive phase. During the propulsive phase, the foot typically supinates to allow for a more rigid mid-foot, so it can act more like a lever (Winlass mechanism) to help propel the body forward. The propulsive phase of gait is sometime broken down even further into an active propulsive and passive propulsive phase. The reason for this division is to isolate the component of the propulsive phase while still in single support, and the passive component of the propulsive phase when in double support. The total propulsive phase is the point the heel comes off for the lead leg to toe-off of the lead leg. This phase makes up 45-55% of the stance phase.
The active propulsive phase is the heel off point from the lead leg to the first contact point for the contralateral leg. This active propulsive phase makes up 31-35% of the propulsive phase.
The passive propulsive phase is the heel contact of the contralateral to toe-off of the lead leg. The passive propulsive phase makes up 14-20% of the propulsive phase.
Measuring And Collecting Gait Data with our Gait Analysis Systems
Tekscan has gait analysis systems to measure gait via in-shoe or platform gait technology.
Spatial Gait Parameters
Looking at gait from a spatial perspective allows us to measure gait asymmetries related to distance between steps and strides lengths. Some typical spatial gait parameters are: step length, stride length, step width and foot angle.
Step length is the length measured parallel to the Line of Progression of the body, from the posterior contact (heel) of the previous footfall to the posterior contact (heel) of the current opposing footfall.
Stride length is the distance measured parallel to the Line of Progression, between the Posterior Heel points of two consecutive footprints of the foot in question
Step width is the distance measured between line of progression of the left foot and the line of progression of the right foot.
Foot angle is the angle between the line of progression and the foot axis. Foot Angle is zero when the foot axis is parallel to the line of progression. The Foot Angle is positive when the foot axis points lateral to the line of progression. The Foot Angle is negative when the foot axis points medial to the line of progression.
Other timing variables can be calculated from this information, step time, stride velocity and step length to leg length ratio. This can be calculated from the leg length of the patient.
Why Gait Cycle Analysis is Important
There are many reasons why gait cycle analysis is important in both clinical and research environments.
Injury Prevention: Identify asymmetries in an un-symptomatic patient, which might not be detected until the patient presents with an injury.
Post Treatment Confirmation: Feel confident that your treatments are making a positive change in your patient’s gait with pre/post treatment or surgery assessments.
Sports Performance: By understanding how an athlete is moving, it can help optimize their performance and build customized training plans to further improve athletic performance.
Evaluating effects of different conditions: Researchers can evaluate the effects of different types of footwear, terrains, floors and many other conditions effect the way a person walks. By studying the effects of different conditions, footwear, workplace environments and countless other types of research we can see improvements in the function of human gait.
Gait Analysis Technology
There are a variety of gait systems and software that can be used to capture spatial/temporal information of patients or athletes during gait.
Motion analysis is one methodology that can accurately capture this information; however, it can take time setting up a patient with the markers necessary for data acquisition and cannot capture continuous kinetic information unless multiple force plates are synchronized.
Force & Pressure Mapping
Force and pressure mapping systems are equipped with thousands of array sensors, arranged into a continuous walkway to enable data collection of multiple sequential foot strikes. These tools require very little set-up, allowing for quick and uninhibited evaluation of a patient or athletes’ gait, which is key in a busy gait clinic. Gait data from one simple data collection can provide spatial (step length, Stride length etc.), temporal (step time, stride time, Stride velocity etc.) and kinetic (vertical force, pressure distribution, center of force) information for a complete gait cycle analysis. The data from these systems can be compared to normative gait data or asymmetries between the feet can be quantified from a spatial, temporal or kinetic point of view. This information can provide important insights towards the type of pathology or injury of the patient/athlete. It can also provide quantitative feedback regarding how the patient or athlete is progressing in their rehabilitation.