Some interesting conversations with my friends who are physiotherapists just lately have prompted this blog post. Many have been asking for me to explain in more detail the gait analysis that we perform at AposTherapy® and what it means. In my experience I have found that having this outcome measure and being able to discuss and explain the results it shows with my patients is extremely valuable. It is a great tool to be able to track patients’ progress and it is great to be able to share this information with my patients during their consultations. Perhaps more importantly, it gives me a functional, objective and quantifiable outcome measure for the efficacy of my treatment which is valuable in physiotherapy.
So….Spatio-Temporal Parameters – What do they mean??
Normal gait is described as a series of rhythmical, alternating movements of the trunk and limbs which result in the forward progression of the centre of gravity and the body.
Gait analysis is used for clinical identification of deviations from normal gait. Kinematic gait analysis is concerned with the description of gait components. It deals with movement as opposed to kinetic which deals with the forces acting on or exerted by the body. For this we can use distance (spatial) and time (temporal) parameters.
At AposTherapy® we use OptoGait technology to measure these parameters. For more detailed information on Optogait technology please see the following links. http://www.optogait.com/what-is-optogait http://www.optogait.com/applications
Below is a brief outline of some of the different spatial and temporal parameters.
Spatial Parameters (Distance parameters) include:
- Step Length –This is the distance between corresponding successive points of heel contact of the opposite feet. If the gait is normal the right step length is equal to left step length. This parameter can give a great insight into a patient’s problem. For example, in a patient with knee osteoarthritis a step length can be reduced on the affected side. This can be indicative of hamstring muscle bracing. The hamstrings can overwork not allowing the knee to fully extend during the gait cycle and therefore shorten the step length. You may see this on your visual gait analysis but having a numerical outcome measure is very valuable.
- Stride Length – This is the distance between successive points of heel contact of the same foot. In normal gait this is equal to double the step length.
Temporal Parameters (Time parameters) include:
- Cadence – This is the number of steps per unit time.
- Speed (Velocity) – This is the distance covered by the body per unit time, usually measured in m/s. Patients with problems tend to walk at a slower velocity in order to decrease the forces and moments they have to cope with in gait. If the patient’s condition is improved the velocity should go up.
- Single limb support- This is the amount of time spent on a limb expressed as a percentage of the gait cycle. This parameter is of great importance as it has been shown that it decreases when there is a problem with the knee joint, for example. This makes a lot of sense, for instance, a person with knee Osteoarthritis or a meniscal problem will not enjoy putting weight through that knee and will therefore try to shift their weight to the other leg as soon as they can. In the clinic we also notice that it drops below normal values whenever there is a problem with other weight bearing joints such as the hip or ankle. This gives us an easy to use, functional, quantifiable, objective measure of the patient’s problem.
So just what are the normal values of these parameter so that we can use for comparisons?
During the AposTherapy® assessment the parameters that we use to inform our clinical assessment are velocity, single limb support and step length. During the gait analysis, the patients are asked to walk at their own comfortable speed as if they were walking down the street. Normal values for Velocity are between 110-140 cm/sec, for step length 55-70cm and single limb support (38.5-40.50%). Deviations from these normal values alongside our clinical assessment all aid in building up a clinical picture of a specific diagnosis and enable us to ascertain whether someone can benefit from AposTherapy®.