Efficient walking is based upon static balance. Before we can move, we must be stable in the standing posture. Dynamic balance is the next step. The biomechanical interplay between the orthosis and the body must be taken into account.
An orthotic support system must incorporate the necessary design and materials to achieve the following:
The orthosis must become part of the body. Old habits and compensations developed over time must be replaced with more efficient movement patterns. Exercise and training combined with the proper orthosis will increase the potential for optimal outcomes.
As the mechanics of walking improve, the outcome can be measured to quantify the efficiency of walking compared to the initial evaluation. Effort, patience and persistence will lead to positive outcomes.
In a preliminary study conducted at a nationally renowned biomechanics laboratory, a patient was evaluated with two DynamicBracingSolutions orthoses. The neurological condition that required bracing caused weakness in the plantar flexor muscles resulting in decreased push off on both sides. This caused an inefficient gait with short steps. She was tested barefoot, with two traditional polypropylene AFO’s and two DynamicBracingSolutions orthoses. A report was written based on the biomechanics laboratory evaluation.
“Peak plantar flexor moments were decreased 50% or more compared to normal gait for the barefoot and polypropylene AFO conditions. Peak plantar flexor moments were consistent with normal values for the dynamic Brace condition.”
“Walking speed was 30% faster in the dynamic braces compared to barefoot gait and only slightly slower than normal speeds. The braces allowed faster progression of center of pressure and increased ankle plantar flexor moments. This allowed the hips to be more extended at push off which allowed longer step lengths. Longer step lengths were responsible for the faster walking speed.”
*Note: Moments refer to the measure of force created by the plantar flexor muscle group. In the case of the dynamic brace condition, this force was simulated through the design of the braces and the floor reaction forces. Center of pressure refers to the forward movement of the body over the foot.
This report is an example of a measurable outcome. It should be noted that the barefoot condition and the polypropylene condition were the same; in other words, there was no difference in efficiency with or without the old style braces. The intended outcome was achieved with DynamicBracingSolutions by design, using triplanar control, carbon composite construction and dynamic response.
Human motion occurs in three planes or axes. Functional activities of daily living rarely occur in one plane; therefore, motion can be described as triplanar or occurring in all three planes simultaneously
The sagittal plane is a vertical plane that divides the body into right and left halves. Motion occurs from front to back. We call this motion flexion and extension. Flexion can be described as two bony levers coming closer together. Extension is the opposite.
The frontal or coronal plane is a vertical plane that divides the body into front and back halves. Motion occurs from side to side. We call this motion abduction and adduction. Abduction is away from the body or outward while adduction is towards the body or inward.
The transverse plane is a horizontal plane that divides the body into upper and lower halves. Rotation is the motion that occurs in this plane. Medial or internal rotation refers to rotation towards the center of the body. Lateral or external rotation refers to rotation away from the center of the body.
Walking is an example of multiple triplanar movement patterns involving the whole body. The legs and feet support the body’s weight providing for balance and forward progression. Bones act as lever arms to form joints or pivot points. Muscles work with gravity and momentum to create the source of power for walking.
The ability to walk efficiently is based upon the proper alignment of the bones of the feet, which in turn affect the alignment of the ankles, knees and hips. Muscle strength from above is also a factor. Weak or missing muscles create abnormal rotational patterns causing mal-alignment of the joints below. An effective brace must provide for triplanar control of the foot and ankle while providing triplanar support for weak muscles. It must work from the ground up and the top down simultaneously. Triplanar control in an orthotic support system is dependent upon the design and materials used.
The design of an orthosis must take into account the intended outcome. Based upon triplanar control of forces acting on the body, skeletal alignment must be restored and support must be applied where it is needed. Stability and balance need to be established as a prerequisite for efficient walking
The design and complexity of fabrication will vary according to individual needs and requirements. In order for the design to be effective, the materials selected must meet the demands of the design.
Technology has provided us with new opportunities to solve old problems. Designs of the past had to rely on the materials available at the time. In a sense, the materials dictated the designs. As new materials were introduced, the old designs persisted. Materials alone do not improve function in an orthosis; however, these new materials provide the basis for new and different designs. Conventional thinking must be replaced with innovation in order to create a more functional orthosis. There cannot be progress without change.
The materials used to make an orthosis must satisfy the requirements of the design and the intended outcome. Carbon composites offer the unique qualities of the rigid support needed for triplanar control and flexibility for dynamic function. Composites may include materials other than carbon that can enhance function. Carbon alone is very rigid. Strength must be combined with flexibility to improve function.
Composites allow the designer to combine materials in one device to create superior performance characteristics. Only research and development will determine the optimal blend of materials. It is important that the attempt be made. There will be no future if we remain in the past. Materials science will ultimately affect the design of an orthosis.
Dynamic response in an orthosis can be described as the ability to store energy and dissipate energy in the gait cycle to achieve smooth efficient walking. A device that is too rigid will provide for stability but will not provide for mobility. A device that is too soft or has joints that allow for excessive motion will provide mobility without stability. The orthotic response must coincide with the weak or missing muscles of each individual. The orthosis must replace the function of these muscles. Motion must be assisted and resisted at the appropriate time in the gait cycle.
This is an ambitious task for an orthosis. Dynamic response is the ultimate characteristic that will improve function; however, there are conditions that must be met for dynamic response to have an effect on efficient walking. The following criteria must be met:
Extraneous or unwanted motion causing deviations or compensations must be eliminated. Motion must be directed in the line of progression in order to achieve efficiency in walking. The orthosis must redirect the abnormal forces causing movement in the wrong direction to more normal movement patterns. Energy is wasted in compensations for balance and security that decrease efficiency.
Dynamic response will provide for optimal outcomes if the preceding criteria are met. Static balance and stability precede dynamic stability. Once proper alignment is restored and weak or missing muscles are supported, design and materials will determine the effectiveness of dynamic response.