requirement for the experimental study - the knee/machine alignment
The first experimental work on the verification of the roto-translational motion, was set on the concept that the knee in the first 30 degrees has a rotation motion around a fixed center, traceable overlaping a rotating system to the knee itself.
The knee/machine alignment
The need to align the axis passing through the center of the initial rotation of the knee with the center of rotation of the movable arm of the evaluation machine, was born from the need to determine a precise point of "marker" from which starting the evaluation as axis " 0 degrees " and make it traceable if you want to repeat that evaluation itself.
Considering that the initial center of rotation of the knee remains fixed for the first 30 degrees of flexion, it can reasonably be deduced that the trajectory of the leg in this fraction of movement must necessarily be an arc of circumference, similar to those of the machine that rotates around a single mechanical pin.
The alignment, therefore, can only be done in an experimental shape comparing the two circular trajectories.
The alignment machine / knee, is performed by executing a flexion-extension with an amplitude of 25-30 degrees after fixing the thigh to the seat of the machine and foot / malleolus (as anthropometric reference) to the the linear feedback placed on the movable arm.
The need to align the axis passing through the center of the initial rotation of the knee with the center of rotation of the movable arm of the evaluation machine, was born from the need to determine a precise point of "marker" from which starting the evaluation as axis " 0 degrees " and make it traceable if you want to repeat that evaluation itself.
Considering that the initial center of rotation of the knee remains fixed for the first 30 degrees of flexion, it can reasonably be deduced that the trajectory of the leg in this fraction of movement must necessarily be an arc of circumference, similar to those of the machine that rotates around a single mechanical pin.
The alignment, therefore, can only be done in an experimental shape comparing the two circular trajectories.
The alignment machine / knee, is performed by executing a flexion-extension with an amplitude of 25-30 degrees after fixing the thigh to the seat of the machine and foot / malleolus (as anthropometric reference) to the the linear feedback placed on the movable arm.
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If during the execution of a flexion-extension of about 30 degrees of the leg, so connected to the movable arm of the machine, it is not highlighted any movement through the linear encoder, we can consider that the
leg has carried out an arc of a circle centered on the initial center of rotation and the latter coincides with the center of rotation of the movable arm. In this case, we can consider that the transverse intercondylar axis of the knee and those passing through the rotation pin of the movable arm are aligned. Conversely, when in the first 30 degrees of flexion is highlighted a displacement of the reply, it is determined a condition of non-alignment that movement is processed by the computer which, through the engine, moves the seat to a new location finding the coincidence between the two axis of rotation. In particular, if the trajectory of the machine is closer than these of the leg, the knee is backward and so must be advanced. If the trajectory of the machine is wile, than these of the leg the knee is advanced and so must be backward. Any vertical movement can be made by tightening or enlarging the"support system". |
The evaluation
After the alignment phase the evaluation is performed by making do to the leg a full flexion up to 135 degrees (goniometric), picking up during the range of motion the values ΔR of the return of the foot only to specific angles of flexion.
After the alignment phase the evaluation is performed by making do to the leg a full flexion up to 135 degrees (goniometric), picking up during the range of motion the values ΔR of the return of the foot only to specific angles of flexion.