Walking

Figure 1 (on left) illustrates the range of motion (ROM), moment and power profiles at the ankle in the shoes only condition while walking. The ROM profile reveals an excessively dorsiflexed position throughout the gait cycle consistent with a crouch gait pattern. Negligible ankle moments and powers are also present which infers that any perceived contributions from muscles about the ankle is passive. This is supported by EMG data that shows no active contraction of the plantarflexor muscles.

Figure 1 (Left) Range of motion, moment and power graphs for the ankle in shoes only condition while walking (normal values within shaded region). Each line represents one the characteristics for one foot, although no considerable differences were found when comparing each side.

Figure 2 (Right) Range of motion, moment and power graphs for the ankle in the shoes only condition and the ESR AFO condition while walking (normal values within shaded region), (Ruder, 2008).

Figure 2 shows the effects of the ESR AFOs at the ankle by comparing them to the shoes only condition and the normal ranges. In the ROM plot there is a definite plantarflexion movement in both the ESR and shoes only conditions. The difference however lies in the timing of this motion. In the ESR AFO condition the timing is like that of the normal region where the ankle is plantarflexing from approximately 50-60% of the gait cycle. In the shoes only condition this motion is delayed. In the plot showing the moments about the ankle there are considerable differences between the two conditions. The moment at the ankle is almost normal in the ESR AFOs condition in both magnitude and timing whereas in the shoes only condition the moments are extremely attenuated and slightly delayed. The power profiles also show improvement in the ESR AFO condition as there is now power generation and increased power absorption. Although the power generation may seem small compared to the normal plot we will see some of the important ramifications of this later.

The results seen in figure 2 are similar to those found in the case study in Chapter 4 albeit within a different patient population. That is an ESR AFO has the ability to control the ROM of the ankle throughout stance phase (as well as swing phase), can generate a plantarflexion moment about the ankle throughout stance phase and can store and return energy at the appropriate times during the gait cycle.

The current case study furthers the body of evidence regarding ESR AFOs by demonstrating its ability to influence the knee joint in a positive manner and demonstrates its usefulness in running. We will first examine the effects of the ESR AFOs on the knees. Figure 3 shows a plot of the moments at the knee in both conditions. It can be seen that the moment curve in the shoes only condition is similarly timed in relation to the normal curve however the magnitude of this curve is far greater. When looking at the crouch gait pattern of the individual this is a reasonable finding as one can see that the line of action of the GRF falls more posterior to the knee joint than one would find in normal gait. In the ESR AFOs condition the moment about the knee is closer in magnitude to the normal than the shoes only condition. This finding is supported by the fact that EMG analysis found that there was a decrease in knee extensor activity when in the ESR AFOs condition. The decrease in moments about the knee is directly related to the more upright posture found in the ESR AFOs condition. This reduction in moments at the knee is significant as it shows that a device which does not encapsulate the knee can still generate appreciable differences in the moments about that joint and subsequently the forces going through that joint. Presuming that the patient is not able to describe what they are feeling using biomechanical terminology how will this difference in moments about the knee present itself in the clinic (hint – think about functional significance)?

Figure 3 - Moment graph for the knee in the shoes only condition and the ESR AFOs condition while walking (normal values within shaded region), (Ruder, 2008).

It should be mentioned that not all available plots have been shown above--for all available plots please refer to the Plots and Parameters section. Note that the benefits are seen at the knee and ankle are not supplemented with deficits at the hip. In other words, there has not been any overloading of the hip to compensate for the ESR AFO.

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