ESR Comparisons

Now that we have a brief understanding of running gait we can discuss the results of the running trials in the present case study. The most notable differences between the normal values and the shoes only condition in running are seen in figure 5 where in the shoes only condition there is an absence of the large plantarflexion moment and subsequent plantarflexor power generation seen in the normal values. Note that the small ankle moment that is generated is due to the passive moment created by the ankle reaching end range dorsiflexion. As well, the small amount of power generation is most likely due to the elastic properties of the plantarflexor muscles and associated soft tissues. EMG confirms that there is no active muscle contraction.

Figure 5 - Range of motion, moment and power graphs for the ankle in the shoes only condition while running (normal values within shaded region), (Ruder, 2008).

Figure 6 - Range of motion, moment and power graphs for the ankle in the shoes only condition and the ESR AFOS condition while running (normal values within shaded region), (Ruder, 2008).

As can be seen in figure 6 the individual shows a marked improvement in the ESR AFOs condition concerning the ankle moments and power absorbtion/generation. In fact, compared to the normal values the amount of improvement is higher in running than in walking. That is, in the walking condition the power generated by the brace is approximately 25% that which is generated in normal walking by the plantarflexors, whereas in the running condition the power generated is approximately 70% of normal. However, when looking at the ankle moments it can be seen that the ESR AFOs condition in walking is more close to the normal values than the ESR AFOs condition in running. This poses a question with respect to “tuning” the stiffness properties of the ESR AFOs. Which is more desirable, a closer to normal moment or power profile? Additional questions can be asked along these lines. How does the plastic architecture and choice of materials affect these moment and/or power curves. It should be noted again that EMG analysis shows no muscle activity during the shoes only and ESR AFOs conditions therefore all differences can be attributed solely to the ESR AFOs.

As with walking the effects of the brace are not only observed at the ankle. As is demonstrated in figure 7 the internal knee extensor moments are reduced significantly. In fact they are reduced to a range within normal values (although still delayed in timing). Similar to the walking condition this is directly related to the more extended position of the knee.

Figure 7 - Moment for the knee in the shoes only condition and the ESR AFO condition while running (normal values within shaded region), (Ruder, 2008).