Questions: Simulation-Based Design to Prevent Ankle Injuries

I.

1. Which degrees of freedom enable ankle inversion/eversion?
2. To tilt the platform in the sagittal plane (i.e. about the axis perpendicular to the sagittal plane), would you change platform_ry or platform_rz?
3. Why do you think the mtp_angle_r coordinate in the model is locked?

II.

1. What is the maximum subtalar angle during the drop landing?
2. Would an ankle inversion injury have occurred during this landing? According to previous research (Siegler et al., 1990; Lapointe et al., 1997), angles larger than 25 degrees (0.436 radians) may cause injury.
3. We simulated for 0.4 s in total, but is it valid to consider the simulation results for this entire duration? (hint: think about how you answered question two and the complexity of our model).

III.

1. You have now simulated three different drop-landing conditions: without an AFO, with a soft AFO, and with a stiffer AFO. What differences in peak ankle inversion do you observe between the simulations?
2. Could this AFO mitigate ankle inversion injuries?

IV. 

1. Note down the combination of parameters (i.e. AFO stiffness, active AFO torque and AFO timing) you determined to limit the maximum ankle inversion angle (report this too).

V.

1. Why is the constant control different between the inverters and everters?
2. What is the peak ankle inversion angle with the “baseline” low co-activation level? Does co-activity of the inverters and everters mitigate an ankle inversion injury?
3. After doubling the “baseline” co-activation levels of the inverters and everters, what is the peak ankle inversion angle after landing? Would an ankle inversion injury have been sustained?
4. Optional: plot the muscle activations for the ankle inverters. How does the addition of the co-activation controller affect muscle activity?

VI.

1. What choices and strategies did you make in designing an “optimal’ AFO device and training program to prevent an ankle inversion injury? What are potential benefits and drawbacks of your design with respect to ankle injury prevention and user wearability?