Table 5.

Post-study survey and interview responses

Q. no.	Which prosthesis do you prefer when …	Survey response
1	… walking at a slow speed on a flat treadmill?	No difference in preference
	Interview response: Swing assistance makes it easier to walk slowly because I do not have to work as hard to swing the leg. But it is uncomfortable to walk slowly, since I have to spend so much time standing on the prosthesis, so it is difficult to notice the difference that was being made by swing assistance.
2	… walking at a comfortable speed on a flat treadmill?	No difference in preference
	Interview response: The ECT did a great job emulating the C-Leg; I had no problem walking with the ECT at these speeds. [The C-Leg and ECT] are very much the same when walking.
3	… walking at a fast speed on a flat treadmill?	Somewhat prefer the C-Leg
	Interview response: The C-Leg was smoother than the ECT. When the knee extended fully at the end of swing, the ECT was hitting harder than I wanted. But the C-Leg did that more smoothly.
4	… walking up-slope on a treadmill?	Somewhat prefer the ECT knee
	Interview response: I liked the swing-assistance for going up-slope. The foot seemed to go into the right place, because the foot extends out further. Like the foot placement was more appropriate for going up a slope. With the C-Leg, my [prosthetic] foot does not get as far out.
5	… walking down-slope on a treadmill?	Somewhat prefer the ECT knee
	Interview response: The ECT had more resistance than the C-Leg. The C-Leg feels like it starts to collapse too soon. The ECT held me up better and I was walking smoother. My steps with the C-Leg end too soon.
6	… walking up-stairs?	Greatly prefer the ECT knee
	Interview response: With the C-Leg, I have to pole-vault up the stairs. I have to put my leg out to the side and stiff leg it up there. That’s not how people climb stairs. With the ECT, I can actually walk up step over step. The motor really helps me climb stairs, to position the foot, with the whole process. I was actually getting pretty good at it. I think with experience and practice I could to it really smoothly. However, the prosthesis takes its time in swing. Getting the foot up there and placing it on the next step was a little slow. I’d like it to go faster than that. Also, it needs more power in stance, probably 50% more power.
7	… walking down-stairs?	Somewhat prefer the ECT knee
	Interview response: I felt like I was in control of the ECT. With the ECT, I could go down-stairs without holding the handrail. I cannot do that with the C-Leg because it collapses too quickly, and I do not want to injure my knee. The ECT went downstairs smoothly. (Note that the subject was instructed to use a handrail during stair descent for safety reasons.)
8	… standing up from a chair?	No difference in preference
	Interview response: I was able to stand up faster with the ECT, and the assistance does help a bit. But my [intact] leg has to do the bulk of the work, so the difference is not that much.
9	… sitting down to a chair?	No difference in preference
	Interview response: The resistance does not matter as much when sitting down because my [intact] leg is doing most of the work. Resistance matters when going down stairs and slopes because I’m putting all my weight on the prosthesis. It might help a little bit, but it’s not enough to put even weight on both legs.
10	Which prosthesis do you prefer overall?	No difference in preference
	Interview response: The ECT was superior when ascending/descending stairs and slopes. The C-Leg was a bit smoother on level-ground walking. And the C-Leg is quieter.