From the paper Expected Values for Steps per Day in Special Populations, the mean steps per day for a post-stroke patient is approximately 4000 steps/day. Since the knee flexion device will only measure the motion of one knee, the number of rotations the device will experience will be 2000 steps/day. For a minimum cycle count of 100k cycles prior to failure, the device will last for at least 50 days of daily use. For a minimum cycle count of 1 million cycles, the device will last for at least 500 days or approx 1 year and 3 months of use on a daily basis. For a minimum cycle count of 25k cycles, the device will last for 12.5 days.
If the device is being used in the clinic, it will be used by approximately 15 patients per week for 20 weeks out of the year. Dr. Mowder approximated that each patient will take 100 steps per session (50 steps per leg). At 50 steps/session, 15 patients per week, a 100k minimum cycle device will function for 133.3 weeks or 6.67 clinic years. A 1 million cycle device will last for 1333.3 weeks or approximately 66.7 clinic years. A 25k cycle device will last for 33.33 weeks, or approximately 1.67 clinic years.
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