Walking is only one ofmany daily activities performed by patients following total knee replacement (TKR).Thepurpose of this study
was to examine the hypotheses (a) that subject activity characteristics are correlated with knee flexion range of motion (ROM) and
(b) that there is a significant difference between the subject’s flexion/extension excursion throughout the day and the ISO specified
input for knee wear testing. In order to characterize activity, the number of walking and stair stepping cycles, the time spent with
dynamic and stationary activities, the number of activity sequences, and the knee flexion/extension excursion of 32 TKR subjects
were collected during daily activity. Flexion/extension profiles were compared with the ISO 14243 simulator input profile using a
level crossing classification algorithm. Subjects took an average of 3102 (range: 343–5857) walking cycles including 65 (range: 0–
319) stair stepping cycles. Active and passive ROMs were positively correlated with stair walking time, stair step counts, and stair
walking sequences. Simulated knee motion according to ISO showed significantly fewer level crossings at the flexion angles 20–40∘
and beyond 50∘ than thosemeasured with the monitor. This suggests that implant wear testing protocols should containmore cycles
and a variety of activities requiring higher knee flexion angles with incorporated resting/transition periods to account for themany
activity sequences.