Methods The subjects were recruited according to the inclusion and exclusion criteria by simple random sampling method, and "General data questionnaire", "International Physical Activity Questionnaire", "Regulation Questionnaire of Physical activity" and "hospital for Special surgery knee score" were adopted to investigate in this study.

Results A total of 112 patients participated in the study. The total average physical activity was (5 087.39±2 234.21), and the low, medium, and high intensity activities were (1 612.89±340.89), (1 009.31±818.23), (267.76±49.89) respectively. The motivation for physical activity was (41.89±11.78), of which the autonomic motivation score was (29.18±8.87), the external adjustment score was (6.59±2.01), the endoscopic adjustment score was (5.43±1.48). The knee joint function assessment score was (71.33±13.01). The age, BMI, knee joint function, physical activity motivation, condition of residence all affected physical activity level (P<0.01).

Conclusion The physical activity level of patients after total knee arthroplasty is low. Age, BMI, knee joint function, physical activity motivation, condition of residence are positive factors of physical activity level.