A Protocol to Self-Familiarize Health Care Professionals with the Detection Limits of a Physical Activity Tracker for Low-Impact Steps in Patients Recovering from Knee Surgery-A Proposal and a First Evaluation.

Physical activity trackers are promising for monitoring physical activity in patients after surgery. However, the remobilization of patients following surgery is characterized by low-impact movements. It is often unclear to health care professionals whether a specific physical activity tracker is able to correctly detect steps in this patient population. A protocol is proposed, which allows health care professionals to familiarize themselves with the detection limits of a physical activity tracker. The professional should walk 20 steps under varying conditions mimicking the situation of patients after knee surgery. Conditions vary in step size, walking direction, use of walking aids, and footwear. The protocol was tested in a group of 14 health care professionals. Participants wore four trackers simultaneously, representing different modalities and different locations. For two trackers, the participants could experience a variation in the detection limits across the different conditions. On one hand, the within-participant reproducibility was substantial on average, though the between-participant reproducibility was only fair. On the other hand, experiencing incorrect step counts varied highly across and within participants. In conclusion, the self-familiarization of health care professionals with the detection limits of a physical activity tracker using specific protocols seems to be a feasible approach. Such protocols can provide valuable tools for facilitating the use of physical activity trackers in clinical applications. Additional research may allow for further refinement of the protocol to generate input that is more comparable across participants and closer to the gait of patients.