To be effective, a prescribed prosthetic device must match the functional requirements and capabilities of each patient. These capabilities are usually assessed by a clinician and reported by the Medicare K-level designation of mobility. However, it is not clear how the K-level designation objectively relates to the use of prostheses outside of a clinical environment. Here, we quantify participant activity using mobile phones and relate activity measured during real world activity to the assigned K-levels. We observe a correlation between K-level and the proportion of moderate to high activity over the course of a week. This relationship suggests that accelerometry-based technologies such as mobile phones can be used to evaluate real world activity for mobility assessment. Quantifying everyday activity promises to improve assessment of real world prosthesis use, leading to a better matching of prostheses to individuals and enabling better evaluations of future prosthetic devices.

This feasibility study demonstrates that the Fitbit activity monitor estimates the activity of subjects with transfemoral amputations, producing results that correlate with their K-level functional activity classifications. The Fitbit activity score is independent of individual variations in age, weight, and height compared with estimated calories for this small sample size. These tools may provide useful insights into prosthetic use in an at-home environment.