  A low-cost, accurate device to measure and record knee range of motion (ROM)
is of the essential need to improve confidence in at-home rehabilitation. It is
to reduce hospital stay duration and overall medical cost after Total Knee
Arthroplasty (TKA) procedures. The shift in Medicare funding from pay-as-you-go
to the Bundled Payments for Care Improvement (BPCI) has created a push towards
at-home care over extended hospital stays. It has heavily affected TKA
patients, who typically undergo physical therapy at the clinic after the
procedure to ensure full recovery of ROM. In this paper, we use accelerometers
to create a ROM sensor that can be integrated into the post-operative surgical
dressing, so that the cost of the sensors can be included in the bundled
payments. In this paper, we demonstrate the efficacy of our method in
comparison to the baseline computer vision method. Our results suggest that
calculating angular displacement from accelerometer sensors demonstrates
accurate ROM recordings under both stationary and walking conditions. The
device would keep track of angle measurements and alert the patient when
certain angle thresholds have been crossed, allowing patients to recover safely
at home instead of going to multiple physical therapy sessions. The
affordability of our sensor makes it more accessible to patients in need.
