Quantifying the relative change in physical activity after Total Knee Arthroplasty using accelerometer based measurements.

Osteoarthritis is amongst the top five most disabling conditions affecting Americans over 65 years of age and imposes an annual economic burden estimated at $ 89.1 billion. Nearly half of the cost of care of Osteoarthritis is attributable to hospitalizations for total knee arthroplasties (TKA) and total hip arthroplasties (THA). The current clinical practice relies predominantly on subjective assessment of physical function and pain via patient reported outcome measures (PROM) that have proven inadequate for providing a validated, reliable and responsive measure of TKA outcomes. Wearable activity monitors, which produce a trace of regularly monitored physical activity derived from accelerometer measurements, provide a novel opportunity to objectively assess physical functional status in Osteoarthritis patients. Using data from the Osteoarthritis Initiative (OAI), we demonstrate the feasibility of quantifying the relative change in physical activity patterns in Osteoarthritis subjects using accelerometer based measurements of daily physical activity.