Most persons who undergo total knee replacement (TKR) do not increase their physical activity following surgery. The authors assessed whether financial incentives and health coaching would improve physical activity in persons undergoing TKR. They designed a factorial randomized controlled trial among persons undergoing TKR for osteoarthritis. Subjects underwent normal perioperative procedures, including post-operative physical therapy, and were assigned to one of four arms: attention control, telephonic health coaching (THC), financial incentives (FI), or THC+FI. They then objectively measured step counts and minutes of physical activity with a commercial accelerometer (Fitbit Zip) and compared the changes from pre-TKR to 6 months post-TKR across the four study arms.
Of the 202 randomized subjects, 150 (74%) provided both pre-TKR and 6 months post-TKR accelerometer data. Among completers, the average daily step count at 6 months ranged from 5619 (SD 381) in the THC arm to 7152 (SD 407) in the THC+FI arm (adjusting for baseline values). Daily step count 6 months post-TKR increased by 680 (95% CI: -94 – 1,454) in the control arm, 274 (95% CI: -473 – 1021) in the THC arm, 826 (95% CI: 89 – 1563) in the FI arm, and 1808 (95% CI: 1010 – 2606) in the THC+FI arm. Physical activity increased by 14 (SD 10), 14 (SD 10), 16 (SD 10), and 39 (SD 11) minutes in the control, THC, FI, and THC+FI arms, respectively. A dual THC+FI intervention led to substantial improvements in step count and physical activity following TKR.