Normative Values for Daily Functional Recovery Patterns Following Total Knee Arthroplasty

Wearable devices provide the ability for clinical teams to continuously monitor patients' rehabilitation progress with objective data. Understanding expected recovery patterns following total knee arthroplasty (TKA) enables prompt identification of patients failing to meet these milestones. The aim of this study was to establish normative values for daily functional recovery in the first 6 weeks after TKA using a wearable device.

This prospective study included patients who underwent TKA between 2020 and 2023, treated by 11 surgeons from 8 institutions. Eligible participants were aged 18 or older, had a primary unilateral TKA, and owned a smartphone. Knee range of motion, total daily steps, cadence, and device usage were measured continuously over 6 weeks. Statistical analysis included analysis of variance using post hoc Tukey honest significant difference tests.

The cohort of 566 participants had a mean age of 65 and 69 for men and women, respectively (range, 50 to 80). Women comprised 61% (n = 345) of study participants. There were 82% of women and 90% of men who had a body mass index > 30. The average daily wear time of the device was 12 hours (±4) for a total of 45 days (±27). Recovery was nonlinear, with the greatest gains in the first 3 weeks postsurgery for all metrics. Men demonstrated greater total daily step counts and cadence when compared to women. Obese patients demonstrated poorer performance when compared to lower body mass index patients.

To our knowledge, this study presents the first normative data for tracking daily functional recovery in TKA patients using wearable sensors. Standardizing the TKA recovery timeline allows surgeons to isolate factors affecting patients' healing processes, accurately counsel them preoperatively, and intervene more promptly postoperatively when rehabilitation is not within standard recovery parameters.