Persona IQ smart implant data correlates to in-office range of motion after total knee arthroplasty

The advancement of smart implant sensor technology presents a significant opportunity to enhance postoperative assessment and rehabilitation outcomes after total knee arthroplasty (TKA). The purpose of this study was to evaluate the accuracy of a smart implant in measuring absolute range of motion (ROM) after TKA.

A total of 150 patients performed by a single surgeon who underwent primary TKA with a smart implant from 2023 to 2025 were identified. Patient demographics and comorbid conditions were evaluated. The smart implant monitored and transmitted data on daily tibial ROM and functional knee ROM. The maximum values of these data points were recorded at 2, 6, and 12 weeks postoperatively and compared to in-office range of motion. Linear regression analyses and paired t-tests were used to assess the correlation between smart implant and in-office ROM. Multivariate analysis was used to assess correlation between gait parameters and in-office ROM.

Absolute in-office ROM was highly correlated to smart implant tibial ROM multiplied by 1.9 (R² = 0.97) and to smart implant functional knee ROM multiplied by 1.86 (R² = 0.98). There was no significant difference between in-office ROM and implant-measured ROM at 2 weeks (85^o vs. 86^o, p = 0.373), 6 weeks (108^o vs. 109^o, p = 0.892), and 12 weeks (115^o vs. 118^o, p = 0.161).

The smart knee implant accurately measured postoperative TKA absolute ROM after multiplying tibial ROM by 1.9 and functional knee ROM by 1.86. Further research is needed to evaluate the efficacy of remote therapeutic monitoring in reducing the number of in-person postoperative visits within the 90-day global period.

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