Improving partial weight bearing compliance with a smart insole: Validity, reliability, and feasibility study

Partial weight bearing (PWB) plays a critical role in early stages of rehabilitation following lower-extremity orthopedic surgery. However, it has been reported patients often have difficulty complying with PWB restrictions, particularly in home setting. The newly designed smart insole system aims to address this issue by remotely monitoring the patient's weight-bearing loads and providing real-time feedback for non-compliant weight-bearing to support PWB compliance. The aim of this study was to assess the validity and reliability of the system in measuring weight-bearing loads and to investigate its feasibility in improving PWB compliance.

The research involved two phases: an experimental design to test validity and reliability in a clinical setting, and a randomized controlled design to test feasibility with remote monitoring at home. Validity and reliability were assessed on a healthy subject using simultaneous load measurements from a smart insole and a force plate under three metronome conditions (30,40, and 60bpm). In the feasibility phase, twelve patients who had undergone microfracture surgery for talar osteochondral lesions were recruited at 4 weeks postoperatively. Participants used Android smartphones and met Ferkel & Scaglione classification criteria I, IIA, and IIB. They were randomized into groups with feedback (FB) or without feedback (NFB) and their compliance with PWB limits was monitored remotely 24-hours for one week using the Insole system.

The insole demonstrated high reliability (SEM:1.67 N, ICC_1.1:0.97) and, excellent agreement with the force plate (R²=0.9175, p < 0.001). The FB group achieved higher compliance with prescribed PWB thresholds compared to the NFB group.

The newly developed insole system is a valid and reliable rehabilitation tool for accurately measuring weight bearing loads. The system's ability to provide continuous remote patient monitoring and real-time feedback on non-compliant weight bearing has proven to be effective in PWB compliance, which is critical in the postoperative recovery period.