Investigation of Foot Sensor Insoles for Measuring Functional Outcome After Total Knee Replacement

Area of Science:

• Orthopedics
• Biomechanics
• Medical Engineering

Background:

• Patient-reported outcome measures (PROMs) are standard for functional assessment.
• Biomechanical testing offers supplementary data for a comprehensive evaluation.
• Instrumented insoles are being explored for measuring ground-to-foot forces.

Purpose of the Study:

• To evaluate instrumented insoles for measuring ground-to-foot forces during basic activities.
• To compare biomechanical data with patient-reported outcome measures (PROMs) in total knee replacement patients.

Main Methods:

• Three groups were assessed: normal controls, preoperative total knee patients, and postoperative total knee patients.
• Functional outcome was measured using the Knee Society Scoring System (KSS) Short Form.
• Biomechanical data was collected using foot pressure sensor insoles during timed-up-and-go (TUG) and sit-to-stand (STS) tests.

Main Results:

• Significant differences in most measured parameters were observed between preoperative, postoperative, and control groups.
• No significant biomechanical differences were found between normal controls and postoperative total knee patients.
• Correlation analysis revealed limited overlap between PROM and biomechanical parameters, with only five of 33 coefficients exceeding 0.5.

Conclusions:

• Biomechanical data from instrumented insoles provides functional evaluation largely independent of PROM data.
• Left-right force ratios during STS and TUG time were identified as the most informative biomechanical parameters.
• Instrumented insoles show promise for augmenting functional outcome assessment in total knee replacement patients.