Integration of force and IMU sensors for developing low-cost portable gait measurement system in lower extremities.

Gait analysis is the method to accumulate walking data. It is useful in diagnosing diseases, follow-up of symptoms, and rehabilitation post-treatment. Several techniques have been developed to assess human gait. In the laboratory, gait parameters are analyzed by using a camera capture and a force plate. However, there are several limitations, such as high operating costs, the need for a laboratory and a specialist to operate the system, and long preparation time. This paper presents the development of a low-cost portable gait measurement system by using the integration of flexible force sensors and IMU sensors in outdoor applications for early detection of abnormal gait in daily living. The developed device is designed to measure ground reaction force, acceleration, angular velocity, and joint angles of the lower extremities. The commercialized device, including the motion capture system (Motive-OptiTrack) and force platform (MatScan), is used as the reference system to validate the performance of the developed system. The results of the system show that it has high accuracy in measuring gait parameters such as ground reaction force and joint angles in lower limbs. The developed device has a strong correlation coefficient compared with the commercialized system. The percent error of the motion sensor is below 8%, and the force sensor is lower than 3%. The low-cost portable device with a user interface was successfully developed to measure gait parameters for non-laboratory applications to support healthcare applications.

Effectiveness of a Simple Auditory Feedback Insole (Sim-Insole) for Touchdown Weight-Bearing Training in At-Risk Volunteers with Poor Compliance: A Crossover Study.

INTRODUCTION: Recent studies have shown that biofeedback devices are effective for weight-bearing (WB) training. However, these devices have limitations due to high costs and inadequate evidence of their effectiveness among poor-compliance individuals. This study aimed to assess WB compliance after touchdown weight-bearing (TDWB) training by the standard bathroom scale (BS) method and to evaluate the efficacy of our innovative simple auditory feedback device (Sim-Insole). METHODS: In this crossover study, healthy volunteers were trained for TDWB (targeting 20% of bodyweight [BW]) with the BS method and assessed with the Sim-Insole without feedback (phase 1), and then completed a 30-min wash-out period and underwent re-assessment with Sim-Insole with feedback (phase 2). Satisfaction was evaluated with a self-assessment questionnaire. Those who had and had not experienced a weight-bearing force (WBF) >25% of BW were classified as high-risk and low-risk groups, respectively. Steps with percentage of WB &15%, 15%-25%, and >25% were defined as under-zone, in-zone, and over-zone, respectively. RESULTS: Fourteen volunteers (70%) were classified as high-risk after the BS method. Without auditory feedback, the high-risk group demonstrated a significantly higher average percentage of WB and higher average lowest WBF compared to the low-risk group (18.8% vs. 13.7% and 74.3N vs. 60.2N, respectively, p=0.002 for both). With the use of auditory feedback with Sim-Insole in the high-risk group, the cadence, percentage of WB, highest absolute WBF, proportion of over-zone step, and confidence for TDWB improved significantly compared to those with the BS method (p&0.05 for all). However, the low-risk group showed only a significant improvement in cadence (p=0.047) and a non-significant trend for improvement in the percentage of WB (p=0.089), compared to the BS method. CONCLUSION: Sim-Insole is effective for TDWB training. This device significantly improved WB compliance with regard to excessive WB, walking speed, and the confidence of volunteers in the high-risk group with poor compliance.

Reliability and Correlation of the Force-PRO Device and Computer-Assisted Navigation System for Measurement of Acetabular Cup Position in Total Hip Arthroplasty.

INTRODUCTION: Acetabular cup malposition is very common in total hip arthroplasty (THA) and is significantly associated with many serious postoperative complications, such as dislocation, wear and loosening, and decreased range of motion. To improve the accuracy of intraoperative assessment, we recently developed an innovative sensor-based navigation system (Force-PRO device) using an inertial measurement unit and a 3D-printed liner for acetabular cup measurement, and aimed to evaluate its reliability and correlate its accuracy with that of a computer-assisted navigation system (CANS). DESIGN: Method-comparison study between the Force-PRO device and a standard CANS in a 1:1 pelvic bone model. METHODS: The test-retest reliability of both the Force-PRO device and CANS, and agreement between the Force-PRO device and CANS, for the measurement of acetabular inclination and anteversion angles, were examined using 40 random acetabular cup positions. Statistical analysis was performed by using limits of agreement and intraclass correlation coefficient (ICC). RESULTS: The mean differences in the inclination angle and anteversion angle in test-retest of the Force-PRO device were -0.43°±1.03° and -0.40°±0.78°, respectively. The mean differences in the inclination angle and anteversion angle between the Force-PRO device and CANS were 0.70°±0.94° and -0.10°±0.44°, respectively. Excellent reliability in the inclination and anteversion angles of the Force-PRO device and excellent agreement between the Force-PRO device and CANS were demonstrated, with ICC values of 0.994 and 0.997, and 0.993 and 0.999, respectively. CONCLUSION: The Force-PRO device showed excellent reliability equivalent to CANS with excellent agreement in acetabular cup position measurement comparable to that with CANS. Future clinical studies will be needed to evaluate the efficacy of this device.

Innovative Force-PRO device to measure force and implant position in total hip arthroplasty.

Total hip arthroplasty (THA) is the appropriate treatment for hip pain, dislocation, and dysfunction. THA refers to surgery to replace a hip implant, which is an effective way to recover normal hip function. The design of an implant imitates hip functions and allows bone growth in the implant area. However, it should be noted that the implant can dislocate after surgery. The main factor that should be considered during surgery is the correct position of the implant component. The acetabular cup of the hip implant should be positioned at [Formula: see text] anteversion and [Formula: see text] inclination. The evaluation of the implant inclination and anteversion during the operation decrease the risk of the implant dislocation after surgery. Developing a new innovative Force-PRO device can aid the doctor in evaluating the force on the surface of the acetabular liner and the angle of the acetabular liner during the hip implant operation. This device consists of two main sensors-force sensors and inertial measurement unit sensors. Furthermore, the 3D printings of an implant's parts should be specifically designed to integrate with these sensors. To develop the graphical user interface application, C[Formula: see text] should be the programming language of use. The graphical user interface application communicates between the device and user via a wireless communication system. CT-based imaging and force gauge measurement are the methods to evaluate the efficiency of this device. For this purpose, the sterile method is considered.