Gait assessment is of interest to clinicians and researchers because it provides information about patients’ functional mobility. Optoelectronic camera-based systems with gait event detection algorithms are considered the gold standard for gait assessment. Yet, the choice of the algorithm used to process data and extract the desired parameters from those detected gait events has an impact on the validity and reliability of the gait parameters computed. There are multiple techniques documented in the literature for computing gait events, including the analysis of the minimal position of the heel and toe markers, the computation of the relative distance between sacrum and foot markers, and the assessment of the smallest distance between the heel and toe markers. Validation studies conducted on these algorithms report variations in accuracy. Yet, these studies were conducted in different conditions, at varying gait velocities, and on different populations. The purpose of this study is to compare accuracy, precision, and robustness of three algorithms using motion capture data obtained from 25 healthy persons and 21 psoriatic arthritic patients walking at three distinct speeds on an instrumented treadmill. Errors in gait events recognition (heel strike—HS and toe-off—TO) and their impact on gait metrics (stance phase and stride length) are reported and compared to ground reaction force events measured with force plates. Over the 9114 collected steps across all walking speeds, more than 99% of gait events were recognized by all algorithms. On average, HS events were detected within 1.2 ms of the reference for two algorithms, while the third one detected HS late, with an average detection error of 40.7 ms. Yet, significant variations in accuracy were noted with gait speed; the performance decreased for all algorithms at slow speed. TO events were identified early by all algorithms, with an average error ranging from 16.0 to 100.0 ms. These gait events errors lead to 2–15% inaccuracies in stance phase assessment, while the impact on stride length remains below 0.3 cm. Overall, the algorithm based on the relative distance between the sacral and foot markers stood out for its accuracy, precision, and robustness at all walking speeds.

The objectives of this study were to assess the accuracy and precision of a system combining an IMU-instrumented sock and a validated algorithm for the estimation of the spatio-temporal parameters of gait. A total of 25 healthy participants (HP) and 21 patients with foot impairments secondary to psoriatic arthritis (PsA) performed treadmill walking at three different speeds and overground walking at a comfortable speed. HP performed the assessment over two sessions. The proposed system’s estimations of cadence (CAD), gait cycle duration (GCD), gait speed (GS), and stride length (SL) obtained for treadmill walking were validated versus those estimated with a motion capture system. The system was also compared with a well-established multi-IMU-based system for treadmill and overground walking. The results showed a good agreement between the motion capture system and the IMU-instrumented sock in estimating the spatio-temporal parameters during the treadmill walking at normal and fast speeds for both HP and PsA participants. The accuracy of GS and SL obtained from the IMU-instrumented sock was better compared to the established multi-IMU-based system in both groups. The precision (inter-session reliability) of the gait parameter estimations obtained from the IMU-instrumented sock was good to excellent for overground walking and treadmill walking at fast speeds, but moderate-to-good for slow and normal treadmill walking. The proposed IMU-instrumented sock offers a novel form factor addressing the wearability issues of IMUs and could potentially be used to measure spatio-temporal parameters under clinical conditions and free-living conditions.

Introduction: Foot involvement is a major concern in psoriatic arthritis (PsA) as it can lead to severe levels of foot pain and disability as well as reduced mobility and quality of life. Previous studies have shown moderate efficacy in reducing foot pain and disability in rheumatoid arthritis patients with the use of custom-made foot orthoses (CFO). However, evidence on the efficacy of CFO in PsA patients is lacking.Objectives: Explore the effects of CFO on foot function, foot and lower limb pain, gait function, and freeliving walking activities (FWA) in PsA patients.Methods: A Pre-experimental study including 20 PsA patients (mean age: 54.10 ± 9.06 y and disease duration: 11.53 ± 10.22 y), was conducted. All the participants received and wore CFO for a 7-week period. Foot and lower limb pain and foot function were measured before and after the intervention using the numerical rating scale (NRS) and the foot function index (FFI). Gait function was assessed from gait spatiotemporal parameters (STPs) extracted during a 10-meter walk test with an gait analysis system (Mobility Lab). Freeliving walking activities (step count, freeliving cadence, time spent in different ambulatory physical activities (APA)) were recorded over 7 days using accelerometer data collected from an instrumented sock worn during waking hours.Results: PsA patients reported severe baseline levels of foot pain (54.46 ± 14.58 %) and disability (46.65 ± 16.14%) on the FFI. Statistically and clinically significant improvements with large effect sizes (Cohen’s effect size > 1, p<0.005) in foot pain and foot function were observed after 7 weeks of CFO use. A significant correlation (r=-0.64, p<0.01) between CFO wear time after the adaption period and foot function on the FFI at 7 weeks was observed. However, no significant changes were demonstrated for gait STP nor for free-living walking activities after 7 weeks of CFO use.Conclusion: Results support the clinical and biomechanical plausibility of using CFO with PsA patients to reduce pain and improve foot function. Larger and controlled studies are needed to confirm these findings and a multidisciplinary approach including the prescription of exercise therapy and physiotherapy in combination with CFO could be relevant to improve STP and promote APA in PsA patients.Study registration: ClinicalTrials.gov, NCT05075343, Retrospectively registered on 29 September 2021.

Background: Foot involvement is a major manifestation of psoriatic arthritis (PsA) and could lead to severe levels of foot pain and disability and impaired functional mobility and quality of life. Gait spatiotemporal parameters (STPs) and gait variability, used as a clinical index of gait stability, have been associated with several adverse health outcomes including risk of falling, functional decline, and mortality in a wide range of populations. Previous studies showed some alterations in STPs in people with PsA. However, gait variability and the relationships between STPs, gait variability and self-reported foot pain and disability have never been studied in this populations. Body-worn inertial measurement units (IMUs) are gaining interest in measuring gait parameters in clinical settings.Objectives: To assess STPs and gait variability in people with PsA using IMUs and, to explore their relationship with self-reported foot pain and function and to investigate the feasibility of using IMUs to discriminate patient groups based on gait speed-critical values.Methods: 21 participants with PsA (Age: 53.9 ± 8.9 yrs; median disease duration: 6 yrs) and 21 age and gender-matched healthy participants (Age 54.23 ± 9.3 yrs) were recruited. All the participants performed three 10-meter walk test trials at their comfortable speed. STPs and gait variability were recorded and calculated using six body-worn IMUs and the Mobility Lab software (APDM®). Foot pain and disability were assessed in participants with PsA using the foot function index (FFI).Results: Cadence, gait speed, stride length, and swing phase, were significantly lower, while double support was significantly higher, in the PsA group (p< 0.006). Strong correlations between STPs and the FFI total score were demonstrated (|r|> 0.57, p< 0.006). Gait variability was significantly increased in the PsA group, but it was not correlated with foot pain and function (p< 0.006). Using the IMUs three subgroups of participants with PsA with clinically meaningful differences in self-reported foot pain and disability were discriminated.Conclusion: STPs were significantly altered in participants with PsA which could be associated with self-reported foot pain and disability. Future studies are required to confirm the increased gait variability highlighted in this study and its potential underlying causes. Using IMUs in clinical settings has been useful to objectively assess foot function in people with PsA. Study registration: ClinicalTrials.gov, NCT05075343, Retrospectively registered on 29 September 2021.