Technical Quality Assurance of GA

1. Technical Quality Assurance of GA • The aim of Technical Quality Assurance (TQA) was to assess the quality of the measurements conducted in the gait labs involved in the WP6: • KU Leuven (KUL); • VU Medisch Centrum (VUA); • Ospedale Pediatrico ‘Bambino Gesù’ (OPBG) • TQA protocol is composed by two experimental sessions: • Low-level session: focused on the comparability of the measurement systems • High-level session: focused on the inter-laboratory/rater repeatability of gait analysis Amsterdam – 23-24 February 2015

2. Low-level session • OS-validation • Wands were moved for 10 s inside the measurement volume • Distances and angles were evaluated and compared with the actual values • Repeatability of parameters was evaluated as RMSE Less accuracy of Bonita system Amsterdam – 23-24 February 2015

3. Low-level session • S-synchro • Signal synchronization between the force platform and the EMG system • EMG Cometa system is provided with Foot-switch sensors (FS) which are acquired synchronously with EMG • Time delay between EMG and FP was individuated when both signals were zero Pointer Foot switch Force platform Values have to be considered in the activation time of muscles Amsterdam – 23-24 February 2015

4. Low-level session • FP-validation • Pointer (LC-P) equipped with a 6-component load cell and 5 markers • Fully rotational ferrule allows LC-P to tilt in several directions • Application of arbitrary forces to each force platform with LC-P: • Oriented along the vertical axis • Tilted of approximately 30°around x and y • F and M were measured by LC-P and FP • F and M were projected on OS reference system • RMSEs were calculated for each pushed point Amsterdam – 23-24 February 2015

5. Low-level session FP-validation • Forces and Moments measured with FP were comparable with the same parameters evaluated by means of LC-P • Differences between curves were observable only at VUA for Fx and Fy Amsterdam – 23-24 February 2015

6. Low-level session FP-validation • Fy and Fx at OPBG and VUA got worse from the center to the edge of platform • Different behavior of platforms at each center was found • RMSE values were lower than the 1% of Full Scale of each platform • RMSEs have to be considered to estimate the contribution of FP to the overall uncertainty of the kinetic variables Amsterdam – 23-24 February 2015

7. High level The aim of high level is the evaluation of the repeatability of measurements conducted in different laboratories. The protocol includes the following features: • Two healthy children have been recruited; • Data were collected in OPBG, KUL and VUA; • Two therapists per center; • Five walking trials were collected. • The considered variables are • Joint angles • Joint moments • Spatiotemporal parameters • Timing on EMG activation • The repeatability indices used : • Coefficient of Multiple Correlation (CMCw) within laboratory • Coefficient of Multiple Correlation (CMCb) between laboratories Amsterdam – 23-24 February 2015

8. Within laboratory repeatability • In the sagittal plane the repeatability within laboratory was excellent • In the frontal and transverse plane the repeatability was lower than sagittal plane • CMC for hip rotation was the lowest value, it could be due to a different marker placement between therapists. Comparable values of CMC for second subjects were found (0.78, 0.83) Amsterdam – 23-24 February 2015

9. Between laboratories repeatability • Two CMC between laboratories were calculated: • CMC between laboratories with PiG model (OPBG and KUL); • CMC between laboratories with different models (OPBG, KUL and VUA). • The repeatability between the three centers was lower than the repeatability between OPBG and KUL, however in the range of a good repeatability, with the exception of hip rotation between the three laboratories. Amsterdam – 23-24 February 2015

10. EMG Signal • The activation time of 8 muscles (4 agonist and 4 antagonist) of one lower limb was calculated • T-tests were performed in order to find significant differences between the operators of the same laboratory • One-way ANOVA was conducted whether t-test was not significant • T-tests were significant only for Anterior Tibialis and Gastrocnemius • Statistical differences between laboratories were found for Gluteus Medius in both subjects • Therapists have to pay specific attention to place electrodes on Anterior Tibialis, Gastrocnemius and Gluteus Medius • Comparability of EMG data of these muscles among centers could be questionable Amsterdam – 23-24 February 2015

11. Future Works • Analysis of comparability of the two models (PiG and HBM) on the same subject and the same gait • In order to do it, we need of: • Gait data from OPBG and KUL taking into account HBM model; • Gait data from VUA taking into account PiG model. Amsterdam – 23-24 February 2015