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Antonio M. López, Diego Álvarez, Rafael C. González, and Juan C. Álvarez

Pedometers are basically step counters usually used to estimate the distance walked by a pedestrian. Although their precision to compute the number of steps is quite accurate (about 1%), their feasibility to estimate the walked distance is very poor, as they do not consider the intrinsic variability of human gait. Reported results show values of 10% of precision in optimal conditions, increasing to 50% when conditions differ. Electronic accelerometer-based pedometers base their functioning on a basic processing of the vertical acceleration of the waist. Recently, different approaches have been proposed to relate such signals to the step length. This can lead to an improvement of the performance of this kind of device for estimating the walked distance. In this article, we analyze four gait models applied to the vertical accelerations of the body’s center of gravity, three biomechanical and one empirical. We compare their precision and accuracy. Results support the superior performance of three of them over an ideal pedometer. We also analyze their feasibility to be implemented in pedometer-like devices.

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Daniel J. Petit, John D. Willson, and Joaquin A. Barrios

Efforts to compare different surface marker configurations in 3-dimensional motion analysis are warranted as more complex and custom marker sets become more common. At the knee, different markers can been used to represent the proximal shank. Often, two anatomical markers are placed over the femoral condyles, with their midpoint defining both the distal thigh and proximal shank segment ends. However, two additional markers placed over the tibial plateaus have been used to define the proximal shank end. For this experiment, simultaneous data for both proximal shank configurations were independently collected at two separate laboratories by different investigators, with one laboratory capturing a walking population and the other a running population. Common discrete knee joint variables were then compared between marker sets in each population. Using the augmented marker set, peak knee flexion after weight acceptance was less (1.2−1.7°, P < .02) and peak knee adduction was greater (0.7−1.4°, P < .001) in both data sets. Similarly, the calculated peak knee flexion moment was less by 15–20% and internal rotation moment was greater by 11–18% (P < .001). These results suggest that the calculation of knee joint mechanics are influenced by the proximal shank’s segment endpoint definition, independent of dynamic task, investigator, laboratory environment, and population in this study.

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Inga Krauss, Thomas Ukelo, Christoph Ziegler, Detlef Axmann, Stefan Grau, Thomas Horstmann, and Alex Stacoff

Results from instrumented gait analysis vary between test situations. Subject characteristics and the biomechanical model can influence the total amount of variability. The purpose of this study was to quantify reliability of gait data in general, and with respect to the applied model, and investigated population group. Reliability was compared between a functional and a predictive gait model in subjects with knee osteoarthritis and healthy controls. Day-to-day consistency for sagittal plane variables was comparable between models and population groups. Transversal plane variables relative to joint excursion showed larger inconsistency for repeated measures, even for a more sophisticated biomechanical approach. In conclusion, the presented reliability data of sagittal plane kinematics should be used for a reasonable interpretation of results derived in clinical gait analysis. Variables of the transversal plane should not be used as long as sources of error are not sufficiently minimized.

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Alexander Nazareth, Nicole M. Mueske, and Tishya A.L. Wren

This study aimed to determine the effect of tibia marker placement on walking kinematics in children with pathological gait. Three-dimensional lower extremity gait data were collected using both a traditional tibia wand (protruding laterally from the distal shank) and a tibia crest marker on 25 children with pathological gait. Kinematic variables during walking and quiet standing were calculated using each marker and the “Plug-in Gait” implementation of the conventional gait model. For walking, average differences in kinematics between tibia markers ranged from 0.1° to 1.9° at the knee and ankle, except in the transverse plane where differences were 6.0° to 7.2°. No significant differences were found during quiet standing, indicating that differences in kinematics derive primarily from dynamic sources, which likely affect the tibia wand more than the tibia crest marker. These results suggest that the tibia crest marker can be used in place of the traditional tibia wand in clinical gait analysis.

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Matthew J. Solomito, Andrew D. Cohen, Erin J. Garibay, and Carl W. Nissen

adduction), and Z rotation described transverse plane motion (internal and external rotation). Lower-extremity joint modeling followed the modified Helen Hayes model, 35 and utilized the 4 marker pelvis common to the Plug-in Gait Model (Vicon Motion Systems). 35 Upper-extremity joint modeling was based

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Moataz Eltoukhy, Christopher Kuenze, Jeonghoon Oh, Eryn Apanovitch, Lauren Butler, and Joseph F. Signorile

 al. 30 The use of the additional lower-extremity markers was done after confirming from our pilot testing that the traditional Plug-in-Gait model is not suitable for such dynamic movement such as the side-cut maneuvers performed in this study. In addition, and as mentioned in various studies such as

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Hamid Reza Bokaeian, Fateme Esfandiarpour, Shahla Zahednejad, Hossein Kouhzad Mohammadi, and Farzam Farahmand

were calculated as the midpoint between the medial and lateral malleoli and femoral epicondyles, respectively. Joint moments were calculated through inverse dynamics via the Plug-in-Gait model programmed in Vicon Nexus 2.6 software (Vicon Oxford; Vicon Motion Systems, 2017 ). In each trial, the first

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Ryan Zerega, Carolyn Killelea, Justin Losciale, Mallory Faherty, and Timothy Sell

, Centennial, CO). Procedures Anthropometric measurements were recorded for each subject, according to the lower body Plug-In Gait model for creation of the biomechanical model in Nexus (Vicon Motion Systems Ltd). 28 About 18 reflective markers were placed on the lower extremities according to the Plug

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Dimitrios-Sokratis Komaris, Cheral Govind, Andrew Murphy, Alistair Ewen, and Philip Riches

attached using double-sided adhesive ring tape to 35 anatomical landmarks as part of the full-body Plug-In Gait model. The markers were positioned on the left and right temple and on the back of the head in the horizontal plane defined by the front head markers with a sports headband, 7th cervical vertebra

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Yi-Ju Tsai, Chieh-Chie Chia, Pei-Yun Lee, Li-Chuan Lin, and Yi-Liang Kuo

analysis system (Vicon T10; Oxford Metrics Group, Yarnton, United Kingdom) with the sampling rate at 200 Hz. Thirty-two reflective markers were placed over bony landmarks according to the Plug-in-Gait model to define the body segments (Figure  1 ). To minimize palpation errors, the same therapist placed