HUMOV 2303 S0167-9457(17)30641-3 10.1016/j.humov.2018.06.003 The Authors Fig. 1 Experimental set-up of the fluoroscopy system and walkway (a) and the participants walking (b). Fig. 2 The origin of the talus was placed at the center of a circle that circumscribed the trochlea tali; the circle included the midpoint of the anteromedial and anterolateral edges and the midpoint of posteromedial and posterolateral edges of the trochlea. Fig. 3 Anatomical coordinate system of the tibia (a), talus (b), and calcaneus (c) from lateral (upper), frontal (middle), and top or bottom (lower) views. o, origin of anatomical coordinate systems in each bone model. Fig. 4 A single fluoroscopic image with 3D bone models superimposed on the radiographic image and registered to the osseous contours of the bones in the image. Fig. 5 Mean results of the talocrural and subtalar joint kinematics at every 10% of stance phase. Rotations are referenced to the static standing posture. Descriptive data are expressed as mean?+/-?standard deviation; *significant difference (males vs. females). Table 1 Sex comparison of rotational angles of the tibia, talus, and calcaneus relative to the global coordinate system in the static reference position. Bone Variable (deg) Male Female Effect size Mean?+/-?SD Mean?+/-?SD pvalue r Tibia Dorsi(+)/plantar(-) flexion 4?+/-?11 -6?+/-?10 0.095 0.42 Eversion(+)/inversion(-) 3?+/-?5 3?+/-?4 0.967 0.01 External(+)/internal(-) rotation -4?+/-?10 0?+/-?9 0.966 0.18 Talus Dorsi(+)/plantar(-) flexion -11?+/-?4 -9?+/-?5 0.393 0.22 Eversion(+)/inversion(-) 1?+/-?3 2?+/-?6 0.191 0.33 External(+)/internal(-) rotation -3?+/-?5 -4?+/-?4 0.757 0.08 Calcaneus Dorsi(+)/plantar(-) flexion 22?+/-?8 23?+/-?5 0.847 0.05 Eversion(+)/inversion(-) 7?+/-?6 8?+/-?5 0.846 0.05 External(+)/internal(-) rotation 5?+/-?5 9?+/-?5 0.149 0.37 *Significant difference; SD, standard deviation. Values are mean?+/-?standard deviation. Table 2 Sex comparison of the total range of motion (ROM) in the talocrural and subtalar joints. Joint Variable (deg) Male Female Effect size Mean?+/-?SD Mean?+/-?SD pvalue r Talocrural joint Dorsi/plantar flexion 13?+/-?4 17?+/-?3 * 0.050 0.05 Eversion/inversion 4?+/-?1 5?+/-?1 0.338 0.25 External/internal rotation 6?+/-?1 7?+/-?2 0.278 0.28 Subtalar joint Dorsi/plantar flexion 4?+/-?2 6?+/-?2 0.191 0.33 Eversion/inversion 8?+/-?3 11?+/-?3 * 0.027 0.54 External/internal rotation 5?+/-?2 7?+/-?2 * 0.040 0.50 Values are mean?+/-?standard deviation. * Significant difference; SD, standard deviation. Full Length Article Sex differences in three-dimensional talocrural and subtalar joint kinematics during stance phase in healthy young adults Mako Fukano a b ? fukano@shibaura-it.ac.jp Toru Fukubayashi b fukuba@waseda.jp Scott Arthur Banks c banks@ufl.edu a College of Engineering, Shibaura Institute of Technology, Saitama, Japan College of Engineering Shibaura Institute of Technology Saitama Japan b Faculty of Sport Sciences, Waseda University, Saitama, Japan Faculty of Sport Sciences Waseda University Saitama Japan c Mechanical & Aerospace Engineering, University of Florida, FL, USA Mechanical & Aerospace Engineering University of Florida FL USA ? Corresponding author at: 307 Fukasaku, Minuma-ku, Saitama-shi, Saitama, Japan. 307 Fukasaku, Minuma-ku, Saitama-shi Saitama Japan Highlights * Range of talocrural dorsi/plantar flexion was larger in females than in males in stance phase. * Range of subtalar eversion/inversion and external/internal rotation were larger in females. * In the reference position orientation of the tibia, talus, and calcaneus were comparable between sexes. Abstract The ankle joint, including the talocrural and subtalar joints, plays an important role in human locomotion. Sex differences in walking patterns among young and old adults have been studied; however, little information exists on sex-based variations in talocrural and subtalar joint kinematics during walking. Thus, the purpose of this study was to investigate sex-based differences in the talocrural and subtalar joint kinematics during walking. We obtained lateral fluoroscopic images from 10 male and 7 female healthy volunteers during stance phase, and determined the three-dimensional bone orientations using 3D-2D model-image registration techniques to compare sex-specific differences. The orientation of the tibia, talus, and calcaneus were comparable in the static reference position. Sex-based differences in the range of motion were observed in talocrural dorsi/plantar flexion, subtalar eversion/inversion and subtalar external/internal rotation while walking. The ranges of motion in talocrural dorsi/plantar flexion (male, 13?+/-?4^o; female, 17?+/-?3^o), subtalar eversion/inversion (male, 8?+/-?3^o; female, 11?+/-?3^o) and subtalar external/internal rotation (male, 5?+/-?2^o; female, 7?+/-?2^o) were significantly larger in females than in males. Differences in rearfoot kinematics between males and females may reflect anatomic, physiologic and locomotor differences. Greater bone rotations in the female hindfoot may predispose women to different pathologies, or merit different treatments, than men based upon subtalar and talocrural kinematics during gait. Abbreviations ROM Range of motion BMI Body mass index ANOVA Analysis of variance CT Computed tomography ICC Interclass correlation coefficient Keywords Joint kinematics Talocrural joint Subtalar joint Walking Sex difference 1 Introduction The synergistic movement of the ankle joint, including the talocrural and subtalar joints, is crucial for human locomotion. Walking is an essential daily activity that habitually loads the joints of the lower extremities and likely contributes to the development and progression of joint degeneration such as osteoarthritis. Therefore, accurate knowledge of the kinematics during walking can contribute to understanding of the etiology of lower extremity joint degeneration. Sex differences in walking patterns and ankle motion among young and old adults have been reported. Young healthy females tended to have shorter stride length, slower gait speed (Cho, Park, & Kwon, 2004), and greater ankle flexion/extension range of motion (ROM) (Bruening, Frimenko, Goodyear, Bowden, & Fullenkamp, 2015) compared to healthy young men while walking at self-selected speeds; additionally, elderly women walked with less hip ROM and greater ankle ROM than elderly men (Boyer, Beaupre, & Andriacchi, 2008; Ko, Tolea, Hausdorff, & Ferrucci, 2011), and adult females ranging from 23 to 62?years old had more plantar flexion at toe-off and early swing than males (Roislien et al., 2009). Despite this knowledge of sex-based kinematic differences in gross motion while walking, it is unknown whether sex-based differences exist specifically in talocrural and subtalar joint kinematics during walking. Sex-based differences in walking mechanics could lead to differences in the occurrence of certain diseases and/or degeneration related to aging (Boyer et al., 2008). For example, ankle osteoarthritis is more frequent in males than in females (Cushnaghan & Dieppe, 1991; Koepp et al., 1999). Deeper understanding of such sex differences might offer insight into the design of interventions to maintain normal gait or prevent mobility limitations (Ko et al., 2011). Thus, we hypothesized that sex-based variations in talocrural and subtalar joint kinematics exist during walking. 3D-2D model image registration techniques have been used to evaluatein vivoankle kinematics in recent years (Campbell, Wilson, LaPrade, & Clanton, 2014; de Asla, Wan, Rubash, & Li, 2006; Fukano, Kuroyanagi, Fukubayashi, & Banks, 2014; Yamaguchi, Sasho, Kato, Kuroyanagi, & Banks, 2009), and an advantage of this method is its ability to describe talocrural and subtalar joint kinematics separately without artifacts produced by skin movement. Current motion analysis techniques using reflective skin markers on selected anatomical landmarks are unable to provide precise talocrural and subtalar joint kinematics due to artifacts produced by skin movement and the absence of palpable landmarks of the talus (Nester et al., 2007; Westblad, Hashimoto, Winson, Lundberg, & Arndt, 2002). Although the 3D-2D model image registration technique can provide good spatial accuracy, to the best of our knowledge, a detailed comparison between sexes of talocrural and subtalar joint movement during stance phase has not been reported. Thus, the purpose of the present study was to investigate sex-based differences in the talocrural and subtalar joint kinematics during walking. 2 Methods This study was approved by the Ethics Committees on Human Research of Waseda University, Tokyo, Japan. Written informed consent regarding the purposes and procedures of this study was obtained from each participant prior to their involvement. Seventeen healthy volunteers, 10 males (age 21.2?+/-?1.2?years; height 171.0?+/-?5.6?cm; weight, 65.6?+/-?5.8?kg) and 7 females (age 24.1?+/-?3.0?years; height 160.3?+/-?4.5?cm; weight, 55.7?+/-?7.8?kg) participated in this study. Regarding the subjects' physical characteristics, the height and weight of the males were significantly greater than that of the females (F?=?3.09 and 0.42 respectively,p?0.95, with average differences from the mean of 0.60?mm for in-plane translations, 1.8?mm for out-of-plane translations, and 0.59^o for rotations (Fukano & Fukubayashi, 2014). Interclass correlation coefficients (ICCs) for the kinematics data were >0.98 for dorsi/plantar flexion, >0.78 for eversion/inversion, and >0.91 for external/internal rotation (Fukano & Fukubayashi, 2014). We analyzed the kinematic data for one stance phase for each subject, from heel strike to toe off, and normalized each stance phase time as a percentage. The average of three measured values was considered an individual's data. Each individual set of kinematic data was referenced to that subject's static reference position, standing on the right leg, so that all rotations in the reference position were zero and dynamic rotational excursions were expressed relative to the reference position. The data were processed in a single-blinded manner from immediately after data collection until kinematic calculation. All statistical analyses were conducted using statistical analysis software (IBM SPSS Statistics ver. 20, IL, USA) A two-tailed unpairedt-test was used to compare the physical characteristics and the rotations of the tibia, talus, and calcaneus relative to the global coordinate system in the static reference pose and the total ROM of the talocrural and subtalar joints between sexes. Changes in kinematic data between sexes (male, female) by time (every 10% of stance phase) were tested using between-within two-way ANOVA. Bonferroni's post hoc analysis was conducted if the ANOVA showed statistically significant main effects and no interaction effects. The significance was set atp?