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Orthoses posted in both the forefoot and rearfoot reduce moments and angular impulses on lower extremity joints during walking Wen-Hao Hsu, Cara L. Lewis, Gail M. Monaghan, Elliot Saltzman, Joseph Hamill, Kenneth G. Holt www.elsevier.com/locate/jbiomech

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S0021-9290(14)00332-7 http://dx.doi.org/10.1016/j.jbiomech.2014.05.021 BM6676

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Journal of Biomechanics

Accepted date: 24 May 2014 Cite this article as: Wen-Hao Hsu, Cara L. Lewis, Gail M. Monaghan, Elliot Saltzman, Joseph Hamill, Kenneth G. Holt, Orthoses posted in both the forefoot and rearfoot reduce moments and angular impulses on lower extremity joints during walking, Journal of Biomechanics, http://dx.doi.org/ 10.1016/j.jbiomech.2014.05.021 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Orthoses posted in both the forefoot and rearfoot reduce moments and angular impulses on lower extremity joints during walking Wen-Hao Hsua,*, Cara L. Lewisa, Gail M. Monaghana, Elliot Saltzmana, Joseph Hamillb, Kenneth G. Holta a

Department of Physical Therapy and Athletic Training, Sargent College of Health and Rehabilitation Sciences, Boston University, Boston, MA b

Department of Kinesiology, University of Massachusetts Amherst, Amherst, MA

*Corresponding author. Department of Physical Therapy and Athletic Training, College of Health and Rehabilitation Sciences: Sargent College, Boston University 635 Commonwealth Avenue, Boston, MA 02215, USA. Tel: +1-917-916-8766. E-mail: [email protected] Abstract The purpose of the present study was to determine the effects of orthoses designed to support the forefoot and rearfoot on the kinematics and kinetics of the lower extremity joints during walking. Fifteen participants volunteered for this study. Kinematic and kinetic variables during overground walking were compared with the participants wearing sandals without orthoses or sandals with orthoses. Orthoses increased knee internal abduction moment during late stance and knee abduction angular impulse, and reduced the medial ground reaction force during late stance, adduction free moment, forefoot eversion angle, ankle inversion moment and angular impulse, hip adduction angle, hip abduction moment, and hip external rotation moment and angular impulse (p < 0.05). Orthoses decreased the torsional forces on the lower extremity and reduced 1

the loading at the hip during walking. These findings combined with our previous studies and those of others suggest that forefoot abnormalities are critically important in influencing lower extremity kinematics and kinetics, and may underlie some non-traumatic lower extremity injuries. Keywords: Custom-made orthoses; Kinematics; Kinetics; Foot varus

1. Introduction It has been claimed that the varus foot, through anatomic and functional constraints (McPoil & Knecht, 1985; Root, Orien, & Weed, 1977), results in an everted calcaneus, excessive subtalar joint pronation, knee abduction, hip adduction and lower extremity internal rotation during gait (Michaud, 1993; Tiberio, 1987, 1988). These abnormal motions caused by the varus foot have often been considered risk factors for running injury (Ferber, Hreljac, & Kendall, 2009; Hamill, van Emmerik, Heiderscheit, & Li, 1999; McClay & Manal, 1998; Messier & Pittala, 1988). Most orthoses designed to prevent excessive pronation focus on controlling rearfoot motion. Nevertheless, a forefoot varus abnormality is considered a ‘destructive foot’ because of its proposed mechanism to cause prolonged excessive pronation in the late stance phase which could affect lower leg biomechanics during gait, create abnormally high torques in the lower extremity and lead to chronic knee, hip and pelvic injury (Holt & Hamill, 1995; Michaud, 1993; Tiberio, 1988). Supporting this supposition, Gross et al. (2007) found that elderly individuals with a large forefoot varus in non-weight bearing had a two times greater incidence of hip osteoarthritis and a five times greater risk for total hip replacement. Recent evidence (Monaghan et al., 2013) has shown that individuals with large forefoot varus (> 15°), at foot contact measured relative to the ground plane (Holt & Hamill, 1995), had a 2

greater range and duration of pronation during stance than those with less forefoot varus. Since such increased and prolonged pronation is claimed to affect the relative motions among the lower extremity joints and stress the hip joint (Michaud, 1993; Tiberio, 1988), this would provide a potential mechanism for the hip pathology observed by Gross et al. (2007). In contrast to the forefoot posture, the rearfoot posture was not related to the amount or timing of pronation (Monaghan et al., 2013) or the incidence of hip osteoarthritis and/or total hip replacement (Gross et al., 2007). Investigations of the effectiveness of orthoses in walking have largely been limited to those designed to control rearfoot motion, with results showing equivocal effects on the motion of the foot (Eng & Pierrynowski, 1994; Ferber & Benson, 2011; McCulloch, Brunt, & Vander Linden, 1993; Novick & Kelley, 1990; Zifchock & Davis, 2008). One experiment indicated a decrease in moments at the foot (Nester, van der Linden, & Bowker, 2003), and reduction of knee frontal plane motion (Eng & Pierrynowski, 1994). The only study that investigated the kinetics of proximal joints in walking showed no effects on the knee and hip (Nester et al., 2003). However, orthoses utilizing medial posting have done so only in the rearfoot with some extended distally to a point proximal to the first metatarsal head. This design may not provide sufficient control during late stance as orthoses posted up to the metatarsophalangeal joint line have dynamical effects only from foot contact to mid-stance (MacLean, Davis, & Hamill, 2006). Once the heel leaves the ground and the body weight transfers to the forefoot, a rearfoot orthosis will not be effective in controlling the pronation in a varus forefoot undergoing a large pronatory torque (Holt & Hamill, 1995). To date, however, there have been no studies investigating the effects of orthoses with medial posting that extended through the forefoot to the end of the first toe during

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walking either in the foot or in the more proximal joints. In the studies that reported forefoot posting, that posting extended only to the first metatarsal head. The purpose of this study was to examine the effects of custom-made orthoses posted in both the forefoot (extended to and including the first toe) and rearfoot on lower extremity kinematics and kinetics during walking. It was hypothesized that such orthoses would diminish the theorized effects of increased and late pronation on lower extremity biomechanics, by: (a) reducing foot eversion, knee internal rotation and hip adduction and internal rotation motions, (b) increasing knee adduction motion, (c) affecting ankle inversion, knee abduction and external rotation, and hip abduction and external rotation moments and angular impulses. 2. Methods 2.1. Participants Fifteen adults (8 females and 7 males; mean age: 22.9 ± 4.9 years) were recruited for this study (Table 1). Using data from the literature a sample size of 15 was estimated to achieve statistical power of 0.8 and alpha level of 0.05 (Mundermann, Nigg, Humble, & Stefanyshyn, 2003; Williams, Davis, & Baitch, 2003). The inclusion criterion was bilateral forefoot varus abnormality greater than 10°. Thirteen of 15 participants had a past history of non-traumatic lower extremity injury. Individuals with lower extremity pain at the time of or during the experiment or between visits were excluded. None of the participants, however, were excluded for this reason. All participants signed a consent form approved by the Institutional Review Boards of Boston University and University of Massachusetts, Amherst.

 

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2.2. Experimental Setup Kinematic and kinetic data were collected using an eight-camera Oqus system (Qualisys, Inc., Gothenburg, Sweden) with a 120 × 60 cm force platform (AMTI, Inc., Watertown, MA) mounted in the center of a 10 m walkway. Kinematic data were sampled at 240 Hz and kinetic data were sampled at 960 Hz. Average walking speed was measured using two photoelectric sensors placed at each end of the walkway. 2.3. Orthoses Custom-made orthoses were posted medially in the rearfoot and extended distally to the end of the first toe (Figure 1), using an expanded orthotic material (Nickelplast Beige; Alimed, Inc., Dedham, MA) adhered to a commercially available semi-rigid insole (Stabilizer; Hickory Brands, Inc., Hickory, NC). Rearfoot and forefoot varus angles were measured using a method introduced previously by Monaghan et al. (2013). The amount of posting was determined based on the measured varus angle for rearfoot (posted at approximately 20% of the measured angle) and forefoot (posted at approximately 50% of the measured angle) (Table 1). This resulted in 0° – 4° posting in the rearfoot and 5° – 15° posting in the forefoot. 2.4. Protocol All participants performed in two half-day visits four weeks apart. The two visits allowed us to test if the effects of the orthoses changed between visits. On the first visit (V1), each participant’s medical history, exercise level, weight, height, and rearfoot and forefoot varus angles were documented. While the orthoses were being made by an experienced physical therapist, a second investigator trained the participant to walk overground at his/her self-selected preferred speed (Table 1) and hit a force platform with the right foot only. 5

Prior to data collection, a total of fifty-five markers were placed. Thirteen individual retroreflective markers were placed on each participant’s sacrum and bilaterally on anterior superior iliac spine, iliac crest, greater trochanter, lateral and medial femoral epicondyle, and patella. Four 4-marker tracking plates were placed on bilateral thigh and shank. Twenty-six markers were placed on bilateral foot (see Figure 2 for details), and used to compute foot motions in a multi-segment foot model (Leardini et al., 2007). Participants wore sport sandals (OS Xtension; Bite, LLC, Redmond, WA) during the data collection. These particular sandals were used in previous studies (MacLean, van Emmerik, & Hamill, 2010; Monaghan et al., 2013) and have straps on the forefoot and rearfoot so that markers can be placed on the foot directly. A firm midsole (single density, 55 durometer C) ensured that the effect of wearing the sandal on the variables of interest was minimized. A static standing calibration trial was recorded as the participant stood quietly on the force platform with feet facing forward and shoulder-width apart. Each participant walked at their preferred walking speed for 5 trials with sandals without orthoses and 5 trials with sandals with orthoses. Only trials within 0.1 m/sec of the designed preferred speed were accepted. The order of conditions was determined randomly. Any trials with visible stride adjustments were excluded. Participants were instructed to wear the orthoses for daily activities between the two visits, and to report immediately to the investigator if any pain was experienced. None of the participants reported pain. After 4 weeks, participants came back for the second visit (V2). All procedures were the same as the first visit.

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2.5. Data Analysis Raw kinematic data and force plate data were processed using Visual3D software (C-Motion, Inc., Germantown, MD). Kinematic data were low-pass filtered using a fourth order, zero-lag Butterworth low-pass filter with cut-off frequency of 8 Hz. Ground reaction force (GRF) data were filtered using a fourth order, zero-lag Butterworth low-pass filter with cut-off frequency of 50 Hz (MacLean et al., 2006). Right foot initial contact and toe-off were identified using a threshold at 15N of the vertical GRF. 2.5.1. Joint Angles Three-dimensional joint angles of the hip, knee, ankle and forefoot were calculated using a Cardan XYZ rotation sequence. For the hip, knee and ankle, the angles were defined as the distal segment referenced to the proximal segment. For the forefoot, the angle was defined as the absolute angle (Winter, 1990) that the forefoot segment made to the ground plane. This was the angle which showed a high risk of hip osteoarthritis with the varus foot (Gross et al., 2007). Because forefoot motion is triplanar, here we used frontal plane eversion/inversion to represent and report as the forefoot pronation/supination. 2.5.2. Joint Moments Joint internal moments of hip, knee and ankle were calculated using inverse dynamics (Winter, 1990) and Dempster’s (1955) anthropometric estimates of body segment. Moments were calculated and referenced to the proximal segment coordinate system. Because the GRF reflects the combined forces on the forefoot and rearfoot during stance, we were not able to assess moments individually for the forefoot and rearfoot using a single force platform (Bruening, Cooney, & Buczek, 2012a, 2012b; Bruening, Cooney, Buczek, & Richards, 2010). Thus, for the 7

purpose of estimating the ankle joint moments, we combined the subtalar joint and ankle complex, and considered the foot a rigid body and three-dimensional moments of the foot were calculated in relation to the tibia. This definition of the ankle moment is consistent with other literature (MacLean et al., 2006). Joint moments were normalized to each participant’s body weight (BW). 2.5.3. Ground Reaction Force and Free Moment Free moment (FM) is a torque about the vertical axis which occurs due to the shear forces between the foot and the ground in the stance phase. There are two directions, one (adduction FM) is resisting the motion of foot abduction (toe out) and the other (abduction FM) is resisting the motion of foot adduction (toe in). FM was calculated in Visual3D as described by Holden & Cavanagh (1991). GRFs were normalized to each participant’s BW, and FM was normalized to each participant’s BW and height (Ht) (Almosnino, Kajaks, & Costigan, 2009; Milner, Davis, & Hamill, 2006). 2.5.4. Angular Impulses Angular impulse is defined as the area under the corresponding positive or negative joint moment curve, and represents the accumulated moments in the stance phase (Stefanyshyn, Stergiou, Lun, Meeuwisse, & Worobets, 2006). Angular impulses were calculated from the moments of interest: ankle inversion, knee abduction and external rotation, and hip abduction and external rotation. All variables were interpolated and standardized to 101 points between initial contact and toe-off to represent the percentage of the stance phase. The time series of the joint angles, joint moments, medio-lateral GRF, and FM were exported to and processed in MATLAB (The 8

MathWorks, Inc., Natick, MA). Peak joint angle, the occurrence of forefoot peak eversion angle, peak joint moment, GRF and FM, and angular impulse were calculated (Table 2). These variables were selected to test the kinematic and kinetic effects of orthoses on the excessive motions in the lower extremity caused by a varus foot and thought to be involved in lower extremity injury. 2.6. Statistical Analysis Statistical analyses were performed using SPSS 15.0 (SPSS, Inc., Chicago, IL). A repeated measures analysis of variance (ANOVA) with two within-group factors, Visit (Visit 1 and Visit 2) × Condition (Sandals and Sandals with orthoses), was applied to all kinematic and kinetic variables. Statistical significance was set at an alpha level of 0.05. Effect size (ES) was calculated for all variables. 3. Results Figure 3 and 4 displays the average curves of medio-lateral ground reaction force, free moment, lower extremity kinematic variables, and lower extremity kinetic variables for all participants. The kinematic, kinetic, and angular impulse results are shown in Tables 3, 4, and 5, respectively.

3.1. Ground Reaction Force and Free Moment Orthoses significantly reduced the peak medial GRF during late stance (ES = 0.40, F(1,14) = 9.313, p = 0.009) (Figure 3a & Table 4), and adduction FM (ES = 0.38, F(1,14) = 8.591, p = 0.011) (Figure 3b & Table 4) compared to sandals alone.

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3.2. Forefoot Orthoses significantly decreased the peak eversion angle of the forefoot (ES = 0.79, F(1,14) = 51.104, p < 0.001) and delayed the occurrence of the peak eversion (ES = 0.34, F(1,14) = 7.272, p = 0.017) (Figure 3c & Table 3). 3.3. Ankle Joint Orthoses significantly reduced peak ankle inversion moment (ES = 0.41, F(1,14) = 9.743, p = 0.008) (Figure 3d & Table 4) and inversion angular impulse (ES = 0.32, F(1,14) = 6.434, p = 0.024) (Table 5). 3.4. Knee With orthoses, peak abduction moment during late stance (ES = 0.53, F(1,14) = 15.703, p = 0.001) (Figure 3f & Table 4) and abduction angular impulse (ES = 0.42, F(1,14) = 10.170, p = 0.007) (Table 5) at the knee joint increased significantly. Orthoses affected neither the peak adduction angle, the peak internal rotation angle, the peak abduction moment during early stance, the external rotation moment, nor the external rotation angular impulse. 3.5. Hip Orthoses significantly decreased peak hip adduction angle (ES = 0.25, F(1,14) = 4.618, p = 0.050) (Figure 4c & Table 3), abduction moment (ES = 0.26, F(1,14) = 4.879, p = 0.044) (Figure 4d & Table 4), external rotation moment (ES = 0.27, F(1,14) = 5.048, p = 0.041) (Figure 4f & Table 4), and external rotation angular impulse (ES = 0.27, F(1,14) = 5.156, p = 0.039) (Table 5) compared to sandals alone. There was no effect of orthoses on the peak internal rotation angle or the abduction angular impulse. 10

There were no visit or interaction effects between visits and conditions for peak angles, occurrence of forefoot peak eversion angle, and peak moments. However, hip abduction angular impulse was lower on the second visit (ES = 0.44, F(1,14) = 4.916, p = 0.044) (Table 5) than on the first visit. 4. Discussion The purpose of this study was to examine the effects of orthoses with a medial post on both the forefoot and rearfoot on lower extremity kinematics and kinetics during walking in individuals with a forefoot varus greater than 10°. As expected, the peak eversion angle of the forefoot was decreased by the physical constraints of the orthoses. Additionally, the peak eversion angle occurred later in the gait cycle suggesting that the orthoses were capable of slowing the rate of pronation. The ankle inversion moment and angular impulse were also decreased by wearing orthoses. This is similar to running studies, in which there was a reduction of the ankle inversion moment with orthoses (Mundermann et al., 2003; Williams et al., 2003). The medial GRF decreased during late stance indicating that a tendency to push-off the first metatarsal and hallux was diminished with the orthoses. In addition, the adduction FM decreased during the entire stance phase because of the reduced foot pronation (Holden & Cavanagh, 1991). Increased inversion moment has been suggested as a risk factor for running injuries (McClay, 2000), particularly for the tibialis anterior and posterior that would normally control the eversion motion (Holt & Hamill, 1995). Similarly, FM is considered as the torsional force in the lower extremity during the stance phase (Almosnino et al., 2009; Creaby & Dixon, 2008; Holden & Cavanagh, 1991), and has been proposed to be as a predictor of tibial stress fracture in female athletes (Milner et al., 2006; Pohl et al., 2008). While it would be difficult to conclude that there

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is a direct relationship between these variables and injury based on our data, our findings suggest that the type of orthoses tested in this study can be effective in treating lower extremity injuries. Orthoses with medial support in the forefoot and rearfoot were also expected to influence more proximal joints. In contrast to the finding of Eng & Pierrynowski (1994), we found that orthoses did not influence the peak angle of knee adduction or internal rotation. However, the peak knee abduction moment increased during late stance and abduction angular impulse increased during entire stance. The different findings could be a result of different participant subjects or different orthoses. These results suggest the effect of orthoses on the knee joint may not be observable in the kinematics, but lower extremity kinetics may be more influenced by orthoses. While the effects of orthoses on the knee biomechanics were not as strong as predicted, the effects on the hip were remarkable. Peak hip adduction angle, and peak abduction moment were significantly reduced with orthoses. The moment arm of the hip abductors, such as the gluteus medius, is longer in a less adducted hip than in a more adducted hip (Figure 5), a claim supported by hip roentgenogram imaging (Olson, Smidt, & Johnston, 1972) and mathematical modeling (Henderson, Marulanda, Cheong, Temple, & Letson, 2011). Although the internal moment includes the effects of muscle, ligament, and soft tissue, the muscle moment provides the major source of the internal moment while the latter two are negligible (Chang et al., 2005; Vrahas, Brand, Brown, & Andrews, 1990). Therefore, one implication of our findings given the inverse relationship between hip adduction angle and abductor moment arm is that the required force production of the hip abductors would be reduced when wearing orthoses. As a result, the joint reaction force at the hip would be decreased. However, while unlikely, it is possible that there could still be high abductor muscle activity with a lower moment if there was cocontraction of 12

the hip adductors. Future studies to determine whether the hip abductor muscle activity is actually reduced when wearing orthoses or whether increased cocontraction occurs is therefore necessary. The decreases in the external rotation moment and angular impulse also suggest that the required work of the hip external rotators, such as the piriformis muscle, and the external rotation loading at the hip joint would be reduced with orthoses. In this study, the orthoses were posted minimally in the rearfoot (0° - 4°) and more substantially in the forefoot (5°-15°). Nevertheless, we cannot determine that it was the forefoot posting alone that influenced the behavior of the foot and lower extremity joints. By the nature of the experimental design, we were unable to investigate the specific effects of the forefoot and rearfoot posting independently. In future studies, we plan to investigate the independent effects of rearfoot and forefoot posting. Nevertheless, the present study showed unique findings. In addition to the kinematic effects on the forefoot and hip joint, moments and angular impulses at the ankle, knee and hip joint changed when wearing orthoses, in contrast to previous studies investigating the effects of rearfoot posting on the rearfoot, knee and hip during walking that only showed kinematic changes at the rearfoot and knee joint (Eng & Pierrynowski, 1994; Nester et al., 2003) and kinetic change at the rearfoot (Nester et al., 2003). From a biomechanical perspective, it is reasonable to assume that, as the body weight is transferred to the forefoot, the moments around it would be greater than those around the rearfoot at heel contact due to the large moment arm of the wider forefoot around its axes of rotation (mid-tarsal joints) compared to the rearfoot around its axis (subtalar joint). By limiting forefoot eversion motion with orthoses, our kinetic findings further support the critical role of the forefoot in producing abnormally high forces and moments in the lower extremity.

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Another caution with respect to the study conclusions is that while non-symptomatic participants were selected, and no obvious gait abnormalities (asymmetries, limp) were observed, it is possible that the nature of participants’ previous injuries may have influenced the response to the orthoses. Nevertheless, this possibility is unlikely given that participants responded in much the same way to the orthoses regardless of previous injury. In future studies, we are interested in exploring the effects of orthoses on individuals with a significant and specific history of injury. Finally, while we have provided evidence that the orthotic design used in this study reduces the potentially injurious effects of forefoot varus abnormality, we do not provide direct evidence that the abnormality results in injury. 5. Conclusion In this study, we investigated the effects of orthoses posted in both the forefoot and rearfoot on the kinematics and kinetics of the foot and lower extremity. Our results suggest that the anatomy of the forefoot is important in influencing lower extremity kinematics and kinetics – a structure that has previously been grossly underestimated. Therefore, forefoot abnormalities and their potential for contributing to lower extremity injuries should be considered when evaluating and treating individuals with chronic, non-traumatic injuries. Acknowledgements This work was supported by Dudley Allen Sargent Research Fund, College of Health and Rehabilitation Sciences: Sargent College, Boston University. Conflict of Interest Statement The authors declare no conflict of interest.

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References Almosnino, S., Kajaks, T., & Costigan, P. A. (2009). The free moment in walking and its change with foot rotation angle. Sports Medicine, Arthroscopy, Rehabilitation, Therapy and Technology, 1(1), 19. Bruening, D. A., Cooney, K. M., & Buczek, F. L. (2012a). Analysis of a kinetic multi-segment foot model. Part I: Model repeatability and kinematic validity. Gait and Posture, 35(4), 529-534. Bruening, D. A., Cooney, K. M., & Buczek, F. L. (2012b). Analysis of a kinetic multi-segment foot model. part II: kinetics and clinical implications. Gait and Posture, 35(4), 535-540. Bruening, D. A., Cooney, K. M., Buczek, F. L., & Richards, J. G. (2010). Measured and estimated ground reaction forces for multi-segment foot models. Journal of Biomechanics, 43(16), 3222-3226. Chang, A., Hayes, K., Dunlop, D., Song, J., Hurwitz, D., Cahue, S., & Sharma, L. (2005). Hip abduction moment and protection against medial tibiofemoral osteoarthritis progression. Arthritis and Rheumatism, 52(11), 3515-3519. Dempster, W. T. (1955). Space requirements of the seated operator: geometrical, kinematic, and mechanical aspects of the body with special reference to the limbs. Wright-Patterson Air Force Base, Ohio: Wright Air Development Center. Eng, J. J., & Pierrynowski, M. R. (1994). The effect of soft foot orthotics on three-dimensional lower-limb kinematics during walking and running. Physical Therapy, 74(9), 836-844. Ferber, R., & Benson, B. (2011). Changes in multi-segment foot biomechanics with a heatmouldable semi-custom foot orthotic device. Journal of Foot and Ankle Research, 4(1), 18. Ferber, R., Hreljac, A., & Kendall, K. D. (2009). Suspected mechanisms in the cause of overuse running injuries: a clinical review. Sports Health, 1(3), 242-246. Gross, K. D., Niu, J., Zhang, Y. Q., Felson, D. T., McLennan, C., Hannan, M. T., . . . Hunter, D. J. (2007). Varus foot alignment and hip conditions in older adults. Arthritis and Rheumatism, 56(9), 2993-2998. Hamill, J., van Emmerik, R. E. A., Heiderscheit, B. C., & Li, L. (1999). A dynamical systems approach to lower extremity running injuries. Clinical Biomechanics, 14(5), 297-308. Henderson, E. R., Marulanda, G. A., Cheong, D., Temple, H. T., & Letson, G. D. (2011). Hip abductor moment arm--a mathematical analysis for proximal femoral replacement. Journal of Orthopaedic Surgery and Research, 6, 6. Holden, J. P., & Cavanagh, P. R. (1991). The free moment of ground reaction in distance running and its changes with pronation. Journal of Biomechanics, 24(10), 887-897. Holt, K. G., & Hamill, J. (1995). Running injuries and treatment: a dynamic approach. In G. J. Sammarco (Ed.), Rehabilitation of the foot and ankle. St. Louis: Mosby. Leardini, A., Benedetti, M. G., Berti, L., Bettinelli, D., Nativo, R., & Giannini, S. (2007). Rearfoot, mid-foot and fore-foot motion during the stance phase of gait. Gait and Posture, 25(3), 453-462. MacLean, C. L., Davis, I., & Hamill, J. (2006). Influence of a custom foot orthotic intervention on lower extremity dynamics in healthy runners. Clinical Biomechanics, 21(6), 623-630. MacLean, C. L., van Emmerik, R., & Hamill, J. (2010). Influence of custom foot orthotic intervention on lower extremity intralimb coupling during a 30-minute run. Journal of Applied Biomechanics, 26(4), 390-399. 15

McClay, I., & Manal, K. (1998). A comparison of three-dimensional lower extremity kinematics during running between excessive pronators and normals. Clinical Biomechanics, 13(3), 195-203. McCulloch, M. U., Brunt, D., & Vander Linden, D. (1993). The effect of foot orthotics and gait velocity on lower limb kinematics and temporal events of stance. Journal of Orthopaedic and Sports Physical Therapy, 17(1), 2-10. McPoil, T. G., & Knecht, H. G. (1985). Biomechanics of the foot in walking: a function approach. Journal of Orthopaedic and Sports Physical Therapy, 7(2), 69-72. Messier, S. P., & Pittala, K. A. (1988). Etiologic factors associated with selected running injuries. Medicine and Science in Sports and Exercise, 20(5), 501-505. Michaud, T. C. (1993). Foot orthoses and other forms of conservative foot care. Baltimore: Williams & Wilkins. Milner, C. E., Davis, I. S., & Hamill, J. (2006). Free moment as a predictor of tibial stress fracture in distance runners. Journal of Biomechanics, 39(15), 2819-2825. Monaghan, G. M., Lewis, C. L., Hsu, W. H., Saltzman, E., Hamill, J., & Holt, K. G. (2013). Forefoot angle determines duration and amplitude of pronation during walking. Gait and Posture, 38(1), 8-13. Mundermann, A., Nigg, B. M., Humble, R. N., & Stefanyshyn, D. J. (2003). Foot orthotics affect lower extremity kinematics and kinetics during running. Clinical Biomechanics, 18(3), 254-262. Nester, C. J., van der Linden, M. L., & Bowker, P. (2003). Effect of foot orthoses on the kinematics and kinetics of normal walking gait. Gait and Posture, 17(2), 180-187. Novick, A., & Kelley, D. L. (1990). Position and movement changes of the foot with orthotic intervention during the loading response of gait. Journal of Orthopaedic and Sports Physical Therapy, 11(7), 301-312. Olson, V. L., Smidt, G. L., & Johnston, R. C. (1972). The maximum torque generated by the eccentric, isometric, and concentric contractions of the hip abductor muscles. Physical Therapy, 52(2), 149-158. Root, M. L., Orien, W. P., & Weed, J. H. (1977). Normal and abnormal function of the foot. Los Angeles: Clinical Biomechanics Corp. Stefanyshyn, D. J., Stergiou, P., Lun, V. M., Meeuwisse, W. H., & Worobets, J. T. (2006). Knee angular impulse as a predictor of patellofemoral pain in runners. American Journal of Sports Medicine, 34(11), 1844-1851. Tiberio, D. (1987). The effect of excessive subtalar joint pronation on patellofemoral mechanics: a theoretical model. Journal of Orthopaedic and Sports Physical Therapy, 9(4), 160-165. Tiberio, D. (1988). Pathomechanics of structural foot deformities. Physical Therapy, 68(12), 1840-1849. Vrahas, M. S., Brand, R. A., Brown, T. D., & Andrews, J. G. (1990). Contribution of passive tissues to the intersegmental moments at the hip. Journal of Biomechanics, 23(4), 357362. Williams, D. S., 3rd, Davis, I., & Baitch, S. P. (2003). Effect of inverted orthoses on lowerextremity mechanics in runners. Medicine and Science in Sports and Exercise, 35(12), 2060-2068. Winter, D. A. (1990). Biomechanics and motor control of human movement. New York: Wiley.

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Zifchock, R. A., & Davis, I. (2008). A comparison of semi-custom and custom foot orthotic devices in high- and low-arched individuals during walking. Clinical Biomechanics, 23(10), 1287-1293.

Table 1. Individual and mean ± standard deviation of the participant characteristics. Participant 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 Mean (n=15)

Age (y) 25 23 37 23 21 30 20 19 24 19 20 19 21 21 21 22.9 ± 4.9

Height (m) 1.75 1.62 1.66 1.66 1.46 1.80 1.91 1.73 1.71 1.78 1.75 1.65 1.64 1.95 1.59 1.71 ± 0.12

Weight (kg) 66 57 62 57.5 50 77 74 60 63 78 67 65 81 90 50 66.5 ± 11.5

FF Varus (°) 18.7 31.5 13.2 31.4 38.0 24.0 28.9 24.9 25.9 25.5 19.0 17.0 31.4 10.0 21.3 24.0 ± 7.6

RF Varus (°) 5.7 5.3 0.4 3.0 4.5 -1.2 13.9 -3.6 -2.8 9.2 13.1 -8.2 20.8 -4.6 12.0 4.5 ± 8.1

Walking Speed (m/s) 1.77 1.88 1.37 1.73 1.75 1.66 1.25 1.60 1.77 1.56 2.03 1.92 1.56 1.84 1.60 1.69 ± 0.21

Previous History PFPS, TPS TPS LBP TPS PFPS TPS SI joint pain PF, Knee pain Ankle pain, Knee pain Gastrocnemius cramps AT LBP, PF, easily rolled ankle PFPS, TPS

Notes: AT – Achilles tendinitis; LBP – Low back pain; PF – Plantar fasciitis; PFPS – Patellofemoral pain syndrome; TPS – Tibialis posterior syndrome 

17

Table 2. Kinematic and kinetic variables. Variable Name Peak angle Forefoot Knee

Peak eversion angle Peak adduction angle Peak internal rotation angle Hip Peak adduction angle Peak internal rotation angle Occurrence of peak angle Forefoot Timing of peak eversion Force and moment Peak medial ground reaction force (GRF) during late stance Peak adduction free moment (FM) Ankle joint Peak inversion moment Knee joint Peak abduction moment during early stance1 Peak abduction moment during late stance2 Peak external rotation moment Hip joint Peak abduction moment Peak external rotation moment Angular impulse Ankle joint Inversion impulse Knee joint Abduction impulse External rotation impulse Hip joint Abduction impulse External rotation impulse

Note: 1

Peak abduction moment during early stance: the first peak of the abduction moment, which occurred around early stance.

2

Peak abduction moment during late stance: the second peak of the abduction moment, which

occurred around late stance. 

18

Table 3. Mean ± standard deviation of all kinematic variables. Statistically significant results are printed in bold (p < 0.05). Kinematics in Walking Forefoot Peak Eversion Angle (°) Timing of Peak Eversion (%) Knee Peak Adduction Angle (°) Peak Internal Rotation Angle (°) Hip Peak Adduction Angle (°) Peak Internal Rotation Angle (°)

Visit 1

Visit 2

Sandals Orthoses

Sandals Orthoses

0.6 ±

-3.0 ±

0.0 ±

-2.9 ±

3.2

3.1

2.4

3.6

62.4 ±

64.2 ±

62.5 ±

63.5 ±

4.8

4.2

4.2

3.6

3.3 ±

3.9 ±

3.5 ±

3.7 ±

2.7

2.5

2.2

3.7

4.3 ±

4.6 ±

3.3 ±

4.2 ±

4.6

4.8

4.6

5.2

6.6 ±

6.1 ±

6.6 ±

5.7 ±

2.4

2.6

2.1

2.2

2.6 ±

2.2 ±

4.7 ±

4.0 ±

4.8

5.4

4.5

5.0

 

19

Visit Effect

p-value Condition Interaction Effect Effect

0.668

< 0.001

0.345

0.750

0.017

0.516

0.391

0.864

0.664

0.346

0.184

0.437

0.726

0.050

0.365

0.069

0.110

0.713

Table 4. Mean ± standard deviation of all kinetic variables. Statistically significant results are printed in bold (p < 0.05). Visit 1 Kinetics in Walking GRF Peak Medial GRF during Late Stance (N/BW) Free Moment Peak Adduction FM (Nm/BW·Ht ) Ankle Joint Peak Inversion Moment (Nm/ BW) Knee Joint Peak Abduction Moment during Early Stance (Nm/ BW) Peak Abduction Moment during Late Stance (Nm/ BW) Peak External Rotation Moment (Nm/ BW) Hip Joint Peak Abduction

Visit 2

Sandal s

Orthose s

Sandal s

Orthose s

0.073 ±

0.063 ±

0.065 ±

0.059 ±

0.033

0.027

0.033

0.031

0.0092 ±

0.0088 ±

0.0106 ±

0.0091 ±

0.0027

0.0028

0.0024

0.0025

0.011 ±

0.007 ±

0.010 ±

0.005 ±

0.015

0.018

0.013

0.011

0.067 ±

0.069 ±

0.072 ±

0.073 ±

0.016

0.018

0.019

0.017

0.033 ±

0.038 ±

0.031 ±

0.037 ±

0.015

0.016

0.021

0.020

0.029 ±

0.029 ±

0.031 ±

0.030 ±

0.007

0.008

0.005

0.005

0.122 ± 0.020

0.122 ± 0.017

0.121 ± 0.019

0.116 ± 0.021

20

Visit Effec t

p-value Conditio Interactio n Effect n Effect

0.093

0.009

0.485

0.069

0.011

0.222

0.770

0.008

0.734

0.181

0.369

0.858

0.731

0.001

0.891

0.573

0.495

0.401

0.504

0.044

0.392

Moment (Nm/ BW) Peak External Rotation Moment (Nm/ BW)

0.022 ±

0.020 ±

0.024 ±

0.021 ±

0.013

0.012

0.017

0.017

0.592

0.041

0.697

 

Table 5. Mean ± standard deviation of all angular impulse variables. Statistically significant results are printed in bold (p < 0.05). Angular Impulse in Walking Ankle Joint Inversion Angular Impulse (Nms) Knee Joint Abduction Angular Impulse (Nms) External Rotatio n Angular Impulse (Nms) Hip Joint Abduction Angular Impulse (Nms) External Rotatio n Angular Impulse (Nms)

Visit 1

Visit 2

Sandals Orthoses

Sandals Orthoses

1.41 ± 1.56

1.00 ± 1.65

1.21 ± 1.18

0.69 ± 0.86

11.57 ±

12.43 ±

11.20 ±

12.36 ±

4.56 3.98 ±

5.26 3.95 ±

5.76 4.03 ±

1.59

1.50

1.25

26.20 ±

26.18 ±

24.24 ±

23.91 ±

2.32

7.62 3.16 ±

2.32

7.14 3.87 ±

3.16

 

21

p-value Condition Interaction Effect Effect

0.498

0.024

0.640

0.659

0.007

0.637

0.765

0.275

0.444

0.044

0.565

0.630

0.868

0.039

0.529

5.88 3.79 ±

1.31

6.96 3.77 ±

Visit Effect

7.20 2.87 ±

2.63

Figure Legends Figure 1. Orthoses used in this study: the (a) rear; (b) front and (c) medial view. Figure 2. The placement of markers on the foot. HALLUX: distal end of the proximal phalanx of the hallux; MT1, MT2, MT5: the base of the first, second, and fifth metatarsal; FMB, SMB, VMB: the head of the first, second, and fifth metatarsal; NAV: navicular tuberosity; PRHE, LAHE, MEHE: upper central, lateral, and medial side of the calcaneus; LAMA, MEMA: lateral and medial malleolus. Triangles represent the forefoot and rearfoot segment. Figure 3. The mean ground reaction force (GRF), free moment, forefoot and knee frontal angles, and ankle and knee frontal moments across the stance phase in walking between visits (V1, V2), sandals (S), and sandals with orthoses (O) condition of all participants. Positive values represent lateral GRF, adduction free moment, inversion in forefoot/ankle frontal plane, and adduction in knee frontal plane. Solid black vertical line represents the approximate location where the peak value was measured. Figure 4. The mean angles and moments in knee transverse, and hip frontal and transverse planes across the stance phase in walking between visits (V1, V2), sandals (S), and sandals with orthoses (O) condition of all participants. Positive values represent adduction in hip frontal plane, and internal rotation in knee/hip transverse planes. Solid black vertical line represents the approximate location where the peak value was measured. Figure 5. The comparison between (a) a less adducted hip in wearing orthoses condition and (b) a more adducted hip in without orthoses condition. Solid femur illustrates the hip at a less adducted posture while dash femur illustrates the hip with a more adducted angle. Gray lines indicate abductor moment arm in both conditions. 22

Figure1

Figure2

Figure3

0.08 0.04 0.00 −0.04 −0.08 −0.12

20 15 10 5 0 −5

8 6 4 2 0 −2 −4 −6

0

0

0

20

20

20

60

V1 − S (a) Mediolateral GRF

40

60

(c) Forefoot Frontal Angle

40

(e) Knee Frontal Angle

40 60 Stance (%)

80

80

80

V1 − O

100

100

100

Free Moment (Nm/BW−Ht) Abd Add Moment (Nm/BW) Ev Inv Moment (Nm/BW) Abd Add

Force (N/BW) Medial Lateral Angle (°) Ev Inv Angle (°) Abd Add

x 10

0

0

V2 − S

12 8 4 0 −4

0.01 0.00 −0.01 −0.02 −0.03

0.02 0.00 −0.02 −0.04 −0.06 −0.08

0

−3

V2 − O

20

20

20

60

(b) Free Moment

40

60

(d) Ankle Frontal Moment

40

(f) Knee Frontal Moment

40 60 Stance (%)

80

80

80

100

100

100

Figure4

6 4 2 0 −2 −4 −6 −8

8 6 4 2 0 −2 −4 −6

6 4 2 0 −2 −4 −6 −8

0

0

0

20

20

20

60

V1 − S (a) Knee Transverse Angle

40

60

(c) Hip Frontal Angle

40

(e) Hip Transverse Angle

40 60 Stance (%)

80

80

80

V1 − O

100

100

100

Moment (Nm/BW) Ext Rot Int Rot Moment (Nm/BW) Abd Add Moment (Nm/BW) Ext Rot Int Rot

Angle (°) Ext Rot Int Rot Angle (°) Abd Add Angle (°) Ext Rot Int Rot

0

0

V2 − S

0.04 0.02 0.00 −0.02 −0.04

0.02 0.00 −0.02 −0.04 −0.06 −0.08 −0.10 −0.12 −0.14

0.01 0.00 −0.01 −0.02 −0.03

0

V2 − O

20

20

20

60

(b) Knee Transverse Moment

40

60

(d) Hip Frontal Moment

40

(f) Hip Transverse Moment

40 60 Stance (%)

80

80

80

100

100

100

Figure5

Pelvis

Hip Abductors

Femur

(a)

(b)