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Foot mechanics during the first six years of independent walking
Journal of Biomechanics 44 (2011) 1321–1327
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Foot mechanics during the first six years of independent walking William Samson a,b,c,d,n, Bruno Dohin e,f, Guillaume Desroches b,c,d, Jean-Luc Chaverot a, ¨ Dumas b,c,d, Laurence Cheze b,c,d Raphael a
´ Professionnel de De ´veloppement Cuir Chaussure Maroquinerie, 4 rue Hermann Frenkel, 69 367 Lyon Cedex 7, France CTC, Comite Universite´ de Lyon, Universite´ Lyon 1, Lyon F-69003, France c Ifsttar, Bron F-69675, France d Laboratoire de Biome´canique et Me´canique des Chocs, UMR_T 9406, Villeurbanne F-69622, France e ´diatrique, Saint Etienne 42055 Cedex 2, France Universite´ Jean Monnet Saint Etienne, Hˆ opital Nord CHU de Saint Etienne, Service de chirurgie pe f Laboratoire Inserm U 864, Universite´ de Lyon, Lyon F-69003, France b
a r t i c l e i n f o
abstract
Article history: Accepted 5 January 2011
Recognition of the changes during gait that occur normally as a part of growth is essential to prevent mislabeling those changes from adult gait as evidence of gait pathology. Currently, in the literature, the definition of a mature age for ankle joint dynamics is controversial (i.e., between 5 and 10 years). Moreover, the mature age of the metatarsophalangeal (MP) joint, which is essential for the functioning of the foot, has not been defined in the literature. Thus, the objective of the present study explored foot mechanics (ankle and MP joints) in young children to define a mature age of foot function. Forty-two healthy children between 1 and 6 years of age and eight adults were measured during gait. The ground reaction force (GRF), the MP and ankle joint angles, moments, powers, and 3D angles between the joint moment and the joint angular velocity vectors (3D angle aM.o) were processed and compared between four age groups (2, 3.5, 5 and adults). Based on statistical analysis, the MP joint biomechanical parameters were similar between children (older than 2 years) and adults, hinting at a quick maturation of this joint mechanics. The ankle joint parameters and the GRFs (except for the frontal plane) showed an adult-like pattern in 5-year-old children. Some ankle joint parameters, such as the joint power and the 3D angle aM.o still evolved significantly until 3.5 years. Based on these results, it would appear that foot maturation during gait is fully achieved at 5 years. & 2011 Elsevier Ltd. All rights reserved.
Keywords: Gait maturation Metatarsophalangeal joint Kinematic Dynamic Ground reaction force
1. Introduction Recognition of the changes that occur normally as a part of growth and body development is essential to prevent mislabeling those changes from adult gait as evidence of gait pathology (Sutherland, 1997). At the foot level, children may reveal numerous variations (e.g., clubfoot, planovalgus, pes planus, equinus and flat foot). There is therefore a need to better define and quantify the foot function during growth. Several approaches have been reported in the literature to better understand the foot mechanics during gait in young healthy children (i.e., younger than 6 years). They include the assessment of plantar pressure distribution (Alvarez et al., 2008; Bosch et al., 2007; Hallemans et al., 2006b, 2003; Bertsch et al., 2004; Hennig et al., 1994; Hennig and Rosenbaum, 1991), ground reaction force n Corresponding author at:. CTC, Comite´ Professionnel de De´veloppement Cuir Chaussure Maroquinerie, 4 rue Hermann Frenkel, 69 367 Lyon Cedex 7, France. Tel.: + 33 4 72 44 80 98; fax: +33 4 72 44 80 54. E-mail address: [email protected] (W. Samson).
0021-9290/$ - see front matter & 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.jbiomech.2011.01.007
(GRF) (Hallemans et al., 2006a; Diop et al., 2005; Stansfield et al., 2001b; Sutherland, 1997; Preis et al., 1997; Takegami, 1992; Beck et al., 1981), and ankle joint kinematics and dynamics (Chester and Wrigley, 2008; Chester et al., 2006; Hallemans et al., 2006b, 2005; Ganley and Powers, 2005; Cupp et al., 1999; Sutherland, 1997; Oeffinger et al., 1997; Stansfield et al., 2001a; Ounpuu et al., 1991). Studies on plantar pressure distribution in young children have shown predominant use of the midfoot to the detriment of the heel and forefoot. This predominance has been explained by the immaturity of the foot skeletal structures and the importance of the fat pad (Alvarez et al., 2008; Bosch et al., 2007; Hallemans et al., 2006b, 2003; Bertsch et al., 2004; Hennig et al., 1994). According to these studies, mature plantar pressure distribution is obtained between 5 and 6 years of age. With regard to GRF results, Hallemans et al. (2006a) reported modifications of the curve pattern of the vertical component from one hump to two humps during the first steps of independent walking which the authors attributed to roll-off immaturity. However, depending on the study, conclusions regarding the definition of a mature age for GRFs patterns varied extensively: from 3 to 8 years
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Like the ankle, the toes are essential for the functioning of the foot (Bojsen-Møller and Lamoreux, 1979). ‘‘Toe dorsiflexion secures support to the longitudinal arch at peak loads, and it enables the ball (i.e., part of the foot composed of the distal heads of the metatarsals and their surrounding fat pad) to withstand the tangential forces to which it is exposed. Toe dorsiflexion also allows the foot to take advantage of different leverage ratios to suit different conditions, resulting in more efficient propulsion’’. Similar to the joint kinematic and dynamic changes during growth, it could be hypothesized that the metatarsophalangeal (MP) joint is not mature immediately after performing the first
(Diop et al., 2005; Stansfield et al., 2001b; Sutherland, 1997; Preis et al., 1997; Takegami, 1992; Beck et al., 1981). In contrast to plantar pressure approaches, few studies have explored ankle biomechanical parameters before 6 years of age (Hallemans et al., 2006b, 2005; Chester et al., 2006; Sutherland, 1997). With respect to joint angles, moments and powers, conclusions regarding maturity of ankle joint were controversial: the ankle joint mechanics was defined as mature between 5 years (Ounpuu et al., 1991), 8 years (Cupp et al., 1999), 9–13 years (Chester and Wrigley, 2008; Chester et al., 2006), or 10 years (Oeffinger et al., 1997).
Table 1 Anthropometric and temporal distance parameters for the four groups. Significant differences are shown with a p-value less than 0.05 (a,b,c: significant difference between group 1 and groups 2 to 4, respectively; d,e: significant difference between group 2 and groups 3 and 4, respectively; f: significant difference between groups 3 and 4; n.s: no significant difference between groups; l0: leg length; g: acceleration of gravity).
N Age range (years) Mean Age (years) Height (cm) Mass (kg) Step length (m/l0) Walking speed (m.s 1/O(gl0)) Cadence (Hz/O(g/l0)) Stance duration (% of gait cycle)
Group 1
Group 2
Group 3
Group 4
14 1.2–2.8 2.17 0.5 86.97 5.2 12.27 1.6 1.107 0.13 0.287 0.03 0.827 0.07 65.47 2.6
14 2.9–4.2 3.6 7 0.4 100.87 5.8 16.5 7 2.3 1.34 7 0.13 0.337 0.39 0.887 0.08 64.8 7 2.68
14 4.3–5.8 5.07 0.5 110.8 7 6.8 18.6 7 3.2 1.38 7 0.13 0.397 0.03 0.747 0.06 63.8 7 1.9
8 23.0–31.0 25.07 2.6 175.0 7 4.0 67.07 5.6 1.67 7 0.05 0.477 0.02 0.737 0.02 63.7 7 1.1
abcdef abcdef abcdef abcef bcdef n.s n.s
Table 2 GRF, MP and ankle variables for statistical analysis. Significant differences are shown with a p-value less than 0.05 (a,b,c: significant difference between group 1 and groups 2 to 4, respectively; d,e: significant difference between group 2 and groups 3 and 4, respectively; f: significant difference between groups 3 and 4; n.s: no significant difference between groups; RoM: range of motion; K.W: Kruskal–Wallis test). Variables
K.W.
GRF Ry1 Ry2 Rx1 Rx2 Rz1 Rz2
Max. Max. Max. Max. Max. Max.
MP MP-RoMz MP-Az1 MP-Az2 MP-Mz MP-Mx MP-Mx MP-P1 MP-P2 MP-3DA
RoM in flex./ext. Max. ext. at midstance Max. flex. at pre-swing Max. ext. moment at midstance Max. ev. moment at midstance Max. abd. moment at pre-swing Max. abs. energy at midstance Max. gen. energy at pre-swing Min. 3D angle aM.o at pre-swing
0.352 0.249 0.056 0.875 0.115 0.257 0.395 0.248 0.153
Ankle A-RoMz A-RoMx A-RoMy A-Az1 A-Az2 A-Az3 A-Ax1 A-Ax2 A-Ax3 A-Mz A-Mx A-My A-P1 A-P2 A-P3 A-3DA1 A-3DA2 A-3DA3
RoM in dorsiflex./plantarflex. RoM in inv./ev. RoM in abd./add. Max. dorsiflex. at midstance Max. plantarflex. at pre-swing Max. dorsiflex. at midswing Max. ev. at early stance Max. inv. at pre-swing Max. ev. at midswing Max. plantarflex. moment at stance Max. ev. moment at midstance Max. abd. moment at pre-swing Max. abs. energy at early stance Max. abs. energy at midstance Max. gen. energy at pres-wing Max. 3D angle aM.o at early stance Max. 3D angle aM.o at midstance Min. 3D angle aM.o at pre-swing
0.181 0.422 0.934 0.248 0.093 0.173 0.248 0.153 0.153 0.697 0.391 0.114 0.008 0.173 0.875 0.009 0.441 0.047
vertical force at early stance vertical force at pre-swing posterior force at early stance anterior force at pre-swing lateral force at early stance lateral force at pre-swing
0.248 0.038 0.607 0.000 0.012 0.153
1–2
1–3
1–4
2–3
2–4
3–4
0.039
0.043
0.003
0.679
0.031
0.062
0.141 0.232
0.001 0.129
0.002 0.002
0.060 0.854
0.007 0.005
0.062 0.004
0.014
0.011
0.001
0.306
0.067
0.443
0.335
0.520
0.014
0.335
0.006
0.073
0.550
0.168
0.009
0.781
0.031
0.073
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independent steps. However, no study has specifically investigated the evolution of this joint in young children. Finally, in a review paper about maturation of gait, Sutherland (1997) proposed future investigations to complete the study of gait’s maturation. At this stage, there is still a need to further describe the kinematics of children between 1 and 4 years and complete the available databases of joint moments and powers between 2 and 4 years. Thus, the present study explored the foot mechanics in young children from the GRF, as well as the MP and ankle joints kinematics and dynamics, to define a mature age of foot function.
compared between the four groups using a Kruskal–Wallis test (p o 0.05) (Table 2, Figs. 1–3). When significant, non-parametric Mann–Whitney tests were performed to show intergroup differences (p o 0.05). As in previous works (Chester and Wrigley, 2008; Chester et al., 2006; Stansfield et al., 2001a,b; Cupp et al., 1999; Oeffinger et al., 1997), a parameter was considered as mature when significant differences with adults disappeared.
2. Methods
Irrespective of the planes, the GRF showed approximately the same curve patterns, except for group 1 (Fig. 1). For this group, the second hump was almost non-existent in the sagittal and the transverse planes, when compared with the older groups. The dimensionless maximum values were smaller in children than in adults for the vertical and the anterior/posterior forces, in contrast to the medial/lateral force. Significant differences appeared at the early stance (0–20% of gait cycle) for the medial/lateral force (0.070, 0.098, 0.098, and 0.111 dimensionless for the groups 1–4, respectively), at pre-swing (50–60% of gait cycle) for the vertical force (0.812, 0.937, 0.936, and 1.117 dimensionless for
2.1. Participants A total of 42 healthy children were included in the study and assigned to three groups of 2, 3.5, and 5 years of age (groups 1–3, respectively). The characteristics of these groups are described in Table 1. Independent walking was acquired before 18 months, and medical examination did not reveal any orthopedic or neurological disorder. Parents gave informed consent for their child to participate in this study which was approved by the local ethics committee. In addition, with a similar protocol and method, eight adults participated in the study to define a reference population (group 4).
3. Results 3.1. GRF
2.2. Experimental setup
R y2
R y1
1.2
V ical reacctionn foorce Verti (N N/m m0.g))
Sixteen markers were fixed on the anatomical landmarks of both the lower limbs (medial and lateral epicondyles, head of fibula, medial and lateral malleoli, first and fifth metatarsal heads, and hallux). The children were allowed to walk at a self-selected speed. Fifteen gait trials were measured for each subject using a Motion Analysiss system with six Eagles cameras (Motion Analysis Corporation, Santa Rosa, USA), two Bertecs force platforms (Bertec, Columbus, USA), and one Footscans plantar pressure platform (RSscan, Olen, Belgium) at a sampling frequency of 100, 1000, and 100 Hz, respectively. All the platforms were synchronized with the Motion Analysis system using a trigger pulse from the plantar pressure platform. Only data of the gait cycles with full contact of the right or left foot on one of the force platforms were processed.
*
Up Group Group Group Group
0.8
0.4
1 2 3 4
0 Down
2.3. Data processing
0
metatarsi and pointing to the right; Y, the unit vector of the line perpendicular to the plane defined by the Z-axis and hallux, and pointing to the top; and X, the unit vector of the common line perpendicular to the Z- and the Y-axes.
The Z-axis of the rearfoot and the forefoot coordinate systems were defined similarly. Consequently, the MP joint was only considered with one degree of freedom. After an estimation of the inertial parameters from scaling equations (Jensen, 1989), the ankle joint moment (net internal moment) was computed by bottom-up 3D inverse dynamics using quaternion algebra (Dumas et al., 2004). Subsequently, the MP joint moment (net internal moment) was computed using the ‘‘ground reaction vector technique’’ (Wells, 1981; Stefanyshyn and Nigg, 1997), transforming the moment from the force platform to the MP joint center using classical rigid body mechanics. Although criticized (Winter and Wells, 1981), this method demonstrated appropriate results when the segments’ inertial parameters are negligible (Dumas et al., 2009). Computation of the MP joint moment was realized as soon as the forefoot was solely in contact with the force platform. This event was defined separately, from the stance timing of the plantar pressure platform. The joint moments were expressed in the proximal SCS. Subsequently, 3D joint powers and 3D angles between the joint moment and the joint angular velocity vectors (3D angle aM.o), previously defined in the literature (Desroches et al., 2010; Samson et al., 2009; Dumas and Che ze, 2008), were computed for the ankle and the MP. Details of 3D joint powers and 3D angles aM.o calculation and interpretation are presented in the Appendix A. Finally, the GRF, joint moments, and joint powers were made dimensionless (Hof, 1996). All the data were re-sampled over 100% of the gait cycle and averaged for the subjects of each group. Because the thirty-three dependent variables did not meet the normality criteria (Shapiro–Wilk test; p o 0.05), those variables were
Annterrior/ppostterio or reeactiion forcce (N N/m m0.g))
O (origin), the middle of the first and the fifth metatarsi; Z (flexion axis), the unit vector of the line connecting the first and the fifth
20
40
60
80
R x2 0.2
100 Anterior
* R x1
0
-0.2
Posterior
0
20
40
60
80
R z1 0.12
Meediaal/latterall reaactioon force (N/m m0.gg)
After signal processing (low-pass zero-lag, 4th-order, Butterworth filter, 6-Hz cutoff frequency) using Matlabs, the segment coordinate systems (SCS) of the leg and the rearfoot were defined according to the international recommendations, as well as the ankle joint coordinate system (Wu and Cavanagh, 1995; Wu et al., 2002). The forefoot coordinate system was defined as follows (right foot):
*
100 Lateral
R z2
0.08 0.04 0 Medial
0
20
40 60 Gait cycle (%)
80
100
Fig. 1. (a–c): Vertical, anterior/posterior and medial/lateral GRF, respectively (* significant difference between groups; l0: leg length; g: acceleration of gravity).
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Fig. 2. MP joints:. (a) flexion/extension joint angle; (b and c) flexion/extension and eversion/inversion joint moment, respectively; (d) joint power; (e) 3D angle aMx (l0: leg length; g: acceleration of gravity).
the groups 1–4, respectively) and anterior/posterior force (0.082, 0.111, 0.142, and 0.201 dimensionless for the groups 1–4, respectively) (Table 2). These significant differences were noted in groups 1 and 2 when compared with group 4, while significant difference only appeared for the medial/lateral force at the early stance between groups 3 and 4.
3.2. MP joint The joint angle, moments and power showed similar curve patterns (Fig. 2a–d). The maximum difference about the range of motion never exceeded 7.11 between the groups. With age, at midstance (20–40% of the gait cycle), the maximum extension moments were almost similar while the maximum eversion moments decreased ( 0.039 and 0.024 dimensionless, for the groups 1 and 4, respectively). At midstance, the maximum absorbed energy was slightly more important in group 1 than in group 4 ( 0.502 and 0.421 dimensionless, respectively). At preswing, the generated energy approached zero in group 1 and increased with the advancement of years (0.017, 0.039, 0.095, and 0.116 dimensionless for groups 1–4, respectively). Finally, at preswing, the 3D angle aM.o showed a stabilization configuration in children, while adults were in a propulsion configuration (76.9, 74.4, 72.0, and 48.41 for groups 1–4, respectively) (Fig. 2e).
Nevertheless, irrespective of the MP variables, no significant difference was observed between the age groups.
3.3. Ankle joint The joint angles and moments showed similar curve patterns (Fig. 3a–d). The maximum difference between the groups with regard to the range of motion never exceeded 7.11 in dorsiflexion/plantarflexion and 2.51 in inversion/eversion, and no significant difference appeared. With age, as noted in the MP joint at midstance, the maximum extension moments were almost similar, while the maximum eversion moments decreased ( 0.035 and 0.015 dimensionless, for the groups 1 and 4, respectively). Moreover, at early stance, a little inversion moment appeared with age. Joint moments revealed no significant difference. The power curves showed two different patterns about the absorbed energy at stance: a single hump in group 1 evolved with age to a double hump, as observed in group 4. Subsequently, the maximum absorbed energy was found to be more important in children at early stance ( 0.387, 0.226, 0.224, and 0.188 dimensionless for groups 1–4, respectively). At pre-swing, the maximum generated energy was almost similar in each group. Finally, during stance, the 3D angle aM.o pattern differed between children and adults. More precisely, a decrease in the
W. Samson et al. / Journal of Biomechanics 44 (2011) 1321–1327
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Fig. 3. Ankle joints: (a and b) dorsiflexion/plantarflexion and eversion/inversion joint angle; (c and d) dorsiflexion/plantarflexion and eversion/inversion joint moment, respectively; (e) joint power; (f) 3D angle aMx (* significant difference between groups; l0: leg length; g: acceleration of gravity).
duration of joint stabilization configuration (79.7%, 75.0%, 75.8%, and 40.0% of stance phase for groups 1–4, respectively) was observed. The maximum resistance and propulsion configurations were statistically less important in groups 1 and 2 than in group 4 at early stance and pre-swing, respectively. No significant difference was observed between groups 3 and 4.
4. Discussion The present study covered a sample of children between 1 and 6 years of age with the same marker set as employed for the adult gait trials, and taking into account not only the GRF and ankle joint, but also the MP joint, currently unexplored to the authors’ knowledge. A previous study of young children has already been done (Samson et al., 2009), focusing on the hip, knee and ankle joint dynamic strategies. These strategies were found different in children compared to adults. With a larger population, the present study investigated three groups of age and defined a mature age of foot function. Concerning the GRF, the most important differences between age groups were revealed on the maximum vertical and anterior/ posterior forces at pre-swing, and the maximum medial/lateral force at early stance. The hump in vertical force at pre-swing was almost absent in young children, as observed in previous studies (Hallemans et al., 2006a; Sutherland, 1997; Preis et al., 1997), and increased with age, as also reported previously (Diop et al., 2005; Takegami, 1992). The maximum value increased for the
anterior/posterior force, in contrast to the work carried out by Diop et al. (2005). It is however to be noticed that the children were older and that a treadmill was used in the aforementioned study. For both the second maximum of the vertical force and the maximum of the anterior force, significant differences between groups 3 and 4 disappeared. Finally, at early stance, the maximum medial/lateral force decreased with age. There were significant differences between children and adults, probably due to a decrease of stride width (Hallemans et al., 2006a). These results are in agreement with those obtained by Takegami (1992), who reported a decrease in the maximum medial/lateral force until the age of eight. The MP revealed explicit curve patterns (Twomey et al., 2010; Stebbins et al., 2006; Simon et al., 2006; Oleson et al., 2005; MacWilliams et al., 2003; Stefanyshyn and Nigg, 1997) that were similar to those reported in the literature with regard to older children and adults. Unfortunately, no work could be found in the literature with regard to such young children that could be used to compare the present results. Age had the most significant influence on the pre-swing phase. An increase in age was associated with an increase in maximum flexion, a decrease in maximum eversion moment and the apparition of a generated energy combined with a 3D angle aM.o evolving from a stabilization configuration to a propulsion configuration. It is probable that young children will give priority to stability to the detriment of propulsion in order to avoid a fall. Nevertheless, no significant difference between age groups was found whatever the MP variables. These results could be an indication for the lesser importance or more passive character of the MP joint. Future
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works should consider a most important sample of children and/ or very younger age groups (e.g. 1.5, 2 and 2.5 years) to detect the mature age of the MP joint use. The ankle joint revealed similar curve patterns as those previously described (Samson et al., 2009; Chester and Wrigley, 2008; Chester et al., 2006; Hallemans et al., 2006b; van der Linden et al., 2002; Stansfield et al., 2001a,b; Cupp et al., 1999; Oeffinger et al., 1997). The eversion moment, the absorbed energy, and the resistance/propulsion configurations showed the most important differences between age groups. First, similar to the MP joint, the maximum eversion moment decreased with age, once again favoring stability in toddlers. Second, the absorbed energy demonstrated similar curve patterns as found in the literature, with a maximum at early stance in children and at midstance in adults (Samson et al., 2009; Chester et al., 2006; Cupp et al., 1999). These differences could be explained either by a roll-off immaturity associated with an incomplete development of the foot arch (Alvarez et al., 2008; Bosch et al., 2007; Hallemans et al., 2006b, 2003; Bertsch et al., 2004; Hennig et al., 1994) or by an immaturity of plantarflexor muscles (Chang et al., 2007; Okamoto et al., 2003; Sutherland, 1997). Third, with age, the main part of the 3D angle aM.o during stance changed from a stabilization configuration to a ‘‘driving’’ configuration (i.e., resistance or propulsion configuration). Moreover, the maxima of resistance and propulsion configurations were statistically smaller in groups 1 and 2 than in group 4. This result is in agreement with a previous work that demonstrated that children seemed to mainly stabilize the ankle and propel the hip, while adults mainly brake and propel the ankle and stabilize the hip (Samson et al., 2009). However, no significant difference was observed between groups 3 and 4, suggesting a mature age, for the 3D angle aM.o, after 5 years. Some limitations must be considered in this study. The MP joint definition only considered one degree of freedom rather than a more accurate foot model (Stebbins et al., 2006; Simon et al., 2006). However, the number of reflective markers required to apply these models could be difficult to locate on small feet. Another limit was the self-selected speed during the gait trials. Previous studies have already shown the predominant effect of walking speed (rather than age) on biomechanical parameters (Stansfield et al., 2001a,b; Schwartz et al., 2008; Diop et al., 2005). However, scaling of the data with speed is hardly applicable (Hollerbach and Flash, 1982) and studying speed groups rather than age groups may not be convenient for a maturation analysis. To summarize, the foot mechanics seems to reach its overall maturity between 3.5 and 5 years of age, with regard to the MP or ankle joint. Few studies have concluded that foot maturation takes place later, based on joint momnts and powers (Chester and Wrigley, 2008; Chester et al., 2006; Cupp et al., 1999; Oeffinger et al., 1997). These differences could be explained by an expression of dynamic parameters as a function of body weight, and not as a function of body weight and leg length, as suggested by Hof (1996). In the present study, the only difference found between groups 3 and 4 concerned the medial/lateral GRF. However, the present study revealed maturity of both MP and ankle joints after 5 years. Subsequently, the medial/lateral GRF’s difference could be due to an immaturity of other joints (i.e., hip abduction joint moment (Cupp et al., 1999; Chester and Wrigley, 2008)). Future works could consider the present database for gait pathologic investigations.
Conflict of interest statement The authors have no conflict of interest.
Acknowledgments This study was funded by La Direction Ge´ne´rale des Entreprises, Ministe re de l’Economie, des Finances et de l’Industrie (convention no. 06 2 90 6149), and by La Re´gion des Pays de la Loire (convention no 2007-03103). This study was supported by the Hospices Civils de Lyon and the Universite´ Lyon 1 Claude Bernard, France.
Appendix A. Supplementary materials Supplementary data associated with this article can be found in the online version at doi:10.1016/j.jbiomech.2011.01.007.
References Alvarez, C., De Vera, M., Chhina, H., Black, A., 2008. Normative data for the dynamic pedobarometric profiles of children. Gait and Posture 28 (2), 309–315. Beck, R.J., Andriacchi, T.P., Kuo, K.N., Fermier, R.W., Galante, J.O., 1981. Changes in the gait patterns of growing children. Journal of Bone and Joint Surgery American 63 (9), 1452–1457. Bertsch, C., Unger, H., Winkelmann, W., Rosenbaum, D., 2004. Evaluation of early walking patterns from plantar pressure distribution measurements. First year results of 42 children. Gait and Posture 19 (3), 235–242. Bojsen-Møller, F., Lamoreux, L., 1979. Significance of free-dorsiflexion of the toes in walking. Acta Orthopaedica Scandinavica 50 (4), 471–479. Bosch, K., Gerss, J., Rosenbaum, D., 2007. Preliminary normative values for foot loading parameters of the developing child. Gait and Posture 26 (2), 238–247. Chang, W.N, Lipton, J.S., Tsirikos, A.T., Miller, F., 2007. Kinesiological surface electromyography in normal children: range of normal activity and pattern analysis. Journal of Electromyography and Kinesiology 17 (4), 437–455. Chester, V.L., Tingley, M., Biden, E.N, 2006. A comparison of kinetic gait parameters for 3–13 year olds. Clinical Biomechanics 21 (7), 726–732. Chester, V.L., Wrigley, A.T., 2008. The identification of age-related differences in kinetic gait parameters using principal component analysis. Clinical Biomechanics 23 (2), 212–220. Cupp, T., Oeffinger, D., Tylkowski, C., Augsburger, S., 1999. Age-related kinetic changes in normal pediatrics. Journal of Pediatric Orthopaedics 19 (4), 475–478. Desroches, G., Dumas, R., Pradon, D., Vaslin, P., Lepoutre, F-X., Che ze, L., 2010. Upper limb joint dynamics during manual wheelchair propulsion. Clinical Biomechanics (Bristol, Avon) 25 (4), 299–306. Diop, M., Rahmani, A., Belli, A., Gautheron, V., Geyssant, A., Cottalorda, J., 2005. Influence of speed variation and age on ground reaction forces and stride parameters of children’s normal gait. International Journal of Sports Medicine 26 (8), 682–687. Dumas, R., Che ze, L., Frossard, L., 2009. Loading applied on prosthetic knee of transfemoral amputee: comparison of inverse dynamics and direct measurements. Gait and Posture 30 (4), 560–562. Dumas, R., Che ze, L., 2008. Hip and knee joints are more stabilized than driven during the stance phase of gait: an analysis of the 3D angle between joint moment and joint angular velocity. Gait and Posture 28 (2), 243–250. Dumas, R., Aissaoui, R., de Guise, J.A., 2004. A 3D generic inverse dynamic method using wrench notation and quaternion algebra. Computer Methods in Biomechanics and Biomedical Engineering 7 (1), 159–166. Ganley, K.J., Powers, C.M., 2005. Gait kinematics and kinetics of 7-year-old children: a comparison to adults using age-specific anthropometric data. Gait and Posture 21 (2), 141–145. Hallemans, A., De Clercq, D., Aerts, P., 2006a. Changes in 3D joint dynamics during the first 5 months after the onset of independent walking: a longitudinal follow-up study. Gait and Posture 24 (3), 270–279. Hallemans, A., De Clercq, D., Van Dongen, D., Aerts, P., 2006b. Changes in footfunction parameters during the first 5 months after the onset of independent walking: a longitudinal follow-up study. Gait and Posture 23 (2), 142–148. Hallemans, A., De Clercq, D., Otten, B., Aerts, P., 2005. 3D joint dynamics of walking in toddlers. A cross-sectional study spanning the first rapid development phase of walking. Gait and Posture 22 (2), 107–118. ˆ t, K., De Clercq, D., Aerts, P., 2003. Pressure distribution Hallemans, A., D’Aou patterns under the feet of new walkers: the first two months of independent walking. Foot and Ankle International 24 (5), 444–453. Hennig, E., Staats, A., Rosenbaum, D., 1994. Plantar pressure distribution patterns of young school children in comparison to adults. Foot and Ankle International 15 (1), 35–40. Hennig, E., Rosenbaum, D., 1991. Pressure distribution patterns under the feet of children in comparison with adults. Foot and Ankle International 11 (5), 306–311. Hof, At.L., 1996. Scaling gait data to body size. Gait and Posture 4 (3), 222–223. Hollerbach, J.M., Flash, T., 1982. Dynamic interactions between limb segments during planar arm movement. Biological Cybernetics 44 (1), 67–77.
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Jensen, R.K., 1989. Changes in segment inertia proportions between 4 and 20 years. Journal of Biomechanics 22 (6-7), 529–536. MacWilliams, B.A., Cowley, M., Nicholson, D.E., 2003. Foot kinematics and kinetics during adolescent gait. Gait and Posture 17 (3), 214–224. Okamoto, T., Okamoto, K., Andrew, P.D., 2003. Electromyographic developmental changes in one individual from newborn stepping to mature walking. Gait and Posture 17 (1), 18–27. Oleson, M., Adler, D., Goldsmith, P., 2005. A comparison of forefoot stiffness in running and running shoe bending stiffness. Journal of Biomechanics 38 (9), 1886–1894. Oeffinger, D.J., Augsburger, S., Cupp, T., 1997. Pediatric kinetics: age related changes in able-bodied populations. Gait and Posture 5 (2), 155–156. Ounpuu, S., Gage, J.R., Davis, R.B., 1991. Three-dimensional lower extremity joint kinetics in normal pediatric gait. Journal of Pediatric Orthopaedics 11 (3), 341–349. ¨ Preis, S., Klemms, A., Muller, K., 1997. Gait analysis by measuring ground reaction forces in children: changes to an adaptive gait pattern between the ages of one and five years. Developmental Medicine and Child Neurology 39 (4), 228–233. Samson, W., Desroches, G., Che ze, L., Dumas, R., 2009. 3D joint dynamics analysis of healthy children’s gait. Journal of Biomechanics 42 (15), 2447–2453. Schwartz, M.H., Rozumalski, A., Trost, J.P., 2008. The effect of walking speed on the gait of typically developing children. Journal of Biomechanics 41 (8), 1639–1650. Simon, J., Doederlein, L., McIntosh, A.S., Metaxiotis, D., Bock, H.G., Wolf, S.I., 2006. The Heidelberg foot measurement method: development, description and assessment. Gait and Posture 23 (4), 411–424. Stansfield, B.W., Hillman, S.J., Hazlewood, M.E., Lawson, A.A., Mann, A.M., Loudon, I.R., Robb, J.E., 2001a. Sagittal joint kinematics, moments, and powers are predominantly characterized by speed of progression, not age, in normal children. Journal of Pediatric Orthopaedics 21 (3), 403–411. Stansfield, B.W., Hillman, S.J., Hazlewood, M.E., Lawson, A.A., Mann, A.M., Loudon, I.R., Robb, J.E., 2001b. Normalized speed, not age, characterizes ground
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reaction force patterns in 5- to 12-year-old children walking at self-selected speeds. Journal of Pediatric Orthopaedics 21 (3), 395–402. Stebbins, J., Harrington, M., Thompson, N., Zavatsky, A., Theologis, T., 2006. Repeatability of a model for measuring multi-segment foot kinematics in children. Gait and Posture 23 (4), 401–410. Stefanyshyn, D.J., Nigg, B.M., 1997. Mechanical energy contribution of the metatarsophalangeal joint to running and sprinting. Journal of Biomechanics 30 (11–12), 1081–1085. Sutherland, D.H., 1997. The development of mature gait. Gait and Posture 6 (2), 163–170. Takegami, Y., 1992. Wave pattern of ground reaction force of growing children. Journal of Pediatric Orthopaedics 12 (4), 522–526. Twomey, D., McIntosh, A.S., Simon, J., Lowe, K., Wolf, S.I., 2010. Kinematic differences between normal and low arched feet in children using the Heidelberg foot measurement method. Gait and Posture 32 (1), 1–5. van der Linden, M.L., Kerr, A.M., Hazlewood, M.E., Hillman, S.J., Robb, J.E., 2002. Kinematic and kinetic gait characteristics of normal children walking at a range of clinically relevant speeds. Journal of Pediatric Orthopaedics 22 (6), 800–806. Wells, R.P., 1981. The projection of the ground reaction force as a predictor of internal joint moments. Bulletin of Prosthetics Research 10-35, 15–19. Winter, D.A., Wells, R.P., 1981. Kinetic assessments of human gait. Journal of Bone and Joint Surgery 63 (8), 1350. Wu, G., Siegler, S., Allard, P., Kirtley, C., Leardini, A., Rosenbaum, D., Whittle, M., D’Lima, D.D., Cristofolini, L., Witte, H., Schmid, O., Stokes, I., 2002. ISB recommendation on definitions of joint coordinate system of various joints for the reporting of human joint motion—part I: ankle, hip, and spine. International Society of Biomechanics. Journal of Biomechanics 35 (4), 543–548. Wu, G., Cavanagh, P., 1995. ISB recommendations for standardization in the reporting of kinematic data. Journal of Biomechanics 28 (10), 1257–1261.
Contents lists available at ScienceDirect
Journal of Biomechanics journal homepage: www.elsevier.com/locate/jbiomech www.JBiomech.com
Foot mechanics during the first six years of independent walking William Samson a,b,c,d,n, Bruno Dohin e,f, Guillaume Desroches b,c,d, Jean-Luc Chaverot a, ¨ Dumas b,c,d, Laurence Cheze b,c,d Raphael a
´ Professionnel de De ´veloppement Cuir Chaussure Maroquinerie, 4 rue Hermann Frenkel, 69 367 Lyon Cedex 7, France CTC, Comite Universite´ de Lyon, Universite´ Lyon 1, Lyon F-69003, France c Ifsttar, Bron F-69675, France d Laboratoire de Biome´canique et Me´canique des Chocs, UMR_T 9406, Villeurbanne F-69622, France e ´diatrique, Saint Etienne 42055 Cedex 2, France Universite´ Jean Monnet Saint Etienne, Hˆ opital Nord CHU de Saint Etienne, Service de chirurgie pe f Laboratoire Inserm U 864, Universite´ de Lyon, Lyon F-69003, France b
a r t i c l e i n f o
abstract
Article history: Accepted 5 January 2011
Recognition of the changes during gait that occur normally as a part of growth is essential to prevent mislabeling those changes from adult gait as evidence of gait pathology. Currently, in the literature, the definition of a mature age for ankle joint dynamics is controversial (i.e., between 5 and 10 years). Moreover, the mature age of the metatarsophalangeal (MP) joint, which is essential for the functioning of the foot, has not been defined in the literature. Thus, the objective of the present study explored foot mechanics (ankle and MP joints) in young children to define a mature age of foot function. Forty-two healthy children between 1 and 6 years of age and eight adults were measured during gait. The ground reaction force (GRF), the MP and ankle joint angles, moments, powers, and 3D angles between the joint moment and the joint angular velocity vectors (3D angle aM.o) were processed and compared between four age groups (2, 3.5, 5 and adults). Based on statistical analysis, the MP joint biomechanical parameters were similar between children (older than 2 years) and adults, hinting at a quick maturation of this joint mechanics. The ankle joint parameters and the GRFs (except for the frontal plane) showed an adult-like pattern in 5-year-old children. Some ankle joint parameters, such as the joint power and the 3D angle aM.o still evolved significantly until 3.5 years. Based on these results, it would appear that foot maturation during gait is fully achieved at 5 years. & 2011 Elsevier Ltd. All rights reserved.
Keywords: Gait maturation Metatarsophalangeal joint Kinematic Dynamic Ground reaction force
1. Introduction Recognition of the changes that occur normally as a part of growth and body development is essential to prevent mislabeling those changes from adult gait as evidence of gait pathology (Sutherland, 1997). At the foot level, children may reveal numerous variations (e.g., clubfoot, planovalgus, pes planus, equinus and flat foot). There is therefore a need to better define and quantify the foot function during growth. Several approaches have been reported in the literature to better understand the foot mechanics during gait in young healthy children (i.e., younger than 6 years). They include the assessment of plantar pressure distribution (Alvarez et al., 2008; Bosch et al., 2007; Hallemans et al., 2006b, 2003; Bertsch et al., 2004; Hennig et al., 1994; Hennig and Rosenbaum, 1991), ground reaction force n Corresponding author at:. CTC, Comite´ Professionnel de De´veloppement Cuir Chaussure Maroquinerie, 4 rue Hermann Frenkel, 69 367 Lyon Cedex 7, France. Tel.: + 33 4 72 44 80 98; fax: +33 4 72 44 80 54. E-mail address: [email protected] (W. Samson).
0021-9290/$ - see front matter & 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.jbiomech.2011.01.007
(GRF) (Hallemans et al., 2006a; Diop et al., 2005; Stansfield et al., 2001b; Sutherland, 1997; Preis et al., 1997; Takegami, 1992; Beck et al., 1981), and ankle joint kinematics and dynamics (Chester and Wrigley, 2008; Chester et al., 2006; Hallemans et al., 2006b, 2005; Ganley and Powers, 2005; Cupp et al., 1999; Sutherland, 1997; Oeffinger et al., 1997; Stansfield et al., 2001a; Ounpuu et al., 1991). Studies on plantar pressure distribution in young children have shown predominant use of the midfoot to the detriment of the heel and forefoot. This predominance has been explained by the immaturity of the foot skeletal structures and the importance of the fat pad (Alvarez et al., 2008; Bosch et al., 2007; Hallemans et al., 2006b, 2003; Bertsch et al., 2004; Hennig et al., 1994). According to these studies, mature plantar pressure distribution is obtained between 5 and 6 years of age. With regard to GRF results, Hallemans et al. (2006a) reported modifications of the curve pattern of the vertical component from one hump to two humps during the first steps of independent walking which the authors attributed to roll-off immaturity. However, depending on the study, conclusions regarding the definition of a mature age for GRFs patterns varied extensively: from 3 to 8 years
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Like the ankle, the toes are essential for the functioning of the foot (Bojsen-Møller and Lamoreux, 1979). ‘‘Toe dorsiflexion secures support to the longitudinal arch at peak loads, and it enables the ball (i.e., part of the foot composed of the distal heads of the metatarsals and their surrounding fat pad) to withstand the tangential forces to which it is exposed. Toe dorsiflexion also allows the foot to take advantage of different leverage ratios to suit different conditions, resulting in more efficient propulsion’’. Similar to the joint kinematic and dynamic changes during growth, it could be hypothesized that the metatarsophalangeal (MP) joint is not mature immediately after performing the first
(Diop et al., 2005; Stansfield et al., 2001b; Sutherland, 1997; Preis et al., 1997; Takegami, 1992; Beck et al., 1981). In contrast to plantar pressure approaches, few studies have explored ankle biomechanical parameters before 6 years of age (Hallemans et al., 2006b, 2005; Chester et al., 2006; Sutherland, 1997). With respect to joint angles, moments and powers, conclusions regarding maturity of ankle joint were controversial: the ankle joint mechanics was defined as mature between 5 years (Ounpuu et al., 1991), 8 years (Cupp et al., 1999), 9–13 years (Chester and Wrigley, 2008; Chester et al., 2006), or 10 years (Oeffinger et al., 1997).
Table 1 Anthropometric and temporal distance parameters for the four groups. Significant differences are shown with a p-value less than 0.05 (a,b,c: significant difference between group 1 and groups 2 to 4, respectively; d,e: significant difference between group 2 and groups 3 and 4, respectively; f: significant difference between groups 3 and 4; n.s: no significant difference between groups; l0: leg length; g: acceleration of gravity).
N Age range (years) Mean Age (years) Height (cm) Mass (kg) Step length (m/l0) Walking speed (m.s 1/O(gl0)) Cadence (Hz/O(g/l0)) Stance duration (% of gait cycle)
Group 1
Group 2
Group 3
Group 4
14 1.2–2.8 2.17 0.5 86.97 5.2 12.27 1.6 1.107 0.13 0.287 0.03 0.827 0.07 65.47 2.6
14 2.9–4.2 3.6 7 0.4 100.87 5.8 16.5 7 2.3 1.34 7 0.13 0.337 0.39 0.887 0.08 64.8 7 2.68
14 4.3–5.8 5.07 0.5 110.8 7 6.8 18.6 7 3.2 1.38 7 0.13 0.397 0.03 0.747 0.06 63.8 7 1.9
8 23.0–31.0 25.07 2.6 175.0 7 4.0 67.07 5.6 1.67 7 0.05 0.477 0.02 0.737 0.02 63.7 7 1.1
abcdef abcdef abcdef abcef bcdef n.s n.s
Table 2 GRF, MP and ankle variables for statistical analysis. Significant differences are shown with a p-value less than 0.05 (a,b,c: significant difference between group 1 and groups 2 to 4, respectively; d,e: significant difference between group 2 and groups 3 and 4, respectively; f: significant difference between groups 3 and 4; n.s: no significant difference between groups; RoM: range of motion; K.W: Kruskal–Wallis test). Variables
K.W.
GRF Ry1 Ry2 Rx1 Rx2 Rz1 Rz2
Max. Max. Max. Max. Max. Max.
MP MP-RoMz MP-Az1 MP-Az2 MP-Mz MP-Mx MP-Mx MP-P1 MP-P2 MP-3DA
RoM in flex./ext. Max. ext. at midstance Max. flex. at pre-swing Max. ext. moment at midstance Max. ev. moment at midstance Max. abd. moment at pre-swing Max. abs. energy at midstance Max. gen. energy at pre-swing Min. 3D angle aM.o at pre-swing
0.352 0.249 0.056 0.875 0.115 0.257 0.395 0.248 0.153
Ankle A-RoMz A-RoMx A-RoMy A-Az1 A-Az2 A-Az3 A-Ax1 A-Ax2 A-Ax3 A-Mz A-Mx A-My A-P1 A-P2 A-P3 A-3DA1 A-3DA2 A-3DA3
RoM in dorsiflex./plantarflex. RoM in inv./ev. RoM in abd./add. Max. dorsiflex. at midstance Max. plantarflex. at pre-swing Max. dorsiflex. at midswing Max. ev. at early stance Max. inv. at pre-swing Max. ev. at midswing Max. plantarflex. moment at stance Max. ev. moment at midstance Max. abd. moment at pre-swing Max. abs. energy at early stance Max. abs. energy at midstance Max. gen. energy at pres-wing Max. 3D angle aM.o at early stance Max. 3D angle aM.o at midstance Min. 3D angle aM.o at pre-swing
0.181 0.422 0.934 0.248 0.093 0.173 0.248 0.153 0.153 0.697 0.391 0.114 0.008 0.173 0.875 0.009 0.441 0.047
vertical force at early stance vertical force at pre-swing posterior force at early stance anterior force at pre-swing lateral force at early stance lateral force at pre-swing
0.248 0.038 0.607 0.000 0.012 0.153
1–2
1–3
1–4
2–3
2–4
3–4
0.039
0.043
0.003
0.679
0.031
0.062
0.141 0.232
0.001 0.129
0.002 0.002
0.060 0.854
0.007 0.005
0.062 0.004
0.014
0.011
0.001
0.306
0.067
0.443
0.335
0.520
0.014
0.335
0.006
0.073
0.550
0.168
0.009
0.781
0.031
0.073
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independent steps. However, no study has specifically investigated the evolution of this joint in young children. Finally, in a review paper about maturation of gait, Sutherland (1997) proposed future investigations to complete the study of gait’s maturation. At this stage, there is still a need to further describe the kinematics of children between 1 and 4 years and complete the available databases of joint moments and powers between 2 and 4 years. Thus, the present study explored the foot mechanics in young children from the GRF, as well as the MP and ankle joints kinematics and dynamics, to define a mature age of foot function.
compared between the four groups using a Kruskal–Wallis test (p o 0.05) (Table 2, Figs. 1–3). When significant, non-parametric Mann–Whitney tests were performed to show intergroup differences (p o 0.05). As in previous works (Chester and Wrigley, 2008; Chester et al., 2006; Stansfield et al., 2001a,b; Cupp et al., 1999; Oeffinger et al., 1997), a parameter was considered as mature when significant differences with adults disappeared.
2. Methods
Irrespective of the planes, the GRF showed approximately the same curve patterns, except for group 1 (Fig. 1). For this group, the second hump was almost non-existent in the sagittal and the transverse planes, when compared with the older groups. The dimensionless maximum values were smaller in children than in adults for the vertical and the anterior/posterior forces, in contrast to the medial/lateral force. Significant differences appeared at the early stance (0–20% of gait cycle) for the medial/lateral force (0.070, 0.098, 0.098, and 0.111 dimensionless for the groups 1–4, respectively), at pre-swing (50–60% of gait cycle) for the vertical force (0.812, 0.937, 0.936, and 1.117 dimensionless for
2.1. Participants A total of 42 healthy children were included in the study and assigned to three groups of 2, 3.5, and 5 years of age (groups 1–3, respectively). The characteristics of these groups are described in Table 1. Independent walking was acquired before 18 months, and medical examination did not reveal any orthopedic or neurological disorder. Parents gave informed consent for their child to participate in this study which was approved by the local ethics committee. In addition, with a similar protocol and method, eight adults participated in the study to define a reference population (group 4).
3. Results 3.1. GRF
2.2. Experimental setup
R y2
R y1
1.2
V ical reacctionn foorce Verti (N N/m m0.g))
Sixteen markers were fixed on the anatomical landmarks of both the lower limbs (medial and lateral epicondyles, head of fibula, medial and lateral malleoli, first and fifth metatarsal heads, and hallux). The children were allowed to walk at a self-selected speed. Fifteen gait trials were measured for each subject using a Motion Analysiss system with six Eagles cameras (Motion Analysis Corporation, Santa Rosa, USA), two Bertecs force platforms (Bertec, Columbus, USA), and one Footscans plantar pressure platform (RSscan, Olen, Belgium) at a sampling frequency of 100, 1000, and 100 Hz, respectively. All the platforms were synchronized with the Motion Analysis system using a trigger pulse from the plantar pressure platform. Only data of the gait cycles with full contact of the right or left foot on one of the force platforms were processed.
*
Up Group Group Group Group
0.8
0.4
1 2 3 4
0 Down
2.3. Data processing
0
metatarsi and pointing to the right; Y, the unit vector of the line perpendicular to the plane defined by the Z-axis and hallux, and pointing to the top; and X, the unit vector of the common line perpendicular to the Z- and the Y-axes.
The Z-axis of the rearfoot and the forefoot coordinate systems were defined similarly. Consequently, the MP joint was only considered with one degree of freedom. After an estimation of the inertial parameters from scaling equations (Jensen, 1989), the ankle joint moment (net internal moment) was computed by bottom-up 3D inverse dynamics using quaternion algebra (Dumas et al., 2004). Subsequently, the MP joint moment (net internal moment) was computed using the ‘‘ground reaction vector technique’’ (Wells, 1981; Stefanyshyn and Nigg, 1997), transforming the moment from the force platform to the MP joint center using classical rigid body mechanics. Although criticized (Winter and Wells, 1981), this method demonstrated appropriate results when the segments’ inertial parameters are negligible (Dumas et al., 2009). Computation of the MP joint moment was realized as soon as the forefoot was solely in contact with the force platform. This event was defined separately, from the stance timing of the plantar pressure platform. The joint moments were expressed in the proximal SCS. Subsequently, 3D joint powers and 3D angles between the joint moment and the joint angular velocity vectors (3D angle aM.o), previously defined in the literature (Desroches et al., 2010; Samson et al., 2009; Dumas and Che ze, 2008), were computed for the ankle and the MP. Details of 3D joint powers and 3D angles aM.o calculation and interpretation are presented in the Appendix A. Finally, the GRF, joint moments, and joint powers were made dimensionless (Hof, 1996). All the data were re-sampled over 100% of the gait cycle and averaged for the subjects of each group. Because the thirty-three dependent variables did not meet the normality criteria (Shapiro–Wilk test; p o 0.05), those variables were
Annterrior/ppostterio or reeactiion forcce (N N/m m0.g))
O (origin), the middle of the first and the fifth metatarsi; Z (flexion axis), the unit vector of the line connecting the first and the fifth
20
40
60
80
R x2 0.2
100 Anterior
* R x1
0
-0.2
Posterior
0
20
40
60
80
R z1 0.12
Meediaal/latterall reaactioon force (N/m m0.gg)
After signal processing (low-pass zero-lag, 4th-order, Butterworth filter, 6-Hz cutoff frequency) using Matlabs, the segment coordinate systems (SCS) of the leg and the rearfoot were defined according to the international recommendations, as well as the ankle joint coordinate system (Wu and Cavanagh, 1995; Wu et al., 2002). The forefoot coordinate system was defined as follows (right foot):
*
100 Lateral
R z2
0.08 0.04 0 Medial
0
20
40 60 Gait cycle (%)
80
100
Fig. 1. (a–c): Vertical, anterior/posterior and medial/lateral GRF, respectively (* significant difference between groups; l0: leg length; g: acceleration of gravity).
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Fig. 2. MP joints:. (a) flexion/extension joint angle; (b and c) flexion/extension and eversion/inversion joint moment, respectively; (d) joint power; (e) 3D angle aMx (l0: leg length; g: acceleration of gravity).
the groups 1–4, respectively) and anterior/posterior force (0.082, 0.111, 0.142, and 0.201 dimensionless for the groups 1–4, respectively) (Table 2). These significant differences were noted in groups 1 and 2 when compared with group 4, while significant difference only appeared for the medial/lateral force at the early stance between groups 3 and 4.
3.2. MP joint The joint angle, moments and power showed similar curve patterns (Fig. 2a–d). The maximum difference about the range of motion never exceeded 7.11 between the groups. With age, at midstance (20–40% of the gait cycle), the maximum extension moments were almost similar while the maximum eversion moments decreased ( 0.039 and 0.024 dimensionless, for the groups 1 and 4, respectively). At midstance, the maximum absorbed energy was slightly more important in group 1 than in group 4 ( 0.502 and 0.421 dimensionless, respectively). At preswing, the generated energy approached zero in group 1 and increased with the advancement of years (0.017, 0.039, 0.095, and 0.116 dimensionless for groups 1–4, respectively). Finally, at preswing, the 3D angle aM.o showed a stabilization configuration in children, while adults were in a propulsion configuration (76.9, 74.4, 72.0, and 48.41 for groups 1–4, respectively) (Fig. 2e).
Nevertheless, irrespective of the MP variables, no significant difference was observed between the age groups.
3.3. Ankle joint The joint angles and moments showed similar curve patterns (Fig. 3a–d). The maximum difference between the groups with regard to the range of motion never exceeded 7.11 in dorsiflexion/plantarflexion and 2.51 in inversion/eversion, and no significant difference appeared. With age, as noted in the MP joint at midstance, the maximum extension moments were almost similar, while the maximum eversion moments decreased ( 0.035 and 0.015 dimensionless, for the groups 1 and 4, respectively). Moreover, at early stance, a little inversion moment appeared with age. Joint moments revealed no significant difference. The power curves showed two different patterns about the absorbed energy at stance: a single hump in group 1 evolved with age to a double hump, as observed in group 4. Subsequently, the maximum absorbed energy was found to be more important in children at early stance ( 0.387, 0.226, 0.224, and 0.188 dimensionless for groups 1–4, respectively). At pre-swing, the maximum generated energy was almost similar in each group. Finally, during stance, the 3D angle aM.o pattern differed between children and adults. More precisely, a decrease in the
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Fig. 3. Ankle joints: (a and b) dorsiflexion/plantarflexion and eversion/inversion joint angle; (c and d) dorsiflexion/plantarflexion and eversion/inversion joint moment, respectively; (e) joint power; (f) 3D angle aMx (* significant difference between groups; l0: leg length; g: acceleration of gravity).
duration of joint stabilization configuration (79.7%, 75.0%, 75.8%, and 40.0% of stance phase for groups 1–4, respectively) was observed. The maximum resistance and propulsion configurations were statistically less important in groups 1 and 2 than in group 4 at early stance and pre-swing, respectively. No significant difference was observed between groups 3 and 4.
4. Discussion The present study covered a sample of children between 1 and 6 years of age with the same marker set as employed for the adult gait trials, and taking into account not only the GRF and ankle joint, but also the MP joint, currently unexplored to the authors’ knowledge. A previous study of young children has already been done (Samson et al., 2009), focusing on the hip, knee and ankle joint dynamic strategies. These strategies were found different in children compared to adults. With a larger population, the present study investigated three groups of age and defined a mature age of foot function. Concerning the GRF, the most important differences between age groups were revealed on the maximum vertical and anterior/ posterior forces at pre-swing, and the maximum medial/lateral force at early stance. The hump in vertical force at pre-swing was almost absent in young children, as observed in previous studies (Hallemans et al., 2006a; Sutherland, 1997; Preis et al., 1997), and increased with age, as also reported previously (Diop et al., 2005; Takegami, 1992). The maximum value increased for the
anterior/posterior force, in contrast to the work carried out by Diop et al. (2005). It is however to be noticed that the children were older and that a treadmill was used in the aforementioned study. For both the second maximum of the vertical force and the maximum of the anterior force, significant differences between groups 3 and 4 disappeared. Finally, at early stance, the maximum medial/lateral force decreased with age. There were significant differences between children and adults, probably due to a decrease of stride width (Hallemans et al., 2006a). These results are in agreement with those obtained by Takegami (1992), who reported a decrease in the maximum medial/lateral force until the age of eight. The MP revealed explicit curve patterns (Twomey et al., 2010; Stebbins et al., 2006; Simon et al., 2006; Oleson et al., 2005; MacWilliams et al., 2003; Stefanyshyn and Nigg, 1997) that were similar to those reported in the literature with regard to older children and adults. Unfortunately, no work could be found in the literature with regard to such young children that could be used to compare the present results. Age had the most significant influence on the pre-swing phase. An increase in age was associated with an increase in maximum flexion, a decrease in maximum eversion moment and the apparition of a generated energy combined with a 3D angle aM.o evolving from a stabilization configuration to a propulsion configuration. It is probable that young children will give priority to stability to the detriment of propulsion in order to avoid a fall. Nevertheless, no significant difference between age groups was found whatever the MP variables. These results could be an indication for the lesser importance or more passive character of the MP joint. Future
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works should consider a most important sample of children and/ or very younger age groups (e.g. 1.5, 2 and 2.5 years) to detect the mature age of the MP joint use. The ankle joint revealed similar curve patterns as those previously described (Samson et al., 2009; Chester and Wrigley, 2008; Chester et al., 2006; Hallemans et al., 2006b; van der Linden et al., 2002; Stansfield et al., 2001a,b; Cupp et al., 1999; Oeffinger et al., 1997). The eversion moment, the absorbed energy, and the resistance/propulsion configurations showed the most important differences between age groups. First, similar to the MP joint, the maximum eversion moment decreased with age, once again favoring stability in toddlers. Second, the absorbed energy demonstrated similar curve patterns as found in the literature, with a maximum at early stance in children and at midstance in adults (Samson et al., 2009; Chester et al., 2006; Cupp et al., 1999). These differences could be explained either by a roll-off immaturity associated with an incomplete development of the foot arch (Alvarez et al., 2008; Bosch et al., 2007; Hallemans et al., 2006b, 2003; Bertsch et al., 2004; Hennig et al., 1994) or by an immaturity of plantarflexor muscles (Chang et al., 2007; Okamoto et al., 2003; Sutherland, 1997). Third, with age, the main part of the 3D angle aM.o during stance changed from a stabilization configuration to a ‘‘driving’’ configuration (i.e., resistance or propulsion configuration). Moreover, the maxima of resistance and propulsion configurations were statistically smaller in groups 1 and 2 than in group 4. This result is in agreement with a previous work that demonstrated that children seemed to mainly stabilize the ankle and propel the hip, while adults mainly brake and propel the ankle and stabilize the hip (Samson et al., 2009). However, no significant difference was observed between groups 3 and 4, suggesting a mature age, for the 3D angle aM.o, after 5 years. Some limitations must be considered in this study. The MP joint definition only considered one degree of freedom rather than a more accurate foot model (Stebbins et al., 2006; Simon et al., 2006). However, the number of reflective markers required to apply these models could be difficult to locate on small feet. Another limit was the self-selected speed during the gait trials. Previous studies have already shown the predominant effect of walking speed (rather than age) on biomechanical parameters (Stansfield et al., 2001a,b; Schwartz et al., 2008; Diop et al., 2005). However, scaling of the data with speed is hardly applicable (Hollerbach and Flash, 1982) and studying speed groups rather than age groups may not be convenient for a maturation analysis. To summarize, the foot mechanics seems to reach its overall maturity between 3.5 and 5 years of age, with regard to the MP or ankle joint. Few studies have concluded that foot maturation takes place later, based on joint momnts and powers (Chester and Wrigley, 2008; Chester et al., 2006; Cupp et al., 1999; Oeffinger et al., 1997). These differences could be explained by an expression of dynamic parameters as a function of body weight, and not as a function of body weight and leg length, as suggested by Hof (1996). In the present study, the only difference found between groups 3 and 4 concerned the medial/lateral GRF. However, the present study revealed maturity of both MP and ankle joints after 5 years. Subsequently, the medial/lateral GRF’s difference could be due to an immaturity of other joints (i.e., hip abduction joint moment (Cupp et al., 1999; Chester and Wrigley, 2008)). Future works could consider the present database for gait pathologic investigations.
Conflict of interest statement The authors have no conflict of interest.
Acknowledgments This study was funded by La Direction Ge´ne´rale des Entreprises, Ministe re de l’Economie, des Finances et de l’Industrie (convention no. 06 2 90 6149), and by La Re´gion des Pays de la Loire (convention no 2007-03103). This study was supported by the Hospices Civils de Lyon and the Universite´ Lyon 1 Claude Bernard, France.
Appendix A. Supplementary materials Supplementary data associated with this article can be found in the online version at doi:10.1016/j.jbiomech.2011.01.007.
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