Fig 1.
Posture during tiptoe standing on a single leg.
(a) Dancers kept their balance on a supporting leg without external support. (b) The metatarsophalangeal and ankle joints in the supporting leg are extended and plantarflexed, respectively, during tiptoe standing. (c) The measured foot inversion/eversion angle (AG_IE) in this study.
Fig 2.
Magnetic resonance images and definitions of angles representing the alignment of a dancer’s metatarsal heads.
(a-c) Views of the horizontal (a), frontal (b), and sagittal (c) images to determine the point on each metatarsal head closest to the sole. (d) Angles between adjacent metatarsal heads. The numbers indicate the first to fifth toes. The thin, medium, and thick arcs indicate angles 1-2-3, 2-3-4, and 3-4-5, respectively. (c) Hallux valgus angle (HVA) determined using the method of Janssen et al. [18].
Table 1.
Definition of the local coordinate system of the pelvis, thigh, and foot.
Table 2.
Interclass correlation coefficient for measuring metatarsal alignment.
Table 3.
Comparison of the alignment of metatarsal bone heads between both legs.
Fig 3.
Correlation between angles representing metatarsal alignment and relevant variables when standing on the non–dominant leg.
AG_IE and MT indicate the mean foot inversion (−)/eversion (+) angle and the % duration when the centre of pressure positions was located medial to the second metatarsal head, respectively, against the total duration of the balancing phase. Graphs with black circle plots indicate significant correlations with the angle representing metatarsal alignment and variables after consideringeffects of the multiple testing. (a) the foot inverts as the angle 1-2-3 becomes significantly wider; (b)% duration to load medially decreases as the angle 1-2-3 becomes significantly wider; (c) the foot inversion/eversion angle does not correlate with the angle 2-3-4; (d) % duration to load medially does not correlate with the angle 2-3-4; (e) the foot inversion/eversion angle does not correlate with the angle 3-4-5; (f) % duration to load medially does not correlate with the angle 3-4-5.
Fig 4.
Correlation between angles representing metatarsal alignment and relevant variables when standing on the dominant leg.
AG_IE and MT indicate the mean foot inversion (−)/eversion (+) angle and the % duration when the centre of pressure positions was located medial to the second metatarsal head, respectively, against the total duration of the balancing phase. Graphs with black circle plots indicate significant correlations with the angle representing metatarsal alignment and variables after considering effects of the multiple testing. (a) the foot inversion/eversion angle does not correlate with the angle 1-2-3; (b)% duration to load medially does not correlate with the angle 1-2-3; (c) the foot inversion/eversion angle does not correlate with the angle 2-3-4; (d) % duration to load medially does not correlate with the angle 2-3-4; (e) the foot inversion/eversion angle does not correlate with the angle 3-4-5; (f) % duration to load medially does not correlate with the angle 3-4-5.
Table 4.
Comparison of kinematics and kinetics between both legs during tiptoe standing.