TY - JOUR
T1 - Inversion-eversion moment arms of gastrocnemius and tibialis anterior measured in vivo
AU - Lee, Sabrina S.M.
AU - Piazza, Stephen J.
N1 - Funding Information:
The authors would like to acknowledge Tamara Cohen, Tracy Norman, and Peter Ripley for their contribution to data collection. This work was supported by NSF BES-0124217.
PY - 2008/12/5
Y1 - 2008/12/5
N2 - In this study, the frontal plane moment arms of tibialis anterior (TA) and the lateral and medial heads of gastrocnemius (LG and MG) were determined using ultrasonography of ten healthy subjects. Analysis of variance was performed to investigate the effects of frontal plane angle, muscle activity, and plantarflexion angle on inversion-eversion moment arm for each muscle. The moment arms of each muscle were found to vary with frontal plane angle (all p<0.001). TA and LG exhibited eversion moment arms when the foot was everted, but MG was found to have a slight inversion moment arm in this position. As the ankle rotated from 0° to 20° inversion, the inversion moment arm of each increased, indicating that the three muscles became increasingly effective inverters. In neutral position, the inverter moment arm of MG was greater than that of LG (p=0.001). Muscle activity had a significant effect on both LG and MG moment arm at all frontal plane positions (all p≤0.005). These results demonstrate the manner in which frontal plane moment arms of gastrocnemius and TA differ across the frontal plane range of motion in healthy subjects. This method for assessing muscle action in vivo used in this study may prove useful for subject-specific planning of surgical treatments for frontal plane foot and ankle deformities.
AB - In this study, the frontal plane moment arms of tibialis anterior (TA) and the lateral and medial heads of gastrocnemius (LG and MG) were determined using ultrasonography of ten healthy subjects. Analysis of variance was performed to investigate the effects of frontal plane angle, muscle activity, and plantarflexion angle on inversion-eversion moment arm for each muscle. The moment arms of each muscle were found to vary with frontal plane angle (all p<0.001). TA and LG exhibited eversion moment arms when the foot was everted, but MG was found to have a slight inversion moment arm in this position. As the ankle rotated from 0° to 20° inversion, the inversion moment arm of each increased, indicating that the three muscles became increasingly effective inverters. In neutral position, the inverter moment arm of MG was greater than that of LG (p=0.001). Muscle activity had a significant effect on both LG and MG moment arm at all frontal plane positions (all p≤0.005). These results demonstrate the manner in which frontal plane moment arms of gastrocnemius and TA differ across the frontal plane range of motion in healthy subjects. This method for assessing muscle action in vivo used in this study may prove useful for subject-specific planning of surgical treatments for frontal plane foot and ankle deformities.
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U2 - 10.1016/j.jbiomech.2008.09.029
DO - 10.1016/j.jbiomech.2008.09.029
M3 - Article
C2 - 19019375
AN - SCOPUS:56549085067
SN - 0021-9290
VL - 41
SP - 3366
EP - 3370
JO - Journal of Biomechanics
JF - Journal of Biomechanics
IS - 16
ER -