Analysis of the asymmetry of thoracic shape at rest: relationship with lateral thoracic deviation

Abstract

[Purpose] We analyzed the relationship between the degree of asymmetry in the shape of the thorax and postural changes in the frontal plane, and examined the mechanism that creates an asymmetry in the thoracic shape. [Participants and Methods] The participants included 19 healthy young males. We calculated the thoracic volume and lateral deviation from the amount of displacement of reflective markers attached to the thoracic area using the Vicon MX 3D-analysis system. [Results] Left-right differences were shown in each area of the thorax, and positive and negative correlations were found with the amount of lateral deviation of the thorax, which captured postural changes in the frontal plane. [Conclusion] The results of this study suggest that postural changes in the frontal plane are factors involved in the mechanism of left-right asymmetry formation in the thoracic shape.

Relationship between the thoracic asymmetry in standing position and the asymmetry of ankle moment in the frontal plane during gait

“…Thus, it is suggested that the right upper ribs in cases of leftward deviation of the thorax are in a forward rotational position and the left is in a backward rotational position relative to the contralateral side, while the lower ribs are in the opposite rotational position to the upper ribs. Several previous studies analyzing the thorax in able-bodied individuals have reported thoracic asymmetry, as shown by our results 1 , 2 , 3 , 4 , 11 ) . We speculate that a possible reason for the similar thoracic asymmetry in many able-bodied individuals is the functional asymmetry of the lower limbs.…”

“…The thorax of the participants in this study was deviated to the left relative to the pelvis in the standing position.​​​​​​​ Furthermore, the UTS had a greater anteroposterior diameter on the left relative to the right, and the LTS had a greater anteroposterior diameter on the right relative to the left. The expansion of the anterior-posterior diameter of the thoracic shape can be regarded as the backward rotation of the ribs, while the reduction can be regarded as the forward rotation of the ribs 1 , 4 , 11 ) . Thus, it is suggested that the right upper ribs in cases of leftward deviation of the thorax are in a forward rotational position and the left is in a backward rotational position relative to the contralateral side, while the lower ribs are in the opposite rotational position to the upper ribs.…”

“…With reference to previous studies 1 , 2 , 3 , 4 , 11 ) , the TLD was calculated from the center of the thorax and pelvis. The midpoints of C and T8 were defined as the center of the thorax, and the midpoints of ASIS and PSIS on each side were calculated and their respective midpoints were defined as the center of the pelvis ( Fig.…”

“…The asymmetrical ratios of the UTS and LTS were calculated from the anteroposterior diameters of the thorax on each side 1 , 4 , 11 ) . The thoracic shape indicates the unevenness of the thoracic surface and reflects the rotational alignment of the ribs 1 , 4 , 11 ) .…”

“…The asymmetrical ratios of the UTS and LTS were calculated from the anteroposterior diameters of the thorax on each side 1 , 4 , 11 ) . The thoracic shape indicates the unevenness of the thoracic surface and reflects the rotational alignment of the ribs 1 , 4 , 11 ) . Thus, the anteroposterior diameter of the thorax at each level can be viewed as an uneven shape of the thoracic surface, reflecting the rotational alignment of the ribs.…”