Analysis of sagittal thoracolumbar spine and hip joint movements during sit-to-stand using a 2D image analysis freeware

[Purpose] This study aimed to verify the utility of an image analysis freeware in the evaluation of thoracolumbar spine and hip joint movements during sit-to-stand movement and show the importance of separately analyzing the movements of the thoracolumbar spine and the hip joint. [Participants and Methods] We used a two-dimensional image analysis freeware to analyze the kinematics of the thoracolumbar spine and the hip joint during sit-to-stand movements in seven healthy young males. We further examined the usefulness of the freeware by verifying the concordance of its angle measurements with those of a three-dimensional motion analysis device. Moreover, we evaluated joint coordination of the thoracolumbar spine with hip joint movements in pregnant female before and after delivery by measuring the relative phase angle. [Results] The trunk angle and relative phase angle between the thoracolumbar spine and the hip joint obtained using the two different analytical methods were fairly consistent. In the analysis of the pregnant female, the degree of thoracolumbar flexion prior to hip flexion tended to decrease. Similarly, the degree of hip extension tended to decrease during pregnancy. [Conclusion] This study shows that a two-dimensional image analysis freeware could be useful and meaningful in the calculation of thoracolumbar spine and hip joint movements and in the detection of synergistic patterns of these entities during sit-to-stand movement.