Deformation analysis of forearm soft tissues surrounding the cephalic vein under shear on the skin surface using ultrasound video images

Abstract

Multilayered skin, subcutaneous tissue, and skeletal muscle exhibit complex mechanical behavior. Deformation of surrounding tissues affects superficial venous circulation, but the deformation behavior of these tissues has not been determined in relation to skin surface shear. This study investigated the effect of shear on the deformation of soft tissues surrounding superficial veins. Motion analysis of five subjects in their 20s was conducted to quantify the deformation of forearm soft tissues with a cephalic vein of about 3 mm in luminal height by ultrasound video imaging with application of shear to the skin surface. Selected points near the skin surface and the top and bottom of the vein were traced on video images. When the top of the vein was at a depth of 2 mm (four subjects; body mass index (BMI) 17–22), the point near the top of the vein moved by almost the same amount as the point near the skin surface, whereas the point near the bottom of the vein moved by only a small amount (three subjects) or by the same amount as the top of the vein (one subject). In one case where the top of the vein was at a depth of 4 mm (one subject, BMI 26; grade 1 overweight according to the World Health Organization classification), the points near the top and bottom of the vein in the thick subcutaneous tissue moved by half the displacement of the skin surface. Finite element analyses were conducted for typical cases of subcutaneous tissue thickness above the vein. The results reproduced the experimental deformation behaviors, with the exception of substantial sliding below the vein. They indicated that BMI category, venous depth, and the sliding mechanism in subcutaneous tissue determine the motion of the vein and surrounding soft tissues under shear.

Keywords

• forearm
• soft tissue
• cephalic vein
• shear
• deformation
• ultrasound image
• finite element method