Analysis of knee-bending motion through three-dimensional scanning for advanced brace design

Knee braces have been increasing in popularity as a means to support joint stability and promote the healing process. In order to enhance the fit, comfort, and design of knee braces, this study investigates knee shape deformations across four knee-bending angles from 0° to 90°. Using three-dimensional (3D) scanning technology, the knee contours of 50 Asian males aged between 22 and 33 were examined. The reliability of the 3D measurements was validated through comparisons with tape measurements on the actual body. The analysis revealed a stretch of the skin covering the patella bone with a notable vertical strain of 19% and horizontal stretching of 7%. The circumference along the muscle belly at the thigh (15 cm above the center of the patella) and at the calf (7.5 cm below the center of the patella) showed no significant changes with different bending angles, and can be used as an indicator for sizing of knee braces. However, at the patella bone level, the bending of the knee from 0° to 90° increased the knee circumference by 6.4%. The results from sectional analysis showed the asymmetry and the lateral shifting of the knee joint during bending. The findings offer guidelines for the design and optimization of knee braces to address knee deformations and individual body shape variations.