Biomechanical analysis of the meniscus and cartilage of the knee during a typical Tai Chi movement-brush-knee and twist-step

This study aimed to analyze the biomechanical response of the knee cartilage and meniscus to a typical Tai Chi (TC) movement, brush-knee and twist-step (BKTS). Kinematic and kinetic data was recorded while an experienced TC practitioner performed normal walking, jogging and BKTS. The kinetic data were then imported into a validated finite element model of the knee joint to examine the biomechanical response of the articular cartilage and meniscus. Compared with walking and jogging, the BKTS movement showed a greater increase in the range of motion (ROM) of the knee. The ROM in the sagittal plane was 56 degrees (walking), 38 degrees (jogging) and 93 degrees (BKTS). In coronal plane, the knee ROM was 8 degrees (walking), 11 degrees (jogging) and 28 degrees (BKTS). And in horizontal plane the ROM was 17 degrees (walking), 15 degrees (jogging) and 29 degrees (BKTS). The finite element simulation demonstrated that the pressure contact stress is much more concentrated during walking and jogging than BKTS, which is consistent with the lower peak contact stresses recorded on the cartilage and meniscus. In conclusion, the TC movement produced a gentler stress state on the meniscus and cartilage, while also requiring a greater knee ROM. Practicing TC may have a lower risk of knee joint injury compared to walking and jogging.