In contrast, square dancing is generally more rhythmic, relatively large range of action, which means that the movement is a little more strenuous than playing tai chi, so it is more injurious to the knees.
While playing tai chi is generally slower, there is a certain buffer, feel uncomfortable when you can self-adjustment, the movement requirements are not so strict, the horse stance servant step and other movements can be done more freely, relatively speaking, as long as a bit of attention, the possibility of injury to the knee will be a little smaller.