Phase 1: There is neither no feeling nor pain in daily life, but when going up and down stairs, the
pressure in the joint cavity increases. There is a slight hyperplasia of bone spurs, which leads to
soreness feeling, but it can be improved as long as you change your lifestyle habits.

Phase 2: When going up and down stairs, squatting or carrying heavy objects, there are soreness
feeling on the knees. The joints have been slightly degraded, the proliferation of bone spurs has
become more obvious. The cartilage worn out which causes the space in the joint cavity to become narrow.
Phase 3: When going up and down stairs, squatting or carrying heavier things, not only have
soreness feeling on the knees, but start to have difficulty in climbing upstairs, especially using squat toilet, and unable to walk far even on the flat ground, pain is severe. The joint has moderately
degenerated, and the space in the joint cavity is less than 1/2 of the original size.

Phase 4: Unable to move normally at all, the cartilage has been totally worn out. There is almost no space in the joint cavity, and it is severely degraded.