The outer legs of the kitten may be deficient in calcium. You should adjust the cat's diet, feed the cat some goat milk powder to supplement nutrition, and take the cat to the sun more to promote the digestion and absorption of calcium. Parasites or injuries in the cat's body can also lead to external symptoms. Owners should pay more attention to the cat's physical condition, bathe and deworm the cat regularly, and treat any wounds on the body immediately.