Humans don't grow kneecap bones (Patella) until around 2 to 5 years old, they start out as just cartilage, and then start to form bone from within after the age of 2.
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Humans don't grow kneecap bones (Patella) until around 2 to 5 years old, they start out as just cartilage, and then start to form bone from within after the age of 2.