Babies are born with pieces of cartilage that will eventually become the bony kneecap, or patella, that adults have.

Like bone, cartilage gives structure where it’s needed in the body, such as the nose, ears, and joints. But cartilage is softer and more flexible than bone.

Babies with bony kneecaps at birth could make the birthing process more difficult or result in birth injuries. Bone is very rigid. Less flexible than cartilage, it’s more likely to break if the wrong kind of pressure is applied.

A kneecap made of cartilage more easily handles the transitions a child makes when learning to crawl and walk.

Babies have far more cartilage in their skeletons than adults do. According to doctors of Rady Children’s Hospital, most children’s kneecaps begin to ossify — turn from cartilage into bone — between the ages of 2 and 6. This is a slow process that takes many years.

Often, several pieces of cartilage will begin to harden into bone at the same time, eventually fusing until the kneecap is one complete bone.

This process continues through the years of childhood. Typically, by age 10 or 12, the kneecap is fully developed into a bone. A small portion of the original cap remains as cartilage, while another small portion is fatty tissue called a fat pad.

Children may be at high risk for complications or injury during kneecap development, because of the complex nature of the knee joint and the large amount of stress placed on it.

Babies are born with a piece of cartilage in their knee joint which forms during the embryonic stage  of fetal development. So yes, babies do have kneecaps made of cartilage. These cartilaginous kneecaps will eventually harden into the bony kneecaps that we have as adults.