The answer is yes and no. 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 Dr. Eric Edmonds 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.
Some of these problems may include:
- Bipartite patella. This happens when the spots of cartilage that start turning into bone don't fuse into one whole bone. The two separate pieces of bone may have no symptoms at all or may cause a child to experience pain.
- Osgood-Schlatter disease. This tendon injury may affect the bone and cause a painful lump below the kneecap. This occurs most commonly in young athletes.
- Tendon or ligament injury. The tendons or ligaments, such as the ACL and MCL, adjoining the kneecap may become strained or torn. This can place additional strain on the kneecap.
- Torn meniscus. The meniscus is a piece of cartilage in the knee joint that if torn can cause pain and movement issues.
The patella is a small, semi-round bone that sits within the quadriceps tendon. It crosses over the knee joint.
The kneecap protects the tendon and ligament structures of the knee joint. It also enhances the movement of the knee. The knee joint is necessary for most types of activity.
The kneecap is surrounded by ligaments, tendons, and pieces of cartilage that help cushion the movement of the joint.
Your knee joint is one of the primary weight-bearing joints in your body. According to Harvard Health, each pound of body weight translates to four pounds of pressure on the knees.
There are some ways you can help improve your knee health and protect yourself from injury. These include:
- Strengthening your muscles. Exercises to strengthen your hamstrings, quadriceps, hips, and core will all help keep your knee joint stable and strong.
- Non-weight-bearing exercise. Exercises such as biking, swimming, and using an elliptical that don't place weight on the knee joint or involve high impact may be beneficial in protecting your knee from extra wear and tear.
- Range-of-motion (ROM) exercises. ROM exercises may help improve knee mobility.
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.