Why Are Babies Born Without Kneecaps?

Parenting a newborn can be quite a ride where you may have a different experience every day. It is common to have all sorts of questions about the baby’s body, behaviours, eating and sleeping patterns. If the question “Do newborns have kneecaps?” has entered your mind, you are not alone.  

This question makes sense when you think about it. Babies’ legs are soft and bendy and so are their knees. As babies grow older, their knees eventually get firmer and stronger. But this raises the question of whether newborns have kneecaps.     In this article, we will share answers to this question and an explanation that helps you understand your baby’s growth better. Stay tuned to the end of the blog to find answers to more questions that you may have about your infant’s kneecaps. 

Do Newborns Have Kneecaps at Birth? 

The answer to this question is not black and white, because it’s both a yes as well as a no. Babies are not born with bones in their kneecaps, but they do have pieces of cartilage that will eventually become the bony kneecap. At this age, their knees are called “Cartilage patellae”, which literally translates to cartilage kneecaps. 

The cartilage gives the body shape and structure wherever it is needed, quite like the bone. They are present in our nose, ears and joints. However, cartilage is much softer and more flexible than bones.  

Why Are Babies Born Without Kneecaps? 

Bones are rigid. If babies had bony kneecaps, it could make the birthing process harder for the mother as well as the baby. With bony kneecaps in newborns, it could result in injuries to the mother during childbirth. Or the baby could have a bone fracture if pressure is applied at the wrong place. Moreover, with softer and more flexible cartilage, babies can easily handle the development of different stages from crawling to walking. 

Cartilage is a flexible, soft substance that prevents friction in the joints. Having cartilage kneecaps is age-appropriate for newborns as it supports the activities that babies do from infancy and beyond while minimising the risk of injuries. Due to this soft cartilage, babies can learn to crawl and walk without risking fractures in their knees. 

Though it may seem like a newborn’s knees are much softer and more delicate than an older child’s kneecaps, Mother Nature has made sure that there is nothing to worry about. Babies' kneecaps are designed to be prone to injuries. 

At What Age Does The Cartilage Develop Into A Bone? 

Not just in the kneecaps, babies have far more cartilage in their bodies compared to adults. Most children’s kneecaps start to ossify or harden at the age of 2 and may take up to 4+ years to completely develop. It is a slow process that takes years, starting from the centre of the kneecaps to the edges. In addition to their kneecaps, many other cartilage pieces will start to harden at the same time in the children’s bodies.  

 Typically, by the age of 10 or 12, the kneecap would have fully developed into a bone, except for a small portion of cartilage that remains as it is. Another small portion of the original cap becomes a fatty tissue called a fat pad. By the time a child reaches their teenage years, the kneecap will have fully ossified and become the bony patella that adults have.  

Potential Issues With Kneecap Development 

It is normal for parents to worry about their baby’s soft knees and the possibility of injuries. However, the baby’s kneecaps are made of pliable and soft cartilage for a reason. They are meant to protect the kids from injuries when they start to crawl and walk.   

That being said, there is a possibility that a growing kid may encounter a condition called “Bipartite Patella”. Ideally, the pieces of soft cartilage should fuse to form a strong, bony adult kneecap like in adults. But a bipartite patella is when these pieces do not fuse properly and result in a split or double kneecap. The good part is that this condition can go away on its own or with the help of physiotherapy. The warning signs to look out for include pain and swelling in your child's knee area.   

Besides Bipartite Patella, there are a few other possible complications with infant kneecaps. Here’s a list of a couple of things that can possibly go wrong.   

1. Osgood-Schlatter disease 

This tendon trauma can impact the bone and lead to a painful lump underneath the kneecap. This condition is more likely to occur in young athletes.  

2. Tendon or ligament sprain 

The tendons or ligaments like the ACL and MCL adjoining the kneecap can get strained or ripped. This may put extra pressure on the kneecap.  

3. Torn meniscus 

The meniscus is a piece of cartilage in the knee joint that if ruptured can lead to pain and movement complications.  

In conclusion, while newborns may not have fully developed bony kneecaps at birth, their cartilage kneecaps serve a crucial purpose in their early development. This flexible structure ensures a smoother birthing process, supports their crawling and walking milestones, and minimises the risk of fractures. Over time, the cartilage gradually ossifies, transforming into the hard patella seen in adults. Though potential complications like Bipartite Patella exist, they are relatively rare and often manageable. Understanding this natural process can help parents feel more confident about their baby’s growth and development. The knowledge also ensures that they provide the right care and attention at each stage of their baby’s development and growth.