Pictures of spine development: the reason a baby should not face forward (edited)

[shilo]

hmm, well, that's a great question. not sure i can do it justice, but i'll tell you what i remember from skeletal development from grad school. hopefully someone with more knowledge/expertise will chime in.

our bones lay down increased densities according to a principle called Wolf's Law (http://en.wikipedia.org/wiki/Wolf's_law). basically, we lay down new/additional bone _over time_ wherever there are sufficient forces put thru an area of bone to encourage an increased density to support those forces.

so i think it holds true that part of what stimulates a growing childs body to put down bone in the place of this initial cartilage are the increased forces going thru those areas. these increased forces come from external things like gravity pulling on an ever increasing body weight as we progress thru development into more upright postures (sitting and then standing) and also from internal forces (muscles and tendons pulling directly on certain areas of bones).

so in the case of the growing childs spine, the density of the bone (and therefore the forces it could withstand) would be a combination of the age of the child (level of expected ossification as well as _time_ for that ossification to take place) along with the stage of development of that particular bones density based on the external and internal forces it had been exposed to. essentially, the only thing that really buys them safety is time... time for the bone to ossify and time for wolf's law to accomplish the laying down of additional density relative to the forces the body experiences.

does that make sense?? hope it answered it at least in part. let me know if i need to clarify.

lori
Sam 5/19/05 How lucky I am that you chose me.

[niccig]

Tam,
I only have pictures for 1 and 6 yr old. I can tell you that the parts of the vertebrae keep fusing into early adulthood. The sacrum is made up of 5 sacral vertebrae and they all fuse together sometime from teenager to about 20 or so. It's an ongoing process.

Lori - great answer. I just answered a question on my final about Wolf's Law, and I wish I was as succinct as you were.

Nicci

[shilo]

>Tam,
>I only have pictures for 1 and 6 yr old. I can tell you that
>the parts of the vertebrae keep fusing into early adulthood.
>The sacrum is made up of 5 sacral vertebrae and they all fuse
>together sometime from teenager to about 20 or so. It's an
>ongoing process.
>
>Lori - great answer. I just answered a question on my final
>about Wolf's Law, and I wish I was as succinct as you were.


heh, thanks, gotta dust out the cobwebs sometimes to remember thru the mommy brain fog, but it's all good :). great thread btw.

re: "it's an ongoing process" i'll just add a 'someone might find it interesting' side note from my clinical practice. it's not only an ongoing thing as we grow up, but also as we age. like the wikipedia article above points out, wolf's law works in reverse as well. when we don't put forces thru our bones, they lose density over time. one of the best things we as women can do to prevent or slow bone loss (osteopenia/osteoporosis) is weight bearing/resistance exercise - keeps wolf's law working in our favor and keeps our bones strong longer :).

[hipmaman]

Thanks ladies!!!

[ShanaMama]

WOW! Thanks for that info. You just eliminated the rf/ff choice for me! DD is just 1 yo & about 20 lbs. We were so excited for that ff milestone, I was looking to skip convertibles and go straight to a ff only seat.
The posts on these message boards were slowly convincing me that rf is best, and I am now completely sold.
Definitely passing this info on to my friends! ;)
Tx!
ShanaMama

[kellyotn]

>We were so
>excited for that ff milestone, I was looking to skip
>convertibles and go straight to a ff only seat.
>The posts on these message boards were slowly convincing me
>that rf is best, and I am now completely sold.
>Definitely passing this info on to my friends! ;)
>Tx!
>ShanaMama

I'm excited to be nearing the "2 year birthday and still rear facing" milestone. ;)

My son is 23 months. I did have him front facing for a week when I was driving a 2 door car briefly last month. Honestly, he kept fighting to get his legs stretched out to rest on the front seat. It was like he was trying to figure out what to do with his legs, "They can't just hang here, can they?" He went back RF when I got my sedan back. He promptly crossed his legs and fell asleep on his first ride back RF.

[niccig]

I posted the photos because eventhough you read the safety information about RF/FF and babies' spines, it's nice to see a photo that shows what's going on. I'm glad you found it useful. I had already decided to keep DS RF, but when I saw these comparisons, and comparisons of other bones, I was even more sure he will stay RF as long as possible.

A question I have now though, is do I pass this information on to RL friends. I've spoken with several about extended RF, and they all keep their children FF (same age as DS). Do I now email these photos, or is that overstepping things as they've never asked for more information. I don't want to be the annoying friend that shoves information down their throats, and imply that their not being as careful as they can. What to do?!

Nicci

[Scatterbunny]

Nicci, I think if you present it a certain way ("I just learned this in my anthropology class and was blown away! I thought I'd share it with you.") it should be fine. They say a picture is worth a thousand words, which is why the crash test video comparisons of a rear-facing and forward-facing seat are so nice, but that isn't enough for some people. They think because they have a "strong" baby that FF is fine, or because the doctor said so, FF is fine. But possibly seeing that a human child's bones are not fully developed until age 3-6 might make a difference.

[kimbe]

Thank you for the information!

[niccig]

Scatterbunny, you made a good suggestion. All my friends know I was up to my ears in bones, I could send an interesting facts about your child's bones. I just don't know how to word the "they should be RF" part, I don't think they'll make the link unless I state it.

Maybe I could have some other photos that I have (skull, femur etc) and then say "and here are pictures of vertebrae, the left is a 1 yr old and the right is a 6 yr old. See how they're in 3 parts, this is why babies can't forward face in the car as the vertebrae in the neck aren't strong enough. They'll fuse into a complete vertebrae by 3-6 years, as you can see in the 6-yr old photo" and leave it at that, they could then draw their own conclusions about FF/RF. They all know I keep DS RF for safety reasons. I want to share the information, but I don't want to lecture them either.

What do people think?

Nicci