Bone Age Delay and Outgrown Seat

lanwenyi

New member
What do I do now?

DS is 5.5yo, but his last bone age scan showed 2y8m. He will not get another bone age scan until July. He has stayed RFing bc of the bone age delay.

Here is the dilemma:
DS has hit 40lbs (scale says 40.5 lbs with clothes and shoes). In one car, he has a rfing radian, so he's fine. In the other, he's in a Nextfit b/c the Radian kept tipping to the middle at an over 45* angle. It was bad. The foot did not stay on the seat.

We can't use LATCH b/c it's a Subaru and, even if the car didn't prohibit it, we can't get the Radian to stay tight using the LATCH strap. (It starts out tight, but is loose by the time we reach our destination EVEN without a kid in the seat). I've tried a locking clip and couldn't get the seat tight enough either.

So, what now?

Do I turn him even though his bones are under 3?
(they might be 3 by now, but even though a year passed between his last 2 bone age scans, his bones only aged 3 months) Our original goal was to not turn him until his bones were 4.

Do I buy yet another seat?

If I turn him, should I keep him harnessed or put him in a booster given his age?
His emotional and motor development are not delayed. He is displaying booster readiness at least for shorter trips, but we'd have to buy one. We have 3 potential FFing seats (Radian, Nextfit, and TrueFit)

If I should buy another seat, which seat do you rec and why?

DS is 41ish" tall (he was 41.25" tall at his endocrinology appt 2 mths ago) and 40 lbs.
 
ADS

ketchupqueen

CPST and ketchup snob
Staff member
I would most certainly not do a booster.

While I'd be more comfortable rear facing (Safety 1st 50rf seat?) his bones are over two, he's tall and turning forward facing is reasonable at this point.

If you choose to ff, this is a case where I would want to be looking at the likes of the frontier because I'd want him harnessed until bone age hits five.
 

lanwenyi

New member
Safety First has a 50lb rfing seat???? What rock have I been under?
Where can I find it?

We thought our only choice was the Clek foonf and I wasn't sure if the additional RFing time would be worth the cost, esp if it is outgrown at 42-43"

Both DH and I would rather keep him rfing. We did not turn our DD ffing until 4.5, but she went straight to a booster for booster training in one car (and full-time while her arm was broken), but stayed RFing over 90% of the time until 5yo.

We've lost both his seat in our Subaru and Grandma's carseat/our travel seat b/c he's over 40lbs now.
 

lanwenyi

New member
I know the 50lb one is new, but does anyone have experience installing the LX or SE? I assume the install would be same or similar. Any install issues I should watch for? Any fit to kid issues?

It looks like we'll pick up one of these and try our second Radian in Grandma's cars (gma and gpa have a 2007 Toyota minivan and a 2014 Prius). If the Radian doesn't work in Gma's car, then we'll either pick up a second one of these or have to turn him FFing in his Sureride (or Radian/TFP/Nextfit, but we like the Sureride for them b/c it's lightweight if they have to remove it themselves).

We've been making him ride in only the car with the Radian (whoever had him drove the car with the Radian). We'll keep doing that until we can get our hands on one of these.
 

lanwenyi

New member
If you choose to ff, this is a case where I would want to be looking at the likes of the frontier because I'd want him harnessed until bone age hits five.

What is the benefit to a ffing harness over a booster until his bone age is 5?

I thought booster vs FFing harness had more to do with maturity and ability to stay in position than anything else. If there is more to it than that, I'd really like to know more about it. Where can I find more info?
 

Aurezalia

New member
What is the benefit to a ffing harness over a booster until his bone age is 5? I thought booster vs FFing harness had more to do with maturity and ability to stay in position than anything else. If there is more to it than that, I'd really like to know more about it. Where can I find more info?

It's largely about hip bone development. Kids younger than that (or with a younger bone age) haven't developed their hips as much as older kids, and they're missing the the beginning of the "crest" on their hips that helps hold the lap belt down and prevent them from submarining under the belt. That has to do with weight also, but bone development is also part of it.
 

ketchupqueen

CPST and ketchup snob
Staff member
It also has to do with bone density/fragility. Until around five ish bones aren't as... tough, for lack of a better word, and the additional spread points in a five vs three point harness may be helpful for force distribution. There is also the fact that the three point anchorage system of belt plus tether allows the seat to channel more forces away from the child; for a child whose bones aren't as strong or developed as his peers this obviously has special benefit.

At some point most kids' bodies are strong enough to take those extra forces with the help of a booster to position the belt (and channel away some of the forces from their less-developed hips.) Since we aren't sure EXACTLY when that happens, and evaluation seems to place the risk going down for kids over five, five is a good safe age (or in this case, bone age.)
 

lanwenyi

New member
Ok. That makes sense. Although, it just makes me more determined to keep him rearfacing as long as possible. If his hips can't handle the load, neither can his neck. If we restrain everything except his head, that is a lot of force on his neck (I'm a science teacher by trade and understand physics). The spaces between the bones in the neck can stretch A LOT more than the spinal cord can take, especially in younger children where they are designed to stretch and move more than an adult's neck bones are.
 

ketchupqueen

CPST and ketchup snob
Staff member
Rear facing is always safer, for everyone. Just like with harnessing, you do run into diminishing returns at some point.

Even though he has delayed bone age, he is proportioned like an older child, right? That's a real benefit as a two year old has a proportionally much larger head. So he has an advantage over an actual two year old.
 

lanwenyi

New member
Yes, he has the body type of 5yo. Because of his size, he is often mistaken for a 2-3yo, but he doesn't look like one to anyone who works with children. He's always had a big head though :)

He is finally growing. During the last nine months, he has climbed from the 0.01%ile to the 4th%ile, so treatment is working. His bone age might be catching up too, but we won't know until July during his annual full work-up by endocrinology. All his other appts are just tracking progress.
 

lanwenyi

New member
My point earlier was simply that my knowledge of physics has me generally agreeing with the Swedish method of going from RFing to booster. That gives the neck more "ride down" time, for lack of a better term, when forward facing, reducing the force on the neck and stretching of the spaces between the bones of the neck. In order to do that though, the child can't be turned FFing until old enough and mature enough to ride safely in a booster.

However, if I have to choose between protecting his neck and massive internal injuries from submarining due to an underdeveloped pelvis, that is no choice. My only choice is to buy another carseat and keep him RFing as long as possible, hopefully until his bone age is 5. (Our original plan was bone age of 4, but you convinced me to do 5).
 

nannykates

New member
My point earlier was simply that my knowledge of physics has me generally agreeing with the Swedish method of going from RFing to booster. That gives the neck more "ride down" time, for lack of a better term, when forward facing, reducing the force on the neck and stretching of the spaces between the bones of the neck. In order to do that though, the child can't be turned FFing until old enough and mature enough to ride safely in a booster.

However, if I have to choose between protecting his neck and massive internal injuries from submarining due to an underdeveloped pelvis, that is no choice. My only choice is to buy another carseat and keep him RFing as long as possible, hopefully until his bone age is 5. (Our original plan was bone age of 4, but you convinced me to do 5).

Pardon my physics discussion here but doesn't that ride down time come with a cost of head excursion as well, increasing the likelihood of head injury? I think this is truly where we get two camps on the ff vs. Booster discussion, it's neck loads vs head excursion.
 

lanwenyi

New member
Pardon my physics discussion here but doesn't that ride down time come with a cost of head excursion as well, increasing the likelihood of head injury? I think this is truly where we get two camps on the ff vs. Booster discussion, it's neck loads vs head excursion.

Yes. That's why you have to pay attention to head excursion numbers and why it's important that the seat be used properly. If the child isn't sitting back, it increases the likelihood that the child's head will fly far enough forward to impact the seat in front. That's why a booster is only a good idea IF the child can sit correctly 100% of the time.

Personally, I also pay attention to where I put the passenger seat in front of the booster, but I suspect that is more of an abundance of caution.

I understand the 2 sides. I just happen to be on the booster side of it. I believe that the likelihood of a severe head injury that a harness would have prevented that would not have resulted in death due to internal decapitation is so highly unlikely as to not merit consideration. That is my personal belief based on my knowledge of physics. Others disagree with me and that is their right. Without definitive studies, we are all making our best guess based on the information avail at this time and our own personal backgrounds and biases. I can accept differences of opinions.

Right now though, I had to make a decision for my DS who has a bone age delay. Age and maturity says a booster is fine, but bone age says its not. FFing is not. DH went out to BRU this afternoon and picked up an Advance Air EX 50 and we have installed it in the car. It went in beautifully. Now we're just waiting for DS to wake up from his nap so we can try him in the carseat.

Our 2nd Radian went in Gma and Gpa's Prius beautifully (except for the RF tether, so no rf tether for him). We won't be able to try their van until the next time we go down to their house, but we're hopeful.

We hate traveling with the Radian, so we might take the AAEX50 with us to Vancouver and Alaska this summer. We'll see.
 

3acorns4Christy

New member
My daughter is 6 and delayed bones of age 3. She's much smaller then your son at least by signature..She's 34lbs and 38". I am absolutely comfortable with her being in a forward facing car seat.
I'm not quite okay with a booster seat for her yet, but have considered it.

My signature is old.
 

MommaMia

New member
What do I do now? DS is 5.5yo, but his last bone age scan showed 2y8m.

We have a similar medical situation - are you part of the FB group specific to what he's going through? Feel free to send me a PM for more info.

We kept DD RFing until bone age >3. She's also 5.5 now and I'm waiting until her next Endo to get her current bone age before I entertain discussions about a booster for carpooling situations. I *think* she's caught up, but I want confirmation...
 

safeinthecar

Moderator - CPS Technician
Y I believe that the likelihood of a severe head injury that a harness would have prevented that would not have resulted in death due to internal decapitation is so highly unlikely as to not merit consideration.

For frontal head contact, you may be right, but harnessing prevents being out of position laterally and head contact to the windows and door pillars as well.
 

lanwenyi

New member
My daughter is 6 and delayed bones of age 3. She's much smaller then your son at least by signature..She's 34lbs and 38". I am absolutely comfortable with her being in a forward facing car seat.
I'm not quite okay with a booster seat for her yet, but have considered it.

My signature is old.

Yes, your daughter is smaller than my son is. I'm not sure where she is percentile wise bc the percentiles for boys and girls will be at different heights, but DS (thanks to medical intervention) has climbed from the 0.01% to the 3%ile. He is growing. However, he had his bone age scan early b/c the endo wanted the results before his appt in July. His bone age is now 2y 10m. He only gained 2 mths of bone age in 1 year, despite gaining 3.5" in height.

We're still uncomfortable having him FFing. Our goal has always been 4. I know many people are comfortable FFing before that, but we aren't. It's becoming more difficult though and we may end up needing to turn him b/c he will outgrow any available seat.

We have a similar medical situation - are you part of the FB group specific to what he's going through? Feel free to send me a PM for more info.

We kept DD RFing until bone age >3. She's also 5.5 now and I'm waiting until her next Endo to get her current bone age before I entertain discussions about a booster for carpooling situations. I *think* she's caught up, but I want confirmation...

Thank you for the sweet offer. Most of the groups I've found are specifically for growth hormone insufficiency. DS does not have that diagnosis. Although he's had some abnormal tests, he does not meet the criteria for diagnosis.

I'm also not on Facebook (as a teacher there are problems with students always wanting to "friend" you). My husband is (albeit using a pseudonym). If the group is more general for growth delays/disorders and he's interested, then I'll pass the info on.

For frontal head contact, you may be right, but harnessing prevents being out of position laterally and head contact to the windows and door pillars as well.

This is a old discussion (from the beginning of April). However, I will absolutely agree with you that harnessing prevents being out of position laterally, which is why I do not advocate boostering 3-4year olds. My previous comment was in reference to kids old enough and mature enough to be in a booster. My preference, in those cases, is a booster. I know others prefer a harness. That is their (and yours, if it is your position) prerogative. I can accept differences of opinion when we do not have definitive studies one way or the other.

My background lends me to generally agree with the Swedish method of keeping kids rfing until mature enough to booster. Some kids, due to late maturity or special needs, that will not work for (it didn't for my niece whom we had to harness until 8 because she simply would NOT sit still in a booster), but it is my preferred method where possible. It is what I did for my DD. It is what I am trying to do for my DS. DS is emotionally mature enough now, but his bones are not physically strong enough, so he stays RFing.
 

3acorns4Christy

New member
My daughter is roughly -10%tile now, but she does have primordial dwarfism.
She doesn't qualify for gh as she has some other metabolic complications that her team isn't comfortable with giving gh.

I tried to be onboard with the Swedish way, but my oldest is on the spectrum and was harnessed until he was 8. My middle is my teeny one, rear facing did start hurting her hips so at 4, her bones had just hit 2, we switched to ff..She will be harnessed for a little longer. So it just doesn't work for us.
 

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