My partner and I were just talking about missed signs and then I come on here and see this discussion. How timely! In hindsight, we definitely had missed signs:
Very obvious leg crease differences (I had no idea this meant anything though)
Preference to sleep with head to only one side
Breastfeeding better on one side
Hated tummy time and would scream her little head off if put on her tummy
Popping sound which chiro said was from her back and just meant that she was likely to be more flexible in her joints. Chiro also had to keep working regularly on a rotation through her lower back
Commando crawled a little late and would favor one leg and kind of drag the other.
Crawled properly a little late
Would tend to stand on toes of one foot and flat foot with the other.
Cruised furniture happily but hesitant to walk forward when held by the hands until just before her surgery.

There were a few other signs but I can't remember them at the moment. The problem was that I didn't know that any of these things were a sign of a problem. Educating parents in greater detail would be a big step forward in minimising the chances of late diagnosis.

Dusty - We have the Safe n Sound Maxi Rider (the one with the Active Headrest) which we picked up second hand and Britax then sent us an extension strap for the crotch strap. It was perfect for the cast but wouldn't be any good for your little one as it is forward facing only. DD was in her capsule right up until she went in for surgery at 13 months but she wasn't in any kind of harness or brace so she still fitted perfectly. I wanted to keep her rearward facing as long as possible so I was disappointed to have to turn her around.

Hmm, where shall I start with answering how things are with the cast. I will give you the short version which is that after a very anxious week where DD developed a cold and her skin continued to deteriorate under the cast, we were faced with a hard choice. Either let her have a general anesthetic whilst she had a cold or risk leaving the cast for a further two weeks passed the six week cast change date knowing that her skin was in a bad way in a number of places that we couldn't reach (and possibly worse where we couldn't see). Luckily we have a wonderful anestheiologist who recommended that we have Amahli admitted as planned on Wednesday at Cabrini, and she could be assessed on the day to determine which issue was more of a priority. We then discovered that my partner had bronchitis so we headed to the doctor on Tuesday to check that DD and I only had colds and hadn't picked up bronchitis from him. Bronchitis would have meant a definite cancellation of the cast change.

The anesthetist assessed DD on Wednesday and was quite confident that we would be okay to go ahead, even though it wasn't by any means an ideal situation with her cold. Thankfully we did because her skin really was deteriorating under the cast, so much so that they didn't put a new cast on!!! I knew it was a possibility that they might leave the cast off if the problem was extreme and then bring us back for a new cast when her skin had healed, so my heart just dropped when the anesthetist came out and said that they hadn't put a new cast on. However it wasn't all bad news as the surgeon had decided to put DD into a rhino cruiser brace for the next six weeks instead. He said that whilst it wasn't ideal, it would allow her skin to heal and he could see that there was some nice shape forming on the acetabulam. Her skin certainly had broken down a bit but it wasn't anything too serious and will heal fairly quickly hopefully.We will have an X-ray in two weeks to determine whether DD needs to go back into a cast or can continue in the brace. Not at all how we expected the day to pan out. We didn't even have her proper size nappies with us as we had only taken the ones that fitted inside the cast...lol...

DD was fitted for the brace about three hours after she came out of recovery and we were allowed to come home the same day. Originally we were told that she would definitely have to stay overnight for monitoring due to her cold but apparently everything went so well that they were happy for her to go home the same day.

We have been told to treat the brace as if it is a cast which means it is not to be removed at all and barely even loosened. It makes nappy changes almost impossible and we can't put clothes under the brace, but it is a small price to pay for the extra freedom that DD now has and the huge smile on her face when she kicks the bottom part of her legs around. And she is so much more squishy now that I just want to keep hugging her all the time...lol...

PakRakMG - Very interesting about your DH. My sister had Spina Bifida and we have since learned that spina bifida children can tend to have a form of hip dysplasia directly associated with the spina bifida itself. Makes me wonder if there is a link there for my DD?

Madcat - I love the description that you gave of your little girl and I think that is a great way to look at things. I think anyone with a late diagnosis feels bitter at times... I know that I sure have. But stories like yours help others earlier in their journey to have hope and I know that reading about your little girl has helped me immensely. :-)

Yep, another novel from me...I just can't help myself! I'm even worse when you talk to me in person...ROFL!!!