Ryan Chown, via facebook asked:
Can we strengthen our skulls? and how can we strengthen our spines?
We put this to Professor Tim Skerry...
Tim - Well this is a really interesting question and itís a question that weíre actively involved in researching at the moment because in fact, you don't need to strengthen your skull. Itís much stronger than it needs to be for the amount you use it during the day and the whole concept of this is an interesting one because if you think about the safety factors of different bones, your long bones have a safety factor of about 4. That means if you bend them four times as much as they bend normally, you may break them. With your skull, itís about 40 and what that really translates into is that if you exercise and do things with your long bones, you bend them by about 0.2% With your skull, no matter what you do, you bend them no more than about 0.02% a 10th as much and we know this because we put strain gauges onto the skull and long bones of one of my PhD students a few years ago, so we know this is absolutely right.
What it tells us is that the cells in the skull are either much more sensitive to load than cells in long bones or much less sensitive to the lack of load, and either of those would be a great thing to be able to understand. So weíre comparing cells from different sites to try and understand the mechanisms behind that so that we might be able to find a drug treatment for helping people with osteoporosis.
Chris - To what extent does this reflect the embryology though because long bones form in a different way, a cartilage model gets replaced by bones, compared with skull which is formed by sheets of bone growing into tissue as the skull forms in development? So, is that a clue?
Tim - You're quite right. That's a really important question. Itís certainly the first thing we thought of. That the axial skeleton, the skull, the spine, and ribs and bits of the pelvis, and the clavicles are formed from the same sort of thing. In fact, it doesnít really fit with that. Itís not just embryological origin. Certainly, when you get those bones and you take the cells from them, they look very similar in adult humans and animals. And really, that doesnít seem to be the difference. There's something fundamental about the way the cells are embedded in the material and the way that they do the mechanical sensing that seems to be different, and that does seem to be a key for the skull, not just any old part of the axial skeleton, because the vertebrae are commonly affected by osteoporosis.
Chris - But you havenít flushed out exactly what yet?
Tim - Like all science, every question you answer raises another five that you need to do things with and weíre in that position.