And is it twenty years down the road or two years down the road?

Dr. Chang: Well it’s really in the first few that they come back that they have any increased incidences of back problems and also it’s while they’re up in space.

It’s great that you’re checking out astronauts and space but what’s that mean for everybody else?

Dr. Chang: That’s a great point, but space presents an extreme laboratory to stress the spine and orthopedic conditions to a way that is not possible here on earth. It gives us a different angle on learning how the body responds and teaches us things that we can’t otherwise learn down here on earth, particularly this idea of cyclic loading as being important not just for our bones but for our soft tissues.

Is there anything that’s universal with all these astronauts that you’re looking at?

Dr. Chang: One really interesting thing is that people are growing, or lengthening, an average of five centimeters, almost two inches when, they’re up in space. That was something that was really kind of eye opening for me.

Do they stay lengthened when they come back down?

Dr. Chang: No they don’t. Part of it is because there’s a natural curvature in the spine that most people aren’t aware of. And the curvature tends to straighten out in space and so some of the height increases just from a loss of the normal curvature and alignment of the spine. Another part of it is the swelling that seems to occur without that daily loading to compress things back down.

So you’re saying without gravity pulling you down, you would think that it would help the spine.

Dr. Chang: Yes, it seems that for a prolonged period of time it’s actually over stretching them in space. Maybe here on earth a little bit of stretch but not too much is the way to go.

What else have you learned from these astronauts?

Dr. Chang:  I’m just fascinated with space. Just to be part of the program and learning all about it. The missions and the personalities and the technology and the engineering, it just blows me away every time I talk to the people involved in the program and learn new tidbits of this and that. It’s just amazing.
One thing that just comes to mind is that it takes them actually three days to get up to the space station between when they launch and when the craft actually goes around the earth enough times to line up perfectly with the space station so they can dock. During that time, the space is so cramped. They have three crew members per mission. They are basically shoulder to shoulder and knee to knee in a tight space for three days while they’re going in orbit around earth to dock up with the space station. It’s so cramped that the commander has to do the steering with these eighteen inch wooden sticks to reach the buttons and dials and stuff in order to control the craft.

So even though we think of them as the toughest men and women, something as simple as back pain is hurting them.

Dr. Chang: Yes, I mean in my field we have a saying you’re only as old as your spine and it’s just amazing how much a small problem can bring your life to a standstill.

How do these patients that are astronauts explain their pain?

Dr. Chang:  It’s sort of the typical kinds of pain that we hear back here on earth too, pain in the back, pain running down the leg, etc.

And it affects their lives just like the factory worker or the janitor.

Dr. Chang: Exactly.





Douglas Chang, MD, PhD

University of California, San Diego

(619) 543-2542