Disc herniation on Earth are common.
The most common age of disc herniation presentation is thought to be between 31-40 years and is found more common in people from rural areas, moderate and heavy workers and vehicle drivers on bad roads (https://ispub.com/IJNS/3/1/5615). In a recent narrative review article in the European Spine Journal, a team of powerful researchers looked at why astronauts get disc herniations when they return to Earth. This was in response to National Aeronautics and Space Administration (NASA) showed an increased risk of intervertebral disc (IVD) herniations in US astronauts (research).
In Disc herniations in astronauts: What causes them, and what does it tell us about herniation on earth? the authors looked at the common themes seen here on Earth in the better understanding why people get disc herniations in general.
We have known for quite some time that astronauts often suffer from back pain. Why is that? Simply it is because of hyperhydration and flexion.
Over the course of the day on Earth the spine undergoes an accordion-like height change losing as much as 20 percent of fluid loss. When astronauts are in space, their discs over-inflate. And when they return to Earth and bend forward in flexion, the posterior annulus is under increased stress and is susceptible to rupture. This is in line with some research showing disc morning pressures are a risk factor of disc herniations (research).
On the other hand, when we lie down (or go to space) the discs swell up to recharge the fluid loss to prepare for more load the following day.
Teaching patients about avoiding flexion first thing in the morning when putting on socks, for example, is important in the management of back pain. ddd models help with this conversation.
Quick Clinical Tip:
Teach patients anterior and posterior structures in the spine. Discs are on the front, the facet joints are on the back. Bending forward compresses the discs. Teach posture tips to maintain neutral posture, especially first thing in the morning to help minimize the risk of disc herniation.
So what can we learn about this research?
It is important to keep the discs balanced with regard to compression and decompression. If discs are over-inflated, they are susceptible to disc herniation injury. On the other hand, if the discs are under-inflated, other problems can develop like degenerated disc disease. Most people fall into the latter category and require more off-loading.