This is something that chiropractors come across all the time. Patients present with stiffness in their neck or back that is relieved by bending their spine until a crack is heard or felt. There are rumours that this can cause arthritis, so here we're going to explain exactly what happens and whether "self-cavitation" (cracking your own spine) is good for you.
The reasons one may feel the need to "crack" a joint within their spine are many, from minor amounts of bruising to the presence of adhesions between the two surfaces of a joint. These can usually be boiled down to postural or traumatic causes, and the first thing to say about cracking your spine is that without identifying and correcting the cause of the stiffness, all you are doing is masking the problem.
What actually happens when you crack a joint requires a separate article to fully describe, but most significantly you are moving a joint.
But consider this:
Next to the stiff joint within your spine will be a normal, mobile joint. So when you bend your back or stretch your neck, which joint is the most likely to move? The mobile one.
So the effect of clicking your spine is to stretch the joint that is already mobile, making it more flexible. That joint will be able to move further, meaning there is less requirement for the adjacent stiff joint to move at all. Over time the joint that was originally stiff will begin to stiffen more and more.
For this reason, people who click their neck or back end up feeling the need to click themselves more and more often. Over many years, the repeated mobilisation of an already mobile joint will lead to accelerated wear and tear, or osteoarthritis.
This leaves us with the question, if clicking my neck isn't moving the stiff joints in my spine, why does it feel like my neck is so much freer afterwards?
The picture below demonstrates this quite nicely. It shows the nerves that carry sensation from the joints within your spine. The yellow, root like, structures are the nerves, and it is relatively easy to see that each nerve goes to more than one joint.
This allows you to confuse your brain into thinking you have moved the stiff joint in your back, leading to a temporary numbing of the stiff feeling, when really you have moved the joint next-door.
The detective skills that a chiropractor uses when performing a physical examination take a long time to learn, and it is this experience and thoroughness that allows a chiropractor to find the joints of your back and neck that really need to be mobilised, and to pick the best technique for moving them.
And, let us not forget, that while doing this our chiropractors will be searching for and correcting the underlying causes of joint stiffness.