SAMAN POURAMINI RESPONDE...
Is it bad to SELF-CRUFF hands or back?
When people ask me this question I always answer that it is neither good nor bad, it really depends on how many times it is done as for many people it produces a sense of relief but for others it becomes a mania or a nervous habit.
The good news is that by self-crunching your hands you are no more likely to get osteoarthritis, according to a recent study, which states that the chance of getting osteoarthritis is the same whether you self-crunch your fingers or not.
The bad news is that if you do it too much it is associated with the The bad news is that if you do it too much it is associated with the hand inflammation
If you crack your back from time to time to produce a sense of relief, e.g. after having been in one position for a long time, nothing happens; but if you do it constantly, you are over-stretching the ligaments that stabilise the spine and cause a state of hypermobility.. 
I sincerely do not recommend self-crushing of the neck.
Especialista: SAMAN POURAMINI.