Hi Mr.Mobin, thanks for writing to HCM.
A certain amount of stiffness
in back muscles tend to occur after an open lumbar discectomy
which will usually disappear in 2-3 months.
It looks like that you still have a Stiff back. I suggest you to undergo a good back rehabilitation
programme in the form of Physiotherapy
for back muscles so as to stretch & strengthen them.
So, approach a good physiotherapist in your locality and follow their advice.
I wish you a quick recovery.
Hope this information is helpful. Good day