He said the surgery was successful.
"The back is fixed. The operation to repair the disc was successful and the back is just fine,'' Murphy said. "In that respect, it is no different to the same operation I had a couple of years ago.
"Obviously there is a wound there that has to heal. It is still swollen but it is coming along as expected. Like last time, there's some nerve damage which slightly affects my calf and we are getting treatment for that.
"I fully expect to be in the car in Hamilton next week and I'm looking forward to it. I am confident I will be race and I don't want to miss racing in the final time at Hamilton.''
Murphy injured the back after a heavy crash during qualifying in the first stop of the V8 Supercars championship in Adelaide.
The 28 V8 Supercars and associated equipment will be airlifted to Auckland early next week in two Boeing 747 freight aircraft, then trucked to Hamilton.
The event begins on Friday next week, with two 200km races on Saturday and Sunday.