Hello and welcome to JustAnswer,
Hello. Prior to any surgery your father needs an MRI of his lower spine to see where the disc is protruding. This will make the decision about what surgery, if any, would be best.
The best option, and it would only be an option for certain kinds of disc problems, would be a MICRODISCECTOMY. This surgery is quick and the recovery also quick.
For other problems that are more complicated involving the disc a LUMBAR FUSION AND DISCECTOMY might be needed.
There are other procedures and other methods for relieving pain surgically, but the key is to define the exact problem. That is done with an MRI. Then, and this is the MOST IMPORTANT PART, your father needs to go to the BEST orthopedic spine surgeon OR neurosurgeon available for a consultation.
If he is going to have his back operated on he needs the most experienced surgeon with the best outcomes.
I am standing by if you have any questions.
And OBTW, i have had both a fusion and a discectomy for different reasons.... the fusion recovery is a long process.