You are right in the information that removal of disc from the spine can be done through a very small incision called microdiscectomy and after this the patient can get up and walk within few days. But this technique can not be used to remove certain types of disc prolapse for which a bigger operation is necessary and also it depends on that some surgeons are using this technique while others still continue to use the bigger incision because all type of discs can be removed with this operation and after two months there is no difference in the final outcome of any of the two methods.