The Spaniard has been struggling with the condition for several weeks, and was off-colour in a shock straight-sets defeat to Croatian teenager Borna Coric in the Swiss Indoors Basel quarter-finals on Friday.
Nadal, who announced earlier on Friday that he will not play at next week's Paris Masters, revealed after his loss to Coric that he will go under the knife on November 3 - meaning he will be unable to compete at the Tour Finals in London, which begin six days later.
"I'm not going to play Paris and London - I'm not [fit] enough to compete," the 14-time grand-slam winner told reporters.
"I'm going to have surgery on November 3. I will have treatment on my back next week - that needs a few days."
World number three Nadal's withdrawal from the Tour Finals means that the player who finishes ninth in the Race to London standings - currently David Ferrer - will qualify for the end-of-season showpiece at the O2 Arena.