The Argentine has not played since a Jan. 24 loss at the Australian Open.
In a letter from Del Potro read on Argentine radio, he said he will have surgery Tuesday at the Mayo Clinic in Rochester, Minn. The fifth-ranked player said previous treatments had not solved the problem.
"This is not a happy time in my life," Del Potro said in the letter. "But I am used to fighting against adversity and I have all the strength to go forward."
He dismissed reports in Argentina that he is suffering from depression, calling them "malicious and false."
Del Potro's agent Ugo Colombini told Argentine media there "is no exact date" for the player's return.