Nadal, an 11-time grand slam winner, has suffered his fair share of niggles over his career but very few long-term injuries and admitted he was unsure of how long this setback may persist.
"That is something I will know when my I feel my knee completely without pain when I start to practice," he said.
"I didn't have in the past this long period of time outside of the tennis court, outside of the competition.
"I can imagine when I come back I will need time to practice and practice more and more every day, maybe that will take one month and a half.
"The most important thing is to continue with the treatment ... when I don't feel nothing, hopefully that will happen soon, I will come back on the tennis court."