Roma team doctor Riccardo Del Vescovo explained Karsdorp's medical uncovered the problem and the 22-year-old will go under the knife on Monday.
"We're doing this because we want to take a closer look at his lateral meniscus after his medical – which was conducted in tandem with Dr Andrea Causarano – revealed findings that called for further investigation," Del Vescovo told Roma Radio.
"It's nothing serious or alarming; the knee is completely normal in terms of the cartilage and ligaments. We were completely aware of the situation. A few days before the medical on Tuesday, a preliminary evaluation had taken place where this problem was discovered.
"The player had been complaining that the discomfort had been hampering him during the final part of the season with Feyenoord."
Roma expect Karsdorp's surgery to be a "quick, efficient" operation, with the full-back – who helped Feyenoord to win the Eredivisie title last season – anticipated to join the squad on pre-season training camps in Trentino and the United States.
"It goes without saying that for the first couple of weeks of pre-season, the player will have to stick to an individual training programme which will be adjusted according to his progress, but that’s the same for any recovery," Del Vescovo said.
"It's important to maintain the right balance between taking our time to help him recover from the operation and ensuring his recovery programme is an effective one.”