The Liverpool centre-back played a vital part in Palace's relegation escape during his loan period in south London, although De Boer has since suggested that despite Sakho's importance last season he is unsure if the club can secure the player's services once again.
"I don't know," De Boer told reporters when questioned about Sakho. "He was a major impact last season, everybody knows what he did. He was not only good on the pitch but also in the dressing room.
"If you can get that kind of quality of player it always benefits your team."