The Netherlands international was taken off five minutes before half-time at the Stadio Olimpico, sparking fears the centre-back may need to go under the knife.
However, following scans on Monday, the Serie A club's worries over De Vrij's long-term fitness were eased.
Club doctor Stefano Lovati told Lazio Style Radio: "The ligaments are healthy and therefore he will not have to undergo any surgery.
"From today he will start therapy and follow a physiotherapy program. Obviously the boy will be monitored.
"When there is a sprain, the ligaments still feel the shock but in our case we are fortunate that they are not damaged."
However, amid De Vrij's injury news, the Lazio coach also learned that a broken rib will sideline Marco Parolo for 20 days while Diego Novaretti will wear a protective hand cast to allow him to return to training later this week.
