Ellis exited Friday's game when he was upended on a hard slide by St. Louis second baseman Tyler Greene.
On Saturday, Ellis underwent a fasciotomy, which team doctors said drained blood and fluid from a contusion in his lower left leg, relieving tension and pressure in the leg. Ellis will remain hospitalized until Tuesday.
"He came in today uncomfortable, it didn't look great," Falsone said. "So we sent him over to the hospital. They did some different testing. Basically what they do is test the pressures inside the leg. He had pressure in his leg to the point where he needed a fasciotomy."
Ellis is hitting .273 this season with two homers and an on-base clip of .373. Hitting in the No. 2 spot, he was a vital part of the Dodgers' lineup, getting on base in front of the club's best hitters.
It's the latest blow to a Dodgers squad that has seen Matt Kemp, Jerry Hairston Jr., Juan Uribe and Juan Rivera hit the DL in the last two weeks.
"He's one of those guys that the more you see him, the better he is," manager Don Mattingly said of Ellis. "It just gets better and better with him. So, again, it's tough. He's a tough guy to replace."
Elian Herrera started at second in Saturday night's game, but Mattingly said his decision will be "matchup-oriented" in the future. Ivan DeJesus was called up from Triple-A Albuquerque, where he was hitting .275 this season, as Ellis was placed on the 15-day disabled list.
Mattingly listed DeJesus, Justin Sellers, Adam Kennedy and Hairston, when he returns next week, as other options.
Falsone said no future operations are likely for Ellis, and as far as she knows, there was no damage done to his left knee. Still, the club plans to run future tests on it to be certain.
She called Saturday's operation "very successful," noting that the nerves and the tissue in his lower left leg were healthy -- a result of the fasciotomy.
Ellis was shaken up on the play in the seventh inning of Friday's game, but stayed in the lineup and even batted in the bottom half before being replaced for the eighth inning.
As for Greene's slide, Mattingly said he felt there was nothing dirty about the play. On a potential double play ball, Greene slid at a bit of an angle and hit Ellis' left leg hard with his own leg. He remained in the basepath while doing so.
"We felt like it was clean," Mattingly said. "It was a good hard slide. Sometimes you just can't -- even though you know it's coming -- get out of the way."