Williams skipped Redskins OTAs and mandatory minicamp this off-season. The seven-time Pro Bowl selection is under contract through 2020.
A source told NFL Network that the latest surgery is "not considered major" and not related to a setback.
Williams' Instagram story footage showed his view of his feet from the hospital bed, with a blanket over him and some nurses in the room. He also had the song Turn Myself In by Lil Durk playing in the background.
The song features lyrics including: "God, can you hear me?" as well as "[expletives] ain't really with me" and "main homies turned against me."
Williams entered the league as the No. 4 overall pick in the 2010 NFL Draft and has spent his entire career with the Redskins. A source told NFL Network that the 6-foot-5, 320-pound left tackle wants a new contract. He signed his current five-year, $66 million pact in 2015. That deal includes $30 million guaranteed and pays Williams a base salary of $11 million in 2019.
The star blindside blocker has missed nine games over the last two seasons due to injuries. Williams also had a tumor removed from his head this off-season. He posted a video to his Instagram in February showing himself at the hospital with bandages attached to his head.
Williams rated as the No. 21 tackle in the NFL last season, according to Pro Football Focus.
Redskins president Bruce Allen addressed the Williams situation Friday. Williams also has been linked to trade rumors.
"I know what Trent told me so I know what the truth is," Allen told NBC Sports Washington. "I'll leave my conversation with Trent between the two of us."
Redskins coach Jay Gruden told reporters Tuesday that he expects Williams to report for training camp.
"I know Trent knows how much we need him and want him back," Gruden said earlier this off-season. "That is the only thing I can do from here. As far as what happened between him and the doctors, that is between him and the doctors and hopefully we get that cleared up soon."
The Redskins wrapped up OTAs Wednesday and report to training camp in late July in Richmond, Va.