The Argentine defender left the pitch in tears on April 12 following Tottenham's 1-0 defeat to Sunderland.
Romero was forced off after colliding with goalkeeper Antonín Kinský, who had been pushed by Sunderland striker Brian Brobbey.
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He was later seen outside Fortius Clinic in London on Monday, April 13, wearing a white knee brace and visibly struggling to walk.
An eyewitness said: "He’s hobbling about the street right outside the physio.
"He didn’t seem too happy – he’s really hobbling and it’s all strapped up his leg."
The injury compounds a difficult season for Tottenham, who remain in the relegation zone after recording their 16th loss of the season in the defeat at Sunderland.