Welbeck was carried off on a stretcher on the half-hour mark of Thursday’s Europa League stalemate with Sporting Lisbon.
The England forward continues to be assessed, with the Gunners set to provide a further update on his condition in the next 72 hours.
He is expected to miss his country’s fixtures against the United States and Croatia during the upcoming international break, having been named in Gareth Southgate’s squad earlier on Thursday.
“Danny remains in hospital and will continue to be assessed,” the club said. “A further update will be issued over the next 72 hours.
” Welbeck has endured a wretched injury record during his career with knee issues costing him months on the sidelines.
His latest setback comes after he landed badly on his right ankle having jumped for a header in the 25th minute of the Group E encounter at the Emirates Stadium.
The 27-year-old received oxygen on the pitch and had his leg in a protective brace as he was taken off.