"It was Mike's shoulder – we don't know yet what the problem is," manager Carlos Carvalhal told Swansea's website https://www.swanseacity.com.
"He cannot move his arm at the moment, but let's see if things get better."
Swansea have six league games left to play and a serious injury would rule Van der Hoorn out for the rest of the season.
The Welsh side host ninth-placed Everton in the league next Saturday.
(Reporting by Aditi Prakash in Bengaluru)
