I think Barça needs to review the quality of the conditioning and medical staff. Protecting our top players from injuries is a matter of highest priority.
I could imagine that Arthur's injury may now be partly blamed on his partying with Neymar. Don't know if this connection makes sense medically, but wrong food/drink and lack of sleep are probably not compatible with a tough playing schedule for a midfielder. Also, RM match was very intense and Arthur was fouled several times, in particular by Modric.