Carl Jenkinson was spending a second year out on loan at West Ham, and seemed to be doing fairly well - getting minutes, learning, getting better, all the things you'd want from a loan stint. All that, though, has come to a screeching halt now:
Carl Jenkinson’s injury is far more serious than we thought and he is out for the rest of the season.— Jack Sullivan (@jsullivanwhu) January 26, 2016
Carl's collision with Sergio Aguero in the early part of West Ham's game against Manchester City resulted in a "knee problem", the extent of which is unknown at this time but, as Sullivan's tweet mentioned, is serious enough that he's done for the year. We await actual confirmation of what the injury is, which will probably come later this week once the swelling has gone down and the painkillers have worn off.
In the short term, of course, this doesn't mean much for Arsenal as Jenks wasn't playing a role with the club; I just hope that he heals quickly and that his development isn't set back too much.