According to the article he's been carrying the injury for some time.
So who is to blame for letting him play on? It could be argued that the decision cost us 3 points against Accrington as his movement was obviously not right, and I reckon that the injury could probably be blamed for at least 2 of the Accrington goals. The first because he threw it out instead of kicking it (as apparently he had been instructed), and either the second or third - the video's not available any longer, but the shot from the left side just outside the box, when he only made the weakest effort to get near the ball.
Of course the nature of the game would have been different if those goals had not been scored, but in retrospect it was a stupid and arguably costly decision to let him play.