Watford captain Troy Deeney defended Arsenal from criticism after allowing David Luiz to play on with a head injury against Wolves, while brain injury association Headway has outlined why the club's actions were worrying.

Brazilian defender David Luiz was involved in a sickening collision of heads with Raul Jimenez in the fifth minute of Arsenal's 2-1 defeat on Sunday.

Jimenez, 29, required oxygen prior to being carried off the pitch on a stretcher after medical professionals tended to him for 10 minutes.

Further highlighting the force of the clash, it was confirmed by Wolves on Monday that the Mexico international suffered a fractured skull, but the club stressed the player is "comfortable" after undergoing surgery.

Protocols in the Premier League state that anyone suspected to be suffering from concussion must be immediately taken off, yet it was not until half-time that – in Mikel Arteta's words – the "really uncomfortable" David Luiz was withdrawn, though the Spaniard insisted guidelines were followed.

In the wake of the incident, Deeney attracted widespread criticism when suggesting players should be trusted to know whether they are capable of playing on or not.

Speaking on TalkSPORT, he said: "At some point there has to be an element of trust between player and doctor. You do have all the protocols in place.

"As a player you know when something's not right. Watching David Luiz for 20 minutes afterwards, he never looked shaky on his feet, his legs weren't going from underneath him.

"They followed all the protocols in terms of he's ticked every box, then afterwards you don't see anything other than blood to suggest he's in a bad way."

Headway picked up on Arteta's assertion David Luiz did not lose consciousness, adding that is only ever prominent in 10 per cent of concussion cases.

The charity is also once again demanding the implementation of a 'concussion substitute' rule akin to that used in cricket and rugby due to the known risks and potential long-term health implications associated with such an injury.

Headway deputy chief executive officer Luke Griggs said: "Only last week we strongly criticised the International Football Association Board (IFAB) for its continued procrastination in introducing concussion substitutes into the sport.

"We have repeatedly warned about the risks to players and the importance of elite-level sport setting a good example for impressionable younger players to follow.

"Too often in football, we see players returning to the pitch having undergone a concussion assessment – only to be withdrawn a few minutes later when it is clear that they are not fit to continue.

"That is the very reason why we urgently need temporary concussion substitutes in football. You simply cannot take a risk with head injuries. They are not like muscular injuries where you can put a player back on 'to see if they can run it off'. One further blow to the head when concussed could have serious consequences.

"The question that has to be asked is, had the concussion substitutes rule been in place, would Luiz have been allowed to return to the field of play? Would that extra time in the treatment room have led to a different decision being made?

"The concussion protocol clearly states that '…anyone with a suspected concussion must be immediately removed from play', while the sport continues to promote an 'if in doubt, sit it out' approach to head injuries.

"Time and time again we are seeing this rhetoric not being borne out by actions on the pitch. Something is not right. This cannot be allowed to continue. How many warnings does football need?"