Ex-Chief Craig Clarke faces uncertain future
Craig Clarke's rugby career could be cut short, after the two-time Super XV-winning Chiefs captain suffered his 10th concussion in 22 months.
The latest incident occurred when the 30-year-old was playing for Irish side Connacht last week, and he is taking an indefinite break from rugby to recover.
Former Chiefs and New Zealand Olympic team doctor Chris Milne said the long-term damage caused by concussions is up for debate.
As with other injuries, players suffering head knocks are at higher risk in the future.
"If you have an ACL injury in your 20s, you're more likely to have arthritis in your 50s. The past tells you a lot about the future," he said.
Rugby has started to wake up to the danger of concussions, and players are no longer sent back on to the field.
"At the moment, there is very little research and very little evidence saying what the long-term effects of concussion are," he said.
"New Zealand doctors have always been better dealing with concussion. We never saw any point sending the player back onto the field, that's what reserves are for.
"Certainly in Australian and American sport, you have seen a lot of cases in the past of players being sent back onto the field after suffering a concussion, and that's not good."
Dr Milne said there is also an "iceberg effect" - concussed club rugby playerswill continue playing, causing more damage, much like their professional counterparts may have done in the past.
Clarke suffered the concussions during the northern hemisphere season and in his final two seasons in Super Rugby, Connacht coach and former Blues coach Pat Lam told Irish website TheScore.
"Craig has had his tenth concussion in 22 months, so he is a big concern," Lam said.
"At this stage he is going to be unavailable indefinitely, until there is a bit more testing and so forth.
"It is obviously a big blow for us but you can just not mess around with that sort of situation.
"The players had a week off after the Saracens game but he was suffering even last week.
"Obviously we favour investigations but more importantly it is just time."
Clarke signed a three-year deal with Connacht after leaving the Chiefs.
Co-captain with Liam Messam, he was instrumental in the franchise's rise from conference wooden-spooners to dominant power during the past three years.
His plight will draw further attention to the issue of concussion and head injuries in rugby.
Lam revealed he had seen former All Black Benson Stanley suffer the same scale of injury two years ago.
Stanley played 53 matches under Lam at the Blues before moving to France to play with Clermont.
"He was considering retiring and he just had to go through the timing and he was thinking about stepping down," Lam said.
"But through timing and treatment and rest he got through and he is playing at Clermont now, so we are hopeful."
Dr Milne said it is a great shame that Clarke has been hit by concussions.
"I think he was a great player and it's a great shame that this has happened to him.
"Hopefully things come right for him. I just wish he was still playing in New Zealand."