Dan Biggar’s return to the field after a clash of heads against Leinster has been questioned by an Irish neurosurgeon.

The Wales fly-half missed a late kick in the Ospreys’ 20-18 defeat at home to Leinster on Saturday, minutes after being allowed back on following a head injury assessment (HIA).

Dublin-based brain injury specialist Dr. Phil O’Halloran took to Twitter to suggest the decision to allow Biggar to carry on showed further weaknesses in the HIA system.

He wrote: “Not the 1st time the great player has had issues!Limitations of #HIA well documented.perhaps lead to missing last kick!??”

Biggar admitted in a post-match TV interview with Sky Sports that he felt “dazed” for the last 10 minutes of the game – an admission that could now be examined further by World Rugby.

In January, the governing body voiced it’s “disappointment” with procedures followed by Northampton following a head injury suffered by Wales wing George North, playing for Saints against Leicester in December.

Northampton had argued that they had followed HIA protocols, as laid down by World Rugby.

Likewise, Ospreys coach Steve Tandy has insisted his medical team and coaching staff had acted within the guidelines over their decision to allow Biggar to play on.

Tandy said: “Dan has gone through the HIA, he’s passed all the tests and we wouldn’t be putting someone back on we didn’t feel was right and ready to partake on the field.”

The defeat was a third in succession for the Ospreys and their fourth in their last six games.

It means they will need to beat the Cardiff Blues in next Saturday’s Judgement Day clash at the Principality Stadium in order to stay in the top four play-off places of the Guinness Pro 12.

Tandy refuted suggestions that Biggar’s missed kick had cost his team the match, at a time when fellow goal-kicker Sam Davies was also on the field.

He added: “There’s definitely no finger pointing, you can go across the board and go back to the last final we won and Biggs’ kick from the sidelines won the match.

“We definitely win and lose as a team but the Blues match is now a massive game for us.

“The Blues are playing pretty well but ultimately we know we need to win that game to stay in control of our own destiny going into the last two games.

“We know Ulster have got some tough games coming up, but we need to stay in control.

“We’re still in the top four but ultimately we know we need to win that game next Saturday.”

After that match, the Ospreys face their two play-off rivals – Ulster at home on April 29 and Scarlets away on May 6.