During the opening term of Saturday's clash between the Tigers and Crows at Adelaide Oval, Parnell gained possession of the ball near the boundary line before being met with a Broad tackle.
The Richmond defender wrapped up the Crow and through a further motion dragged Parnell across the boundary and into the ground, with the latter's head colliding with the surface in a worrying turn of events.
Parnell was left on the ground for some time before medical staff came to his aid, with the 21-year-old slowly getting to his feet and looking groggy as he was assisted to the interchange.
"He picked him up and spun him around," analyst Jason Dunstall said on the Fox Footy broadcast.
"That's the sort of action we're trying to prevent. That can bring head injuries into play."
'That's the sort of action we are trying to prevent'
Is Broad in trouble for this tackle on Parnell?
— Fox Footy (@FOXFOOTY) March 25, 2023
While required to undergo concussion testing, Adelaide was quick to sub Parnell out of the match, bringing tall forward and tactical sub Riley Thilthorpe into the match midway through the first stanza.
The fallout spells trouble for Broad ahead of the MRO's findings for Saturday's match, which will be released on Sunday evening.
Broad's actions are likely to gain a charge of rough conduct by the MRO, with the impact of the tackle to be a key area of concern given Parnell's worrying head knock.
The tackle came the same afternoon Port Adelaide defender Ryan Burton was pinned for a dangerous tackle on Collingwood's Jamie Elliott, with the Power backman likely to join Broad in gaining the attention of the MRO.
Likely to spend some time on the sidelines through suspension, Broad may miss his side's upcoming clash with Collingwood in Round 3. The Tigers are scheduled to face the Western Bulldogs, Sydney and Melbourne in the following rounds.