Morgan joined Sheffield United from Barnsley in 2003
The Football Association has confirmed that no further action will be taken against Sheffield United's Chris Morgan for his challenge on Iain Hume.
The Barnsley striker, 25, suffered a fractured skull in the incident and left hospital last week, only to be readmitted on Tuesday as a precaution.
A Barnsley statement said they were "considering recourse outside of the normal football processes".
Morgan, 31, was booked but the FA said it cannot upgrade yellow cards to red.
A statement on Barnsley's website said the club "is extremely disappointed and concerned" by the FA decision.
"The decision by the FA to disconnect a violent act from its consequences runs contrary to the principles of civil and criminal law," continued the Barnsley statement.
"The FA's failure to act has let Iain Hume down badly and the only option now remaining is for recourse outside of the normal football processes."
Having reviewed all available evidence in this case, including submissions made by Barnsley, there is no basis on which an additional charge could be brought.
FA spokesman
An FA spokesman earlier said: "When judging whether to take disciplinary action in this case, the FA has had to consider the challenge itself and not the outcome of it.
"The FA has been given express direction from Fifa that we cannot upgrade yellow cards to red.
"On this basis, we can only bring additional charges in the most exceptional cases and only if it can be proved beyond doubt that the actions of a player were a deliberate attempt to injure an opponent.
"Having reviewed all available evidence in this case, including submissions made by Barnsley, there is no basis on which an additional charge could be brought."
Hume spent time in a high dependency unit in hospital following the clash on 8 November where he underwent surgery on his fractured skull and for internal bleeding.
He was readmitted after complaining of feeling unwell and a Tykes spokesman said: "Iain began feeling unwell at home and we hope it's a case of better safe than sorry."
On his original release from hospital, Hume had told BBC Radio Sheffield: "I'm happy that I am out of hospital and I will be back (playing football). Nothing will stop me from playing, it's my life."
A spokesman for Sheffield United told BBC Sport that they would not be making any further comment on the matter.
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