Injured Knights hooker Slade Griffin has been tasked with strengthening Newcastle's defensive deficiencies next season, but the 27-year-old will have to complete his role from the sidelines as his playing future remains in serious doubt.

Having suffered a fourth ACL injury last season, Griffin's career is hanging by a thread and The Newcastle Herald reports he is almost no chance of taking the field in 2019.

Even if his rehabilitation goes to plan, Newcastle coach Nathan Brown doesn't expect Griffin to be ready for the gruelling physical demands of the NRL.

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“He has to see his specialist and if everything is really good healing-wise from his first operation, you’d expect with his next operation, if that goes well, he may play very late in the season,” Brown said.

“But I’d suggest it wouldn’t be in the NRL. He’d be aiming to have a few games at the back end in reserve grade.

“Even that would hinge on him being right to have the second operation straight away. If it hasn’t healed enough and he has got to wait another month or two, he’ll be struggling to even get back at all next year.”

However, he still remains a key part of their plans in 2019 after the club opened the door for the luckless rake to become their wresting coach in hope of utilising his defensive expertise, potentially setting him up for life after football.

The Knights ranked as the second-worst defensive side in 2018 behind Manly, leaking an alarming 607 points.

It's why Brown has also reshaped his coaching staff, bringing in Tongan coach Kristian Woolf to oversee the club's defensive structures alongside Griffin and NSW Cup coach Rory Kostjasyn.

During his time in Melbourne, Griffin was widely recognised as the best wrestler in the club and his defensive strengths were a major reason behind Newcastle's interest.

At 27, the injury-riddled playmaker has made just 41 career starts and his stint at Newcastle was cut short at just 16 appearances.